package bot

import (
	"database/sql"
	"errors"
	"fmt"
	"log/slog"
	"time"

	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"

	"worktimeBot/internal/db"
)

type Handler struct {
	Bot          *tgbotapi.BotAPI
	DB           *db.Store
	AllowedUsers map[int64]bool
}

func NewHandler(bot *tgbotapi.BotAPI, store *db.Store, allowed map[int64]bool) *Handler {
	return &Handler{Bot: bot, DB: store, AllowedUsers: allowed}
}

type actionFunc func(int64) (string, error)

func (h *Handler) handleActionMsg(msg *tgbotapi.Message, fn actionFunc) {
	text, err := fn(msg.Chat.ID)
	if err != nil {
		h.sendText(msg.Chat.ID, err.Error())
	} else {
		h.sendSuccessWithMenu(msg.Chat.ID, text)
	}
}

func (h *Handler) handleActionCallback(chatID int64, msgID int, callbackID string, fn actionFunc) {
	defer h.Bot.Request(tgbotapi.NewCallback(callbackID, ""))
	text, err := fn(chatID)
	if err != nil {
		text = err.Error()
	}
	edit := tgbotapi.NewEditMessageText(chatID, msgID, text)
	kb := backKeyboard()
	edit.ReplyMarkup = &kb
	h.Bot.Send(edit)
}

// --- Entry points ---

func (h *Handler) HandleMessage(update tgbotapi.Update) {
	msg := update.Message
	if len(h.AllowedUsers) > 0 && !h.AllowedUsers[msg.Chat.ID] {
		slog.Warn("unauthorized message", "chat_id", msg.Chat.ID, "user", msg.From.UserName, "text", msg.Text)
		return
	}
	slog.Info("message", "chat_id", msg.Chat.ID, "text", msg.Text)
	switch msg.Text {
	case "/start":
		h.handleStart(msg)
	case "/clockin", "Clock In":
		h.handleActionMsg(msg, h.clockIn)
	case "/clockout", "Clock Out":
		h.handleActionMsg(msg, h.clockOut)
	case "/remote":
		h.handleActionMsg(msg, h.toggleRemote)
	case "/report":
		h.handleActionMsg(msg, h.report)
	case "/export":
		h.handleExport(msg)
	case "/dayoff":
		h.handleActionMsg(msg, h.dayOff)
	default:
		h.sendText(msg.Chat.ID, "Unknown command")
	}
}

func (h *Handler) HandleCallback(update tgbotapi.Update) {
	cb := update.CallbackQuery
	if len(h.AllowedUsers) > 0 && !h.AllowedUsers[cb.Message.Chat.ID] {
		slog.Warn("unauthorized callback", "chat_id", cb.Message.Chat.ID, "data", cb.Data)
		h.Bot.Request(tgbotapi.NewCallback(cb.ID, "Unauthorized"))
		return
	}
	slog.Info("callback", "chat_id", cb.Message.Chat.ID, "data", cb.Data)
	chatID := cb.Message.Chat.ID
	msgID := cb.Message.MessageID
	switch cb.Data {
	case "clockin":
		h.handleActionCallback(chatID, msgID, cb.ID, h.clockIn)
	case "clockout":
		h.handleActionCallback(chatID, msgID, cb.ID, h.clockOut)
	case "remote":
		h.handleActionCallback(chatID, msgID, cb.ID, h.toggleRemote)
	case "report":
		h.handleActionCallback(chatID, msgID, cb.ID, h.report)
	case "export":
		h.exportCallback(chatID, msgID, cb.ID)
	case "dayoff":
		h.handleActionCallback(chatID, msgID, cb.ID, h.dayOff)
	case "back_menu":
		h.backToMenu(chatID, msgID, cb.ID)
	}
}

// --- Actions (shared by msg + callback) ---

func (h *Handler) clockIn(chatID int64) (string, error) {
	today := time.Now().Format("2006-01-02")
	isOff, err := h.DB.IsDayOff(chatID, today)
	if err != nil {
		return "", err
	}
	if isOff {
		return "", errors.New("Today is a day off. Use /dayoff to remove it first.")
	}
	last, err := h.DB.GetLastEvent(chatID)
	if err != nil && err != sql.ErrNoRows {
		return "", err
	}
	if last != nil && last.EventType == "in" {
		return "", errors.New("Already clocked in")
	}
	if _, err := h.DB.GetSetting(chatID, "remote_flag"); err != nil {
		h.DB.SetSetting(chatID, "remote_flag", "onsite")
	}
	if err := h.DB.CreateEvent(chatID, "in", time.Now().Unix(), ""); err != nil {
		return "", err
	}
	return "Clocked in at " + time.Now().Format("15:04"), nil
}

