package bot

import (
	"bytes"
	"context"
	"fmt"
	"log/slog"
	"strings"
	"time"

	bot "github.com/go-telegram/bot"
	"github.com/go-telegram/bot/models"
	"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, calendar string, calYear, calMonth int, start, end time.Time) ([]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 := formatMonthTitle(calendar, calYear, calMonth)
	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 := loadLocation(timezone)

	row := 3

	userDays, err := store.GetUserDaysInRange(userID, start.Format("2006-01-02"), end.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 := start; !d.After(end); d = d.AddDate(0, 0, 1) {
		dateStr := d.Format("2006-01-02")
		displayDate := formatDateForCalendar(dateStr, calendar)

		// Determine if this day exists, its events, and day-off status.
		var (
			day       *db.Day
			events    []db.Event
			hasDayOff bool
		)
		if existing, ok := dayMap[dateStr]; ok {
			day = existing
			events, err = store.EventsForDayByDayID(day.ID)
			if err != nil {
				return nil, err
			}
			hasDayOff = day.IsDayOff
		}

		// Write the date cell for every day.
		cellDate, _ := excelize.CoordinatesToCellName(1, row)
		f.SetCellValue(sheet, cellDate, displayDate)
		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 len(events) > 0 {
			lastEvent := events[len(events)-1]
			if 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)
			}
		}

		// Type column: day-off, work-type label, or empty.
		var typeLabel string
		if hasDayOff {
			if day.DayOffReason != "" {
				typeLabel = "Day Off (" + day.DayOffReason + ")"
			} else {
				typeLabel = "Day Off"
			}
		} else if len(events) > 0 {
			typeLabel = workTypeLabel(store, day, events)
		}
		cellType, _ := excelize.CoordinatesToCellName(4, row)
		f.SetCellValue(sheet, cellType, typeLabel)
		f.SetCellStyle(sheet, cellType, cellType, dataStyle)

		// Work and Break columns — compute totals only when there are events.
		var workSec, breakSec int64
		if len(events) > 0 && day != nil {
			dayStart := time.Date(d.Year(), d.Month(), d.Day(), 0, 0, 0, 0, loc).Unix()
			dayEnd := time.Date(d.Year(), d.Month(), d.Day(), 23, 59, 59, 0, loc).Unix()
			totals := ComputeDailyTotals(events, day.MinBreakThreshold, dayStart, dayEnd)
			workSec = totals.TotalSeconds
			breakSec = totals.BreakSeconds
			totalWork += workSec
			totalBreak += breakSec
		}

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

		cellBreak, _ := excelize.CoordinatesToCellName(6, row)
		f.SetCellValue(sheet, cellBreak, fmtHHMM(breakSec))
		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)
}

// handleExport processes the /export command, showing the month picker or exporting directly.
func (h *Handler) handleExport(ctx context.Context, msg *models.Message) {
	user, err := h.getOrCreateUser(msg.Chat.ID)
	if err != nil {
		h.sendText(ctx, msg.Chat.ID, "Error loading profile")
		return
	}
	loc := loadLocation(user.Timezone)
	now := time.Now().In(loc)

	cy, cm := now.Year(), int(now.Month())
	switch user.Calendar {
	case "jalali":
		cy, cm, _ = gregorianToJalali(cy, cm, now.Day())
	case "hijri":
		cy, cm, _ = gregorianToHijri(cy, cm, now.Day())
	}

	args := strings.Fields(msg.Text)
	if len(args) > 0 && args[0][0] == '/' {
		args = args[1:]
	}
	if len(args) >= 1 {
		if n, _ := fmt.Sscanf(args[0], "%d-%d", &cy, &cm); n == 2 {
			if cy < 0 || cm < 1 || cm > 12 {
				h.sendText(ctx, msg.Chat.ID, "Invalid date. Use: /export YYYY-MM")
				return
			}
		}
	}

	h.sendExportDirect(ctx, msg.Chat.ID, user, cy, cm)
}

// sendExportDirect generates and sends an Excel report for the given calendar month.
func (h *Handler) sendExportDirect(ctx context.Context, chatID int64, user *db.User, calYear, calMonth int) {
	last, err := h.DB.GetLastEvent(user.ID)
	if err == nil && last != nil && last.EventType == "in" {
		h.sendText(ctx, chatID, "You are currently clocked in. Please clock out first, then try again.")
		return
	}

