package main

import (
	"fmt"
	"time"

	"github.com/jung-kurt/gofpdf"
)

func GenerateYearlySummaryPDF(schoolYear *SchoolYear, summary []WeeklyHours) ([]byte, error) {
	pdf := gofpdf.New("P", "mm", "A4", "")
	pdf.AddPage()

	pdf.SetFont("Arial", "B", 20)

	title := fmt.Sprintf("Stundenjahresübersicht für Schuljahr %s", schoolYear.Name)
	pdf.Cell(0, 15, title)
	pdf.Ln(10)

	pdf.SetFont("Arial", "", 12)
	subtitle := fmt.Sprintf("%s bis %s", schoolYear.StartDate, schoolYear.EndDate)
	pdf.Cell(0, 10, subtitle)
	pdf.Ln(15)

	pdf.SetFont("Arial", "B", 10)
	pdf.SetFillColor(52, 152, 219)
	pdf.SetTextColor(255, 255, 255)

	colWidths := []float64{60, 40, 40, 40}
	headers := []string{"Mitarbeiter", "Soll (Std.)", "Ist (Std.)", "Differenz (Std.)"}

	for i, header := range headers {
		pdf.CellFormat(colWidths[i], 10, header, "1", 0, "C", true, 0, "")
	}
	pdf.Ln(-1)

	pdf.SetFont("Arial", "", 10)
	pdf.SetTextColor(0, 0, 0)
	fill := false

	for _, entry := range summary {
		if fill {
			pdf.SetFillColor(240, 240, 240)
		} else {
			pdf.SetFillColor(255, 255, 255)
		}

		pdf.CellFormat(colWidths[0], 8, entry.Username, "1", 0, "L", true, 0, "")

		pdf.CellFormat(colWidths[1], 8, fmt.Sprintf("%.1f", entry.YearlyTarget), "1", 0, "R", true, 0, "")

		pdf.CellFormat(colWidths[2], 8, fmt.Sprintf("%.1f", entry.YearlyActual), "1", 0, "R", true, 0, "")

		diffStr := fmt.Sprintf("%.1f", entry.RemainingYearly)
		if entry.RemainingYearly > 0 {
			pdf.SetTextColor(220, 53, 69)
		} else {
			pdf.SetTextColor(40, 167, 69)
		}
		pdf.CellFormat(colWidths[3], 8, diffStr, "1", 0, "R", true, 0, "")
		pdf.SetTextColor(0, 0, 0)

		pdf.Ln(-1)
		fill = !fill
	}

	pdf.Ln(5)
	pdf.SetFont("Arial", "B", 10)

	totalTarget := 0.0
	totalActual := 0.0
	totalRemaining := 0.0

	for _, entry := range summary {
		totalTarget += entry.YearlyTarget
		totalActual += entry.YearlyActual
		totalRemaining += entry.RemainingYearly
	}

	pdf.SetFillColor(52, 152, 219)
	pdf.SetTextColor(255, 255, 255)

	pdf.CellFormat(colWidths[0], 10, "GESAMT", "1", 0, "L", true, 0, "")
	pdf.CellFormat(colWidths[1], 10, fmt.Sprintf("%.1f", totalTarget), "1", 0, "R", true, 0, "")
	pdf.CellFormat(colWidths[2], 10, fmt.Sprintf("%.1f", totalActual), "1", 0, "R", true, 0, "")
	pdf.CellFormat(colWidths[3], 10, fmt.Sprintf("%.1f", totalRemaining), "1", 0, "R", true, 0, "")

	pdf.Ln(15)
	pdf.SetFont("Arial", "I", 8)
	pdf.SetTextColor(128, 128, 128)
	pdf.Cell(0, 10, fmt.Sprintf("Erstellt am: %s", time.Now().Format("02.01.2006 15:04")))

	var buf []byte
	w := &pdfWriter{buf: &buf}
	err := pdf.Output(w)
	if err != nil {
		return nil, err
	}

	return buf, nil
}

type pdfWriter struct {
	buf *[]byte
}

func (w *pdfWriter) Write(p []byte) (n int, err error) {
	*w.buf = append(*w.buf, p...)
	return len(p), nil
}