func (h *Handler) clockOut(chatID int64) (string, error) {
	today := time.Now().Format("2006-01-02")
	isOff, err := h.DB.IsDayOff(chatID, today)
	if err != nil {
		return "", err
	}
	if isOff {
		return "", errors.New("Today is a day off. Use /dayoff to remove it first.")
	}
	last, err := h.DB.GetLastEvent(chatID)
	if err != nil {
		return "", err
	}
	if last == nil {
		return "", errors.New("No clock-in found. Start with /clockin first")
	}
	if last.EventType == "out" {
		return "", errors.New("Already clocked out")
	}
	if err := h.DB.CreateEvent(chatID, "out", time.Now().Unix(), ""); err != nil {
		return "", err
	}
	return "Clocked out at " + time.Now().Format("15:04"), nil
}

func (h *Handler) toggleRemote(chatID int64) (string, error) {
	current, err := h.DB.GetSetting(chatID, "remote_flag")
	if err != nil {
		current = "onsite"
	}
	var newMode, text string
	if current == "remote" {
		newMode = "onsite"
		text = "Onsite mode enabled"
	} else {
		newMode = "remote"
		text = "Remote mode enabled"
	}
	if err := h.DB.SetSetting(chatID, "remote_flag", newMode); err != nil {
		return "", err
	}
	return text, nil
}

func (h *Handler) dayOff(chatID int64) (string, error) {
	today := time.Now().Format("2006-01-02")
	isOff, err := h.DB.IsDayOff(chatID, today)
	if err != nil {
		return "", err
	}
	if isOff {
		if err := h.DB.RemoveDayOff(chatID, today); err != nil {
			return "", err
		}
		return "Day off removed", nil
	}
	if err := h.DB.SetDayOff(chatID, today, ""); err != nil {
		return "", err
	}
	return "Today marked as day off", nil
}

func (h *Handler) report(chatID int64) (string, error) {
	return h.buildDailyReport(chatID, time.Now()), nil
}

// --- /start ---

func (h *Handler) handleStart(msg *tgbotapi.Message) {
	h.DB.SetSetting(0, "report_chat_id", fmt.Sprintf("%d", msg.Chat.ID))
	slog.Info("start", "chat_id", msg.Chat.ID)
	reply := tgbotapi.NewMessage(msg.Chat.ID, "We hope you have a happy day working.")
	reply.ReplyMarkup = quickKeyboard()
	h.Bot.Send(reply)
	menu := tgbotapi.NewMessage(msg.Chat.ID, "Welcome. Choose an action:")
	menu.ReplyMarkup = mainKeyboard()
	h.Bot.Send(menu)
}

// --- Export (different flow — sends a file) ---

func (h *Handler) handleExport(msg *tgbotapi.Message) {
	now := time.Now()
	slog.Info("export", "chat_id", msg.Chat.ID, "year", now.Year(), "month", now.Month())
	data, err := GenerateMonthlyReport(h.DB, msg.Chat.ID, now.Year(), now.Month())
	if err != nil {
		slog.Error("generate report", "error", err)
		h.sendText(msg.Chat.ID, "Error generating report")
		return
	}
	slog.Info("report generated", "bytes", len(data))
	doc := tgbotapi.NewDocument(msg.Chat.ID, tgbotapi.FileBytes{
		Name:  fmt.Sprintf("worktime_%s.xlsx", now.Format("2006_01")),
		Bytes: data,
	})
	if _, err := h.Bot.Send(doc); err != nil {
		slog.Error("send document", "error", err)
		h.sendText(msg.Chat.ID, "Error sending file")
	}
}

func (h *Handler) exportCallback(chatID int64, msgID int, callbackID string) {
	defer h.Bot.Request(tgbotapi.NewCallback(callbackID, ""))
	now := time.Now()
	slog.Info("export", "chat_id", chatID, "year", now.Year(), "month", now.Month())
	data, err := GenerateMonthlyReport(h.DB, chatID, now.Year(), now.Month())
	if err != nil {
		slog.Error("generate report", "error", err)
		edit := tgbotapi.NewEditMessageText(chatID, msgID, "Error generating report")
		kb := backKeyboard()
		edit.ReplyMarkup = &kb
		h.Bot.Send(edit)
		return
	}
	slog.Info("report generated", "bytes", len(data))
	edit := tgbotapi.NewEditMessageText(chatID, msgID, "Report ready:")
	kb := backKeyboard()
	edit.ReplyMarkup = &kb
	h.Bot.Send(edit)
	doc := tgbotapi.NewDocument(chatID, tgbotapi.FileBytes{
		Name:  fmt.Sprintf("worktime_%s.xlsx", now.Format("2006_01")),
		Bytes: data,
	})
	if _, err := h.Bot.Send(doc); err != nil {
		slog.Error("send document", "error", err)
	}
}