	loc := loadLocation(user.Timezone)
	startStr, endStr := monthGregorianRange(user.Calendar, calYear, calMonth)
	start, err := time.Parse("2006-01-02", startStr)
	if err != nil {
		start = time.Date(calYear, time.Month(calMonth), 1, 0, 0, 0, 0, loc)
	}
	end, err := time.Parse("2006-01-02", endStr)
	if err != nil {
		startOfMonth := time.Date(calYear, time.Month(calMonth), 1, 0, 0, 0, 0, loc)
		end = startOfMonth.AddDate(0, 1, -1)
	}

	slog.Info("export", "user_id", user.ID, "cal", user.Calendar, "cal_y", calYear, "cal_m", calMonth, "from", startStr, "to", endStr)
	data, err := GenerateMonthlyReport(h.DB, user.ID, user.Timezone, user.ExportAccent, user.Calendar, calYear, calMonth, start, end)
	if err != nil {
		slog.Error("generate report", "error", err)
		h.sendText(ctx, chatID, "Error generating report")
		return
	}
	slog.Info("report generated", "bytes", len(data))
	if _, err := h.Bot.SendDocument(ctx, &bot.SendDocumentParams{
		ChatID: chatID,
		Document: &models.InputFileUpload{
			Filename: fmt.Sprintf("worktime_%s.xlsx", fmt.Sprintf("%04d_%02d", calYear, calMonth)),
			Data:     bytes.NewReader(data),
		},
	}); err != nil {
		slog.Error("send document", "error", err)
	}
}

// exportCallback opens the export month picker.
func (h *Handler) exportCallback(ctx context.Context, chatID int64, msgID int, callbackID string) {
	defer h.Bot.AnswerCallbackQuery(ctx, &bot.AnswerCallbackQueryParams{CallbackQueryID: callbackID})
	user, err := h.getOrCreateUser(chatID)
	if err != nil {
		return
	}
	loc := loadLocation(user.Timezone)
	now := time.Now().In(loc)
	cy, cm := now.Year(), int(now.Month())
	switch user.Calendar {
	case "jalali":
		cy, cm, _ = gregorianToJalali(cy, cm, now.Day())
	case "hijri":
		cy, cm, _ = gregorianToHijri(cy, cm, now.Day())
	}
	h.editExportMonthPicker(ctx, chatID, msgID, cy, cm, user)
}

// sendExportMonthPicker sends the export month picker as a new message.
func (h *Handler) sendExportMonthPicker(ctx context.Context, chatID int64, msgID int, year, month int, user *db.User) {
	h.editExportMonthPicker(ctx, chatID, msgID, year, month, user)
}

// editExportMonthPicker renders a year-based month picker with 12 month buttons.
func (h *Handler) editExportMonthPicker(ctx context.Context, chatID int64, msgID int, year, _ int, user *db.User) {
	months := gregMonthNames
	switch user.Calendar {
	case "jalali":
		months = jalaliMonthNames
	case "hijri":
		months = hijriMonthNames
	}

	kbRows := [][]models.InlineKeyboardButton{
		// Year navigation
		{
			{Text: "<", CallbackData: fmt.Sprintf("exp_year_prev_%d", year)},
			{Text: fmt.Sprintf("%d", year), CallbackData: "noop"},
			{Text: ">", CallbackData: fmt.Sprintf("exp_year_next_%d", year)},
		},
	}

	// 4 columns x 3 rows of month buttons
	for i := 0; i < 12; i += 4 {
		row := []models.InlineKeyboardButton{}
		for j := i; j < i+4 && j < 12; j++ {
			row = append(row, models.InlineKeyboardButton{
				Text: months[j], CallbackData: fmt.Sprintf("exp_do_%d_%d", year, j+1),
			})
		}
		kbRows = append(kbRows, row)
	}

	kbRows = append(kbRows, []models.InlineKeyboardButton{
		{Text: "Back to Menu", CallbackData: "back_menu"},
	})

	kb := models.InlineKeyboardMarkup{InlineKeyboard: kbRows}
	if msgID == 0 {
		h.Bot.SendMessage(ctx, &bot.SendMessageParams{ChatID: chatID, Text: "Select month to export:", ReplyMarkup: &kb})
	} else {
		h.Bot.EditMessageText(ctx, &bot.EditMessageTextParams{ChatID: chatID, MessageID: msgID, Text: "Select month to export:", ReplyMarkup: &kb})
	}
}

