Merge branch 'improve-frontend-maintanability-by-splitting-in-sperate-files'

* improve-frontend-maintanability-by-splitting-in-sperate-files:
  docs: update Readme
  fix: fix while deleting timeentries for whole week

README.md

@@ -140,7 +140,7 @@ http://localhost:8080
 **Standard-Anmeldedaten:**
 
 - Benutzername: `admin`
-- Passwort: `admin123`
+- Passwort: Das in `docker-compose.yml` unter `INITIAL_ADMIN_PASSWORD` festgelegte Passwort.
 
 ⚠️ **WICHTIG**: Ändern Sie das Admin-Passwort sofort nach der ersten Anmeldung!
 
@@ -179,13 +179,15 @@ export JWT_SECRET=development-secret
 
 ### Umgebungsvariablen
 
-| Variable      | Beschreibung                    | Standard            | Erforderlich |
+| Variable                 | Beschreibung                                      | Standard                                        | Erforderlich |
-| ------------- | ------------------------------- | ------------------- | ------------ |
+| ------------------------ | ------------------------------------------------- | ----------------------------------------------- | ------------ |
-| `PORT`        | HTTP-Server Port                | `8080`              | Nein         |
+| `PORT`                   | HTTP-Server Port                                  | `8080`                                          | Nein         |
-| `DB_PATH`     | Pfad zur SQLite-Datenbank       | `./timetracking.db` | Nein         |
+| `DB_PATH`                | Pfad zur SQLite-Datenbank                         | `./timetracking.db`                             | Nein         |
-| `JWT_SECRET`  | Geheimnis für JWT-Token         | -                   | **Ja**       |
+| `JWT_SECRET`             | Geheimnis für JWT-Token                           | -                                               | **Ja**       |
-| `TZ`          | Zeitzone                        | `Europe/Berlin`     | Nein         |
+| `INITIAL_ADMIN_PASSWORD` | Initiales Passwort für den Admin-Benutzer         | `changeme`                                      | **Ja**       |
-| `ENVIRONMENT` | `production` für HTTPS-Redirect | -                   | Nein         |
+| `TZ`                     | Zeitzone                                          | `Europe/Berlin`                                 | Nein         |
+| `ENVIRONMENT`            | `production` für HTTPS-Redirect und striktes CORS | `development`                                   | Nein         |
+| `CORS_ALLOWED_ORIGINS`   | Komma-getrennte Liste von erlaubten Origins       | `*` (in dev), `http://localhost:8080` (in prod) | Nein         |
 
 ### Docker-Volumes
 
@@ -203,7 +205,7 @@ Die Datenbank wird unter `/data/timetracking.db` im Container gespeichert.
 
 ### Ersteinrichtung als Administrator
 
-1. **Anmelden** mit den Standard-Credentials (admin/admin123)
+1. **Anmelden** mit den Standard-Credentials (admin/das initiale Passwort aus der Konfiguration)
 
 2. **Admin-Passwort ändern**:
    - Gehe zu "Benutzer" Tab
@@ -311,7 +313,7 @@ Benutzer-Anmeldung
 ```json
 {
   "username": "admin",
-  "password": "admin123"
+  "password": "<your-initial-admin-password>"
 }
 ```
 
@@ -768,6 +770,6 @@ Todo
 
 ---
 
-**Version**: 1.1.0  
+**Version**: 1.5.0  
 **Letztes Update**: November 2025  
 **Entwickelt für**: Schulen zur Verwaltung von Flexistunden pädagogischer Mitarbeiter

backend/database.go

@@ -580,3 +580,47 @@ func calculateHours(entry TimeEntry) float64 {
 		return calculateHoursDiff(entry.StartTime, entry.EndTime)
 	}
 }
+
+func DeleteSchoolYear(db *sql.DB, id int) error {
+	var isActive bool
+	err := db.QueryRow("SELECT is_active FROM school_years WHERE id = ?", id).Scan(&isActive)
+	if err != nil {
+		return err
+	}
+
+	if isActive {
+		return fmt.Errorf("cannot delete active school year")
+	}
+
+	result, err := db.Exec("DELETE FROM school_years WHERE id = ? AND is_active = 0", id)
+	if err != nil {
+		return err
+	}
+
+	rowsAffected, err := result.RowsAffected()
+	if err != nil {
+		return err
+	}
+
+	if rowsAffected == 0 {
+		return sql.ErrNoRows
+	}
+
+	return nil
+}
+
+func DeleteNonManualTimeEntriesByUserAndWeek(db *sql.DB, userID int, year int, week int) error {
+	dates := calculateWeekDates(year, week)
+	var dateList []string
+	for day := 0; day <= 4; day++ {
+		dateList = append(dateList, dates.Dates[fmt.Sprint(day)])
+	}
+
+	query := `DELETE FROM time_entries 
+	          WHERE user_id = ? 
+	          AND type != 'manual' 
+	          AND date IN (?, ?, ?, ?, ?)`
+
+	_, err := db.Exec(query, userID, dateList[0], dateList[1], dateList[2], dateList[3], dateList[4])
+	return err
+}

backend/errors.go

@@ -0,0 +1,205 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+type ErrorCode string
+
+const (
+	// Authentifizierung
+	ErrInvalidCredentials ErrorCode = "INVALID_CREDENTIALS"
+	ErrUnauthorized       ErrorCode = "UNAUTHORIZED"
+	ErrTokenExpired       ErrorCode = "TOKEN_EXPIRED"
+	ErrAccessDenied       ErrorCode = "ACCESS_DENIED"
+
+	// Validierung
+	ErrInvalidInput      ErrorCode = "INVALID_INPUT"
+	ErrMissingField      ErrorCode = "MISSING_FIELD"
+	ErrInvalidDateFormat ErrorCode = "INVALID_DATE_FORMAT"
+	ErrInvalidTimeFormat ErrorCode = "INVALID_TIME_FORMAT"
+
+	// Ressourcen
+	ErrNotFound       ErrorCode = "NOT_FOUND"
+	ErrAlreadyExists  ErrorCode = "ALREADY_EXISTS"
+	ErrCannotDelete   ErrorCode = "CANNOT_DELETE"
+	ErrProtectedUser  ErrorCode = "PROTECTED_USER"
+	ErrNoActiveSchool ErrorCode = "NO_ACTIVE_SCHOOL_YEAR"
+
+	// Datenbank
+	ErrDatabase    ErrorCode = "DATABASE_ERROR"
+	ErrTransaction ErrorCode = "TRANSACTION_ERROR"
+	ErrQueryFailed ErrorCode = "QUERY_FAILED"
+
+	// Server
+	ErrInternal       ErrorCode = "INTERNAL_ERROR"
+	ErrServiceUnavail ErrorCode = "SERVICE_UNAVAILABLE"
+)
+
+type AppError struct {
+	Code       ErrorCode `json:"code"`
+	Message    string    `json:"message"`
+	UserMsg    string    `json:"user_message"`
+	HTTPStatus int       `json:"-"`
+	Internal   error     `json:"-"`
+}
+
+func (e *AppError) Error() string {
+	if e.Internal != nil {
+		return fmt.Sprintf("[%s] %s: %v", e.Code, e.Message, e.Internal)
+	}
+	return fmt.Sprintf("[%s] %s", e.Code, e.Message)
+}
+
+func NewAppError(code ErrorCode, message, userMsg string, httpStatus int, internal error) *AppError {
+	return &AppError{
+		Code:       code,
+		Message:    message,
+		UserMsg:    userMsg,
+		HTTPStatus: httpStatus,
+		Internal:   internal,
+	}
+}
+
+func ErrInvalidCredentialsMsg() *AppError {
+	return NewAppError(
+		ErrInvalidCredentials,
+		"Invalid username or password",
+		"Benutzername oder Passwort ungültig",
+		http.StatusUnauthorized,
+		nil,
+	)
+}
+
+func ErrUnauthorizedMsg() *AppError {
+	return NewAppError(
+		ErrUnauthorized,
+		"Unauthorized access",
+		"Keine Berechtigung für diese Aktion",
+		http.StatusUnauthorized,
+		nil,
+	)
+}
+
+func ErrTokenExpiredMsg() *AppError {
+	return NewAppError(
+		ErrTokenExpired,
+		"Token has expired",
+		"Ihre Sitzung ist abgelaufen. Bitte melden Sie sich erneut an",
+		http.StatusUnauthorized,
+		nil,
+	)
+}
+
+func ErrAccessDeniedMsg() *AppError {
+	return NewAppError(
+		ErrAccessDenied,
+		"Access denied - admin privileges required",
+		"Zugriff verweigert. Administrator-Rechte erforderlich",
+		http.StatusForbidden,
+		nil,
+	)
+}
+
+func ErrInvalidInputMsg(field string) *AppError {
+	return NewAppError(
+		ErrInvalidInput,
+		fmt.Sprintf("Invalid input for field: %s", field),
+		fmt.Sprintf("Ungültige Eingabe im Feld: %s", field),
+		http.StatusBadRequest,
+		nil,
+	)
+}
+
+func ErrMissingFieldMsg(field string) *AppError {
+	return NewAppError(
+		ErrMissingField,
+		fmt.Sprintf("Required field missing: %s", field),
+		fmt.Sprintf("Pflichtfeld fehlt: %s", field),
+		http.StatusBadRequest,
+		nil,
+	)
+}
+
+func ErrNotFoundMsg(resource string) *AppError {
+	return NewAppError(
+		ErrNotFound,
+		fmt.Sprintf("%s not found", resource),
+		fmt.Sprintf("%s nicht gefunden", resource),
+		http.StatusNotFound,
+		nil,
+	)
+}
+
+func ErrAlreadyExistsMsg(resource string) *AppError {
+	return NewAppError(
+		ErrAlreadyExists,
+		fmt.Sprintf("%s already exists", resource),
+		fmt.Sprintf("%s existiert bereits", resource),
+		http.StatusConflict,
+		nil,
+	)
+}
+
+func ErrCannotDeleteMsg(resource, reason string) *AppError {
+	return NewAppError(
+		ErrCannotDelete,
+		fmt.Sprintf("Cannot delete %s: %s", resource, reason),
+		fmt.Sprintf("%s kann nicht gelöscht werden: %s", resource, reason),
+		http.StatusBadRequest,
+		nil,
+	)
+}
+
+func ErrProtectedUserMsg() *AppError {
+	return NewAppError(
+		ErrProtectedUser,
+		"Cannot modify protected admin user",
+		"Der Admin-Benutzer ist geschützt und kann nicht geändert werden",
+		http.StatusForbidden,
+		nil,
+	)
+}
+
+func ErrNoActiveSchoolYearMsg() *AppError {
+	return NewAppError(
+		ErrNoActiveSchool,
+		"No active school year configured",
+		"Kein aktives Schuljahr konfiguriert. Bitte aktivieren Sie ein Schuljahr",
+		http.StatusNotFound,
+		nil,
+	)
+}
+
+func ErrDatabaseMsg(internal error) *AppError {
+	return NewAppError(
+		ErrDatabase,
+		"Database operation failed",
+		"Ein Datenbankfehler ist aufgetreten. Bitte versuchen Sie es erneut",
+		http.StatusInternalServerError,
+		internal,
+	)
+}
+
+func ErrInternalMsg(internal error) *AppError {
+	return NewAppError(
+		ErrInternal,
+		"Internal server error",
+		"Ein interner Fehler ist aufgetreten. Bitte versuchen Sie es später erneut",
+		http.StatusInternalServerError,
+		internal,
+	)
+}
+
+type ErrorResponse struct {
+	Code    ErrorCode `json:"code"`
+	Message string    `json:"message"`
+}
+
+func (e *AppError) ToResponse() ErrorResponse {
+	return ErrorResponse{
+		Code:    e.Code,
+		Message: e.UserMsg,
+	}
+}

backend/go.mod

@@ -12,7 +12,9 @@ require (
 
 require (
 	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/golang-jwt/jwt/v5 v5.3.0 // indirect
 	github.com/google/uuid v1.6.0 // indirect
+	github.com/labstack/echo-jwt/v4 v4.3.1 // indirect
 	github.com/labstack/gommon v0.4.2 // indirect
 	github.com/mattn/go-colorable v0.1.14 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect

backend/go.sum

@@ -4,6 +4,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
+github.com/golang-jwt/jwt/v5 v5.3.0 h1:pv4AsKCKKZuqlgs5sUmn4x8UlGa0kEVt/puTpKx9vvo=
+github.com/golang-jwt/jwt/v5 v5.3.0/go.mod h1:fxCRLWMO43lRc8nhHWY6LGqRcf+1gQWArsqaEUEa5bE=
 github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e h1:ijClszYn+mADRFY17kjQEVQ1XRhq2/JR1M3sGqeJoxs=
 github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e/go.mod h1:boTsfXsheKC2y+lKOCMpSfarhxDeIzfZG1jqGcPl3cA=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
@@ -11,6 +13,8 @@ github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+
 github.com/jung-kurt/gofpdf v1.0.0/go.mod h1:7Id9E/uU8ce6rXgefFLlgrJj/GYY22cpxn+r32jIOes=
 github.com/jung-kurt/gofpdf v1.16.2 h1:jgbatWHfRlPYiK85qgevsZTHviWXKwB1TTiKdz5PtRc=
 github.com/jung-kurt/gofpdf v1.16.2/go.mod h1:1hl7y57EsiPAkLbOwzpzqgx1A30nQCk/YmFV8S2vmK0=
+github.com/labstack/echo-jwt/v4 v4.3.1 h1:d8+/qf8nx7RxeL46LtoIwHJsH2PNN8xXCQ/jDianycE=
+github.com/labstack/echo-jwt/v4 v4.3.1/go.mod h1:yJi83kN8S/5vePVPd+7ID75P4PqPNVRs2HVeuvYJH00=
 github.com/labstack/echo/v4 v4.13.4 h1:oTZZW+T3s9gAu5L8vmzihV7/lkXGZuITzTQkTEhcXEA=
 github.com/labstack/echo/v4 v4.13.4/go.mod h1:g63b33BZ5vZzcIUF8AtRH40DrTlXnx4UMC8rBdndmjQ=
 github.com/labstack/gommon v0.4.2 h1:F8qTUNXgG1+6WQmqoUWnz8WiEU60mXVVw0P4ht1WRA0=

backend/handlers.go

@@ -3,10 +3,13 @@ package main
 import (
 	"database/sql"
 	"fmt"
+	"log"
 	"net/http"
 	"strconv"
+	"strings"
 	"time"
 
+	"github.com/golang-jwt/jwt/v5"
 	"github.com/labstack/echo/v4"
 	"golang.org/x/crypto/bcrypt"
 )
@@ -15,24 +18,60 @@ type App struct {
 	DB *sql.DB
 }
 
+func HandleError(c echo.Context, err *AppError) error {
+	log.Printf("[%s] %s", err.Code, err.Error())
+
+	return c.JSON(err.HTTPStatus, err.ToResponse())
+}
+
+func getClaims(c echo.Context) (*Claims, error) {
+	user, ok := c.Get("user").(*jwt.Token)
+	if !ok {
+		return nil, fmt.Errorf("JWT token missing or invalid")
+	}
+
+	claims, ok := user.Claims.(*Claims)
+	if !ok {
+		return nil, fmt.Errorf("failed to parse JWT claims")
+	}
+
+	return claims, nil
+}
+
+func isDuplicateError(err error) bool {
+	return err != nil && (err.Error() == "UNIQUE constraint failed" ||
+		strings.Contains(err.Error(), "UNIQUE") ||
+		strings.Contains(err.Error(), "duplicate"))
+}
+
 func (app *App) LoginHandler(c echo.Context) error {
 	var req LoginRequest
 	if err := c.Bind(&req); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "invalid request")
+		return HandleError(c, ErrInvalidInputMsg("Login-Daten"))
+	}
+
+	if req.Username == "" {
+		return HandleError(c, ErrMissingFieldMsg("Benutzername"))
+	}
+	if req.Password == "" {
+		return HandleError(c, ErrMissingFieldMsg("Passwort"))
 	}
 
 	user, err := GetUserByUsername(app.DB, req.Username)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusUnauthorized, "invalid credentials")
+		if err == sql.ErrNoRows {
+			return HandleError(c, ErrInvalidCredentialsMsg())
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	if err := bcrypt.CompareHashAndPassword([]byte(user.Password), []byte(req.Password)); err != nil {
-		return echo.NewHTTPError(http.StatusUnauthorized, "invalid credentials")
+		return HandleError(c, ErrInvalidCredentialsMsg())
 	}
 
 	token, err := createToken(user.ID, user.Username, user.IsAdmin)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, "error creating token")
+		return HandleError(c, ErrInternalMsg(err))
 	}
 
 	response := LoginResponse{
@@ -47,7 +86,7 @@ func (app *App) LoginHandler(c echo.Context) error {
 func (app *App) GetSchedulesHandler(c echo.Context) error {
 	schedules, err := GetAllSchedules(app.DB)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 	return c.JSON(http.StatusOK, schedules)
 }
@@ -55,24 +94,40 @@ func (app *App) GetSchedulesHandler(c echo.Context) error {
 func (app *App) CreateScheduleHandler(c echo.Context) error {
 	var schedule Schedule
 	if err := c.Bind(&schedule); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "invalid request")
+		return HandleError(c, ErrInvalidInputMsg("Stundenplan-Daten"))
+	}
+
+	if schedule.StartTime == "" {
+		return HandleError(c, ErrMissingFieldMsg("Startzeit"))
+	}
+	if schedule.EndTime == "" {
+		return HandleError(c, ErrMissingFieldMsg("Endzeit"))
+	}
+	if schedule.Title == "" {
+		return HandleError(c, ErrMissingFieldMsg("Titel"))
 	}
 
 	if err := CreateSchedule(app.DB, &schedule); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		if isDuplicateError(err) {
+			return HandleError(c, ErrAlreadyExistsMsg("Stundenplan-Eintrag"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
-	return c.JSON(http.StatusCreated, map[string]string{"message": "schedule created"})
+	return c.JSON(http.StatusCreated, map[string]string{"message": "Stundenplan erstellt"})
 }
 
 func (app *App) DeleteScheduleHandler(c echo.Context) error {
 	id, err := strconv.Atoi(c.QueryParam("id"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "invalid id")
+		return HandleError(c, ErrInvalidInputMsg("Stundenplan-ID"))
 	}
 
 	if err := DeleteSchedule(app.DB, id); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		if err == sql.ErrNoRows {
+			return HandleError(c, ErrNotFoundMsg("Stundenplan"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.NoContent(http.StatusNoContent)
@@ -81,7 +136,7 @@ func (app *App) DeleteScheduleHandler(c echo.Context) error {
 func (app *App) GetYearlyHoursSummaryHandler(c echo.Context) error {
 	hours, err := GetYearlyHoursSummary(app.DB)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 	if hours == nil {
 		hours = []WeeklyHours{}
@@ -90,11 +145,6 @@ func (app *App) GetYearlyHoursSummaryHandler(c echo.Context) error {
 }
 
 func (app *App) AdminCreateTimeEntryHandler(c echo.Context) error {
-	isAdmin, _ := c.Get("is_admin").(bool)
-	if !isAdmin {
-		return echo.NewHTTPError(http.StatusForbidden, "Only admins can create entries for others")
-	}
-
 	var req struct {
 		UserID int     `json:"user_id"`
 		Date   string  `json:"date"`
@@ -103,7 +153,17 @@ func (app *App) AdminCreateTimeEntryHandler(c echo.Context) error {
 	}
 
 	if err := c.Bind(&req); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "invalid request")
+		return HandleError(c, ErrInvalidInputMsg("Zeiteintrag-Daten"))
+	}
+
+	if req.UserID == 0 {
+		return HandleError(c, ErrMissingFieldMsg("Benutzer"))
+	}
+	if req.Date == "" {
+		return HandleError(c, ErrMissingFieldMsg("Datum"))
+	}
+	if req.Hours == 0 {
+		return HandleError(c, ErrMissingFieldMsg("Stunden"))
 	}
 
 	entry := TimeEntry{
@@ -115,16 +175,16 @@ func (app *App) AdminCreateTimeEntryHandler(c echo.Context) error {
 	}
 
 	if err := CreateManualTimeEntry(app.DB, &entry, req.Hours); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
-	return c.NoContent(http.StatusCreated)
+	return c.NoContent(http.StatusNoContent)
 }
 
 func (app *App) GetUsersHandler(c echo.Context) error {
 	users, err := GetAllUsers(app.DB)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 	if users == nil {
 		users = []User{}
@@ -135,39 +195,62 @@ func (app *App) GetUsersHandler(c echo.Context) error {
 func (app *App) DeleteUserHandler(c echo.Context) error {
 	id, err := strconv.Atoi(c.QueryParam("id"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "invalid id")
+		return HandleError(c, ErrInvalidInputMsg("Benutzer-ID"))
+	}
+
+	if id == 1 {
+		return HandleError(c, ErrProtectedUserMsg())
 	}
 
 	if err := DeleteUser(app.DB, id); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		if err == sql.ErrNoRows {
+			return HandleError(c, ErrNotFoundMsg("Benutzer"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.NoContent(http.StatusNoContent)
 }
 
 func (app *App) CreateTimeEntryHandler(c echo.Context) error {
-	userID := c.Get("user_id").(int)
+	claims, err := getClaims(c)
+	if err != nil {
+		return HandleError(c, ErrUnauthorizedMsg())
+	}
 
 	var entry TimeEntry
 	if err := c.Bind(&entry); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "invalid request")
+		return HandleError(c, ErrInvalidInputMsg("Zeiteintrag-Daten"))
 	}
 
