package handler

import (
	"context"
	"fmt"
	"log/slog"
	"math"
	"os"
	"path/filepath"
	"strings"
	"time"

	tgbot "github.com/go-telegram/bot"
	"github.com/go-telegram/bot/models"

	"uptodownBot/internal/dl"
	"uptodownBot/internal/domain"
)

type stepState struct {
	URL           string
	MediaInfo     *domain.MediaInfo
	Step          int
	MainFormatID  string
	MainFormat    *domain.Format
	SecondaryID   string
	SecondaryFmt  *domain.Format
	Language      string
	Container     string
	FormatIDs     []string
	PlaylistState *domain.PlaylistState
}

func (h *Handler) getUserStepState(chatID int64) *stepState {
	h.mu.Lock()
	defer h.mu.Unlock()
	return h.stepStates[chatID]
}

func (h *Handler) setUserStepState(chatID int64, ss *stepState) {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.stepStates[chatID] = ss
}

func (h *Handler) clearStepState(chatID int64) {
	h.mu.Lock()
	defer h.mu.Unlock()
	delete(h.stepStates, chatID)
}

// handleURLInput is the entry point when a user sends a URL or types in Download mode.
func (h *Handler) handleURLInput(ctx context.Context, chatID int64, text string, userID int64) {
	url, ok := domain.ValidateURL(text)
	if !ok {
		h.sendText(ctx, chatID, "Please send a valid URL (http/https).")
		return
	}

	if job := h.getActiveJob(userID); job != nil {
		h.sendText(ctx, chatID, "You already have an active download. Cancel it first.")
		return
	}

	info, err := h.YtDlp.GetMediaInfo(url)
	if err != nil {
		errMsg := err.Error()

		// DRM content (Spotify, etc.): fall back to YouTube search
		if strings.Contains(errMsg, "DRM") {
			youtubeURL, ytTitle, searchErr := h.YtDlp.SearchYoutube(text)
			if searchErr != nil {
				kb := models.InlineKeyboardMarkup{
					InlineKeyboard: [][]models.InlineKeyboardButton{
						{{Text: "Search on YouTube", CallbackData: "drm_search"}},
						{{Text: "Cancel", CallbackData: "pending_cancel"}},
					},
				}
				h.Bot.SendMessage(ctx, &tgbot.SendMessageParams{
					ChatID: chatID, Text: "This content is DRM protected and no YouTube alternative was found automatically. Try searching by name:", ReplyMarkup: kb,
				})
				return
			}
			h.sendText(ctx, chatID, fmt.Sprintf("This content is DRM protected. Found on YouTube: %s", ytTitle))
			info, err = h.YtDlp.GetMediaInfo(youtubeURL)
			if err != nil {
				h.sendText(ctx, chatID, fmt.Sprintf("YouTube fallback failed: %s", err.Error()))
				return
			}
			url = youtubeURL
		} else {
			switch {
			case strings.Contains(errMsg, "Unsupported URL") || strings.Contains(errMsg, "is not a valid URL"):
				h.sendText(ctx, chatID, "This URL is not supported.")
			case strings.Contains(errMsg, "HTTP Error 403") || strings.Contains(errMsg, "cookies"):
				h.sendText(ctx, chatID, "This content requires authentication (cookies).")
			case strings.Contains(errMsg, "live"):
				h.sendText(ctx, chatID, "Cannot download live streams.")
			default:
				h.sendText(ctx, chatID, fmt.Sprintf("Error: %s", errMsg))
			}
			return
		}
	}

	if info.IsPlaylist {
		h.handlePlaylist(ctx, chatID, userID, url, info)
		return
	}

	if len(info.Formats) == 0 {
		h.sendText(ctx, chatID, "No formats available for this URL.")
		return
	}

	q, err := h.Repo.GetOrCreateQuotas(userID)
	if err == nil {
		q = h.resetQuotasIfNeeded(q)
		estimatedMB := info.EstimatedSize / (1024 * 1024)
		if estimatedMB > 0 {
			if q.DailyUsedMB+estimatedMB > q.DailyLimitMB ||
				q.WeeklyUsedMB+estimatedMB > q.WeeklyLimitMB ||
				q.MonthlyUsedMB+estimatedMB > q.MonthlyLimitMB {
				h.sendText(ctx, chatID, fmt.Sprintf(
					"Quota exceeded. Daily: %d/%d MB, Weekly: %d/%d MB, Monthly: %d/%d MB.",
					q.DailyUsedMB, q.DailyLimitMB, q.WeeklyUsedMB, q.WeeklyLimitMB, q.MonthlyUsedMB, q.MonthlyLimitMB))
				return
			}
		}
	}

	ss := &stepState{
		URL:       url,
		MediaInfo: info,
		Step:      0,
	}

	h.sendMediaPreview(ctx, chatID, info)

