package bot

import (
	"fmt"
	"time"

	"github.com/xuri/excelize/v2"

	"worktimeBot/internal/db"
)

type themeColors struct {
	headerFill string
	border     string
	totalFill  string
}

var themes = map[string]themeColors{
	"ocean":      {headerFill: "4472C4", border: "D9D9D9", totalFill: "D9E2F3"},
	"beach":      {headerFill: "C87D3C", border: "E8D5B7", totalFill: "FFF0E0"},
	"rose":       {headerFill: "B86C80", border: "F0D0E0", totalFill: "FCE8F0"},
	"catppuccin": {headerFill: "B48DED", border: "D9D0E8", totalFill: "F0E8FC"},
}

func GenerateMonthlyReport(store *db.Store, userID int64, timezone, accent string, year int, month time.Month) ([]byte, error) {
	theme, ok := themes[accent]
	if !ok {
		theme = themes["ocean"]
	}

	f := excelize.NewFile()
	defer f.Close()

	sheet := "Report"
	index, err := f.NewSheet(sheet)
	if err != nil {
		return nil, err
	}
	f.SetActiveSheet(index)
	f.DeleteSheet("Sheet1")

	titleStyle, _ := f.NewStyle(&excelize.Style{
		Font:      &excelize.Font{Bold: true, Size: 14, Color: "FFFFFF"},
		Fill:      excelize.Fill{Type: "pattern", Pattern: 1, Color: []string{theme.headerFill}},
		Alignment: &excelize.Alignment{Horizontal: "center", Vertical: "center"},
	})
	headerStyle, _ := f.NewStyle(&excelize.Style{
		Font: &excelize.Font{Bold: true, Color: "FFFFFF"},
		Fill: excelize.Fill{Type: "pattern", Pattern: 1, Color: []string{theme.headerFill}},
		Border: []excelize.Border{
			{Type: "left", Color: "FFFFFF", Style: 1},
			{Type: "right", Color: "FFFFFF", Style: 1},
			{Type: "top", Color: "FFFFFF", Style: 1},
			{Type: "bottom", Color: "FFFFFF", Style: 1},
		},
		Alignment: &excelize.Alignment{Horizontal: "center", Vertical: "center"},
	})
	dataStyle, _ := f.NewStyle(&excelize.Style{
		Border: []excelize.Border{
			{Type: "left", Color: theme.border, Style: 1},
			{Type: "right", Color: theme.border, Style: 1},
			{Type: "top", Color: theme.border, Style: 1},
			{Type: "bottom", Color: theme.border, Style: 1},
		},
		Alignment: &excelize.Alignment{Horizontal: "center", Vertical: "center"},
	})
	totalStyle, _ := f.NewStyle(&excelize.Style{
		Font: &excelize.Font{Bold: true, Size: 11},
		Fill: excelize.Fill{Type: "pattern", Pattern: 1, Color: []string{theme.totalFill}},
		Border: []excelize.Border{
			{Type: "left", Color: theme.border, Style: 1},
			{Type: "right", Color: theme.border, Style: 1},
			{Type: "top", Color: theme.border, Style: 1},
			{Type: "bottom", Color: theme.border, Style: 2},
		},
		Alignment: &excelize.Alignment{Horizontal: "center", Vertical: "center"},
	})

	monthName := time.Date(year, month, 1, 0, 0, 0, 0, time.UTC).Format("January 2006")
	f.SetCellValue(sheet, "A1", fmt.Sprintf("Work Time Report - %s", monthName))
	f.MergeCell(sheet, "A1", "F1")
	f.SetCellStyle(sheet, "A1", "F1", titleStyle)
	f.SetRowHeight(sheet, 1, 30)

	headers := []string{"Date", "Clock In", "Clock Out", "Type", "Work", "Break"}
	for i, h := range headers {
		cell, _ := excelize.CoordinatesToCellName(i+1, 2)
		f.SetCellValue(sheet, cell, h)
		f.SetCellStyle(sheet, cell, cell, headerStyle)
	}
	f.SetRowHeight(sheet, 2, 22)

	f.SetColWidth(sheet, "A", "A", 14)
	f.SetColWidth(sheet, "B", "B", 10)
	f.SetColWidth(sheet, "C", "C", 10)
	f.SetColWidth(sheet, "D", "D", 12)
	f.SetColWidth(sheet, "E", "E", 10)
	f.SetColWidth(sheet, "F", "F", 10)

	loc, err := time.LoadLocation(timezone)
	if err != nil {
		loc = time.UTC
	}

	row := 3
	firstDay := time.Date(year, month, 1, 0, 0, 0, 0, loc)
	lastDay := firstDay.AddDate(0, 1, -1)