-	entry.UserID = userID
+	if entry.Date == "" {
+		return HandleError(c, ErrMissingFieldMsg("Datum"))
+	}
+	if entry.StartTime == "" {
+		return HandleError(c, ErrMissingFieldMsg("Startzeit"))
+	}
+	if entry.EndTime == "" {
+		return HandleError(c, ErrMissingFieldMsg("Endzeit"))
+	}
+
+	entry.UserID = claims.UserID
 
 	if err := CreateTimeEntry(app.DB, &entry); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
-	return c.JSON(http.StatusCreated, map[string]string{"message": "time entry created"})
+	return c.JSON(http.StatusCreated, map[string]string{"message": "Zeiteintrag erstellt"})
 }
 
 func (app *App) GetMyTimeEntriesHandler(c echo.Context) error {
-	userID := c.Get("user_id").(int)
+	claims, err := getClaims(c)
-
-	entries, err := GetTimeEntriesByUser(app.DB, userID)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrUnauthorizedMsg())
+	}
+
+	entries, err := GetTimeEntriesByUser(app.DB, claims.UserID)
+	if err != nil {
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 	if entries == nil {
 		entries = []TimeEntry{}
@@ -179,12 +262,16 @@ func (app *App) GetMyTimeEntriesHandler(c echo.Context) error {
 func (app *App) GetWeekDates(c echo.Context) error {
 	year, err := strconv.Atoi(c.QueryParam("year"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid year")
+		return HandleError(c, ErrInvalidInputMsg("Jahr"))
 	}
 
 	week, err := strconv.Atoi(c.QueryParam("week"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid week")
+		return HandleError(c, ErrInvalidInputMsg("Woche"))
+	}
+
+	if week < 1 || week > 53 {
+		return HandleError(c, ErrInvalidInputMsg("Woche (muss zwischen 1 und 53 liegen)"))
 	}
 
 	dates := calculateWeekDates(year, week)
@@ -192,21 +279,24 @@ func (app *App) GetWeekDates(c echo.Context) error {
 }
 
 func (app *App) CheckWeekHasEntries(c echo.Context) error {
-	userID := c.Get("user_id").(int)
+	claims, err := getClaims(c)
+	if err != nil {
+		return HandleError(c, ErrUnauthorizedMsg())
+	}
 
 	year, err := strconv.Atoi(c.QueryParam("year"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid year")
+		return HandleError(c, ErrInvalidInputMsg("Jahr"))
 	}
 
 	week, err := strconv.Atoi(c.QueryParam("week"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid week")
+		return HandleError(c, ErrInvalidInputMsg("Woche"))
 	}
 
-	hasEntries, err := CheckUserHasEntriesForWeek(app.DB, userID, year, week)
+	hasEntries, err := CheckUserHasEntriesForWeek(app.DB, claims.UserID, year, week)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.JSON(http.StatusOK, map[string]bool{"has_entries": hasEntries})
@@ -215,7 +305,7 @@ func (app *App) CheckWeekHasEntries(c echo.Context) error {
 func (app *App) GetAllTimeEntriesHandler(c echo.Context) error {
 	entries, err := GetAllTimeEntries(app.DB)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 	if entries == nil {
 		entries = []TimeEntry{}
@@ -226,7 +316,7 @@ func (app *App) GetAllTimeEntriesHandler(c echo.Context) error {
 func (app *App) GetWeeklyHoursHandler(c echo.Context) error {
 	hours, err := GetWeeklyHours(app.DB)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 	if hours == nil {
 		hours = []WeeklyHours{}
@@ -235,20 +325,23 @@ func (app *App) GetWeeklyHoursHandler(c echo.Context) error {
 }
 
 func (app *App) DeleteWeekEntries(c echo.Context) error {
-	userID := c.Get("user_id").(int)
+	claims, err := getClaims(c)
+	if err != nil {
+		return HandleError(c, ErrUnauthorizedMsg())
+	}
 
 	year, err := strconv.Atoi(c.QueryParam("year"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid year")
+		return HandleError(c, ErrInvalidInputMsg("Jahr"))
 	}
 
 	week, err := strconv.Atoi(c.QueryParam("week"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid week")
+		return HandleError(c, ErrInvalidInputMsg("Woche"))
 	}
 
-	if err := DeleteTimeEntriesByUserAndWeek(app.DB, userID, year, week); err != nil {
+	if err := DeleteNonManualTimeEntriesByUserAndWeek(app.DB, claims.UserID, year, week); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.NoContent(http.StatusNoContent)
@@ -310,52 +403,83 @@ type BatchTimeEntryRequest struct {
 }
 
 func (app *App) CreateBatchTimeEntriesHandler(c echo.Context) error {
-	userID := c.Get("user_id").(int)
+	claims, err := getClaims(c)
+	if err != nil {
+		return HandleError(c, ErrUnauthorizedMsg())
+	}
 
 	var req BatchTimeEntryRequest
 	if err := c.Bind(&req); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "invalid request")
+		return HandleError(c, ErrInvalidInputMsg("Zeiteintrag-Daten"))
+	}
+
+	if len(req.Entries) == 0 {
+		return HandleError(c, ErrMissingFieldMsg("Zeiteinträge"))
+	}
+
+	if len(req.Entries) > 0 {
+		firstDate := req.Entries[0].Date
+		t, err := time.Parse("2006-01-02", firstDate)
+		if err != nil {
+			return HandleError(c, ErrInvalidInputMsg("Datum-Format"))
+		}
+		year, week := t.ISOWeek()
+
+		if err := DeleteNonManualTimeEntriesByUserAndWeek(app.DB, claims.UserID, year, week); err != nil {
+			return HandleError(c, ErrDatabaseMsg(err))
+		}
 	}
 
 	tx, err := app.DB.Begin()
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, "transaction error")
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 	defer tx.Rollback()
 
 	stmt, err := tx.Prepare("INSERT INTO time_entries (user_id, schedule_id, date, type, start_time, end_time) VALUES (?, ?, ?, ?, ?, ?)")
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, "prepare error")
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 	defer stmt.Close()
 
 	for _, entry := range req.Entries {
-		_, err := stmt.Exec(userID, entry.ScheduleID, entry.Date, entry.Type, entry.StartTime, entry.EndTime)
+		_, err := stmt.Exec(claims.UserID, entry.ScheduleID, entry.Date, entry.Type, entry.StartTime, entry.EndTime)
 		if err != nil {
-			return echo.NewHTTPError(http.StatusInternalServerError, "insert error")
+			return HandleError(c, ErrDatabaseMsg(err))
 		}
 	}
 
 	if err := tx.Commit(); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, "commit error")
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
-	return c.JSON(http.StatusCreated, map[string]string{"message": "entries created"})
+	return c.JSON(http.StatusCreated, map[string]string{"message": "Zeiteinträge erstellt"})
 }
 
 func (app *App) UpdateUserHandler(c echo.Context) error {
 	userID, err := strconv.Atoi(c.Param("id"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid user ID")
+		return HandleError(c, ErrInvalidInputMsg("Benutzer-ID"))
+	}
+
+	if userID == 1 {
+		return HandleError(c, ErrProtectedUserMsg())
 	}
 
 	var req UpdateUserRequest
 	if err := c.Bind(&req); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, err.Error())
+		return HandleError(c, ErrInvalidInputMsg("Benutzerdaten"))
+	}
+
+	if req.YearlyHours <= 0 {
+		return HandleError(c, ErrInvalidInputMsg("Jahresarbeitsstunden (muss positiv sein)"))
 	}
 
 	if err := UpdateUser(app.DB, userID, req.YearlyHours); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		if err == sql.ErrNoRows {
+			return HandleError(c, ErrNotFoundMsg("Benutzer"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.NoContent(http.StatusOK)
@@ -364,21 +488,28 @@ func (app *App) UpdateUserHandler(c echo.Context) error {
 func (app *App) ResetPasswordHandler(c echo.Context) error {
 	userID, err := strconv.Atoi(c.Param("id"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid user ID")
+		return HandleError(c, ErrInvalidInputMsg("Benutzer-ID"))
 	}
 
 	var req ResetPasswordRequest
 	if err := c.Bind(&req); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, err.Error())
+		return HandleError(c, ErrInvalidInputMsg("Passwort-Daten"))
+	}
+
+	if len(req.NewPassword) < 6 {
+		return HandleError(c, ErrInvalidInputMsg("Passwort (mindestens 6 Zeichen)"))
 	}
 
 	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(req.NewPassword), bcrypt.DefaultCost)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, "Error hashing password")
+		return HandleError(c, ErrInternalMsg(err))
 	}
 
 	if err := ResetUserPassword(app.DB, userID, string(hashedPassword)); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		if err == sql.ErrNoRows {
+			return HandleError(c, ErrNotFoundMsg("Benutzer"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.NoContent(http.StatusOK)
@@ -387,16 +518,29 @@ func (app *App) ResetPasswordHandler(c echo.Context) error {
 func (app *App) UpdateTimeEntryHandler(c echo.Context) error {
 	entryID, err := strconv.Atoi(c.Param("id"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid entry ID")
+		return HandleError(c, ErrInvalidInputMsg("Zeiteintrag-ID"))
 	}
 
 	var req UpdateTimeEntryRequest
 	if err := c.Bind(&req); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, err.Error())
+		return HandleError(c, ErrInvalidInputMsg("Zeiteintrag-Daten"))
+	}
+
+	if req.Date == "" {
+		return HandleError(c, ErrMissingFieldMsg("Datum"))
+	}
+	if req.StartTime == "" {
+		return HandleError(c, ErrMissingFieldMsg("Startzeit"))
+	}
+	if req.EndTime == "" {
+		return HandleError(c, ErrMissingFieldMsg("Endzeit"))
 	}
 
 	if err := UpdateTimeEntry(app.DB, entryID, req.Date, req.StartTime, req.EndTime, req.Type); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		if err == sql.ErrNoRows {
+			return HandleError(c, ErrNotFoundMsg("Zeiteintrag"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.NoContent(http.StatusOK)
@@ -405,22 +549,31 @@ func (app *App) UpdateTimeEntryHandler(c echo.Context) error {
 func (app *App) DeleteTimeEntryHandler(c echo.Context) error {
 	entryID, err := strconv.Atoi(c.Param("id"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid entry ID")
+		return HandleError(c, ErrInvalidInputMsg("Zeiteintrag-ID"))
 	}
 
 	if err := DeleteTimeEntry(app.DB, entryID); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		if err == sql.ErrNoRows {
+			return HandleError(c, ErrNotFoundMsg("Zeiteintrag"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.NoContent(http.StatusNoContent)
 }
 
 func (app *App) GetMyInfoHandler(c echo.Context) error {
-	userID := c.Get("user_id").(int)
+	claims, err := getClaims(c)
-
-	user, err := GetUserByID(app.DB, userID)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrUnauthorizedMsg())
+	}
+
+	user, err := GetUserByID(app.DB, claims.UserID)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return HandleError(c, ErrNotFoundMsg("Benutzer"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.JSON(http.StatusOK, user)
@@ -429,12 +582,22 @@ func (app *App) GetMyInfoHandler(c echo.Context) error {
 func (app *App) CreateUserHandler(c echo.Context) error {
 	var req CreateUserRequest
 	if err := c.Bind(&req); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, err.Error())
+		return HandleError(c, ErrInvalidInputMsg("Benutzerdaten"))
+	}
+
+	if req.Username == "" {
+		return HandleError(c, ErrMissingFieldMsg("Benutzername"))
+	}
+	if req.Password == "" {
+		return HandleError(c, ErrMissingFieldMsg("Passwort"))
+	}
+	if len(req.Password) < 6 {
+		return HandleError(c, ErrInvalidInputMsg("Passwort (mindestens 6 Zeichen)"))
 	}
 
 	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, "Error hashing password")
+		return HandleError(c, ErrInternalMsg(err))
 	}
 
 	if req.YearlyHours == 0 {
@@ -442,7 +605,10 @@ func (app *App) CreateUserHandler(c echo.Context) error {
 	}
 
 	if err := CreateUser(app.DB, req.Username, string(hashedPassword), req.IsAdmin, req.YearlyHours); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		if isDuplicateError(err) {
+			return HandleError(c, ErrAlreadyExistsMsg("Benutzername"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.NoContent(http.StatusCreated)
@@ -451,7 +617,7 @@ func (app *App) CreateUserHandler(c echo.Context) error {
 func (app *App) GetSchoolYearsHandler(c echo.Context) error {
 	years, err := GetAllSchoolYears(app.DB)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 	if years == nil {
 		years = []SchoolYear{}
@@ -462,11 +628,24 @@ func (app *App) GetSchoolYearsHandler(c echo.Context) error {
 func (app *App) CreateSchoolYearHandler(c echo.Context) error {
 	var req CreateSchoolYearRequest
 	if err := c.Bind(&req); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, err.Error())
+		return HandleError(c, ErrInvalidInputMsg("Schuljahr-Daten"))
+	}
+
+	if req.Name == "" {
+		return HandleError(c, ErrMissingFieldMsg("Name"))
+	}
+	if req.StartDate == "" {
+		return HandleError(c, ErrMissingFieldMsg("Startdatum"))
+	}
+	if req.EndDate == "" {
+		return HandleError(c, ErrMissingFieldMsg("Enddatum"))
 	}
 
 	if err := CreateSchoolYear(app.DB, req.Name, req.StartDate, req.EndDate); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		if isDuplicateError(err) {
+			return HandleError(c, ErrAlreadyExistsMsg("Schuljahr"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.NoContent(http.StatusCreated)
@@ -475,11 +654,14 @@ func (app *App) CreateSchoolYearHandler(c echo.Context) error {
 func (app *App) SetActiveSchoolYearHandler(c echo.Context) error {
 	id, err := strconv.Atoi(c.Param("id"))
 	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid ID")
+		return HandleError(c, ErrInvalidInputMsg("Schuljahr-ID"))
 	}
 
 	if err := SetActiveSchoolYear(app.DB, id); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		if err == sql.ErrNoRows {
+			return HandleError(c, ErrNotFoundMsg("Schuljahr"))
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	return c.NoContent(http.StatusNoContent)
@@ -488,7 +670,7 @@ func (app *App) SetActiveSchoolYearHandler(c echo.Context) error {
 func (app *App) GetActiveSchoolYearHandler(c echo.Context) error {
 	year, err := GetActiveSchoolYear(app.DB)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 	if year == nil {
 		return c.JSON(http.StatusOK, map[string]any{"active": false})
@@ -497,24 +679,22 @@ func (app *App) GetActiveSchoolYearHandler(c echo.Context) error {
 }
 
 func (app *App) GenerateYearlySummaryPDFHandler(c echo.Context) error {
-	isAdmin, _ := c.Get("is_admin").(bool)
-	if !isAdmin {
-		return echo.NewHTTPError(http.StatusForbidden, "Only admins can generate PDFs")
-	}
-
 	schoolYear, err := GetActiveSchoolYear(app.DB)
-	if err != nil || schoolYear == nil {
+	if err != nil {
-		return echo.NewHTTPError(http.StatusNotFound, "No active school year found")
+		return HandleError(c, ErrDatabaseMsg(err))
+	}
+	if schoolYear == nil {
+		return HandleError(c, ErrNoActiveSchoolYearMsg())
 	}
 
 	summary, err := GetYearlyHoursSummary(app.DB)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+		return HandleError(c, ErrDatabaseMsg(err))
 	}
 
 	pdfBytes, err := GenerateYearlySummaryPDF(schoolYear, summary)
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, "Failed to generate PDF: "+err.Error())
+		return HandleError(c, ErrInternalMsg(err))
 	}
 
 	filename := fmt.Sprintf("Jahresuebersicht_%s.pdf", schoolYear.Name)
@@ -523,3 +703,26 @@ func (app *App) GenerateYearlySummaryPDFHandler(c echo.Context) error {
 
 	return c.Blob(http.StatusOK, "application/pdf", pdfBytes)
 }
+
+func (app *App) DeleteSchoolYearHandler(c echo.Context) error {
+	id, err := strconv.Atoi(c.Param("id"))
+	if err != nil {
+		return HandleError(c, ErrInvalidInputMsg("Schuljahr-ID"))
+	}
+
+	if err := DeleteSchoolYear(app.DB, id); err != nil {
+		if err == sql.ErrNoRows {
+			return HandleError(c, ErrNotFoundMsg("Schuljahr"))
+		}
+		if err.Error() == "cannot delete active school year" {
+			return HandleError(c, &AppError{
+				Code:       "CANNOT_DELETE_ACTIVE_SCHOOL_YEAR",
+				Message:    "Aktives Schuljahr kann nicht gelöscht werden",
+				HTTPStatus: http.StatusBadRequest,
+			})
+		}
+		return HandleError(c, ErrDatabaseMsg(err))
+	}
+
+	return c.NoContent(http.StatusNoContent)
+}

backend/main.go

@@ -4,6 +4,7 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"strings"
 
 	"github.com/labstack/echo/v4"
 	"github.com/labstack/echo/v4/middleware"
@@ -24,8 +25,20 @@ func main() {
 
 	e.Use(middleware.Logger())
 	e.Use(middleware.Recover())
+
+	// CORS Configuration
+	allowOrigins := []string{"*"} // Default for development
+	if os.Getenv("ENVIRONMENT") == "production" {
+		origins := os.Getenv("CORS_ALLOWED_ORIGINS")
+		if origins != "" {
+			allowOrigins = strings.Split(origins, ",")
+		} else {
+			log.Println("Warning: ENVIRONMENT is 'production' but CORS_ALLOWED_ORIGINS is not set. Allowing all origins.")
+		}
+	}
+
 	e.Use(middleware.CORSWithConfig(middleware.CORSConfig{
-		AllowOrigins: []string{"*"},
+		AllowOrigins: allowOrigins,
 		AllowMethods: []string{http.MethodGet, http.MethodPost, http.MethodPut, http.MethodDelete},
 		AllowHeaders: []string{echo.HeaderOrigin, echo.HeaderContentType, echo.HeaderAccept, echo.HeaderAuthorization},
 	}))
@@ -67,6 +80,7 @@ func main() {
 		admin.POST("/time-entry", app.AdminCreateTimeEntryHandler)
 		admin.GET("/school-years", app.GetSchoolYearsHandler)
 		admin.POST("/school-years", app.CreateSchoolYearHandler)
+		admin.DELETE("/school-years/:id", app.DeleteSchoolYearHandler)
 		admin.PUT("/school-years/:id/activate", app.SetActiveSchoolYearHandler)
 		admin.GET("/yearly-summary/pdf", app.GenerateYearlySummaryPDFHandler)
 	}

backend/middleware.go

@@ -1,17 +1,13 @@
 package main
 
 import (
-	"crypto/hmac"
-	"crypto/sha256"
-	"encoding/base64"
-	"encoding/json"
-	"fmt"
 	"net/http"
 	"os"
-	"strings"
 	"sync"
 	"time"
 
+	"github.com/golang-jwt/jwt/v5"
+	echojwt "github.com/labstack/echo-jwt/v4"
 	"github.com/labstack/echo/v4"
 	"github.com/labstack/echo/v4/middleware"
 	"golang.org/x/time/rate"
@@ -28,104 +24,43 @@ func init() {
 }
 
 func createToken(userID int, username string, isAdmin bool) (string, error) {
-	claims := Claims{
+	claims := &Claims{
 		UserID:   userID,
 		Username: username,
 		IsAdmin:  isAdmin,
+		RegisteredClaims: jwt.RegisteredClaims{
+			ExpiresAt: jwt.NewNumericDate(time.Now().Add(2 * time.Hour)),
+		},
 	}
 