	// Build unified format list: video formats first, then audio
	deduped := dl.DeduplicateResolutions(info.Formats)
	var videoFmts, audioFmts []domain.Format
	for _, f := range deduped {
		if f.HasVideo {
			videoFmts = append(videoFmts, f)
		} else {
			audioFmts = append(audioFmts, f)
		}
	}
	ss.FormatIDs = make([]string, 0, len(deduped)+1)
	labels := make([]string, 0, len(deduped)+1)
	ss.FormatIDs = append(ss.FormatIDs, "best")
	labels = append(labels, "Best")
	for _, f := range videoFmts {
		ss.FormatIDs = append(ss.FormatIDs, f.ID)
		labels = append(labels, formatLabelForDisplay(f))
	}
	for _, f := range audioFmts {
		ss.FormatIDs = append(ss.FormatIDs, f.ID)
		labels = append(labels, formatLabelForDisplay(f))
	}

	h.setUserStepState(chatID, ss)
	kb := formatKeyboard("format_", labels, ss.FormatIDs)
	h.sendWithKB(ctx, chatID, "Select format:", kb)
}

// handleFormatSelection processes a format pick from the unified list.
func (h *Handler) handleFormatSelection(ctx context.Context, chatID int64, msgID int, userID int64, formatID string) {
	ss := h.getUserStepState(chatID)
	if ss == nil {
		return
	}
	ss.MainFormatID = formatID

	if formatID == "best" {
		if ss.MediaInfo.IsAudioOnlyContent() {
			ss.MainFormat = &domain.Format{ID: "best", HasAudio: true, IsAudioOnly: true}
		} else {
			ss.MainFormat = &domain.Format{ID: "best", HasVideo: true, HasAudio: true}
		}
		h.advanceToLanguage(ctx, chatID, msgID, userID, ss)
		return
	}

	for i := range ss.MediaInfo.Formats {
		f := &ss.MediaInfo.Formats[i]
		if f.ID == formatID {
			ss.MainFormat = f
			break
		}
	}
	if ss.MainFormat == nil {
		return
	}

	// Video-only: always offer audio track
	if ss.MainFormat.HasVideo && !ss.MainFormat.HasAudio {
		h.showSecondaryFormats(ctx, chatID, msgID, userID, ss, "audio")
		return
	}
	// Audio-only: ask if they want to add video
	if !ss.MainFormat.HasVideo && ss.MainFormat.HasAudio {
		if ss.MediaInfo.IsAudioOnlyContent() {
			h.advanceToLanguage(ctx, chatID, msgID, userID, ss)
			return
		}
		text := "This format is audio-only. Add video?"
		kb := models.InlineKeyboardMarkup{
			InlineKeyboard: [][]models.InlineKeyboardButton{
				{{Text: "Add Video", CallbackData: "secondary_video"}},
				{{Text: "Audio Only", CallbackData: "secondary_skip"}},
				{{Text: "Back", CallbackData: "back_step"}, {Text: "Cancel", CallbackData: "cancel_dl"}},
			},
		}
		h.editText(ctx, chatID, msgID, text, &kb)
		return
	}
	// Has both: proceed
	h.advanceToLanguage(ctx, chatID, msgID, userID, ss)
}

// showSecondaryFormats shows formats of the missing type to combine.
func (h *Handler) showSecondaryFormats(ctx context.Context, chatID int64, msgID int, userID int64, ss *stepState, kind string) {
	var mt domain.MediaType
	if kind == "audio" {
		mt = domain.MediaTypeAudio
	} else {
		mt = domain.MediaTypeVideo
	}

	filtered := dl.FilterFormatsByType(ss.MediaInfo.Formats, mt)
	if len(filtered) == 0 {
		ss.SecondaryFmt = nil
		h.advanceToLanguage(ctx, chatID, msgID, userID, ss)
		return
	}
	deduped := dl.DeduplicateResolutions(filtered)
	ids := make([]string, len(deduped))
	labels := make([]string, len(deduped))
	for i, f := range deduped {
		ids[i] = f.ID
		labels[i] = formatLabelForDisplay(f)
	}
	ss.FormatIDs = ids
	h.setUserStepState(chatID, ss)

	prompt := fmt.Sprintf("Select %s format to combine:", kind)
	kb := formatKeyboard("secondary_", labels, ids)
	h.editText(ctx, chatID, msgID, prompt, &kb)
}