// formatMonthTitle returns the localized month name and year for a given calendar.
func formatMonthTitle(cal string, year, month int) string {
	switch cal {
	case "jalali":
		return fmt.Sprintf("%s %d", jalaliMonthNames[month-1], year)
	case "hijri":
		return fmt.Sprintf("%s %d", hijriMonthNames[month-1], year)
	default:
		return fmt.Sprintf("%s %d", gregMonthNames[month-1], year)
	}
}

// handleExportCallback routes export inline button presses (year nav, month select).
func (h *Handler) handleExportCallback(ctx context.Context, chatID int64, msgID int, callbackID, data string) {
	defer h.Bot.AnswerCallbackQuery(ctx, &bot.AnswerCallbackQueryParams{CallbackQueryID: callbackID})
	user, err := h.getOrCreateUser(chatID)
	if err != nil {
		return
	}

	var y, m int

	// Navigate to previous year
	if n, _ := fmt.Sscanf(data, "exp_year_prev_%d", &y); n == 1 {
		h.editExportMonthPicker(ctx, chatID, msgID, y-1, 0, user)
		return
	}
	// Navigate to next year
	if n, _ := fmt.Sscanf(data, "exp_year_next_%d", &y); n == 1 {
		h.editExportMonthPicker(ctx, chatID, msgID, y+1, 0, user)
		return
	}

	// Export a specific month
	if n, _ := fmt.Sscanf(data, "exp_do_%d_%d", &y, &m); n == 2 {
		last, err := h.DB.GetLastEvent(user.ID)
		if err == nil && last != nil && last.EventType == "in" {
			h.Bot.EditMessageText(ctx, &bot.EditMessageTextParams{
				ChatID:    chatID,
				MessageID: msgID,
				Text:      "You are currently clocked in. Please clock out first, then try again.",
				ReplyMarkup: &models.InlineKeyboardMarkup{
					InlineKeyboard: [][]models.InlineKeyboardButton{
						{
							{Text: "Back to Menu", CallbackData: "back_menu"},
						},
					},
				},
			})
			return
		}

		startStr, endStr := monthGregorianRange(user.Calendar, y, m)
		start, err := time.Parse("2006-01-02", startStr)
		if err != nil {
			h.sendText(ctx, chatID, "Error processing date")
			return
		}
		end, err := time.Parse("2006-01-02", endStr)
		if err != nil {
			h.sendText(ctx, chatID, "Error processing date")
			return
		}

		slog.Info("export", "user_id", user.ID, "cal", user.Calendar, "cal_y", y, "cal_m", m, "from", startStr, "to", endStr)
		data, err := GenerateMonthlyReport(h.DB, user.ID, user.Timezone, user.ExportAccent, user.Calendar, y, m, start, end)
		if err != nil {
			slog.Error("generate report", "error", err)
			h.Bot.EditMessageText(ctx, &bot.EditMessageTextParams{
				ChatID:    chatID,
				MessageID: msgID,
				Text:      "Error generating report",
				ReplyMarkup: &models.InlineKeyboardMarkup{
					InlineKeyboard: [][]models.InlineKeyboardButton{
						{
							{Text: "Back to Menu", CallbackData: "back_menu"},
						},
					},
				},
			})
			return
		}

		slog.Info("report generated", "bytes", len(data))
		h.Bot.EditMessageText(ctx, &bot.EditMessageTextParams{
			ChatID:    chatID,
			MessageID: msgID,
			Text:      "Report ready:",
			ReplyMarkup: &models.InlineKeyboardMarkup{
				InlineKeyboard: [][]models.InlineKeyboardButton{
					{
						{Text: "Back to Menu", CallbackData: "back_menu"},
					},
				},
			},
		})

		if _, err := h.Bot.SendDocument(ctx, &bot.SendDocumentParams{
			ChatID: chatID,
			Document: &models.InputFileUpload{
				Filename: fmt.Sprintf("worktime_%s.xlsx", fmt.Sprintf("%04d_%02d", y, m)),
				Data:     bytes.NewReader(data),
			},
		}); err != nil {
			slog.Error("send document", "error", err)
		}
	}
}