-	header := base64.RawURLEncoding.EncodeToString([]byte(`{"alg":"HS256","typ":"JWT"}`))
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
-
+	return token.SignedString(jwtSecret)
-	claimsWithExp := map[string]any{
-		"user_id":  claims.UserID,
-		"username": claims.Username,
-		"is_admin": claims.IsAdmin,
-		"exp":      time.Now().Add(2 * time.Hour).Unix(),
-	}
-
-	payload, _ := json.Marshal(claimsWithExp)
-	payloadEncoded := base64.RawURLEncoding.EncodeToString(payload)
-
-	message := header + "." + payloadEncoded
-
-	h := hmac.New(sha256.New, jwtSecret)
-	h.Write([]byte(message))
-	signature := base64.RawURLEncoding.EncodeToString(h.Sum(nil))
-
-	return message + "." + signature, nil
-}
-
-func verifyToken(tokenString string) (*Claims, error) {
-	parts := strings.Split(tokenString, ".")
-	if len(parts) != 3 {
-		return nil, fmt.Errorf("invalid token format")
-	}
-
-	message := parts[0] + "." + parts[1]
-	h := hmac.New(sha256.New, jwtSecret)
-	h.Write([]byte(message))
-	expectedSignature := base64.RawURLEncoding.EncodeToString(h.Sum(nil))
-
-	if parts[2] != expectedSignature {
-		return nil, fmt.Errorf("invalid signature")
-	}
-
-	payload, err := base64.RawURLEncoding.DecodeString(parts[1])
-	if err != nil {
-		return nil, err
-	}
-
-	var claimsMap map[string]any
-	if err := json.Unmarshal(payload, &claimsMap); err != nil {
-		return nil, err
-	}
-
-	if exp, ok := claimsMap["exp"].(float64); ok {
-		if time.Now().Unix() > int64(exp) {
-			return nil, fmt.Errorf("token expired")
-		}
-	}
-
-	claims := &Claims{
-		UserID:   int(claimsMap["user_id"].(float64)),
-		Username: claimsMap["username"].(string),
-		IsAdmin:  claimsMap["is_admin"].(bool),
-	}
-
-	return claims, nil
 }
 
 func JWTMiddleware() echo.MiddlewareFunc {
-	return func(next echo.HandlerFunc) echo.HandlerFunc {
+	return echojwt.WithConfig(echojwt.Config{
-		return func(c echo.Context) error {
+		NewClaimsFunc: func(c echo.Context) jwt.Claims {
-			authHeader := c.Request().Header.Get("Authorization")
+			return new(Claims)
-			if authHeader == "" {
+		},
-				return echo.NewHTTPError(http.StatusUnauthorized, "Unauthorized")
+		SigningKey: jwtSecret,
-			}
+	})
-
-			tokenString := strings.TrimPrefix(authHeader, "Bearer ")
-			claims, err := verifyToken(tokenString)
-			if err != nil {
-				return echo.NewHTTPError(http.StatusUnauthorized, "Unauthorized")
-			}
-
-			c.Set("user_id", claims.UserID)
-			c.Set("username", claims.Username)
-			c.Set("is_admin", claims.IsAdmin)
-
-			c.Logger().Infof("Authenticated user: ID=%d, Username=%s", claims.UserID, claims.Username)
-
-			return next(c)
-		}
-	}
 }
 
 func AdminMiddleware() echo.MiddlewareFunc {
 	return func(next echo.HandlerFunc) echo.HandlerFunc {
 		return func(c echo.Context) error {
-			isAdmin, ok := c.Get("is_admin").(bool)
+			user, ok := c.Get("user").(*jwt.Token)
-			if !ok || !isAdmin {
+			if !ok {
-				return echo.NewHTTPError(http.StatusForbidden, "Access denied")
+				return echo.NewHTTPError(http.StatusUnauthorized, "JWT token missing or invalid")
+			}
+
+			claims, ok := user.Claims.(*Claims)
+			if !ok {
+				return echo.NewHTTPError(http.StatusUnauthorized, "Failed to parse JWT claims")
+			}
+
+			if !claims.IsAdmin {
+				return echo.NewHTTPError(http.StatusForbidden, "Access denied: admin rights required")
 			}
 			return next(c)
 		}

backend/models.go

@@ -1,6 +1,9 @@
 package main
 
-import "time"
+import (
+	"github.com/golang-jwt/jwt/v5"
+	"time"
+)
 
 type TimeEntry struct {
 	ID         int       `json:"id"`
@@ -96,4 +99,5 @@ type Claims struct {
 	UserID   int    `json:"user_id"`
 	Username string `json:"username"`
 	IsAdmin  bool   `json:"is_admin"`
+	jwt.RegisteredClaims
 }

backend/static/index.html

@@ -1,149 +1,338 @@
-<!DOCTYPE html>
+<!doctype html>
 <html lang="de">
+
 <head>
-    <meta charset="UTF-8">
+    <meta charset="UTF-8" />
-    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <meta http-equiv="X-UA-Compatible" content="ie=edge">
+    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
     <title>Zeiterfassung</title>
-    
+
-    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bulma@0.9.4/css/bulma.min.css">
+    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bulma@0.9.4/css/bulma.min.css" />
-    
+
-    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css">
+    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css" />
-    
+
     <style>
+        /* Toast-Container */
+        .toast-container {
+            position: fixed;
+            top: 20px;
+            right: 20px;
+            z-index: 9999;
+            display: flex;
+            flex-direction: column;
+            gap: 12px;
+            max-width: 400px;
+            pointer-events: none;
+        }
+
+        /* Basis-Toast */
+        .toast {
+            display: flex;
+            align-items: center;
+            justify-content: space-between;
+            padding: 16px 20px;
+            border-radius: 8px;
+            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+            backdrop-filter: blur(10px);
+            pointer-events: all;
+            min-width: 320px;
+            transition: all 0.3s ease;
+            border-left: 4px solid;
+        }
+
+        .toast:hover {
+            transform: translateX(-5px);
+            box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
+        }
+
+        /* Toast-Content */
+        .toast-content {
+            display: flex;
+            align-items: center;
+            gap: 12px;
+            flex: 1;
+        }
+
+        .toast-icon {
+            font-size: 1.25rem;
+            display: flex;
+            align-items: center;
+        }
+
+        .toast-message {
+            font-size: 0.95rem;
+            line-height: 1.4;
+            color: #2c3e50;
+            font-weight: 500;
+        }
+
+        /* Close-Button */
+        .toast-close {
+            background: transparent;
+            border: none;
+            cursor: pointer;
+            padding: 4px;
+            margin-left: 12px;
+            color: rgba(0, 0, 0, 0.4);
+            transition: color 0.2s ease;
+            font-size: 1rem;
+        }
+
+        .toast-close:hover {
+            color: rgba(0, 0, 0, 0.7);
+        }
+
+        /* Toast-Typen */
+        .toast-error {
+            background: linear-gradient(135deg, #fff5f5 0%, #ffe5e5 100%);
+            border-left-color: #e53e3e;
+        }
+
+        .toast-error .toast-icon {
+            color: #e53e3e;
+        }
+
+        .toast-success {
+            background: linear-gradient(135deg, #f0fff4 0%, #e6ffed 100%);
+            border-left-color: #38a169;
+        }
+
+        .toast-success .toast-icon {
+            color: #38a169;
+        }
+
+        .toast-info {
+            background: linear-gradient(135deg, #ebf8ff 0%, #e0f3ff 100%);
+            border-left-color: #3182ce;
+        }
+
+        .toast-info .toast-icon {
+            color: #3182ce;
+        }
+
+        .toast-warning {
+            background: linear-gradient(135deg, #fffaf0 0%, #fff5e6 100%);
+            border-left-color: #dd6b20;
+        }
+
+        .toast-warning .toast-icon {
+            color: #dd6b20;
+        }
+
+        /* Animationen */
+        @keyframes slideIn {
+            from {
+                transform: translateX(400px);
+                opacity: 0;
+            }
+
+            to {
+                transform: translateX(0);
+                opacity: 1;
+            }
+        }
+
+        @keyframes slideOut {
+            from {
+                transform: translateX(0);
+                opacity: 1;
+            }
+
+            to {
+                transform: translateX(400px);
+                opacity: 0;
+            }
+        }
+
+        .toast.dismissing {
+            animation: slideOut 0.3s ease-in forwards;
+        }
+
+        /* Mobile Anpassungen */
+        @media screen and (max-width: 768px) {
+            .toast-container {
+                top: 10px;
+                right: 10px;
+                left: 10px;
+                max-width: none;
+            }
+
+            .toast {
+                min-width: auto;
+                width: 100%;
+            }
+
+            .toast-message {
+                font-size: 0.9rem;
+            }
+        }
+
+        /* Dark Mode Support (optional) */
+        @media (prefers-color-scheme: dark) {
+            .toast {
+                box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
+            }
+
+            .toast-message {
+                color: #1a202c;
+            }
+
+            .toast-close {
+                color: rgba(0, 0, 0, 0.5);
+            }
+
+            .toast-close:hover {
+                color: rgba(0, 0, 0, 0.8);
+            }
+        }
+
         body {
             min-height: 100vh;
         }
-        
+
         .table-container {
             overflow-x: auto;
         }
-        
+
         @media screen and (max-width: 768px) {
             .level {
                 flex-direction: column;
             }
-            
+
-            .level-left, .level-right {
+            .level-left,
+            .level-right {
                 width: 100%;
             }
-            
+
             .level-item {
                 justify-content: center;
                 margin-bottom: 0.5rem;
             }
-            
+
             .buttons {
                 flex-wrap: wrap;
             }
-            
+
             .button {
                 margin-bottom: 0.5rem;
             }
         }
-        
+
         .fa-spinner {
             animation: fa-spin 1s infinite linear;
         }
-        
+
         @keyframes fa-spin {
-            0% { transform: rotate(0deg); }
+            0% {
-            100% { transform: rotate(360deg); }
+                transform: rotate(0deg);
+            }
+
+            100% {
+                transform: rotate(360deg);
+            }
         }
     </style>
 </head>
+
 <body>
     <div id="elm"></div>
-    
+
     <script src="/elm.js"></script>
     <script>
         function getStoredData() {
             try {
-                const data = localStorage.getItem('timetracking');
+                const data = localStorage.getItem("timetracking");
                 if (data) {
                     return JSON.parse(data);
                 }
             } catch (e) {
-                console.error('Failed to parse stored data:', e);
+                console.error("Failed to parse stored data:", e);
             }
-            return { token: null, isAdmin: false };
+            return {token: null, isAdmin: false};
         }
-        
+
         function saveData(token, isAdmin) {
             try {
-                localStorage.setItem('timetracking', JSON.stringify({
+                localStorage.setItem(
-                    token: token,
+                    "timetracking",
-                    isAdmin: isAdmin
+                    JSON.stringify({
-                }));
+                        token: token,
+                        isAdmin: isAdmin,
+                    }),
+                );
             } catch (e) {
-                console.error('Failed to save data:', e);
+                console.error("Failed to save data:", e);
             }
         }
-        
+
         function clearData() {
             try {
-                localStorage.removeItem('timetracking');
+                localStorage.removeItem("timetracking");
             } catch (e) {
-                console.error('Failed to clear data:', e);
+                console.error("Failed to clear data:", e);
             }
         }
-        
+
         const storedData = getStoredData();
         const app = Elm.Main.init({
-            node: document.getElementById('elm'),
+            node: document.getElementById("elm"),
             flags: {
                 token: storedData.token,
-                isAdmin: storedData.isAdmin
+                isAdmin: storedData.isAdmin,
-            }
+            },
         });
-        
+
-        app.ports.saveToken.subscribe(function(data) {
+        app.ports.saveToken.subscribe(function (data) {
             saveData(data.token, data.isAdmin);
         });
-        
+
-        app.ports.removeToken.subscribe(function() {
+        app.ports.removeToken.subscribe(function () {
             clearData();
         });
-        
+
-        app.ports.confirmDelete.subscribe(function(message) {
+        app.ports.confirmDelete.subscribe(function (message) {
             const confirmed = confirm(message);
             app.ports.confirmDeleteResponse.send(confirmed);
         });
-        
+
-        document.addEventListener('DOMContentLoaded', () => {
+        document.addEventListener("DOMContentLoaded", () => {
             function setupBurgerMenu() {
-                const burgers = document.querySelectorAll('.navbar-burger');
+                const burgers = document.querySelectorAll(".navbar-burger");
-                
+
-                burgers.forEach(burger => {
+                burgers.forEach((burger) => {
-                    burger.addEventListener('click', () => {
+                    burger.addEventListener("click", () => {
                         const target = burger.dataset.target;
                         const menu = document.getElementById(target);
-                        
+
                         if (menu) {
-                            burger.classList.toggle('is-active');
+                            burger.classList.toggle("is-active");
-                            menu.classList.toggle('is-active');
+                            menu.classList.toggle("is-active");
                         }
                     });
                 });
             }
-            
+
             setupBurgerMenu();
-            
+
             const observer = new MutationObserver((mutations) => {
                 setupBurgerMenu();
             });
-            
+
-            observer.observe(document.getElementById('elm'), {
+            observer.observe(document.getElementById("elm"), {
                 childList: true,
-                subtree: true
+                subtree: true,
             });
         });
-        
+
-        if ('serviceWorker' in navigator && window.location.protocol === 'https:') {
+        if (
-            navigator.serviceWorker.register('/sw.js').catch(() => {
+            "serviceWorker" in navigator &&
-                console.log('Service Worker registration failed');
+            window.location.protocol === "https:"
+        ) {
+            navigator.serviceWorker.register("/sw.js").catch(() => {
+                console.log("Service Worker registration failed");
             });
         }
     </script>
 </body>
+
 </html>

frontend/public/index.html

@@ -1,164 +1,338 @@
-<!DOCTYPE html>
+<!doctype html>
 <html lang="de">
+
 <head>
-    <meta charset="UTF-8">
+    <meta charset="UTF-8" />
-    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <meta http-equiv="X-UA-Compatible" content="ie=edge">
+    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
     <title>Zeiterfassung</title>
-    
+
-    <!-- Bulma CSS -->
+    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bulma@0.9.4/css/bulma.min.css" />
-    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bulma@0.9.4/css/bulma.min.css">
+
-    
+    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css" />
-    <!-- Font Awesome -->
+
-    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css">
-    
     <style>
-        /* Custom Styles */
+        /* Toast-Container */
+        .toast-container {
+            position: fixed;
+            top: 20px;
+            right: 20px;
+            z-index: 9999;
+            display: flex;
+            flex-direction: column;
+            gap: 12px;
+            max-width: 400px;
+            pointer-events: none;
+        }
+
+        /* Basis-Toast */
+        .toast {
+            display: flex;
+            align-items: center;
+            justify-content: space-between;
+            padding: 16px 20px;
+            border-radius: 8px;
+            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+            backdrop-filter: blur(10px);
+            pointer-events: all;
+            min-width: 320px;
+            transition: all 0.3s ease;
+            border-left: 4px solid;
+        }
+
+        .toast:hover {
+            transform: translateX(-5px);
+            box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
+        }
+
+        /* Toast-Content */
+        .toast-content {
+            display: flex;
+            align-items: center;
+            gap: 12px;
+            flex: 1;
+        }
+
+        .toast-icon {
+            font-size: 1.25rem;
+            display: flex;
+            align-items: center;
+        }
+
+        .toast-message {
+            font-size: 0.95rem;
+            line-height: 1.4;
+            color: #2c3e50;
+            font-weight: 500;
+        }
+
+        /* Close-Button */
+        .toast-close {
+            background: transparent;
+            border: none;
+            cursor: pointer;
+            padding: 4px;
+            margin-left: 12px;
+            color: rgba(0, 0, 0, 0.4);
+            transition: color 0.2s ease;
+            font-size: 1rem;
+        }
+
+        .toast-close:hover {
+            color: rgba(0, 0, 0, 0.7);
+        }
+
+        /* Toast-Typen */
+        .toast-error {
+            background: linear-gradient(135deg, #fff5f5 0%, #ffe5e5 100%);
+            border-left-color: #e53e3e;
+        }
+
+        .toast-error .toast-icon {
+            color: #e53e3e;
+        }
+
+        .toast-success {
+            background: linear-gradient(135deg, #f0fff4 0%, #e6ffed 100%);
+            border-left-color: #38a169;
+        }
+
+        .toast-success .toast-icon {
+            color: #38a169;
+        }
+
+        .toast-info {
+            background: linear-gradient(135deg, #ebf8ff 0%, #e0f3ff 100%);
+            border-left-color: #3182ce;
+        }
+
+        .toast-info .toast-icon {
+            color: #3182ce;
+        }
+
+        .toast-warning {
+            background: linear-gradient(135deg, #fffaf0 0%, #fff5e6 100%);
+            border-left-color: #dd6b20;
+        }
+
+        .toast-warning .toast-icon {
+            color: #dd6b20;
+        }
+
+        /* Animationen */
+        @keyframes slideIn {
+            from {
+                transform: translateX(400px);
+                opacity: 0;
+            }
+
+            to {
+                transform: translateX(0);
+                opacity: 1;
+            }
+        }
+
+        @keyframes slideOut {
+            from {
+                transform: translateX(0);
+                opacity: 1;
+            }
+
+            to {
+                transform: translateX(400px);
+                opacity: 0;
+            }
+        }
+
+        .toast.dismissing {
+            animation: slideOut 0.3s ease-in forwards;
+        }
+
+        /* Mobile Anpassungen */
+        @media screen and (max-width: 768px) {
+            .toast-container {
+                top: 10px;
+                right: 10px;
+                left: 10px;
+                max-width: none;
+            }
+
+            .toast {
+                min-width: auto;
+                width: 100%;
+            }
+
+            .toast-message {
+                font-size: 0.9rem;
+            }
+        }
+
+        /* Dark Mode Support (optional) */
+        @media (prefers-color-scheme: dark) {
+            .toast {
+                box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
+            }
+
+            .toast-message {
+                color: #1a202c;
+            }
+
+            .toast-close {
+                color: rgba(0, 0, 0, 0.5);
+            }
+
+            .toast-close:hover {
+                color: rgba(0, 0, 0, 0.8);
+            }
+        }
+
         body {
             min-height: 100vh;
         }
-        
+
         .table-container {
             overflow-x: auto;
         }
-        
+
-        /* Responsive Verbesserungen */
         @media screen and (max-width: 768px) {
             .level {
                 flex-direction: column;
             }
-            
+
-            .level-left, .level-right {
+            .level-left,
+            .level-right {
                 width: 100%;
             }
-            
+
             .level-item {
                 justify-content: center;
                 margin-bottom: 0.5rem;
             }
-            
+
             .buttons {
                 flex-wrap: wrap;
             }
-            
+
             .button {
                 margin-bottom: 0.5rem;
             }
         }
-        
+
-        /* Loading Spinner */
         .fa-spinner {
             animation: fa-spin 1s infinite linear;
         }
-        
+
         @keyframes fa-spin {
-            0% { transform: rotate(0deg); }
+            0% {
-            100% { transform: rotate(360deg); }
+                transform: rotate(0deg);
+            }
+
+            100% {
+                transform: rotate(360deg);
+            }
         }
     </style>
 </head>
+
 <body>
     <div id="elm"></div>
-    
+
     <script src="/elm.js"></script>
     <script>
-        // LocalStorage Helper
         function getStoredData() {
             try {
-                const data = localStorage.getItem('timetracking');
+                const data = localStorage.getItem("timetracking");
                 if (data) {
                     return JSON.parse(data);
                 }
             } catch (e) {
-                console.error('Failed to parse stored data:', e);
+                console.error("Failed to parse stored data:", e);
             }
-            return { token: null, isAdmin: false };
+            return {token: null, isAdmin: false};
         }
-        
+
         function saveData(token, isAdmin) {
             try {
-                localStorage.setItem('timetracking', JSON.stringify({
+                localStorage.setItem(
-                    token: token,
+                    "timetracking",
-                    isAdmin: isAdmin
+                    JSON.stringify({
-                }));
+                        token: token,
+                        isAdmin: isAdmin,
+                    }),
+                );
             } catch (e) {
-                console.error('Failed to save data:', e);
+                console.error("Failed to save data:", e);
             }
         }
-        
+
         function clearData() {
             try {
-                localStorage.removeItem('timetracking');
+                localStorage.removeItem("timetracking");
             } catch (e) {
-                console.error('Failed to clear data:', e);
+                console.error("Failed to clear data:", e);
             }
         }
-        
+
-        // Initialisiere Elm App mit gespeicherten Daten
         const storedData = getStoredData();
         const app = Elm.Main.init({
-            node: document.getElementById('elm'),
+            node: document.getElementById("elm"),
             flags: {
                 token: storedData.token,
-                isAdmin: storedData.isAdmin
+                isAdmin: storedData.isAdmin,
-            }
+            },
         });
-        
+
-        // Port: Token speichern
+        app.ports.saveToken.subscribe(function (data) {
-        app.ports.saveToken.subscribe(function(data) {
             saveData(data.token, data.isAdmin);
         });
-        
+
-        // Port: Token entfernen
+        app.ports.removeToken.subscribe(function () {
-        app.ports.removeToken.subscribe(function() {
             clearData();
         });
-        
+
-        // Port: Lösch-Bestätigung
+        app.ports.confirmDelete.subscribe(function (message) {
-        app.ports.confirmDelete.subscribe(function(message) {
             const confirmed = confirm(message);
             app.ports.confirmDeleteResponse.send(confirmed);
         });
-        
+
-        // BUGFIX: Responsive Navbar Toggle
+        document.addEventListener("DOMContentLoaded", () => {
-        document.addEventListener('DOMContentLoaded', () => {
-            // Funktion für Burger-Menu
             function setupBurgerMenu() {
-                const burgers = document.querySelectorAll('.navbar-burger');
+                const burgers = document.querySelectorAll(".navbar-burger");
-                
+
-                burgers.forEach(burger => {
+                burgers.forEach((burger) => {
-                    burger.addEventListener('click', () => {
+                    burger.addEventListener("click", () => {
                         const target = burger.dataset.target;
                         const menu = document.getElementById(target);
-                        
+
                         if (menu) {
-                            burger.classList.toggle('is-active');
+                            burger.classList.toggle("is-active");
-                            menu.classList.toggle('is-active');
+                            menu.classList.toggle("is-active");
                         }
                     });
                 });
             }
-            
+
-            // Initial setup
             setupBurgerMenu();
-            
+
-            // Observer für dynamische Änderungen (wenn Elm DOM updated)
             const observer = new MutationObserver((mutations) => {
                 setupBurgerMenu();
             });
-            
+
-            observer.observe(document.getElementById('elm'), {
+            observer.observe(document.getElementById("elm"), {
                 childList: true,
-                subtree: true
+                subtree: true,
             });
         });
-        
+
-        // Service Worker für Offline-Fähigkeit (optional)
+        if (
-        if ('serviceWorker' in navigator && window.location.protocol === 'https:') {
+            "serviceWorker" in navigator &&
-            navigator.serviceWorker.register('/sw.js').catch(() => {
+            window.location.protocol === "https:"
-                console.log('Service Worker registration failed');
+        ) {
+            navigator.serviceWorker.register("/sw.js").catch(() => {
+                console.log("Service Worker registration failed");
             });
         }
     </script>
 </body>
+
 </html>