// handleSecondarySelection processes the secondary format selection.
func (h *Handler) handleSecondarySelection(ctx context.Context, chatID int64, msgID int, userID int64, formatID string) {
	ss := h.getUserStepState(chatID)
	if ss == nil {
		return
	}

	if formatID == "skip" || formatID == "video" || formatID == "audio" {
		// Handle the skip / add-video decisions from the audio-only prompt
		if formatID == "video" {
			h.showSecondaryFormats(ctx, chatID, msgID, userID, ss, "video")
			return
		}
		// skip — just proceed
		h.advanceToLanguage(ctx, chatID, msgID, userID, ss)
		return
	}

	ss.SecondaryID = formatID
	for i := range ss.MediaInfo.Formats {
		f := &ss.MediaInfo.Formats[i]
		if f.ID == formatID {
			ss.SecondaryFmt = f
			break
		}
	}
	h.advanceToLanguage(ctx, chatID, msgID, userID, ss)
}

// advanceToLanguage moves to language selection, or skips to container if N/A.
func (h *Handler) advanceToLanguage(ctx context.Context, chatID int64, msgID int, userID int64, ss *stepState) {
	ss.Step = 2
	h.setUserStepState(chatID, ss)

	if len(ss.MediaInfo.Languages) > 1 {
		kb := languageKeyboard(ss.MediaInfo.Languages)
		h.editText(ctx, chatID, msgID, "Select language:", &kb)
		return
	}
	h.advanceToContainer(ctx, chatID, msgID, userID, ss)
}

// advanceToContainer shows the container picker.
func (h *Handler) advanceToContainer(ctx context.Context, chatID int64, msgID int, userID int64, ss *stepState) {
	ss.Step = 3
	h.setUserStepState(chatID, ss)

	containers := dl.ContainerOptions(ss.determineMediaType())
	kb := containerKeyboard(containers)
	h.editText(ctx, chatID, msgID, "Select container format:", &kb)
}

func (ss *stepState) determineMediaType() domain.MediaType {
	if ss.MainFormat == nil {
		return domain.MediaTypeVideoAudio
	}
	if ss.MainFormat.IsAudioOnly && ss.SecondaryFmt == nil {
		return domain.MediaTypeAudio
	}
	return domain.MediaTypeVideoAudio
}

func (ss *stepState) buildFormatString() string {
	if ss.MainFormatID == "best" {
		return ""
	}
	if ss.SecondaryFmt != nil {
		return ss.MainFormatID + "+" + ss.SecondaryID
	}
	return ss.MainFormatID
}

// handleLanguageSelection processes the language choice.
func (h *Handler) handleLanguageSelection(ctx context.Context, chatID int64, msgID int, userID int64, language string) {
	ss := h.getUserStepState(chatID)
	if ss == nil {
		return
	}
	ss.Language = language
	h.advanceToContainer(ctx, chatID, msgID, userID, ss)
}

// handleContainerSelection processes the container choice and starts the download.
func (h *Handler) handleContainerSelection(ctx context.Context, chatID int64, msgID int, userID int64, container string) {
	ss := h.getUserStepState(chatID)
	if ss == nil {
		return
	}
	ss.Container = container

	mediaType := ss.determineMediaType()
	formatString := ss.buildFormatString()

	format := &domain.Format{ID: ss.MainFormatID}
	if ss.MainFormat != nil {
		format = ss.MainFormat
	}

	job := &domain.DownloadJob{
		ID:             h.generateJobID(),
		UserID:         userID,
		ChatID:         chatID,
		MessageID:      msgID,
		URL:            ss.URL,
		MediaType:      mediaType,
		SelectedFormat: format,
		FormatString:   formatString,
		Container:      container,
		Language:       ss.Language,
		Status:         domain.StatusDownloading,
		Title:          ss.MediaInfo.Title,
		FileSize:       format.Filesize,
	}

	h.setActiveJob(userID, job)
	h.clearStepState(chatID)

