package helpers

import (
	"fmt"
	"log/slog"
	"regexp"
	"strings"
	"time"
	"watch-tool/models"
)

var (
	syslogPattern = regexp.MustCompile(`^(\w{3} \d{2} \d{2}:\d{2}:\d{2}) ([^\s]+) ([^:]+):\s*(.*)$`)
)

func ExtractSyslogHeader(line string) (models.SyslogFields, string) {
	var syslogFields models.SyslogFields

	matches := syslogPattern.FindStringSubmatch(strings.TrimSpace(line))
	if len(matches) != 5 {
		return syslogFields, line
	}

	sysTime, err := ParseSyslogTimeToRFC3339(matches[1])
	if err != nil {
		slog.Error("cant parse sys log time", "error", err)
	}
	syslogFields.SysLogTimestamp = sysTime
	syslogFields.Hostname = matches[2]
	syslogFields.ProcessInfo = matches[3]

	return syslogFields, matches[4]
}

func GetNamedGroup(match []string, regex *regexp.Regexp, groupName string) string {
	names := regex.SubexpNames()
	for i, name := range names {
		if name == groupName && i < len(match) {
			return match[i]
		}
	}
	return ""
}

func ParseRFC3339WithOptionalZ(timeStr string) (time.Time, error) {
	if !strings.HasSuffix(timeStr, "Z") && !strings.ContainsAny(timeStr[len(timeStr)-6:], "+-") {
		timeStr += "Z"
	}
	return time.Parse(time.RFC3339Nano, timeStr)
}

var deToEnMonth = map[string]string{
	"Jan": "Jan", "Feb": "Feb", "Mär": "Mar", "Apr": "Apr", "Mai": "May",
	"Jun": "Jun", "Jul": "Jul", "Aug": "Aug", "Sep": "Sep", "Okt": "Oct",
	"Nov": "Nov", "Dez": "Dec",
}

func translateMonth(syslogTime string) string {
	for de, en := range deToEnMonth {
		if strings.HasPrefix(syslogTime, de) {
			return strings.Replace(syslogTime, de, en, 1)
		}
	}
	return syslogTime
}

func ParseSyslogTimeToRFC3339(syslogTime string) (time.Time, error) {
	const syslogLayout = "Jan 02 15:04:05"
	syslogTime = translateMonth(syslogTime)
	t, err := time.Parse(syslogLayout, syslogTime)
	if err != nil {
		return t, fmt.Errorf("cannot parse syslog time %q: %w", syslogTime, err)
	}
	now := time.Now()
	t = t.AddDate(now.Year(), 0, 0)
	return t, nil
}