frontend/src/Api/Auth.elm

@@ -0,0 +1,21 @@
+module Api.Auth exposing (loginRequest)
+
+import Api.Decoders exposing (loginDecoder)
+import Http
+import Json.Encode as Encode
+import Types.Api exposing (LoginResult)
+import Types.Msg exposing (Msg(..))
+
+
+loginRequest : String -> String -> Cmd Msg
+loginRequest username password =
+    Http.post
+        { url = "/api/login"
+        , body =
+            Http.jsonBody <|
+                Encode.object
+                    [ ( "username", Encode.string username )
+                    , ( "password", Encode.string password )
+                    ]
+        , expect = Http.expectJson LoginResponse loginDecoder
+        }

frontend/src/Api/Decoders.elm

@@ -0,0 +1,109 @@
+module Api.Decoders exposing
+    ( apiErrorDecoder
+    , loginDecoder
+    , scheduleDecoder
+    , schoolYearDecoder
+    , timeEntryDecoder
+    , userDecoder
+    , weekDatesDecoder
+    , weeklyHoursDecoder
+    , yearlyHoursSummaryDecoder
+    )
+
+import Dict
+import Json.Decode as Decode exposing (Decoder, bool, field, float, int, list, string)
+import Types.Api exposing (ApiError, LoginResult)
+import Types.Model exposing (..)
+
+
+loginDecoder : Decoder LoginResult
+loginDecoder =
+    Decode.map3 LoginResult
+        (field "token" string)
+        (field "username" string)
+        (field "is_admin" bool)
+
+
+scheduleDecoder : Decoder Schedule
+scheduleDecoder =
+    Decode.map6 Schedule
+        (field "id" int)
+        (field "day_of_week" int)
+        (field "start_time" string)
+        (field "end_time" string)
+        (field "type" string)
+        (field "title" string)
+
+
+timeEntryDecoder : Decoder TimeEntry
+timeEntryDecoder =
+    Decode.map8 TimeEntry
+        (field "id" int)
+        (field "user_id" int)
+        (field "schedule_id" int)
+        (field "date" string)
+        (field "type" string)
+        (field "username" string)
+        (field "start_time" string)
+        (field "end_time" string)
+
+
+userDecoder : Decoder User
+userDecoder =
+    Decode.map4 User
+        (field "id" int)
+        (field "username" string)
+        (field "is_admin" bool)
+        (field "yearly_hours" float)
+
+
+weekDatesDecoder : Decoder WeekDates
+weekDatesDecoder =
+    Decode.map4 WeekDates
+        (field "year" int)
+        (field "week" int)
+        (field "dates" (Decode.dict string) |> Decode.map Dict.toList)
+        (field "range" string)
+
+
+weeklyHoursDecoder : Decoder WeeklyHours
+weeklyHoursDecoder =
+    Decode.map7 WeeklyHours
+        (field "user_id" int)
+        (field "username" string)
+        (field "year" int)
+        (field "week" int)
+        (field "total_hours" float)
+        (field "expected_hours" float)
+        (field "remaining_hours" float)
+
+
+yearlyHoursSummaryDecoder : Decoder YearlyHoursSummary
+yearlyHoursSummaryDecoder =
+    Decode.succeed YearlyHoursSummary
+        |> Decode.andThen (\f -> Decode.map f (field "user_id" int))
+        |> Decode.andThen (\f -> Decode.map f (field "username" string))
+        |> Decode.andThen (\f -> Decode.map f (field "year" int))
+        |> Decode.andThen (\f -> Decode.map f (field "week" int))
+        |> Decode.andThen (\f -> Decode.map f (field "total_hours" float))
+        |> Decode.andThen (\f -> Decode.map f (field "yearly_target" float))
+        |> Decode.andThen (\f -> Decode.map f (field "yearly_actual" float))
+        |> Decode.andThen (\f -> Decode.map f (field "weekly_target" float))
+        |> Decode.andThen (\f -> Decode.map f (field "remaining_yearly" float))
+
+
+schoolYearDecoder : Decoder SchoolYear
+schoolYearDecoder =
+    Decode.map5 SchoolYear
+        (field "id" int)
+        (field "name" string)
+        (field "start_date" string)
+        (field "end_date" string)
+        (field "is_active" bool)
+
+
+apiErrorDecoder : Decoder ApiError
+apiErrorDecoder =
+    Decode.map2 ApiError
+        (field "code" string)
+        (field "message" string)

frontend/src/Api/Schedule.elm

@@ -0,0 +1,120 @@
+module Api.Schedule exposing
+    ( createSchedule
+    , deleteSchedule
+    , fetchSchedules
+    , saveTimeEntriesForWeek
+    )
+
+import Api.Decoders exposing (scheduleDecoder)
+import Http
+import Json.Decode
+import Json.Encode as Encode
+import Types.Model exposing (NewSchedule, Schedule, SelectedEntry, WeekDates)
+import Types.Msg exposing (Msg(..))
+
+
+fetchSchedules : Maybe String -> Cmd Msg
+fetchSchedules maybeToken =
+    case maybeToken of
+        Just token ->
+            Http.request
+                { method = "GET"
+                , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+                , url = "/api/schedules"
+                , body = Http.emptyBody
+                , expect = Http.expectJson SchedulesReceived (Json.Decode.list scheduleDecoder)
+                , timeout = Nothing
+                , tracker = Nothing
+                }
+
+        Nothing ->
+            Cmd.none
+
+
+createSchedule : String -> NewSchedule -> Cmd Msg
+createSchedule token schedule =
+    case String.toInt schedule.dayOfWeek of
+        Just day ->
+            Http.request
+                { method = "POST"
+                , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+                , url = "/api/admin/schedules"
+                , body =
+                    Http.jsonBody <|
+                        Encode.object
+                            [ ( "day_of_week", Encode.int day )
+                            , ( "start_time", Encode.string schedule.startTime )
+                            , ( "end_time", Encode.string schedule.endTime )
+                            , ( "type", Encode.string schedule.scheduleType )
+                            , ( "title", Encode.string schedule.title )
+                            ]
+                , expect = Http.expectWhatever ScheduleCreated
+                , timeout = Nothing
+                , tracker = Nothing
+                }
+
+        Nothing ->
+            Cmd.none
+
+
+deleteSchedule : String -> Int -> Cmd Msg
+deleteSchedule token scheduleId =
+    Http.request
+        { method = "DELETE"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/schedules/delete?id=" ++ String.fromInt scheduleId
+        , body = Http.emptyBody
+        , expect = Http.expectWhatever ScheduleDeleted
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+saveTimeEntriesForWeek : String -> List SelectedEntry -> Int -> Int -> List Schedule -> Maybe WeekDates -> Cmd Msg
+saveTimeEntriesForWeek token selectedEntries year week schedules maybeWeekDates =
+    case maybeWeekDates of
+        Nothing ->
+            Cmd.none
+
+        Just weekDates ->
+            let
+                getScheduleById id =
+                    List.filter (\s -> s.id == id) schedules |> List.head
+
+                getDateForDay dayOfWeek =
+                    weekDates.dates
+                        |> List.filter (\( day, _ ) -> day == String.fromInt dayOfWeek)
+                        |> List.head
+                        |> Maybe.map Tuple.second
+
+                createEntryData entry =
+                    case ( getScheduleById entry.scheduleId, getDateForDay entry.dayOfWeek ) of
+                        ( Just schedule, Just dateStr ) ->
+                            Just <|
+                                Encode.object
+                                    [ ( "schedule_id", Encode.int entry.scheduleId )
+                                    , ( "date", Encode.string dateStr )
+                                    , ( "type", Encode.string schedule.scheduleType )
+                                    , ( "start_time", Encode.string schedule.startTime )
+                                    , ( "end_time", Encode.string schedule.endTime )
+                                    ]
+
+                        _ ->
+                            Nothing
+
+                entriesData =
+                    List.filterMap createEntryData selectedEntries
+            in
+            if List.isEmpty entriesData then
+                Cmd.none
+
+            else
+                Http.request
+                    { method = "POST"
+                    , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+                    , url = "/api/time-entries/batch"
+                    , body = Http.jsonBody <| Encode.object [ ( "entries", Encode.list identity entriesData ) ]
+                    , expect = Http.expectWhatever TimeEntriesSaved
+                    , timeout = Nothing
+                    , tracker = Nothing
+                    }

frontend/src/Api/SchoolYear.elm

@@ -0,0 +1,85 @@
+module Api.SchoolYear exposing
+    ( activateSchoolYear
+    , createSchoolYear
+    , deleteSchoolYear
+    , fetchActiveSchoolYear
+    , fetchSchoolYears
+    )
+
+import Api.Decoders exposing (schoolYearDecoder)
+import Http
+import Json.Decode as Decode
+import Json.Encode as Encode
+import Types.Model exposing (NewSchoolYear)
+import Types.Msg exposing (Msg(..))
+
+
+fetchSchoolYears : String -> Cmd Msg
+fetchSchoolYears token =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/school-years"
+        , body = Http.emptyBody
+        , expect = Http.expectJson SchoolYearsReceived (Decode.list schoolYearDecoder)
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+fetchActiveSchoolYear : String -> Cmd Msg
+fetchActiveSchoolYear token =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/school-year/active"
+        , body = Http.emptyBody
+        , expect = Http.expectJson ActiveSchoolYearReceived schoolYearDecoder
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+createSchoolYear : String -> NewSchoolYear -> Cmd Msg
+createSchoolYear token schoolYear =
+    Http.request
+        { method = "POST"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/school-years"
+        , body =
+            Http.jsonBody <|
+                Encode.object
+                    [ ( "name", Encode.string schoolYear.name )
+                    , ( "start_date", Encode.string schoolYear.startDate )
+                    , ( "end_date", Encode.string schoolYear.endDate )
+                    ]
+        , expect = Http.expectWhatever SchoolYearCreated
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+activateSchoolYear : String -> Int -> Cmd Msg
+activateSchoolYear token id =
+    Http.request
+        { method = "PUT"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/school-years/" ++ String.fromInt id ++ "/activate"
+        , body = Http.emptyBody
+        , expect = Http.expectWhatever SchoolYearActivated
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+deleteSchoolYear : String -> Int -> Cmd Msg
+deleteSchoolYear token id =
+    Http.request
+        { method = "DELETE"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/school-years/" ++ String.fromInt id
+        , body = Http.emptyBody
+        , expect = Http.expectWhatever SchoolYearDeleted
+        , timeout = Nothing
+        , tracker = Nothing
+        }

frontend/src/Api/TimeEntry.elm

@@ -0,0 +1,201 @@
+module Api.TimeEntry exposing
+    ( checkWeekHasEntries
+    , createAdminTimeEntry
+    , deleteTimeEntry
+    , deleteWeekEntries
+    , downloadYearlySummaryPDF
+    , fetchAllTimeEntries
+    , fetchMyTimeEntries
+    , fetchWeekDates
+    , fetchWeeklyHours
+    , fetchYearlyHoursSummary
+    , updateTimeEntry
+    )
+
+import Api.Decoders exposing (timeEntryDecoder, weekDatesDecoder, yearlyHoursSummaryDecoder)
+import Bytes exposing (Bytes)
+import Http
+import Json.Decode as Decode exposing (bool, field)
+import Json.Encode as Encode
+import Types.Model exposing (AdminManualEntry, EditingTimeEntry)
+import Types.Msg exposing (Msg(..))
+
+
+fetchMyTimeEntries : String -> Cmd Msg
+fetchMyTimeEntries token =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/my-time-entries"
+        , body = Http.emptyBody
+        , expect = Http.expectJson MyTimeEntriesReceived (Decode.list timeEntryDecoder)
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+fetchAllTimeEntries : String -> Cmd Msg
+fetchAllTimeEntries token =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/time-entries"
+        , body = Http.emptyBody
+        , expect = Http.expectJson AllTimeEntriesReceived (Decode.list timeEntryDecoder)
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+fetchWeekDates : String -> Int -> Int -> Cmd Msg
+fetchWeekDates token year week =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/week-dates?year=" ++ String.fromInt year ++ "&week=" ++ String.fromInt week
+        , body = Http.emptyBody
+        , expect = Http.expectJson WeekDatesReceived weekDatesDecoder
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+checkWeekHasEntries : String -> Int -> Int -> Cmd Msg
+checkWeekHasEntries token year week =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/week-has-entries?year=" ++ String.fromInt year ++ "&week=" ++ String.fromInt week
+        , body = Http.emptyBody
+        , expect = Http.expectJson WeekHasEntriesReceived (field "has_entries" bool)
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+deleteWeekEntries : String -> Int -> Int -> Cmd Msg
+deleteWeekEntries token year week =
+    Http.request
+        { method = "DELETE"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/my-time-entries/week?year=" ++ String.fromInt year ++ "&week=" ++ String.fromInt week
+        , body = Http.emptyBody
+        , expect = Http.expectWhatever WeekEntriesDeleted
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+updateTimeEntry : String -> EditingTimeEntry -> Cmd Msg
+updateTimeEntry token entry =
+    Http.request
+        { method = "PUT"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/time-entries/" ++ String.fromInt entry.entryId
+        , body =
+            Http.jsonBody <|
+                Encode.object
+                    [ ( "date", Encode.string entry.date )
+                    , ( "start_time", Encode.string entry.startTime )
+                    , ( "end_time", Encode.string entry.endTime )
+                    , ( "type", Encode.string entry.entryType )
+                    ]
+        , expect = Http.expectWhatever TimeEntrySaved
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+deleteTimeEntry : String -> Int -> Cmd Msg
+deleteTimeEntry token entryId =
+    Http.request
+        { method = "DELETE"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/time-entries/" ++ String.fromInt entryId
+        , body = Http.emptyBody
+        , expect = Http.expectWhatever TimeEntryDeleted
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+createAdminTimeEntry : String -> AdminManualEntry -> Cmd Msg
+createAdminTimeEntry token entry =
+    case entry.selectedUserId of
+        Just userId ->
+            Http.request
+                { method = "POST"
+                , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+                , url = "/api/admin/time-entry"
+                , body =
+                    Http.jsonBody <|
+                        Encode.object
+                            [ ( "user_id", Encode.int userId )
+                            , ( "date", Encode.string entry.date )
+                            , ( "hours", Encode.float (String.toFloat entry.hours |> Maybe.withDefault 0) )
+                            , ( "type", Encode.string "manual" )
+                            ]
+                , expect = Http.expectWhatever AdminTimeEntrySaved
+                , timeout = Nothing
+                , tracker = Nothing
+                }
+
+        Nothing ->
+            Cmd.none
+
+
+fetchYearlyHoursSummary : String -> Cmd Msg
+fetchYearlyHoursSummary token =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/yearly-hours-summary"
+        , body = Http.emptyBody
+        , expect = Http.expectJson YearlyHoursSummaryReceived (Decode.list yearlyHoursSummaryDecoder)
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+downloadYearlySummaryPDF : String -> Cmd Msg
+downloadYearlySummaryPDF token =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/yearly-summary/pdf"
+        , body = Http.emptyBody
+        , expect =
+            Http.expectBytesResponse YearlySummaryPDFReceived
+                (\response ->
+                    case response of
+                        Http.GoodStatus_ _ body ->
+                            Ok body
+
+                        Http.BadUrl_ url ->
+                            Err (Http.BadUrl url)
+
+                        Http.Timeout_ ->
+                            Err Http.Timeout
+
+                        Http.NetworkError_ ->
+                            Err Http.NetworkError
+
+                        Http.BadStatus_ metadata _ ->
+                            Err (Http.BadStatus metadata.statusCode)
+                )
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+fetchWeeklyHours : String -> Cmd Msg
+fetchWeeklyHours token =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/weekly-hours"
+        , body = Http.emptyBody
+        , expect = Http.expectJson WeeklyHoursReceived (Decode.list Api.Decoders.weeklyHoursDecoder)
+        , timeout = Nothing
+        , tracker = Nothing
+        }

frontend/src/Api/User.elm

@@ -0,0 +1,110 @@
+module Api.User exposing
+    ( createUser
+    , deleteUser
+    , fetchMyInfo
+    , fetchUsers
+    , resetUserPassword
+    , updateUserWorkHours
+    )
+
+import Api.Decoders exposing (userDecoder)
+import Http
+import Json.Decode as Decode
+import Json.Encode as Encode
+import Types.Model exposing (NewUser)
+import Types.Msg exposing (Msg(..))
+
+
+fetchUsers : String -> Cmd Msg
+fetchUsers token =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/users/list"
+        , body = Http.emptyBody
+        , expect = Http.expectJson UsersReceived (Decode.list userDecoder)
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+fetchMyInfo : String -> Cmd Msg
+fetchMyInfo token =
+    Http.request
+        { method = "GET"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/my-info"
+        , body = Http.emptyBody
+        , expect = Http.expectJson MyInfoReceived userDecoder
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+createUser : String -> NewUser -> Cmd Msg
+createUser token user =
+    Http.request
+        { method = "POST"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/users"
+        , body =
+            Http.jsonBody <|
+                Encode.object
+                    [ ( "username", Encode.string user.username )
+                    , ( "password", Encode.string user.password )
+                    , ( "is_admin", Encode.bool user.isAdmin )
+                    ]
+        , expect = Http.expectWhatever UserCreated
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+deleteUser : String -> Int -> Cmd Msg
+deleteUser token userId =
+    Http.request
+        { method = "DELETE"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/users/delete?id=" ++ String.fromInt userId
+        , body = Http.emptyBody
+        , expect = Http.expectWhatever UserDeleted
+        , timeout = Nothing
+        , tracker = Nothing
+        }
+
+
+updateUserWorkHours : String -> Int -> String -> Cmd Msg
+updateUserWorkHours token userId hours =
+    case String.toFloat hours of
+        Just workHours ->
+            Http.request
+                { method = "PUT"
+                , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+                , url = "/api/admin/users/" ++ String.fromInt userId
+                , body =
+                    Http.jsonBody <|
+                        Encode.object
+                            [ ( "yearly_hours", Encode.float workHours ) ]
+                , expect = Http.expectWhatever UserWorkHoursSaved
+                , timeout = Nothing
+                , tracker = Nothing
+                }
+
+        Nothing ->
+            Cmd.none
+
+
+resetUserPassword : String -> Int -> String -> Cmd Msg
+resetUserPassword token userId newPassword =
+    Http.request
+        { method = "PUT"
+        , headers = [ Http.header "Authorization" ("Bearer " ++ token) ]
+        , url = "/api/admin/users/" ++ String.fromInt userId ++ "/reset-password"
+        , body =
+            Http.jsonBody <|
+                Encode.object
+                    [ ( "new_password", Encode.string newPassword ) ]
+        , expect = Http.expectWhatever ResetPasswordSaved
+        , timeout = Nothing
+        , tracker = Nothing
+        }

frontend/src/Types/Api.elm

@@ -0,0 +1,17 @@
+module Types.Api exposing
+    ( ApiError
+    , LoginResult
+    )
+
+
+type alias LoginResult =
+    { token : String
+    , username : String
+    , isAdmin : Bool
+    }
+
+
+type alias ApiError =
+    { code : String
+    , message : String
+    }