	userDays, err := store.GetUserDaysInRange(userID, firstDay.Format("2006-01-02"), lastDay.Format("2006-01-02"))
	if err != nil {
		return nil, err
	}

	dayMap := make(map[string]*db.Day)
	for i := range userDays {
		dayMap[userDays[i].Date] = &userDays[i]
	}

	var totalWork, totalBreak int64

	for d := firstDay; !d.After(lastDay); d = d.AddDate(0, 0, 1) {
		dateStr := d.Format("2006-01-02")

		day, exists := dayMap[dateStr]
		if !exists {
			continue
		}
		if day.IsDayOff {
			continue
		}

		events, err := store.EventsForDayByDayID(day.ID)
		if err != nil {
			return nil, err
		}
		if len(events) == 0 {
			continue
		}

		totals := ComputeDailyTotals(events, day.MinBreakThreshold)
		totalWork += totals.TotalSeconds
		totalBreak += totals.BreakSeconds

		cellDate, _ := excelize.CoordinatesToCellName(1, row)
		f.SetCellValue(sheet, cellDate, dateStr)
		f.SetCellStyle(sheet, cellDate, cellDate, dataStyle)

		if len(events) > 0 {
			cellIn, _ := excelize.CoordinatesToCellName(2, row)
			f.SetCellValue(sheet, cellIn, time.Unix(events[0].OccurredAt, 0).In(loc).Format("15:04"))
			f.SetCellStyle(sheet, cellIn, cellIn, dataStyle)
		}
		if lastEvent := events[len(events)-1]; lastEvent.EventType == "out" {
			cellOut, _ := excelize.CoordinatesToCellName(3, row)
			f.SetCellValue(sheet, cellOut, time.Unix(lastEvent.OccurredAt, 0).In(loc).Format("15:04"))
			f.SetCellStyle(sheet, cellOut, cellOut, dataStyle)
		}

		wtLabel := workTypeLabel(store, day, events)
		cellType, _ := excelize.CoordinatesToCellName(4, row)
		f.SetCellValue(sheet, cellType, wtLabel)
		f.SetCellStyle(sheet, cellType, cellType, dataStyle)

		cellWork, _ := excelize.CoordinatesToCellName(5, row)
		f.SetCellValue(sheet, cellWork, fmtHHMM(totals.TotalSeconds))
		f.SetCellStyle(sheet, cellWork, cellWork, dataStyle)

		cellBreak, _ := excelize.CoordinatesToCellName(6, row)
		f.SetCellValue(sheet, cellBreak, fmtHHMM(totals.BreakSeconds))
		f.SetCellStyle(sheet, cellBreak, cellBreak, dataStyle)

		row++
	}

	row++

	f.SetCellValue(sheet, fmt.Sprintf("A%d", row), "Total")
	f.SetCellStyle(sheet, fmt.Sprintf("A%d", row), fmt.Sprintf("A%d", row), totalStyle)
	f.SetCellValue(sheet, fmt.Sprintf("E%d", row), fmtDDHHMM(totalWork))
	f.SetCellStyle(sheet, fmt.Sprintf("E%d", row), fmt.Sprintf("E%d", row), totalStyle)
	f.SetCellValue(sheet, fmt.Sprintf("F%d", row), fmtDDHHMM(totalBreak))
	f.SetCellStyle(sheet, fmt.Sprintf("F%d", row), fmt.Sprintf("F%d", row), totalStyle)

	buf, err := f.WriteToBuffer()
	if err != nil {
		return nil, err
	}
	return buf.Bytes(), nil
}

func workTypeLabel(store *db.Store, day *db.Day, events []db.Event) string {
	wtSeen := make(map[int64]bool)
	for _, e := range events {
		if e.WorkTypeID != nil {
			wtSeen[*e.WorkTypeID] = true
		}
	}
	if len(wtSeen) == 0 {
		wt, err := store.GetWorkType(day.CurrentWorkTypeID)
		if err == nil {
			return wt.Name
		}
		return ""
	}
	if len(wtSeen) == 1 {
		for id := range wtSeen {
			wt, err := store.GetWorkType(id)
			if err == nil {
				return wt.Name
			}
		}
	}
	return "mixed"
}

func fmtHHMM(seconds int64) string {
	hours := seconds / 3600
	mins := (seconds % 3600) / 60
	return fmt.Sprintf("%d:%02d", hours, mins)
}

func fmtDDHHMM(seconds int64) string {
	days := seconds / 86400
	rem := seconds % 86400
	hours := rem / 3600
	mins := (rem % 3600) / 60
	return fmt.Sprintf("%d:%02d:%02d", days, hours, mins)
}