// --- Back to menu ---

func (h *Handler) backToMenu(chatID int64, msgID int, callbackID string) {
	defer h.Bot.Request(tgbotapi.NewCallback(callbackID, ""))
	edit := tgbotapi.NewEditMessageText(chatID, msgID, "Welcome. Choose an action:")
	kb := mainKeyboard()
	edit.ReplyMarkup = &kb
	h.Bot.Send(edit)
}

// --- Daily report builder ---

func (h *Handler) buildDailyReport(chatID int64, now time.Time) string {
	dateStr := now.Format("2006-01-02")

	isOff, _ := h.DB.IsDayOff(chatID, dateStr)

	events, err := h.DB.EventsForDay(chatID, dateStr)
	if err != nil {
		return "Error fetching events."
	}

	if len(events) == 0 {
		if isOff {
			return fmt.Sprintf("%s — Day Off", dateStr)
		}
		return fmt.Sprintf("%s — No events recorded.", dateStr)
	}

	mode := "Onsite"
	current, err := h.DB.GetSetting(chatID, "remote_flag")
	if err == nil && current == "remote" {
		mode = "Remote"
	}

	totals := ComputeDailyTotals(events)
	if totals.PairCount == 0 {
		t := time.Unix(events[0].OccurredAt, 0).Format("15:04")
		return fmt.Sprintf("%s\nMode: %s\nClocked in at %s\n\nStill working — no clock-out yet.", dateStr, mode, t)
	}

	lines := fmt.Sprintf("Report for %s\nMode: %s", dateStr, mode)
	if isOff {
		lines += "\nDay Off: Yes"
	}
	lines += "\n\n"

	for _, e := range events {
		t := time.Unix(e.OccurredAt, 0).Format("15:04")
		label := "IN"
		action := "Clock In"
		if e.EventType == "out" {
			label = "OUT"
			action = "Clock Out"
		}
		lines += fmt.Sprintf("%s %s — %s\n", label, t, action)
	}

	workStr := formatDuration(totals.TotalSeconds)
	breakStr := formatDuration(totals.BreakSeconds)
	lines += fmt.Sprintf("\nSummary:\n  Work: %s\n  Break: %s\n", workStr, breakStr)

	return lines
}

// --- Scheduled report ---

func (h *Handler) SendDailyReport(chatID int64) {
	text := h.buildDailyReport(chatID, time.Now())
	reply := tgbotapi.NewMessage(chatID, text)
	reply.ReplyMarkup = quickKeyboard()
	h.Bot.Send(reply)
}

// --- Keyboards ---

func quickKeyboard() tgbotapi.ReplyKeyboardMarkup {
	return tgbotapi.NewReplyKeyboard(
		tgbotapi.NewKeyboardButtonRow(
			tgbotapi.NewKeyboardButton("Clock In"),
			tgbotapi.NewKeyboardButton("Clock Out"),
		),
	)
}

func mainKeyboard() tgbotapi.InlineKeyboardMarkup {
	return tgbotapi.NewInlineKeyboardMarkup(
		tgbotapi.NewInlineKeyboardRow(
			tgbotapi.NewInlineKeyboardButtonData("Clock In", "clockin"),
			tgbotapi.NewInlineKeyboardButtonData("Clock Out", "clockout"),
		),
		tgbotapi.NewInlineKeyboardRow(
			tgbotapi.NewInlineKeyboardButtonData("Report", "report"),
			tgbotapi.NewInlineKeyboardButtonData("Export", "export"),
		),
		tgbotapi.NewInlineKeyboardRow(
			tgbotapi.NewInlineKeyboardButtonData("Toggle Remote/Onsite", "remote"),
			tgbotapi.NewInlineKeyboardButtonData("Day Off", "dayoff"),
		),
	)
}

func backKeyboard() tgbotapi.InlineKeyboardMarkup {
	return tgbotapi.NewInlineKeyboardMarkup(
		tgbotapi.NewInlineKeyboardRow(
			tgbotapi.NewInlineKeyboardButtonData("Back to Menu", "back_menu"),
		),
	)
}

// --- Helpers ---

func formatDuration(seconds int64) string {
	hours := seconds / 3600
	mins := (seconds % 3600) / 60
	if hours > 0 {
		return fmt.Sprintf("%dh %dm", hours, mins)
	}
	return fmt.Sprintf("%dm", mins)
}

func (h *Handler) sendText(chatID int64, text string) {
	reply := tgbotapi.NewMessage(chatID, text)
	reply.ReplyMarkup = quickKeyboard()
	h.Bot.Send(reply)
}

func (h *Handler) sendSuccessWithMenu(chatID int64, text string) {
	reply := tgbotapi.NewMessage(chatID, text)
	reply.ReplyMarkup = mainKeyboard()
	h.Bot.Send(reply)
}