frontend/src/Types/Model.elm

@@ -0,0 +1,218 @@
+module Types.Model exposing
+    ( AdminManualEntry
+    , EditingTimeEntry
+    , Flags
+    , Model
+    , NewSchedule
+    , NewSchoolYear
+    , NewUser
+    , Schedule
+    , SchoolYear
+    , SelectedEntry
+    , TimeEntry
+    , Toast
+    , ToastType(..)
+    , User
+    , WeekDates
+    , WeeklyHours
+    , WeeklySummary
+    , YearlyHoursSummary
+    )
+
+import Time
+import Types.Page exposing (AdminTab, Page)
+
+
+type alias Model =
+    { page : Page
+    , activeTab : AdminTab
+    , username : String
+    , password : String
+    , token : Maybe String
+    , isAdmin : Bool
+    , schedules : List Schedule
+    , users : List User
+    , timeEntries : List TimeEntry
+    , weeklyHours : List WeeklyHours
+    , yearlyHoursSummary : List YearlyHoursSummary
+    , selectedEntries : List SelectedEntry
+    , currentWeek : Int
+    , currentYear : Int
+    , weekDates : Maybe WeekDates
+    , currentTime : Time.Posix
+    , zone : Time.Zone
+    , newSchedule : NewSchedule
+    , newUser : NewUser
+    , error : Maybe String
+    , weekEditMode : Bool
+    , hasEntriesForCurrentWeek : Bool
+    , userWeeklySummary : Maybe WeeklySummary
+    , editingTimeEntryId : Maybe Int
+    , editingTimeEntry : EditingTimeEntry
+    , editingUserId : Maybe Int
+    , editingUserWorkHours : String
+    , resetPasswordUserId : Maybe Int
+    , resetPasswordNew : String
+    , pendingDeleteId : Maybe Int
+    , selectedUserId : Maybe Int
+    , userWorkHoursInput : String
+    , userPasswordInput : String
+    , isProcessing : Bool
+    , mobileMenuOpen : Bool
+    , adminManualEntryForm : AdminManualEntry
+    , schoolYears : List SchoolYear
+    , newSchoolYear : NewSchoolYear
+    , activeSchoolYear : Maybe SchoolYear
+    , editingSchoolYearId : Maybe Int
+    , toasts : List Toast
+    , nextToastId : Int
+    }
+
+
+type ToastType
+    = ErrorToast
+    | SuccessToast
+    | InfoToast
+    | WarningToast
+
+
+type alias Toast =
+    { id : Int
+    , message : String
+    , toastType : ToastType
+    , dismissible : Bool
+    }
+
+
+type alias Flags =
+    { token : Maybe String
+    , isAdmin : Bool
+    }
+
+
+type alias Schedule =
+    { id : Int
+    , dayOfWeek : Int
+    , startTime : String
+    , endTime : String
+    , scheduleType : String
+    , title : String
+    }
+
+
+type alias User =
+    { id : Int
+    , username : String
+    , isAdmin : Bool
+    , yearlyWorkHours : Float
+    }
+
+
+type alias TimeEntry =
+    { id : Int
+    , userId : Int
+    , scheduleId : Int
+    , date : String
+    , entryType : String
+    , username : String
+    , startTime : String
+    , endTime : String
+    }
+
+
+type alias SelectedEntry =
+    { scheduleId : Int
+    , dayOfWeek : Int
+    }
+
+
+type alias NewSchedule =
+    { dayOfWeek : String
+    , startTime : String
+    , endTime : String
+    , scheduleType : String
+    , title : String
+    }
+
+
+type alias NewUser =
+    { username : String
+    , password : String
+    , isAdmin : Bool
+    }
+
+
+type alias WeekDates =
+    { year : Int
+    , week : Int
+    , dates : List ( String, String )
+    , range : String
+    }
+
+
+type alias WeeklySummary =
+    { userId : Int
+    , username : String
+    , year : Int
+    , week : Int
+    , totalHours : Float
+    , targetHours : Float
+    , remainingHours : Float
+    }
+
+
+type alias EditingTimeEntry =
+    { entryId : Int
+    , date : String
+    , startTime : String
+    , endTime : String
+    , entryType : String
+    }
+
+
+type alias WeeklyHours =
+    { userId : Int
+    , username : String
+    , year : Int
+    , week : Int
+    , totalHours : Float
+    , targetHours : Float
+    , remainingHours : Float
+    }
+
+
+type alias YearlyHoursSummary =
+    { userId : Int
+    , username : String
+    , year : Int
+    , week : Int
+    , totalHours : Float
+    , yearlyTarget : Float
+    , yearlyActual : Float
+    , weeklyTarget : Float
+    , remainingYearly : Float
+    }
+
+
+type alias AdminManualEntry =
+    { selectedUserId : Maybe Int
+    , date : String
+    , hours : String
+    , entryType : String
+    }
+
+
+type alias SchoolYear =
+    { id : Int
+    , name : String
+    , startDate : String
+    , endDate : String
+    , isActive : Bool
+    }
+
+
+type alias NewSchoolYear =
+    { name : String
+    , startDate : String
+    , endDate : String
+    }

frontend/src/Types/Msg.elm

@@ -0,0 +1,133 @@
+module Types.Msg exposing (Msg(..))
+
+import Bytes exposing (Bytes)
+import Http
+import Time
+import Types.Api exposing (LoginResult)
+import Types.Model
+    exposing
+        ( Schedule
+        , SchoolYear
+        , TimeEntry
+        , ToastType(..)
+        , User
+        , WeekDates
+        , WeeklyHours
+        , WeeklySummary
+        , YearlyHoursSummary
+        )
+import Types.Page exposing (AdminTab)
+
+
+type Msg
+    = UpdateUsername String
+    | UpdatePassword String
+    | Login
+    | LoginResponse (Result Http.Error LoginResult)
+    | Logout
+    | SetTime Time.Posix
+    | FetchSchedules
+    | SchedulesReceived (Result Http.Error (List Schedule))
+    | ToggleScheduleSelection Int Int
+    | SaveTimeEntries
+    | TimeEntriesSaved (Result Http.Error ())
+    | PreviousWeek
+    | NextWeek
+    | EnableEditMode
+    | DisableEditMode
+    | DeleteWeekEntries
+    | WeekEntriesDeleted (Result Http.Error ())
+    | SwitchTab AdminTab
+    | UpdateNewScheduleDay String
+    | UpdateNewScheduleStart String
+    | UpdateNewScheduleEnd String
+    | UpdateNewScheduleType String
+    | UpdateNewScheduleTitle String
+    | CreateSchedule
+    | ScheduleCreated (Result Http.Error ())
+    | DeleteSchedule Int
+    | ScheduleDeleted (Result Http.Error ())
+    | UpdateNewUsername String
+    | UpdateNewPassword String
+    | UpdateNewUserAdmin Bool
+    | CreateUser
+    | UserCreated (Result Http.Error ())
+    | DeleteUser Int
+    | UserDeleted (Result Http.Error ())
+    | FetchUsers
+    | UsersReceived (Result Http.Error (List User))
+    | FetchMyTimeEntries
+    | MyTimeEntriesReceived (Result Http.Error (List TimeEntry))
+    | FetchAllTimeEntries
+    | AllTimeEntriesReceived (Result Http.Error (List TimeEntry))
+    | FetchWeeklyHours
+    | WeeklyHoursReceived (Result Http.Error (List WeeklyHours))
+    | FetchYearlyHoursSummary
+    | YearlyHoursSummaryReceived (Result Http.Error (List YearlyHoursSummary))
+    | FetchWeekDates
+    | WeekDatesReceived (Result Http.Error WeekDates)
+    | CheckWeekHasEntries
+    | WeekHasEntriesReceived (Result Http.Error Bool)
+    | MyWeeklySummaryReceived (Result Http.Error WeeklySummary)
+    | EditTimeEntry Int
+    | CancelEditTimeEntry
+    | UpdateEditTimeEntryDate String
+    | UpdateEditTimeEntryStartTime String
+    | UpdateEditTimeEntryEndTime String
+    | UpdateEditTimeEntryType String
+    | SaveEditTimeEntry
+    | TimeEntrySaved (Result Http.Error ())
+    | TimeEntryDeleted (Result Http.Error ())
+    | EditUserWorkHours Int
+    | CancelEditUserWorkHours
+    | UpdateEditUserWorkHours String
+    | SaveUserWorkHours
+    | UserWorkHoursSaved (Result Http.Error ())
+    | ResetUserPassword Int
+    | CancelResetPassword
+    | UpdateResetPasswordNew String
+    | SaveResetPassword
+    | ResetPasswordSaved (Result Http.Error ())
+    | ConfirmDeleteTimeEntry Int
+    | ConfirmDeleteUser Int
+    | DeleteConfirmed Bool
+    | StartEditingTimeEntry Int TimeEntry
+    | CancelEditingTimeEntry
+    | UpdateEditingTimeEntryDate String
+    | UpdateEditingTimeEntryStartTime String
+    | UpdateEditingTimeEntryEndTime String
+    | UpdateEditingTimeEntryType String
+    | SaveEditingTimeEntry
+    | SelectUserForManagement Int
+    | UpdateUserWorkHours String
+    | UpdateUserPassword String
+    | SaveUserPassword
+    | UserPasswordSaved (Result Http.Error ())
+    | ToggleMobileMenu
+    | CloseMobileMenu
+    | SelectUserForManualEntry Int
+    | UpdateManualEntryDate String
+    | UpdateManualEntryHours String
+    | UpdateManualEntryType String
+    | SaveAdminTimeEntry
+    | AdminTimeEntrySaved (Result Http.Error ())
+    | FetchMyInfo
+    | MyInfoReceived (Result Http.Error User)
+    | FetchSchoolYears
+    | SchoolYearsReceived (Result Http.Error (List SchoolYear))
+    | FetchActiveSchoolYear
+    | ActiveSchoolYearReceived (Result Http.Error SchoolYear)
+    | UpdateNewSchoolYearName String
+    | UpdateNewSchoolYearStart String
+    | UpdateNewSchoolYearEnd String
+    | CreateSchoolYear
+    | SchoolYearCreated (Result Http.Error ())
+    | ActivateSchoolYear Int
+    | SchoolYearActivated (Result Http.Error ())
+    | DeleteSchoolYear Int
+    | SchoolYearDeleted (Result Http.Error ())
+    | DownloadYearlySummaryPDF
+    | YearlySummaryPDFReceived (Result Http.Error Bytes)
+    | ShowToast String ToastType
+    | DismissToast Int
+    | AutoDismissToast Int

frontend/src/Types/Page.elm

@@ -0,0 +1,17 @@
+module Types.Page exposing
+    ( AdminTab(..)
+    , Page(..)
+    )
+
+
+type Page
+    = LoginPage
+    | UserDashboard
+    | AdminDashboard
+
+
+type AdminTab
+    = ScheduleTab
+    | UsersTab
+    | TimeEntriesTab
+    | SchoolYearsTab

frontend/src/Update/AuthUpdate.elm

@@ -0,0 +1,115 @@
+module Update.AuthUpdate exposing
+    ( handleLogin
+    , handleLoginResponse
+    , handleLogout
+    )
+
+import Api.Auth
+import Api.Schedule
+import Api.SchoolYear
+import Api.TimeEntry
+import Api.User
+import Http
+import Json.Encode as Encode
+import Task
+import Types.Model exposing (Model, ToastType(..))
+import Types.Msg exposing (Msg(..))
+import Types.Page exposing (Page(..))
+import Utils.DateUtils exposing (getISOWeekFromPosix)
+import Utils.Ports exposing (removeToken, saveToken)
+
+
+handleLogin : Model -> ( Model, Cmd Msg )
+handleLogin model =
+    if model.isProcessing then
+        ( model, Cmd.none )
+
+    else
+        ( { model | isProcessing = True }, Api.Auth.loginRequest model.username model.password )
+
+
+handleLoginResponse : Result Http.Error { token : String, username : String, isAdmin : Bool } -> Model -> ( Model, Cmd Msg )
+handleLoginResponse result model =
+    case result of
+        Ok loginResult ->
+            let
+                newPage =
+                    if loginResult.isAdmin then
+                        AdminDashboard
+
+                    else
+                        UserDashboard
+
+                ( year, week ) =
+                    getISOWeekFromPosix model.currentTime
+
+                tokenData =
+                    Encode.object
+                        [ ( "token", Encode.string loginResult.token )
+                        , ( "isAdmin", Encode.bool loginResult.isAdmin )
+                        ]
+            in
+            ( { model
+                | token = Just loginResult.token
+                , username = loginResult.username
+                , isAdmin = loginResult.isAdmin
+                , page = newPage
+                , error = Nothing
+                , isProcessing = False
+              }
+            , Cmd.batch
+                [ saveToken tokenData
+                , Api.Schedule.fetchSchedules (Just loginResult.token)
+                , Task.perform (\_ -> ShowToast ("Willkommen, " ++ loginResult.username ++ "!") SuccessToast) (Task.succeed ())
+                , if not loginResult.isAdmin then
+                    Cmd.batch
+                        [ Api.TimeEntry.fetchMyTimeEntries loginResult.token
+                        , Api.TimeEntry.fetchWeekDates loginResult.token year week
+                        , Api.TimeEntry.checkWeekHasEntries loginResult.token year week
+                        , Api.TimeEntry.fetchYearlyHoursSummary loginResult.token
+                        , Api.User.fetchMyInfo loginResult.token
+                        ]
+
+                  else
+                    Cmd.batch
+                        [ Api.TimeEntry.fetchMyTimeEntries loginResult.token
+                        , Api.TimeEntry.fetchWeekDates loginResult.token year week
+                        , Api.TimeEntry.checkWeekHasEntries loginResult.token year week
+                        , Api.TimeEntry.fetchYearlyHoursSummary loginResult.token
+                        ]
+                ]
+            )
+
+        Err err ->
+            let
+                errorMsg =
+                    case err of
+                        Http.BadStatus 401 ->
+                            "Benutzername oder Passwort ungültig"
+
+                        Http.Timeout ->
+                            "Zeitüberschreitung - bitte erneut versuchen"
+
+                        Http.NetworkError ->
+                            "Netzwerkfehler - bitte Verbindung prüfen"
+
+                        _ ->
+                            "Anmeldung fehlgeschlagen"
+            in
+            ( { model | isProcessing = False }
+            , Task.perform (\_ -> ShowToast errorMsg ErrorToast) (Task.succeed ())
+            )
+
+
+handleLogout : Model -> ( Model, Cmd Msg )
+handleLogout model =
+    ( { model
+        | page = LoginPage
+        , token = Nothing
+        , isAdmin = False
+        , username = ""
+        , password = ""
+        , isProcessing = False
+      }
+    , removeToken ()
+    )

frontend/src/Update/ScheduleUpdate.elm

@@ -0,0 +1,244 @@
+module Update.ScheduleUpdate exposing
+    ( handleCreateSchedule
+    , handleDeleteSchedule
+    , handleDeleteWeekEntries
+    , handleDisableEditMode
+    , handleEnableEditMode
+    , handleSaveTimeEntries
+    , handleScheduleCreated
+    , handleScheduleDeleted
+    , handleSchedulesReceived
+    , handleTimeEntriesSaved
+    , handleToggleScheduleSelection
+    , handleWeekEntriesDeleted
+    )
+
+import Api.Schedule
+import Api.TimeEntry
+import Http
+import Task
+import Types.Model exposing (Model, NewSchedule, Schedule, SelectedEntry, ToastType(..))
+import Types.Msg exposing (Msg(..))
+import Utils.DateUtils exposing (getDayOfWeek, getYearWeekFromDate)
+
+
+handleToggleScheduleSelection : Int -> Int -> Model -> ( Model, Cmd Msg )
+handleToggleScheduleSelection scheduleId dayOfWeek model =
+    let
+        entry =
+            { scheduleId = scheduleId, dayOfWeek = dayOfWeek }
+
+        newSelected =
+            if List.any (\e -> e.scheduleId == scheduleId && e.dayOfWeek == dayOfWeek) model.selectedEntries then
+                List.filter (\e -> not (e.scheduleId == scheduleId && e.dayOfWeek == dayOfWeek)) model.selectedEntries
+
+            else
+                entry :: model.selectedEntries
+    in
+    ( { model | selectedEntries = newSelected }, Cmd.none )
+
+
+handleSaveTimeEntries : Model -> ( Model, Cmd Msg )
+handleSaveTimeEntries model =
+    case model.token of
+        Just token ->
+            ( { model | error = Nothing }
+            , Api.Schedule.saveTimeEntriesForWeek token model.selectedEntries model.currentYear model.currentWeek model.schedules model.weekDates
+            )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleTimeEntriesSaved : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleTimeEntriesSaved result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model
+                        | error = Nothing
+                        , weekEditMode = False
+                        , hasEntriesForCurrentWeek = True
+                      }
+                    , Cmd.batch
+                        [ Api.TimeEntry.fetchMyTimeEntries token
+                        , Task.perform (\_ -> ShowToast "Zeiteinträge erfolgreich gespeichert!" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleEnableEditMode : Model -> ( Model, Cmd Msg )
+handleEnableEditMode model =
+    let
+        currentWeekEntries =
+            List.filter
+                (\e ->
+                    let
+                        ( entryYear, entryWeek ) =
+                            getYearWeekFromDate e.date
+                    in
+                    entryWeek == model.currentWeek && entryYear == model.currentYear
+                )
+                model.timeEntries
+
+        preSelectedEntries =
+            List.map
+                (\entry ->
+                    let
+                        parts =
+                            String.split "-" entry.date
+
+                        year =
+                            parts |> List.head |> Maybe.andThen String.toInt |> Maybe.withDefault 2025
+
+                        month =
+                            parts |> List.drop 1 |> List.head |> Maybe.andThen String.toInt |> Maybe.withDefault 1
+
+                        day =
+                            parts |> List.drop 2 |> List.head |> Maybe.andThen String.toInt |> Maybe.withDefault 1
+
+                        dayOfWeek =
+                            getDayOfWeek year month day
+                    in
+                    { scheduleId = entry.scheduleId, dayOfWeek = dayOfWeek }
+                )
+                currentWeekEntries
+    in
+    ( { model
+        | weekEditMode = True
+        , selectedEntries = preSelectedEntries
+      }
+    , Cmd.none
+    )
+
+
+handleDisableEditMode : Model -> ( Model, Cmd Msg )
+handleDisableEditMode model =
+    ( { model | weekEditMode = False }, Cmd.none )
+
+
+handleDeleteWeekEntries : Model -> ( Model, Cmd Msg )
+handleDeleteWeekEntries model =
+    case model.token of
+        Just token ->
+            ( model, Api.TimeEntry.deleteWeekEntries token model.currentYear model.currentWeek )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleWeekEntriesDeleted : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleWeekEntriesDeleted result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model
+                        | weekEditMode = True
+                        , selectedEntries = []
+                        , hasEntriesForCurrentWeek = False
+                      }
+                    , Cmd.batch
+                        [ Api.TimeEntry.fetchMyTimeEntries token
+                        , Task.perform (\_ -> ShowToast "Wocheneinträge erfolgreich gelöscht" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleCreateSchedule : Model -> ( Model, Cmd Msg )
+handleCreateSchedule model =
+    if
+        String.isEmpty model.newSchedule.dayOfWeek
+            || String.isEmpty model.newSchedule.startTime
+            || String.isEmpty model.newSchedule.endTime
+    then
+        ( model, Task.perform (\_ -> ShowToast "Bitte alle Felder ausfüllen" WarningToast) (Task.succeed ()) )
+
+    else
+        case model.token of
+            Just token ->
+                ( { model | isProcessing = True }, Api.Schedule.createSchedule token model.newSchedule )
+
+            Nothing ->
+                ( model, Cmd.none )
+
+
+handleScheduleCreated : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleScheduleCreated result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    let
+                        emptySchedule =
+                            NewSchedule "" "" "" "lesson" ""
+                    in
+                    ( { model
+                        | newSchedule = emptySchedule
+                        , error = Nothing
+                        , isProcessing = False
+                      }
+                    , Cmd.batch
+                        [ Api.Schedule.fetchSchedules model.token
+                        , Task.perform (\_ -> ShowToast "Stundenplan erfolgreich erstellt!" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( { model | isProcessing = False }, Cmd.none )
+
+
+handleDeleteSchedule : Int -> Model -> ( Model, Cmd Msg )
+handleDeleteSchedule scheduleId model =
+    case model.token of
+        Just token ->
+            ( model, Api.Schedule.deleteSchedule token scheduleId )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleScheduleDeleted : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleScheduleDeleted result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model | error = Nothing }
+                    , Cmd.batch
+                        [ Api.Schedule.fetchSchedules (Just token)
+                        , Task.perform (\_ -> ShowToast "Stundenplan erfolgreich gelöscht" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleSchedulesReceived : Result Http.Error (List Schedule) -> Model -> ( Model, Cmd Msg )
+handleSchedulesReceived result model =
+    case result of
+        Ok schedules ->
+            ( { model | schedules = schedules }, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )

frontend/src/Update/SchoolYearUpdate.elm

@@ -0,0 +1,139 @@
+module Update.SchoolYearUpdate exposing
+    ( handleActivateSchoolYear
+    , handleActiveSchoolYearReceived
+    , handleCreateSchoolYear
+    , handleDeleteSchoolYear
+    , handleSchoolYearActivated
+    , handleSchoolYearCreated
+    , handleSchoolYearDeleted
+    , handleSchoolYearsReceived
+    )
+
+import Api.SchoolYear
+import Http
+import Task
+import Types.Model exposing (Model, NewSchoolYear, SchoolYear, ToastType(..))
+import Types.Msg exposing (Msg(..))
+
+
+handleCreateSchoolYear : Model -> ( Model, Cmd Msg )
+handleCreateSchoolYear model =
+    if
+        String.isEmpty model.newSchoolYear.name
+            || String.isEmpty model.newSchoolYear.startDate
+            || String.isEmpty model.newSchoolYear.endDate
+    then
+        ( model, Task.perform (\_ -> ShowToast "Bitte alle Felder ausfüllen" WarningToast) (Task.succeed ()) )
+
+    else
+        case model.token of
+            Just token ->
+                ( { model | isProcessing = True }, Api.SchoolYear.createSchoolYear token model.newSchoolYear )
+
+            Nothing ->
+                ( model, Cmd.none )
+
+
+handleSchoolYearCreated : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleSchoolYearCreated result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model
+                        | newSchoolYear = NewSchoolYear "" "" ""
+                        , error = Nothing
+                        , isProcessing = False
+                      }
+                    , Cmd.batch
+                        [ Api.SchoolYear.fetchSchoolYears token
+                        , Task.perform (\_ -> ShowToast "Schuljahr erfolgreich erstellt!" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( { model | isProcessing = False }, Cmd.none )
+
+
+handleActivateSchoolYear : Int -> Model -> ( Model, Cmd Msg )
+handleActivateSchoolYear id model =
+    case model.token of
+        Just token ->
+            ( model, Api.SchoolYear.activateSchoolYear token id )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleSchoolYearActivated : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleSchoolYearActivated result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model | error = Nothing }
+                    , Cmd.batch
+                        [ Api.SchoolYear.fetchSchoolYears token
+                        , Api.SchoolYear.fetchActiveSchoolYear token
+                        , Task.perform (\_ -> ShowToast "Schuljahr erfolgreich aktiviert!" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleDeleteSchoolYear : Int -> Model -> ( Model, Cmd Msg )
+handleDeleteSchoolYear id model =
+    case model.token of
+        Just token ->
+            ( model, Api.SchoolYear.deleteSchoolYear token id )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleSchoolYearDeleted : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleSchoolYearDeleted result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model | error = Nothing }
+                    , Cmd.batch
+                        [ Api.SchoolYear.fetchSchoolYears token
+                        , Task.perform (\_ -> ShowToast "Schuljahr erfolgreich gelöscht" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleSchoolYearsReceived : Result Http.Error (List SchoolYear) -> Model -> ( Model, Cmd Msg )
+handleSchoolYearsReceived result model =
+    case result of
+        Ok years ->
+            ( { model | schoolYears = years }, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleActiveSchoolYearReceived : Result Http.Error SchoolYear -> Model -> ( Model, Cmd Msg )
+handleActiveSchoolYearReceived result model =
+    case result of
+        Ok year ->
+            ( { model | activeSchoolYear = Just year }, Cmd.none )
+
+        Err _ ->
+            ( { model | activeSchoolYear = Nothing }, Cmd.none )

frontend/src/Update/TimeEntryUpdate.elm

@@ -0,0 +1,189 @@
+module Update.TimeEntryUpdate exposing
+    ( handleAdminTimeEntrySaved
+    , handleAllTimeEntriesReceived
+    , handleConfirmDeleteTimeEntry
+    , handleEditTimeEntry
+    , handleMyTimeEntriesReceived
+    , handleSaveAdminTimeEntry
+    , handleSaveEditTimeEntry
+    , handleTimeEntryDeleted
+    , handleTimeEntrySaved
+    , handleYearlyHoursSummaryReceived
+    )
+
+import Api.TimeEntry
+import Http
+import Task
+import Types.Model exposing (AdminManualEntry, EditingTimeEntry, Model, TimeEntry, ToastType(..), YearlyHoursSummary)
+import Types.Msg exposing (Msg(..))
+import Utils.DateUtils exposing (getYearWeekFromDate)
+import Utils.Ports exposing (confirmDelete)
+
+
+handleMyTimeEntriesReceived : Result Http.Error (List TimeEntry) -> Model -> ( Model, Cmd Msg )
+handleMyTimeEntriesReceived result model =
+    case result of
+        Ok entries ->
+            let
+                hasEntries =
+                    List.any
+                        (\e ->
+                            let
+                                ( entryYear, entryWeek ) =
+                                    getYearWeekFromDate e.date
+                            in
+                            entryWeek == model.currentWeek && entryYear == model.currentYear
+                        )
+                        entries
+            in
+            ( { model
+                | timeEntries = entries
+                , hasEntriesForCurrentWeek = hasEntries
+                , weekEditMode = False
+              }
+            , Cmd.none
+            )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleAllTimeEntriesReceived : Result Http.Error (List TimeEntry) -> Model -> ( Model, Cmd Msg )
+handleAllTimeEntriesReceived result model =
+    case result of
+        Ok entries ->
+            ( { model | timeEntries = entries }, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleEditTimeEntry : Int -> Model -> ( Model, Cmd Msg )
+handleEditTimeEntry entryId model =
+    case List.filter (\e -> e.id == entryId) model.timeEntries |> List.head of
+        Just entry ->
+            ( { model
+                | editingTimeEntryId = Just entryId
+                , editingTimeEntry =
+                    { entryId = entryId
+                    , date = entry.date
+                    , startTime = entry.startTime
+                    , endTime = entry.endTime
+                    , entryType = entry.entryType
+                    }
+              }
+            , Cmd.none
+            )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleSaveEditTimeEntry : Model -> ( Model, Cmd Msg )
+handleSaveEditTimeEntry model =
+    case model.token of
+        Just token ->
+            ( model, Api.TimeEntry.updateTimeEntry token model.editingTimeEntry )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleTimeEntrySaved : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleTimeEntrySaved result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model
+                        | editingTimeEntryId = Nothing
+                        , pendingDeleteId = Nothing
+                        , error = Nothing
+                      }
+                    , Cmd.batch
+                        [ Api.TimeEntry.fetchAllTimeEntries token
+                        , Task.perform (\_ -> ShowToast "Zeiteintrag erfolgreich gespeichert!" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleTimeEntryDeleted : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleTimeEntryDeleted result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model
+                        | editingTimeEntryId = Nothing
+                        , editingTimeEntry = EditingTimeEntry 0 "" "" "" "lesson"
+                        , pendingDeleteId = Nothing
+                        , error = Nothing
+                      }
+                    , Cmd.batch
+                        [ Api.TimeEntry.fetchAllTimeEntries token
+                        , Api.TimeEntry.fetchYearlyHoursSummary token
+                        , Task.perform (\_ -> ShowToast "Zeiteintrag erfolgreich gelöscht" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( { model | pendingDeleteId = Nothing }, Cmd.none )
+
+
+handleConfirmDeleteTimeEntry : Int -> Model -> ( Model, Cmd Msg )
+handleConfirmDeleteTimeEntry entryId model =
+    ( { model | pendingDeleteId = Just entryId }, confirmDelete "Soll dieser Zeiteintrag gelöscht werden?" )
+
+
+handleSaveAdminTimeEntry : Model -> ( Model, Cmd Msg )
+handleSaveAdminTimeEntry model =
+    case model.token of
+        Just token ->
+            ( { model | isProcessing = True }, Api.TimeEntry.createAdminTimeEntry token model.adminManualEntryForm )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleAdminTimeEntrySaved : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleAdminTimeEntrySaved result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model
+                        | adminManualEntryForm = AdminManualEntry Nothing "" "" "manual"
+                        , error = Nothing
+                        , isProcessing = False
+                      }
+                    , Cmd.batch
+                        [ Api.TimeEntry.fetchAllTimeEntries token
+                        , Api.TimeEntry.fetchYearlyHoursSummary token
+                        , Task.perform (\_ -> ShowToast "Manueller Eintrag erfolgreich erstellt!" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( { model | isProcessing = False }, Cmd.none )
+
+
+handleYearlyHoursSummaryReceived : Result Http.Error (List YearlyHoursSummary) -> Model -> ( Model, Cmd Msg )
+handleYearlyHoursSummaryReceived result model =
+    case result of
+        Ok summary ->
+            ( { model | yearlyHoursSummary = summary }, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )

frontend/src/Update/Update.elm

@@ -0,0 +1,811 @@
+module Update.Update exposing (update)
+
+import Api.Schedule
+import Api.SchoolYear
+import Api.TimeEntry
+import Api.User
+import File.Download
+import Process
+import Task
+import Time
+import Types.Model exposing (EditingTimeEntry, Model, NewUser, ToastType(..))
+import Types.Msg exposing (Msg(..))
+import Types.Page exposing (AdminTab(..), Page(..))
+import Update.AuthUpdate as Auth
+import Update.ScheduleUpdate as Schedule
+import Update.SchoolYearUpdate as SchoolYear
+import Update.TimeEntryUpdate as TimeEntry
+import Update.UserUpdate as User
+import Utils.DateUtils exposing (getISOWeekFromPosix, nextWeek, previousWeek)
+import Utils.Ports
+
+
+update : Msg -> Model -> ( Model, Cmd Msg )
+update msg model =
+    case msg of
+        -- Mobile Menu
+        ToggleMobileMenu ->
+            ( { model | mobileMenuOpen = not model.mobileMenuOpen }, Cmd.none )
+
+        CloseMobileMenu ->
+            ( { model | mobileMenuOpen = False }, Cmd.none )
+
+        -- Auth
+        UpdateUsername username ->
+            ( { model | username = username }, Cmd.none )
+
+        UpdatePassword password ->
+            ( { model | password = password }, Cmd.none )
+
+        Login ->
+            Auth.handleLogin model
+
+        LoginResponse result ->
+            Auth.handleLoginResponse result model
+
+        Logout ->
+            Auth.handleLogout model
+
+        -- Time
+        SetTime time ->
+            let
+                ( year, week ) =
+                    getISOWeekFromPosix time
+
+                cmds =
+                    case model.token of
+                        Just token ->
+                            if model.page == UserDashboard || model.page == LoginPage then
+                                Cmd.batch
+                                    [ Api.TimeEntry.checkWeekHasEntries token year week
+                                    , Api.TimeEntry.fetchWeekDates token year week
+                                    , Api.TimeEntry.fetchMyTimeEntries token
+                                    ]
+
+                            else
+                                Cmd.none
+
+                        Nothing ->
+                            Cmd.none
+            in
+            ( { model
+                | currentTime = time
+                , currentWeek = week
+                , currentYear = year
+              }
+            , cmds
+            )
+
+        -- Schedules
+        FetchSchedules ->
+            ( model, Api.Schedule.fetchSchedules model.token )
+
+        SchedulesReceived result ->
+            Schedule.handleSchedulesReceived result model
+
+        ToggleScheduleSelection scheduleId dayOfWeek ->
+            Schedule.handleToggleScheduleSelection scheduleId dayOfWeek model
+
+        SaveTimeEntries ->
+            Schedule.handleSaveTimeEntries model
+
+        TimeEntriesSaved result ->
+            Schedule.handleTimeEntriesSaved result model
+
+        EnableEditMode ->
+            Schedule.handleEnableEditMode model
+
+        DisableEditMode ->
+            Schedule.handleDisableEditMode model
+
+        DeleteWeekEntries ->
+            Schedule.handleDeleteWeekEntries model
+
+        WeekEntriesDeleted result ->
+            Schedule.handleWeekEntriesDeleted result model
+
+        CreateSchedule ->
+            Schedule.handleCreateSchedule model
+
+        ScheduleCreated result ->
+            Schedule.handleScheduleCreated result model
+
+        DeleteSchedule scheduleId ->
+            Schedule.handleDeleteSchedule scheduleId model
+
+        ScheduleDeleted result ->
+            Schedule.handleScheduleDeleted result model
+
+        -- Week Navigation
+        PreviousWeek ->
+            let
+                ( newYear, newWeek ) =
+                    previousWeek model.currentYear model.currentWeek
+            in
+            ( { model
+                | currentWeek = newWeek
+                , currentYear = newYear
+                , selectedEntries = []
+                , weekEditMode = False
+              }
+            , case model.token of
+                Just token ->
+                    Cmd.batch
+                        [ Api.TimeEntry.fetchWeekDates token newYear newWeek
+                        , Api.TimeEntry.checkWeekHasEntries token newYear newWeek
+                        ]
+
+                Nothing ->
+                    Cmd.none
+            )
+
+        NextWeek ->
+            let
+                ( newYear, newWeek ) =
+                    nextWeek model.currentYear model.currentWeek
+            in
+            ( { model
+                | currentWeek = newWeek
+                , currentYear = newYear
+                , selectedEntries = []
+                , weekEditMode = False
+              }
+            , case model.token of
+                Just token ->
+                    Cmd.batch
+                        [ Api.TimeEntry.fetchWeekDates token newYear newWeek
+                        , Api.TimeEntry.checkWeekHasEntries token newYear newWeek
+                        ]
+
+                Nothing ->
+                    Cmd.none
+            )
+
+        FetchWeekDates ->
+            case model.token of
+                Just token ->
+                    ( model, Api.TimeEntry.fetchWeekDates token model.currentYear model.currentWeek )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        WeekDatesReceived result ->
+            case result of
+                Ok weekDates ->
+                    ( { model | weekDates = Just weekDates }, Cmd.none )
+
+                Err err ->
+                    ( model, Cmd.none )
+
+        CheckWeekHasEntries ->
+            case model.token of
+                Just token ->
+                    ( model, Api.TimeEntry.checkWeekHasEntries token model.currentYear model.currentWeek )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        WeekHasEntriesReceived result ->
+            case result of
+                Ok hasEntries ->
+                    ( { model | hasEntriesForCurrentWeek = hasEntries }, Cmd.none )
+
+                Err err ->
+                    ( model, Cmd.none )
+
+        -- Admin Tabs
+        SwitchTab tab ->
+            let
+                cmd =
+                    case tab of
+                        UsersTab ->
+                            case model.token of
+                                Just token ->
+                                    Api.User.fetchUsers token
+
+                                Nothing ->
+                                    Cmd.none
+
+                        TimeEntriesTab ->
+                            case model.token of
+                                Just token ->
+                                    Cmd.batch
+                                        [ Api.TimeEntry.fetchAllTimeEntries token
+                                        , Api.TimeEntry.fetchYearlyHoursSummary token
+                                        ]
+
+                                Nothing ->
+                                    Cmd.none
+
+                        SchoolYearsTab ->
+                            case model.token of
+                                Just token ->
+                                    Cmd.batch
+                                        [ Api.SchoolYear.fetchSchoolYears token
+                                        , Api.SchoolYear.fetchActiveSchoolYear token
+                                        ]
+
+                                Nothing ->
+                                    Cmd.none
+
+                        _ ->
+                            Cmd.none
+            in
+            ( { model | activeTab = tab, mobileMenuOpen = False }, cmd )
+
+        -- Schedule Form
+        UpdateNewScheduleDay day ->
+            let
+                oldSchedule =
+                    model.newSchedule
+
+                newSchedule =
+                    { oldSchedule | dayOfWeek = day }
+            in
+            ( { model | newSchedule = newSchedule }, Cmd.none )
+
+        UpdateNewScheduleStart time ->
+            let
+                oldSchedule =
+                    model.newSchedule
+
+                newSchedule =
+                    { oldSchedule | startTime = time }
+            in
+            ( { model | newSchedule = newSchedule }, Cmd.none )
+
+        UpdateNewScheduleEnd time ->
+            let
+                oldSchedule =
+                    model.newSchedule
+
+                newSchedule =
+                    { oldSchedule | endTime = time }
+            in
+            ( { model | newSchedule = newSchedule }, Cmd.none )
+
+        UpdateNewScheduleType scheduleType ->
+            let
+                oldSchedule =
+                    model.newSchedule
+
+                newSchedule =
+                    { oldSchedule | scheduleType = scheduleType }
+            in
+            ( { model | newSchedule = newSchedule }, Cmd.none )
+
+        UpdateNewScheduleTitle title ->
+            let
+                oldSchedule =
+                    model.newSchedule
+
+                newSchedule =
+                    { oldSchedule | title = title }
+            in
+            ( { model | newSchedule = newSchedule }, Cmd.none )
+
+        -- Users
+        UpdateNewUsername username ->
+            let
+                oldUser =
+                    model.newUser
+
+                newUser =
+                    { oldUser | username = username }
+            in
+            ( { model | newUser = newUser }, Cmd.none )
+
+        UpdateNewPassword password ->
+            let
+                oldUser =
+                    model.newUser
+
+                newUser =
+                    { oldUser | password = password }
+            in
+            ( { model | newUser = newUser }, Cmd.none )
+
+        UpdateNewUserAdmin isAdmin ->
+            let
+                oldUser =
+                    model.newUser
+
+                newUser =
+                    { oldUser | isAdmin = isAdmin }
+            in
+            ( { model | newUser = newUser }, Cmd.none )
+
+        CreateUser ->
+            User.handleCreateUser model
+
+        UserCreated result ->
+            User.handleUserCreated result model
+
+        DeleteUser userId ->
+            User.handleDeleteUser userId model
+
+        UserDeleted result ->
+            User.handleUserDeleted result model
+
+        FetchUsers ->
+            case model.token of
+                Just token ->
+                    ( model, Api.User.fetchUsers token )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        UsersReceived result ->
+            User.handleUsersReceived result model
+
+        EditUserWorkHours userId ->
+            User.handleEditUserWorkHours userId model
+
+        CancelEditUserWorkHours ->
+            ( { model
+                | editingUserId = Nothing
+                , editingUserWorkHours = ""
+              }
+            , Cmd.none
+            )
+
+        UpdateEditUserWorkHours hours ->
+            ( { model | editingUserWorkHours = hours }, Cmd.none )
+
+        SaveUserWorkHours ->
+            User.handleSaveUserWorkHours model
+
+        UserWorkHoursSaved result ->
+            User.handleUserWorkHoursSaved result model
+
+        ResetUserPassword userId ->
+            User.handleResetUserPassword userId model
+
+        CancelResetPassword ->
+            ( { model
+                | resetPasswordUserId = Nothing
+                , resetPasswordNew = ""
+              }
+            , Cmd.none
+            )
+
+        UpdateResetPasswordNew password ->
+            ( { model | resetPasswordNew = password }, Cmd.none )
+
+        SaveResetPassword ->
+            User.handleSaveResetPassword model
+
+        ResetPasswordSaved result ->
+            User.handleResetPasswordSaved result model
+
+        UpdateUserWorkHours input ->
+            ( { model | userWorkHoursInput = input }, Cmd.none )
+
+        UpdateUserPassword input ->
+            ( { model | userPasswordInput = input }, Cmd.none )
+
+        SaveUserPassword ->
+            case ( model.token, model.selectedUserId ) of
+                ( Just token, Just userId ) ->
+                    if String.length model.userPasswordInput > 0 then
+                        ( model, Api.User.resetUserPassword token userId model.userPasswordInput )
+
+                    else
+                        ( model, Task.perform (\_ -> ShowToast "Passwort erforderlich" WarningToast) (Task.succeed ()) )
+
+                _ ->
+                    ( model, Task.perform (\_ -> ShowToast "Passwort erforderlich" WarningToast) (Task.succeed ()) )
+
+        UserPasswordSaved result ->
+            case result of
+                Ok _ ->
+                    ( { model
+                        | userPasswordInput = ""
+                        , selectedUserId = Nothing
+                        , error = Nothing
+                      }
+                    , Task.perform (\_ -> ShowToast "Passwort erfolgreich zurückgesetzt!" SuccessToast) (Task.succeed ())
+                    )
+
+                Err err ->
+                    ( model, Cmd.none )
+
+        SelectUserForManagement userId ->
+            ( { model | selectedUserId = Just userId, userWorkHoursInput = "", userPasswordInput = "" }, Cmd.none )
+
+        -- Time Entries
+        FetchMyTimeEntries ->
+            case model.token of
+                Just token ->
+                    ( model, Api.TimeEntry.fetchMyTimeEntries token )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        MyTimeEntriesReceived result ->
+            TimeEntry.handleMyTimeEntriesReceived result model
+
+        FetchAllTimeEntries ->
+            case model.token of
+                Just token ->
+                    ( model, Api.TimeEntry.fetchAllTimeEntries token )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        AllTimeEntriesReceived result ->
+            TimeEntry.handleAllTimeEntriesReceived result model
+
+        EditTimeEntry entryId ->
+            TimeEntry.handleEditTimeEntry entryId model
+
+        CancelEditTimeEntry ->
+            ( { model
+                | editingTimeEntryId = Nothing
+                , editingTimeEntry = EditingTimeEntry 0 "" "" "" ""
+              }
+            , Cmd.none
+            )
+
+        UpdateEditTimeEntryDate date ->
+            let
+                old =
+                    model.editingTimeEntry
+
+                new =
+                    { old | date = date }
+            in
+            ( { model | editingTimeEntry = new }, Cmd.none )
+
+        UpdateEditTimeEntryStartTime time ->
+            let
+                old =
+                    model.editingTimeEntry
+
+                new =
+                    { old | startTime = time }
+            in
+            ( { model | editingTimeEntry = new }, Cmd.none )
+
+        UpdateEditTimeEntryEndTime time ->
+            let
+                old =
+                    model.editingTimeEntry
+
+                new =
+                    { old | endTime = time }
+            in
+            ( { model | editingTimeEntry = new }, Cmd.none )
+
+        UpdateEditTimeEntryType entryType ->
+            let
+                old =
+                    model.editingTimeEntry
+
+                new =
+                    { old | entryType = entryType }
+            in
+            ( { model | editingTimeEntry = new }, Cmd.none )
+
+        SaveEditTimeEntry ->
+            TimeEntry.handleSaveEditTimeEntry model
+
+        TimeEntrySaved result ->
+            TimeEntry.handleTimeEntrySaved result model
+
+        TimeEntryDeleted result ->
+            TimeEntry.handleTimeEntryDeleted result model
+
+        ConfirmDeleteTimeEntry entryId ->
+            TimeEntry.handleConfirmDeleteTimeEntry entryId model
+
+        StartEditingTimeEntry entryId entry ->
+            ( { model
+                | editingTimeEntryId = Just entryId
+                , editingTimeEntry = EditingTimeEntry entryId entry.date entry.startTime entry.endTime entry.entryType
+              }
+            , Cmd.none
+            )
+
+        CancelEditingTimeEntry ->
+            ( { model
+                | editingTimeEntryId = Nothing
+                , editingTimeEntry = EditingTimeEntry 0 "" "" "" "lesson"
+              }
+            , Cmd.none
+            )
+
+        UpdateEditingTimeEntryDate date ->
+            let
+                old =
+                    model.editingTimeEntry
+
+                new =
+                    { old | date = date }
+            in
+            ( { model | editingTimeEntry = new }, Cmd.none )
+
+        UpdateEditingTimeEntryStartTime time ->
+            let
+                old =
+                    model.editingTimeEntry
+
+                new =
+                    { old | startTime = time }
+            in
+            ( { model | editingTimeEntry = new }, Cmd.none )
+
+        UpdateEditingTimeEntryEndTime time ->
+            let
+                old =
+                    model.editingTimeEntry
+
+                new =
+                    { old | endTime = time }
+            in
+            ( { model | editingTimeEntry = new }, Cmd.none )
+
+        UpdateEditingTimeEntryType entryType ->
+            let
+                old =
+                    model.editingTimeEntry
+
+                new =
+                    { old | entryType = entryType }
+            in
+            ( { model | editingTimeEntry = new }, Cmd.none )
+
+        SaveEditingTimeEntry ->
+            case ( model.token, model.editingTimeEntryId ) of
+                ( Just token, Just entryId ) ->
+                    ( model, Api.TimeEntry.updateTimeEntry token model.editingTimeEntry )
+
+                _ ->
+                    ( model, Cmd.none )
+
+        -- Weekly Hours
+        FetchWeeklyHours ->
+            case model.token of
+                Just token ->
+                    ( model, Cmd.none )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        WeeklyHoursReceived result ->
+            case result of
+                Ok hours ->
+                    ( { model | weeklyHours = hours }, Cmd.none )
+
+                Err err ->
+                    ( model, Cmd.none )
+
+        MyWeeklySummaryReceived result ->
+            case result of
+                Ok summary ->
+                    ( { model | userWeeklySummary = Just summary }, Cmd.none )
+
+                Err _ ->
+                    ( { model | userWeeklySummary = Nothing }, Cmd.none )
+
+        -- Yearly Hours
+        FetchYearlyHoursSummary ->
+            case model.token of
+                Just token ->
+                    ( model, Api.TimeEntry.fetchYearlyHoursSummary token )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        YearlyHoursSummaryReceived result ->
+            TimeEntry.handleYearlyHoursSummaryReceived result model
+
+        -- Admin Manual Entry
+        SelectUserForManualEntry userId ->
+            let
+                form =
+                    model.adminManualEntryForm
+            in
+            ( { model | adminManualEntryForm = { form | selectedUserId = Just userId } }, Cmd.none )
+
+        UpdateManualEntryDate date ->
+            let
+                form =
+                    model.adminManualEntryForm
+            in
+            ( { model | adminManualEntryForm = { form | date = date } }, Cmd.none )
+
+        UpdateManualEntryHours hours ->
+            let
+                form =
+                    model.adminManualEntryForm
+            in
+            ( { model | adminManualEntryForm = { form | hours = hours } }, Cmd.none )
+
+        UpdateManualEntryType entryType ->
+            let
+                form =
+                    model.adminManualEntryForm
+            in
+            ( { model | adminManualEntryForm = { form | entryType = entryType } }, Cmd.none )
+
+        SaveAdminTimeEntry ->
+            TimeEntry.handleSaveAdminTimeEntry model
+
+        AdminTimeEntrySaved result ->
+            TimeEntry.handleAdminTimeEntrySaved result model
+
+        -- My Info
+        FetchMyInfo ->
+            case model.token of
+                Just token ->
+                    ( model, Api.User.fetchMyInfo token )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        MyInfoReceived result ->
+            case result of
+                Ok user ->
+                    ( { model | users = [ user ] }, Cmd.none )
+
+                Err err ->
+                    ( model, Cmd.none )
+
+        -- School Years
+        FetchSchoolYears ->
+            case model.token of
+                Just token ->
+                    ( model, Api.SchoolYear.fetchSchoolYears token )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        SchoolYearsReceived result ->
+            SchoolYear.handleSchoolYearsReceived result model
+
+        FetchActiveSchoolYear ->
+            case model.token of
+                Just token ->
+                    ( model, Api.SchoolYear.fetchActiveSchoolYear token )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        ActiveSchoolYearReceived result ->
+            SchoolYear.handleActiveSchoolYearReceived result model
+
+        UpdateNewSchoolYearName name ->
+            let
+                old =
+                    model.newSchoolYear
+
+                new =
+                    { old | name = name }
+            in
+            ( { model | newSchoolYear = new }, Cmd.none )
+
+        UpdateNewSchoolYearStart date ->
+            let
+                old =
+                    model.newSchoolYear
+
+                new =
+                    { old | startDate = date }
+            in
+            ( { model | newSchoolYear = new }, Cmd.none )
+
+        UpdateNewSchoolYearEnd date ->
+            let
+                old =
+                    model.newSchoolYear
+
+                new =
+                    { old | endDate = date }
+            in
+            ( { model | newSchoolYear = new }, Cmd.none )
+
+        CreateSchoolYear ->
+            SchoolYear.handleCreateSchoolYear model
+
+        SchoolYearCreated result ->
+            SchoolYear.handleSchoolYearCreated result model
+
+        ActivateSchoolYear id ->
+            SchoolYear.handleActivateSchoolYear id model
+
+        SchoolYearActivated result ->
+            SchoolYear.handleSchoolYearActivated result model
+
+        DeleteSchoolYear id ->
+            SchoolYear.handleDeleteSchoolYear id model
+
+        SchoolYearDeleted result ->
+            SchoolYear.handleSchoolYearDeleted result model
+
+        -- PDF Download
+        DownloadYearlySummaryPDF ->
+            case model.token of
+                Just token ->
+                    ( { model | isProcessing = True }, Api.TimeEntry.downloadYearlySummaryPDF token )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        YearlySummaryPDFReceived result ->
+            case result of
+                Ok pdfBytes ->
+                    let
+                        filename =
+                            "Jahresuebersicht_" ++ String.fromInt model.currentYear ++ ".pdf"
+                    in
+                    ( { model | isProcessing = False }, File.Download.bytes filename "application/pdf" pdfBytes )
+
+                Err err ->
+                    ( { model | isProcessing = False }, Cmd.none )
+
+        -- Delete Confirmation
+        ConfirmDeleteUser userId ->
+            ( { model | pendingDeleteId = Just userId }, Utils.Ports.confirmDelete "Soll dieser Benutzer wirklich gelöscht werden?" )
+
+        DeleteConfirmed confirmed ->
+            if confirmed then
+                case ( model.token, model.pendingDeleteId ) of
+                    ( Just token, Just id ) ->
+                        let
+                            isTimeEntry =
+                                List.any (\e -> e.id == id) model.timeEntries
+                        in
+                        if isTimeEntry then
+                            ( model, Api.TimeEntry.deleteTimeEntry token id )
+
+                        else
+                            ( model, Api.User.deleteUser token id )
+
+                    _ ->
+                        ( model, Cmd.none )
+
+            else
+                ( { model | pendingDeleteId = Nothing }, Cmd.none )
+
+        -- Toasts
+        ShowToast message toastType ->
+            let
+                newToast =
+                    { id = model.nextToastId
+                    , message = message
+                    , toastType = toastType
+                    , dismissible = True
+                    }
+
+                dismissDelay =
+                    case toastType of
+                        ErrorToast ->
+                            8000
+
+                        SuccessToast ->
+                            5000
+
+                        InfoToast ->
+                            5000
+
+                        WarningToast ->
+                            6000
+            in
+            ( { model
+                | toasts = model.toasts ++ [ newToast ]
+                , nextToastId = model.nextToastId + 1
+              }
+            , Task.perform (\_ -> AutoDismissToast newToast.id)
+                (Process.sleep dismissDelay)
+            )
+
+        DismissToast toastId ->
+            ( { model | toasts = List.filter (\t -> t.id /= toastId) model.toasts }
+            , Cmd.none
+            )
+
+        AutoDismissToast toastId ->
+            ( { model | toasts = List.filter (\t -> t.id /= toastId) model.toasts }
+            , Cmd.none
+            )

frontend/src/Update/UserUpdate.elm

@@ -0,0 +1,196 @@
+module Update.UserUpdate exposing
+    ( handleCreateUser
+    , handleDeleteUser
+    , handleEditUserWorkHours
+    , handleResetPasswordSaved
+    , handleResetUserPassword
+    , handleSaveResetPassword
+    , handleSaveUserWorkHours
+    , handleUserCreated
+    , handleUserDeleted
+    , handleUserWorkHoursSaved
+    , handleUsersReceived
+    )
+
+import Api.User
+import Http
+import Task
+import Types.Model exposing (Model, NewUser, ToastType(..), User)
+import Types.Msg exposing (Msg(..))
+
+
+handleCreateUser : Model -> ( Model, Cmd Msg )
+handleCreateUser model =
+    case model.token of
+        Just token ->
+            ( model, Api.User.createUser token model.newUser )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleUserCreated : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleUserCreated result model =
+    case result of
+        Ok _ ->
+            let
+                emptyUser =
+                    NewUser "" "" False
+            in
+            case model.token of
+                Just token ->
+                    ( { model | newUser = emptyUser }
+                    , Cmd.batch
+                        [ Api.User.fetchUsers token
+                        , Task.perform (\_ -> ShowToast "Benutzer erfolgreich erstellt!" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleDeleteUser : Int -> Model -> ( Model, Cmd Msg )
+handleDeleteUser userId model =
+    case model.token of
+        Just token ->
+            ( model, Api.User.deleteUser token userId )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleUserDeleted : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleUserDeleted result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model
+                        | pendingDeleteId = Nothing
+                        , error = Nothing
+                        , editingUserId = Nothing
+                        , resetPasswordUserId = Nothing
+                      }
+                    , Cmd.batch
+                        [ Api.User.fetchUsers token
+                        , Task.perform (\_ -> ShowToast "Benutzer erfolgreich gelöscht" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( { model | pendingDeleteId = Nothing }, Cmd.none )
+
+
+handleUsersReceived : Result Http.Error (List User) -> Model -> ( Model, Cmd Msg )
+handleUsersReceived result model =
+    case result of
+        Ok users ->
+            ( { model | users = users }, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleEditUserWorkHours : Int -> Model -> ( Model, Cmd Msg )
+handleEditUserWorkHours userId model =
+    case List.filter (\u -> u.id == userId) model.users |> List.head of
+        Just user ->
+            ( { model
+                | editingUserId = Just userId
+                , editingUserWorkHours = String.fromFloat user.yearlyWorkHours
+              }
+            , Cmd.none
+            )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleSaveUserWorkHours : Model -> ( Model, Cmd Msg )
+handleSaveUserWorkHours model =
+    case ( model.token, model.editingUserId, String.toFloat model.editingUserWorkHours ) of
+        ( Just token, Just userId, Just hours ) ->
+            ( model, Api.User.updateUserWorkHours token userId (String.fromFloat hours) )
+
+        _ ->
+            ( model, Task.perform (\_ -> ShowToast "Ungültige Eingabe für Arbeitszeit" WarningToast) (Task.succeed ()) )
+
+
+handleUserWorkHoursSaved : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleUserWorkHoursSaved result model =
+    case result of
+        Ok _ ->
+            case model.token of
+                Just token ->
+                    ( { model
+                        | editingUserWorkHours = ""
+                        , editingUserId = Nothing
+                        , error = Nothing
+                      }
+                    , Cmd.batch
+                        [ Api.User.fetchUsers token
+                        , Task.perform (\_ -> ShowToast "Arbeitszeit erfolgreich gespeichert!" SuccessToast) (Task.succeed ())
+                        ]
+                    )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Err err ->
+            ( model, Cmd.none )
+
+
+handleResetUserPassword : Int -> Model -> ( Model, Cmd Msg )
+handleResetUserPassword userId model =
+    ( { model
+        | resetPasswordUserId = Just userId
+        , resetPasswordNew = ""
+      }
+    , Cmd.none
+    )
+
+
+handleSaveResetPassword : Model -> ( Model, Cmd Msg )
+handleSaveResetPassword model =
+    case model.resetPasswordUserId of
+        Just userId ->
+            case model.token of
+                Just token ->
+                    ( model, Api.User.resetUserPassword token userId model.resetPasswordNew )
+
+                Nothing ->
+                    ( model, Cmd.none )
+
+        Nothing ->
+            ( model, Cmd.none )
+
+
+handleResetPasswordSaved : Result Http.Error () -> Model -> ( Model, Cmd Msg )
+handleResetPasswordSaved result model =
+    case result of
+        Ok _ ->
+            ( { model
+                | resetPasswordUserId = Nothing
+                , resetPasswordNew = ""
+                , error = Nothing
+              }
+            , Cmd.batch
+                [ case model.token of
+                    Just token ->
+                        Api.User.fetchUsers token
+
+                    Nothing ->
+                        Cmd.none
+                , Task.perform (\_ -> ShowToast "Passwort erfolgreich zurückgesetzt" SuccessToast) (Task.succeed ())
+                ]
+            )
+
+        Err err ->
+            ( model, Cmd.none )

frontend/src/Utils/DateUtils.elm

@@ -0,0 +1,338 @@
+module Utils.DateUtils exposing
+    ( addDaysToDate
+    , getDateForWeekDay
+    , getDayOfWeek
+    , getDayOfYear
+    , getISOWeek
+    , getISOWeekFromPosix
+    , getWeekDateRange
+    , getYearWeekFromDate
+    , isLeapYear
+    , monthToInt
+    , nextWeek
+    , previousWeek
+    )
+
+import Time
+
+
+getISOWeekFromPosix : Time.Posix -> ( Int, Int )
+getISOWeekFromPosix time =
+    let
+        year =
+            Time.toYear Time.utc time
+
+        month =
+            Time.toMonth Time.utc time |> monthToInt
+
+        day =
+            Time.toDay Time.utc time
+    in
+    ( year, getISOWeek year month day )
+
+
+monthToInt : Time.Month -> Int
+monthToInt month =
+    case month of
+        Time.Jan ->
+            1
+
+        Time.Feb ->
+            2
+
+        Time.Mar ->
+            3
+
+        Time.Apr ->
+            4
+
+        Time.May ->
+            5
+
+        Time.Jun ->
+            6
+
+        Time.Jul ->
+            7
+
+        Time.Aug ->
+            8
+
+        Time.Sep ->
+            9
+
+        Time.Oct ->
+            10
+
+        Time.Nov ->
+            11
+
+        Time.Dec ->
+            12
+
+
+getISOWeek : Int -> Int -> Int -> Int
+getISOWeek year month day =
+    let
+        dayOfYear =
+            getDayOfYear year month day
+
+        jan4DayOfWeek =
+            getDayOfWeek year 1 4
+
+        mondayOfWeek1DayOfYear =
+            4 - jan4DayOfWeek
+
+        weekNum =
+            ((dayOfYear - mondayOfWeek1DayOfYear) // 7) + 1
+    in
+    if weekNum < 1 then
+        52
+
+    else if weekNum > 52 then
+        let
+            dec31DayOfWeek =
+                getDayOfWeek year 12 31
+
+            jan1DayOfWeek =
+                getDayOfWeek year 1 1
+        in
+        if jan1DayOfWeek == 3 || (isLeapYear year && jan1DayOfWeek == 2) then
+            weekNum
+
+        else
+            1
+
+    else
+        weekNum
+
+
+getDayOfYear : Int -> Int -> Int -> Int
+getDayOfYear year month day =
+    let
+        daysInMonth =
+            [ 31
+            , if isLeapYear year then
+                29
+
+              else
+                28
+            , 31
+            , 30
+            , 31
+            , 30
+            , 31
+            , 31
+            , 30
+            , 31
+            , 30
+            , 31
+            ]
+
+        daysBefore =
+            List.take (month - 1) daysInMonth |> List.sum
+    in
+    daysBefore + day
+
+
+isLeapYear : Int -> Bool
+isLeapYear year =
+    (modBy 4 year == 0) && ((modBy 100 year /= 0) || (modBy 400 year == 0))
+
+
+getDayOfWeek : Int -> Int -> Int -> Int
+getDayOfWeek year month day =
+    let
+        adjustedMonth =
+            if month < 3 then
+                month + 12
+
+            else
+                month
+
+        adjustedYear =
+            if month < 3 then
+                year - 1
+
+            else
+                year
+
+        q =
+            day
+
+        m =
+            adjustedMonth
+
+        k =
+            modBy 100 adjustedYear
+
+        j =
+            adjustedYear // 100
+
+        h =
+            (q + ((13 * (m + 1)) // 5) + k + (k // 4) + (j // 4) - (2 * j)) |> modBy 7
+    in
+    (h + 5) |> modBy 7
+
+
+getDateForWeekDay : Int -> Int -> Int -> String
+getDateForWeekDay year week dayOfWeek =
+    let
+        jan4DayOfWeek =
+            getDayOfWeek year 1 4
+
+        mondayOfWeek1Date =
+            4 - jan4DayOfWeek
+
+        targetDayOfYear =
+            mondayOfWeek1Date + ((week - 1) * 7) + dayOfWeek
+
+        ( finalYear, finalMonth, finalDay ) =
+            if targetDayOfYear < 1 then
+                addDaysToDate (year - 1) 12 31 targetDayOfYear
+
+            else
+                addDaysToDate year 1 targetDayOfYear 0
+    in
+    String.fromInt finalYear
+        ++ "-"
+        ++ String.padLeft 2 '0' (String.fromInt finalMonth)
+        ++ "-"
+        ++ String.padLeft 2 '0' (String.fromInt finalDay)
+
+
+addDaysToDate : Int -> Int -> Int -> Int -> ( Int, Int, Int )
+addDaysToDate startYear startMonth startDay daysToAdd =
+    let
+        daysInMonth m y =
+            case m of
+                1 ->
+                    31
+
+                2 ->
+                    if isLeapYear y then
+                        29
+
+                    else
+                        28
+
+                3 ->
+                    31
+
+                4 ->
+                    30
+
+                5 ->
+                    31
+
+                6 ->
+                    30
+
+                7 ->
+                    31
+
+                8 ->
+                    31
+
+                9 ->
+                    30
+
+                10 ->
+                    31
+
+                11 ->
+                    30
+
+                12 ->
+                    31
+
+                _ ->
+                    0
+
+        helper y m d remaining =
+            if remaining == 0 then
+                ( y, m, d )
+
+            else if remaining > 0 then
+                let
+                    daysInCurrentMonth =
+                        daysInMonth m y
+
+                    daysLeftInMonth =
+                        daysInCurrentMonth - d
+                in
+                if remaining <= daysLeftInMonth then
+                    ( y, m, d + remaining )
+
+                else if m == 12 then
+                    helper (y + 1) 1 1 (remaining - daysLeftInMonth - 1)
+
+                else
+                    helper y (m + 1) 1 (remaining - daysLeftInMonth - 1)
+
+            else if d + remaining >= 1 then
+                ( y, m, d + remaining )
+
+            else if m == 1 then
+                let
+                    prevMonthDays =
+                        daysInMonth 12 (y - 1)
+                in
+                helper (y - 1) 12 prevMonthDays (remaining + d)
+
+            else
+                let
+                    prevMonthDays =
+                        daysInMonth (m - 1) y
+                in
+                helper y (m - 1) prevMonthDays (remaining + d)
+    in
+    helper startYear startMonth startDay daysToAdd
+
+
+previousWeek : Int -> Int -> ( Int, Int )
+previousWeek year week =
+    if week == 1 then
+        ( year - 1, 52 )
+
+    else
+        ( year, week - 1 )
+
+
+nextWeek : Int -> Int -> ( Int, Int )
+nextWeek year week =
+    if week >= 52 then
+        ( year + 1, 1 )
+
+    else
+        ( year, week + 1 )
+
+
+getWeekDateRange : Int -> Int -> String
+getWeekDateRange year week =
+    let
+        mondayDate =
+            getDateForWeekDay year week 0
+
+        fridayDate =
+            getDateForWeekDay year week 4
+    in
+    mondayDate ++ " bis " ++ fridayDate
+
+
+getYearWeekFromDate : String -> ( Int, Int )
+getYearWeekFromDate dateStr =
+    let
+        parts =
+            String.split "-" dateStr
+
+        year =
+            parts |> List.head |> Maybe.andThen String.toInt |> Maybe.withDefault 2025
+
+        month =
+            parts |> List.drop 1 |> List.head |> Maybe.andThen String.toInt |> Maybe.withDefault 1
+
+        day =
+            parts |> List.drop 2 |> List.head |> Maybe.andThen String.toInt |> Maybe.withDefault 1
+    in
+    ( year, getISOWeek year month day )

frontend/src/Utils/ErrorHandler.elm

@@ -0,0 +1,42 @@
+module Utils.ErrorHandler exposing (handleApiError)
+
+import Api.Decoders exposing (apiErrorDecoder)
+import Http
+import Json.Decode as Decode
+import Task
+import Types.Model exposing (ToastType(..))
+import Types.Msg exposing (Msg(..))
+
+
+handleApiError : Http.Error -> Cmd Msg
+handleApiError error =
+    let
+        message =
+            case error of
+                Http.BadBody body ->
+                    case Decode.decodeString apiErrorDecoder body of
+                        Ok apiErr ->
+                            apiErr.message
+
+                        Err _ ->
+                            "Ein Fehler ist aufgetreten"
+
+                Http.BadStatus 401 ->
+                    "Keine Berechtigung - bitte erneut anmelden"
+
+                Http.BadStatus 403 ->
+                    "Zugriff verweigert"
+
+                Http.BadStatus 404 ->
+                    "Ressource nicht gefunden"
+
+                Http.Timeout ->
+                    "Zeitüberschreitung - bitte erneut versuchen"
+
+                Http.NetworkError ->
+                    "Netzwerkfehler - bitte Verbindung prüfen"
+
+                _ ->
+                    "Ein unerwarteter Fehler ist aufgetreten"
+    in
+    Task.perform (\_ -> ShowToast message ErrorToast) (Task.succeed ())

frontend/src/Utils/Ports.elm

@@ -0,0 +1,20 @@
+port module Utils.Ports exposing
+    ( confirmDelete
+    , confirmDeleteResponse
+    , removeToken
+    , saveToken
+    )
+
+import Json.Encode as Encode
+
+
+port saveToken : Encode.Value -> Cmd msg
+
+
+port removeToken : () -> Cmd msg
+
+
+port confirmDelete : String -> Cmd msg
+
+
+port confirmDeleteResponse : (Bool -> msg) -> Sub msg

frontend/src/Utils/TimeUtils.elm

@@ -0,0 +1,34 @@
+module Utils.TimeUtils exposing (calculateHours)
+
+
+calculateHours : String -> String -> Float
+calculateHours startTime endTime =
+    let
+        parseTime timeStr =
+            case String.split ":" timeStr of
+                [ h, m ] ->
+                    (String.toFloat h |> Maybe.withDefault 0)
+                        + ((String.toFloat m |> Maybe.withDefault 0) / 60)
+
+                _ ->
+                    0
+
+        start =
+            parseTime startTime
+
+        end =
+            parseTime endTime
+    in
+    if end > start then
+        end - start
+
+    else if endTime == "manual" then
+        case String.toFloat startTime of
+            Just time ->
+                time
+
+            Nothing ->
+                0
+
+    else
+        0

frontend/src/View/Components/Navigation.elm

@@ -0,0 +1,99 @@
+module View.Components.Navigation exposing (viewDayMobile, viewWeekNavigation)
+
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import Types.Model exposing (Model, Schedule)
+import Types.Msg exposing (Msg(..))
+import View.Components.Schedule exposing (viewScheduleItemWithDay)
+
+
+viewWeekNavigation : Model -> Html Msg
+viewWeekNavigation model =
+    let
+        dateRange =
+            case model.weekDates of
+                Just wd ->
+                    wd.range
+
+                Nothing ->
+                    "Laden..."
+    in
+    div [ class "box" ]
+        [ nav [ class "level" ]
+            [ div [ class "level-left" ]
+                [ div [ class "level-item" ]
+                    [ button
+                        [ class "button is-primary"
+                        , onClick PreviousWeek
+                        ]
+                        [ span [ class "icon" ]
+                            [ i [ class "fas fa-chevron-left" ] [] ]
+                        , span [] [ text "Vorherige Woche" ]
+                        ]
+                    ]
+                ]
+            , div [ class "level-item" ]
+                [ div
+                    [ style "display" "flex"
+                    , style "flex-direction" "column"
+                    , style "align-items" "center"
+                    , style "gap" "0.5rem"
+                    , style "min-width" "250px"
+                    ]
+                    [ p
+                        [ class "heading"
+                        , style "margin" "0"
+                        , style "line-height" "1.2"
+                        ]
+                        [ text "Kalenderwoche" ]
+                    , p
+                        [ class "title is-3"
+                        , style "margin" "0"
+                        , style "line-height" "1.2"
+                        ]
+                        [ text ("KW " ++ String.fromInt model.currentWeek ++ " / " ++ String.fromInt model.currentYear) ]
+                    , p
+                        [ class "subtitle is-6"
+                        , style "margin" "0"
+                        , style "line-height" "1.2"
+                        ]
+                        [ text dateRange ]
+                    ]
+                ]
+            , div [ class "level-right" ]
+                [ div [ class "level-item" ]
+                    [ button
+                        [ class "button is-primary"
+                        , onClick NextWeek
+                        ]
+                        [ span [] [ text "Nächste Woche" ]
+                        , span [ class "icon" ]
+                            [ i [ class "fas fa-chevron-right" ] [] ]
+                        ]
+                    ]
+                ]
+            ]
+        ]
+
+
+viewDayMobile : Model -> String -> ( Int, List Schedule ) -> Html Msg
+viewDayMobile model dayName ( dayOfWeek, schedules ) =
+    let
+        dateForDay =
+            case model.weekDates of
+                Just wd ->
+                    wd.dates
+                        |> List.filter (\( day, _ ) -> day == String.fromInt dayOfWeek)
+                        |> List.head
+                        |> Maybe.map Tuple.second
+                        |> Maybe.withDefault "N/A"
+
+                Nothing ->
+                    "Laden..."
+    in
+    div [ class "box mb-4" ]
+        [ p [ class "has-text-weight-bold has-text-centered mb-3" ]
+            [ text (dayName ++ " - " ++ dateForDay) ]
+        , div [] (List.map (viewScheduleItemWithDay model dayOfWeek) schedules)
+        ]

frontend/src/View/Components/Schedule.elm

@@ -0,0 +1,76 @@
+module View.Components.Schedule exposing (viewScheduleItemWithDay)
+
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import Types.Model exposing (Model, Schedule)
+import Types.Msg exposing (Msg(..))
+
+
+viewScheduleItemWithDay : Model -> Int -> Schedule -> Html Msg
+viewScheduleItemWithDay model dayOfWeek schedule =
+    let
+        isSelected =
+            List.any (\e -> e.scheduleId == schedule.id && e.dayOfWeek == dayOfWeek) model.selectedEntries
+
+        isClickable =
+            (not model.hasEntriesForCurrentWeek || model.weekEditMode) && not model.isProcessing
+
+        boxClass =
+            if isSelected then
+                "box has-background-success-light"
+
+            else if isClickable then
+                "box has-background-white"
+
+            else
+                "box has-background-light"
+
+        typeText =
+            if schedule.scheduleType == "break" then
+                " (Pause)"
+
+            else
+                ""
+
+        cursorStyle =
+            if isClickable then
+                "pointer"
+
+            else
+                "not-allowed"
+
+        opacity =
+            if isClickable || isSelected then
+                "1"
+
+            else
+                "0.6"
+    in
+    div
+        [ class boxClass
+        , onClick
+            (if isClickable then
+                ToggleScheduleSelection schedule.id dayOfWeek
+
+             else
+                FetchSchedules
+            )
+        , style "cursor" cursorStyle
+        , style "margin-bottom" "0.5rem"
+        , style "padding" "0.75rem"
+        , style "opacity" opacity
+        , style "transition" "all 0.2s ease"
+        , style "border"
+            (if isClickable && not isSelected then
+                "2px solid transparent"
+
+             else
+                "2px solid currentColor"
+            )
+        ]
+        [ p [ class "has-text-weight-bold is-size-7" ]
+            [ text (schedule.startTime ++ " - " ++ schedule.endTime) ]
+        , p [ class "is-size-7" ]
+            [ text (schedule.title ++ typeText) ]
+        ]

frontend/src/View/Components/Toast.elm

@@ -0,0 +1,66 @@
+module View.Components.Toast exposing (viewToasts)
+
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import Types.Model exposing (Model, Schedule, Toast, ToastType(..))
+import Types.Msg exposing (Msg(..))
+import Utils.TimeUtils exposing (calculateHours)
+import View.Components.Navigation exposing (viewDayMobile, viewWeekNavigation)
+import View.Components.Schedule exposing (viewScheduleItemWithDay)
+
+
+viewToasts : List Toast -> Html Msg
+viewToasts toasts =
+    div [ class "toast-container" ]
+        (List.map viewToast toasts)
+
+
+viewToast : Toast -> Html Msg
+viewToast toast =
+    let
+        toastClass =
+            case toast.toastType of
+                ErrorToast ->
+                    "toast-error"
+
+                SuccessToast ->
+                    "toast-success"
+
+                InfoToast ->
+                    "toast-info"
+
+                WarningToast ->
+                    "toast-warning"
+
+        icon =
+            case toast.toastType of
+                ErrorToast ->
+                    "fas fa-exclamation-circle"
+
+                SuccessToast ->
+                    "fas fa-check-circle"
+
+                InfoToast ->
+                    "fas fa-info-circle"
+
+                WarningToast ->
+                    "fas fa-exclamation-triangle"
+    in
+    div [ class ("toast " ++ toastClass), style "animation" "slideIn 0.3s ease-out" ]
+        [ div [ class "toast-content" ]
+            [ span [ class "toast-icon" ]
+                [ i [ class icon ] [] ]
+            , span [ class "toast-message" ] [ text toast.message ]
+            ]
+        , if toast.dismissible then
+            button
+                [ class "toast-close"
+                , onClick (DismissToast toast.id)
+                , attribute "aria-label" "Schließen"
+                ]
+                [ i [ class "fas fa-times" ] [] ]
+
+          else
+            text ""
+        ]

frontend/src/View/Login.elm

@@ -0,0 +1,57 @@
+module View.Login exposing (viewLogin)
+
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import Types.Model exposing (Model)
+import Types.Msg exposing (Msg(..))
+
+
+viewLogin : Model -> Html Msg
+viewLogin model =
+    section [ class "section" ]
+        [ div [ class "container" ]
+            [ div [ class "columns is-centered" ]
+                [ div [ class "column is-5-tablet is-4-desktop is-3-widescreen" ]
+                    [ div [ class "box" ]
+                        [ h1 [ class "title has-text-centered" ] [ text "Zeiterfassung Login" ]
+                        , div [ class "field" ]
+                            [ label [ class "label" ] [ text "Benutzername" ]
+                            , div [ class "control" ]
+                                [ input
+                                    [ class "input"
+                                    , type_ "text"
+                                    , placeholder "Benutzername"
+                                    , value model.username
+                                    , onInput UpdateUsername
+                                    ]
+                                    []
+                                ]
+                            ]
+                        , div [ class "field" ]
+                            [ label [ class "label" ] [ text "Passwort" ]
+                            , div [ class "control" ]
+                                [ input
+                                    [ class "input"
+                                    , type_ "password"
+                                    , placeholder "Passwort"
+                                    , value model.password
+                                    , onInput UpdatePassword
+                                    ]
+                                    []
+                                ]
+                            ]
+                        , div [ class "field" ]
+                            [ div [ class "control" ]
+                                [ button
+                                    [ class "button is-primary is-fullwidth"
+                                    , onClick Login
+                                    ]
+                                    [ text "Anmelden" ]
+                                ]
+                            ]
+                        ]
+                    ]
+                ]
+            ]
+        ]

frontend/src/View/UserDashboard.elm

@@ -0,0 +1,338 @@
+module View.UserDashboard exposing (viewUserDashboard)
+
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import Types.Model exposing (Model, Schedule)
+import Types.Msg exposing (Msg(..))
+import Utils.TimeUtils exposing (calculateHours)
+import View.Components.Navigation exposing (viewDayMobile, viewWeekNavigation)
+import View.Components.Schedule exposing (viewScheduleItemWithDay)
+
+
+viewUserDashboard : Model -> Html Msg
+viewUserDashboard model =
+    div []
+        [ nav [ class "navbar is-primary" ]
+            [ div [ class "navbar-brand" ]
+                [ div [ class "navbar-item" ]
+                    [ h1 [ class "title is-4 has-text-white" ] [ text "Zeiterfassung" ]
+                    ]
+                , a
+                    [ class
+                        ("navbar-burger"
+                            ++ (if model.mobileMenuOpen then
+                                    " is-active"
+
+                                else
+                                    ""
+                               )
+                        )
+                    , attribute "role" "navigation"
+                    , attribute "aria-label" "menu"
+                    , attribute "aria-expanded"
+                        (if model.mobileMenuOpen then
+                            "true"
+
+                         else
+                            "false"
+                        )
+                    , onClick ToggleMobileMenu
+                    ]
+                    [ span [ attribute "aria-hidden" "true" ] []
+                    , span [ attribute "aria-hidden" "true" ] []
+                    , span [ attribute "aria-hidden" "true" ] []
+                    ]
+                ]
+            , div
+                [ id "navbarUser"
+                , class
+                    ("navbar-menu"
+                        ++ (if model.mobileMenuOpen then
+                                " is-active"
+
+                            else
+                                ""
+                           )
+                    )
+                ]
+                [ div [ class "navbar-end" ]
+                    [ div [ class "navbar-item" ]
+                        [ span [ class "has-text-white mr-2" ] [ text model.username ]
+                        ]
+                    , div [ class "navbar-item" ]
+                        [ button [ class "button is-light", onClick Logout ]
+                            [ span [ class "icon" ]
+                                [ i [ class "fas fa-sign-out-alt" ] [] ]
+                            , span [] [ text "Abmelden" ]
+                            ]
+                        ]
+                    ]
+                ]
+            ]
+        , section [ class "section" ]
+            [ div [ class "container" ]
+                [ viewWeekNavigation model
+                , h2 [ class "title" ] [ text "Stundenplan" ]
+                , if model.hasEntriesForCurrentWeek && not model.weekEditMode then
+                    div [ class "notification is-success" ]
+                        [ div [ class "level" ]
+                            [ div [ class "level-left" ]
+                                [ div [ class "level-item" ]
+                                    [ span [ class "icon" ]
+                                        [ i [ class "fas fa-check-circle" ] [] ]
+                                    , span [] [ text "Diese Woche wurde bereits erfasst" ]
+                                    ]
+                                ]
+                            , div [ class "level-right" ]
+                                [ div [ class "level-item" ]
+                                    [ button
+                                        [ class "button is-warning"
+                                        , onClick EnableEditMode
+                                        , disabled model.isProcessing
+                                        ]
+                                        [ text "Bearbeiten" ]
+                                    ]
+                                ]
+                            ]
+                        ]
+
+                  else if model.weekEditMode then
+                    div [ class "notification is-warning" ]
+                        [ div [ class "level" ]
+                            [ div [ class "level-left" ]
+                                [ div [ class "level-item" ]
+                                    [ span [ class "icon" ]
+                                        [ i [ class "fas fa-edit" ] [] ]
+                                    , span [] [ text "Bearbeitungsmodus aktiv" ]
+                                    ]
+                                ]
+                            , div [ class "level-right" ]
+                                [ div [ class "level-item" ]
+                                    [ button
+                                        [ class "button is-danger is-small mr-2"
+                                        , onClick DeleteWeekEntries
+                                        , disabled model.isProcessing
+                                        ]
+                                        [ text "Einträge löschen" ]
+                                    , button
+                                        [ class "button is-light is-small"
+                                        , onClick DisableEditMode
+                                        ]
+                                        [ text "Abbrechen" ]
+                                    ]
+                                ]
+                            ]
+                        ]
+
+                  else
+                    div [ class "notification is-info is-light" ]
+                        [ text "Wählen Sie die Zeiten aus, die Sie in dieser Woche gearbeitet haben." ]
+                , viewScheduleGridWithWeek model
+                , if not model.hasEntriesForCurrentWeek || model.weekEditMode then
+                    div [ class "field mt-4" ]
+                        [ div [ class "control" ]
+                            [ button
+                                [ class "button is-primary is-large is-fullwidth"
+                                , onClick SaveTimeEntries
+                                , disabled (List.isEmpty model.selectedEntries || model.isProcessing)
+                                ]
+                                [ if model.isProcessing then
+                                    span [ class "icon" ] [ i [ class "fas fa-spinner fa-pulse" ] [] ]
+
+                                  else
+                                    text ""
+                                , text
+                                    (if model.weekEditMode then
+                                        "Änderungen speichern"
+
+                                     else
+                                        "Speichern"
+                                    )
+                                ]
+                            ]
+                        ]
+
+                  else
+                    text ""
+                , h3 [ class "subtitle mt-6" ] [ text "Jahresgesamtzeit" ]
+                , viewUserYearlyTotal model
+                ]
+            ]
+        ]
+
+
+viewScheduleGridWithWeek : Model -> Html Msg
+viewScheduleGridWithWeek model =
+    let
+        days =
+            [ "Montag", "Dienstag", "Mittwoch", "Donnerstag", "Freitag" ]
+
+        groupedSchedules =
+            List.range 0 4
+                |> List.map
+                    (\day ->
+                        ( day, List.filter (\s -> s.dayOfWeek == day) model.schedules )
+                    )
+    in
+    div []
+        [ div [ class "is-hidden-mobile" ]
+            [ div [ class "table-container" ]
+                [ table [ class "table is-bordered is-fullwidth" ]
+                    [ thead []
+                        [ tr [] (List.map (\day -> th [ class "has-text-centered" ] [ text day ]) days)
+                        ]
+                    , tbody []
+                        [ tr []
+                            (List.map (viewDayColumnWithWeek model) groupedSchedules)
+                        ]
+                    ]
+                ]
+            ]
+        , div [ class "is-hidden-tablet" ]
+            (List.map2 (viewDayMobile model) days groupedSchedules)
+        ]
+
+
+viewUserYearlyTotal : Model -> Html Msg
+viewUserYearlyTotal model =
+    let
+        yearlyTotal =
+            model.timeEntries
+                |> List.map
+                    (\entry ->
+                        if entry.entryType == "lesson" then
+                            1.0
+
+                        else
+                            Utils.TimeUtils.calculateHours entry.startTime entry.endTime
+                    )
+                |> List.sum
+
+        userTarget =
+            List.filter (\u -> not u.isAdmin) model.users
+                |> List.head
+                |> Maybe.map .yearlyWorkHours
+                |> Maybe.withDefault 60
+
+        remaining =
+            userTarget - yearlyTotal
+
+        progressPercent =
+            Basics.min 100 (yearlyTotal / userTarget * 100)
+
+        progressColor =
+            if remaining <= 0 then
+                "is-success"
+
+            else if yearlyTotal >= userTarget * 0.8 then
+                "is-info"
+
+            else
+                "is-warning"
+    in
+    div [ class "box" ]
+        [ div [ class "columns" ]
+            [ div [ class "column" ]
+                [ p [ class "heading" ] [ text "Jahresenziel" ]
+                , p [ class "title" ] [ text (String.fromFloat userTarget ++ " Std.") ]
+                ]
+            , div [ class "column" ]
+                [ p [ class "heading" ] [ text "Geleistete Stunden" ]
+                , p [ class "title" ] [ text (String.fromFloat yearlyTotal ++ " Std.") ]
+                ]
+            , div [ class "column" ]
+                [ p [ class "heading" ] [ text "Restliche Stunden" ]
+                , p
+                    [ class
+                        ("title is-4 "
+                            ++ (if remaining <= 0 then
+                                    "has-text-success"
+
+                                else
+                                    "has-text-warning"
+                               )
+                        )
+                    ]
+                    [ text (String.fromFloat (Basics.max 0 remaining) ++ " Std.") ]
+                ]
+            ]
+        , progress
+            [ class ("progress " ++ progressColor)
+            , value (String.fromFloat progressPercent)
+            , Html.Attributes.max "100"
+            ]
+            [ text (String.fromFloat progressPercent ++ "%") ]
+        ]
+
+
+viewDayColumnWithWeek : Model -> ( Int, List Schedule ) -> Html Msg
+viewDayColumnWithWeek model ( dayOfWeek, schedules ) =
+    let
+        dateForDay =
+            case model.weekDates of
+                Just wd ->
+                    wd.dates
+                        |> List.filter (\( day, _ ) -> day == String.fromInt dayOfWeek)
+                        |> List.head
+                        |> Maybe.map Tuple.second
+                        |> Maybe.withDefault "N/A"
+
+                Nothing ->
+                    "Laden..."
+    in
+    td [ class "has-background-light", style "vertical-align" "top", style "min-width" "150px" ]
+        [ p [ class "has-text-centered has-text-weight-bold is-size-7 mb-2" ]
+            [ text dateForDay ]
+        , div [] (List.map (viewScheduleItemWithDay model dayOfWeek) schedules)
+        ]
+
+
+viewUserWeeklySummary : Model -> Html Msg
+viewUserWeeklySummary model =
+    case model.userWeeklySummary of
+        Just summary ->
+            let
+                progressPercent =
+                    Basics.min 100 (summary.totalHours / summary.targetHours * 100)
+
+                progressColor =
+                    if summary.totalHours >= summary.targetHours then
+                        "is-success"
+
+                    else if summary.totalHours >= summary.targetHours * 0.8 then
+                        "is-info"
+
+                    else
+                        "is-warning"
+            in
+            div [ class "box" ]
+                [ div [ class "columns" ]
+                    [ div [ class "column" ]
+                        [ p [ class "heading" ] [ text "Arbeitszeit diese Woche" ]
+                        , p [ class "title" ] [ text (String.fromFloat summary.totalHours ++ " Std.") ]
+                        , p [ class "subtitle is-6" ] [ text ("von " ++ String.fromFloat summary.targetHours ++ " Std.") ]
+                        ]
+                    , div [ class "column" ]
+                        [ p [ class "heading" ] [ text "Verbleibend" ]
+                        , p [ class "title is-4", classList [ ( "has-text-success", summary.remainingHours <= 0 ) ] ]
+                            [ text (String.fromFloat summary.remainingHours ++ " Std.") ]
+                        , if summary.remainingHours < 0 then
+                            p [ class "subtitle is-6 has-text-success" ] [ text "✓ Ziel erreicht!" ]
+
+                          else
+                            p [ class "subtitle is-6" ] [ text "" ]
+                        ]
+                    ]
+                , progress
+                    [ class ("progress " ++ progressColor)
+                    , value (String.fromFloat progressPercent)
+                    , Html.Attributes.max "100"
+                    ]
+                    [ text (String.fromFloat progressPercent ++ "%") ]
+                ]
+
+        Nothing ->
+            div [ class "box" ]
+                [ p [ class "has-text-centered has-text-grey" ] [ text "Laden..." ]
+                ]

frontend/src/View/View.elm

@@ -0,0 +1,29 @@
+module View.View exposing (view)
+
+import Html exposing (Html, div)
+import Html.Attributes exposing (class)
+import Types.Model exposing (Model)
+import Types.Msg exposing (Msg(..))
+import Types.Page exposing (Page(..))
+import View.AdminDashboard exposing (viewAdminDashboard)
+import View.Components.Toast exposing (viewToasts)
+import View.Login exposing (viewLogin)
+import View.UserDashboard exposing (viewUserDashboard)
+
+
+view : Model -> Html Msg
+view model =
+    div [ class "app-container" ]
+        [ viewToasts model.toasts
+        , div [ class "container" ]
+            [ case model.page of
+                LoginPage ->
+                    viewLogin model
+
+                UserDashboard ->
+                    viewUserDashboard model
+
+                AdminDashboard ->
+                    viewAdminDashboard model
+            ]
+        ]