	go h.runDownload(context.Background(), job)
}

// runDownload manages the download lifecycle, progress, and completion.
func (h *Handler) runDownload(ctx context.Context, job *domain.DownloadJob) {
	kb := progressKeyboard(0, "", "")
	msg, err := h.Bot.SendMessage(ctx, &tgbot.SendMessageParams{
		ChatID:      job.ChatID,
		Text:        fmt.Sprintf("Downloading: %s", job.Title),
		ReplyMarkup: &kb,
	})
	if err != nil {
		slog.Error("send progress msg failed", "error", err)
		return
	}
	job.MessageID = msg.ID

	updates, err := h.YtDlp.StartDownload(job, h.downloadDir)
	if err != nil {
		h.editText(ctx, job.ChatID, job.MessageID, fmt.Sprintf("Download failed: %s", err.Error()), nil)
		job.Status = domain.StatusFailed
		h.mu.Lock()
		delete(h.activeJobs, job.UserID)
		h.mu.Unlock()
		return
	}

	lastProgress := 0.0
	for upd := range updates {
		slog.Info("progress update", "pct", upd.Progress, "speed", upd.Speed, "status", upd.Status)

		h.mu.Lock()
		currentJob := h.activeJobs[job.UserID]
		h.mu.Unlock()
		if currentJob == nil {
			return
		}

		if upd.Status == domain.StatusCancelled {
			h.editText(ctx, job.ChatID, job.MessageID, "Download cancelled.", nil)
			h.mu.Lock()
			delete(h.activeJobs, job.UserID)
			h.mu.Unlock()
			return
		}

		if upd.Status == domain.StatusFailed {
			h.editText(ctx, job.ChatID, job.MessageID, "Download failed.", nil)
			h.mu.Lock()
			delete(h.activeJobs, job.UserID)
			h.mu.Unlock()
			return
		}

		// Always show the first real progress update, then throttle at 5% intervals
		if upd.Progress > 0 && lastProgress == 0 {
			lastProgress = upd.Progress
		} else if upd.Progress-lastProgress < domain.ProgressThreshold && upd.Status != domain.StatusCompleted {
			continue
		} else {
			lastProgress = upd.Progress
		}

		if upd.Progress > domain.QuotaProgressThreshold && !job.QuotaApplied && job.FileSize > 0 {
			job.QuotaApplied = true
			h.applyQuota(job.UserID, job.FileSize)
		}

		kb := progressKeyboard(upd.Progress, upd.Speed, upd.ETA)
		text := fmt.Sprintf("Downloading: %s", job.Title)
		h.editText(ctx, job.ChatID, job.MessageID, text, &kb)
	}

	h.mu.Lock()
	delete(h.activeJobs, job.UserID)
	h.mu.Unlock()

	if job.Status == domain.StatusCompleted {
		pattern := filepath.Join(h.downloadDir, job.ID+"_*")
		files, err := filepath.Glob(pattern)
		if err == nil && len(files) > 0 {
			f := files[0]
			fileInfo, err := os.Stat(f)
			if err == nil {
				if fileInfo.Size() > h.maxFileSize {
					h.editText(ctx, job.ChatID, job.MessageID,
						fmt.Sprintf("File too large (%s). Max: %s", formatBytes(fileInfo.Size()), formatBytes(h.maxFileSize)), nil)
					os.Remove(f)
					return
				}

				if !job.QuotaApplied && job.FileSize > 0 {
					job.QuotaApplied = true
					h.applyQuota(job.UserID, job.FileSize)
				}

				formatID := job.SelectedFormat.ID
				h.sendDocument(ctx, job.ChatID, f, job.Title)
				os.Remove(f)

				_ = h.Repo.AddHistory(job.UserID, &domain.DownloadRecord{
					URL:       job.URL,
					Title:     job.Title,
					MediaType: job.MediaType.String(),
					FormatID:  formatID,
					Container: job.Container,
					FileSize:  job.FileSize,
					Status:    "completed",
				})

				h.editText(ctx, job.ChatID, job.MessageID, "Download completed!", nil)
				return
			}
		}
		h.editText(ctx, job.ChatID, job.MessageID, "Download completed but file not found.", nil)
	}
}

func (h *Handler) sendDocument(ctx context.Context, chatID int64, filePath, title string) {
	f, err := os.Open(filePath)
	if err != nil {
		slog.Error("open file for send", "path", filePath, "error", err)
		return
	}
	defer f.Close()

	doc := &models.InputFileUpload{
		Filename: title + filepath.Ext(filePath),
		Data:     f,
	}

	if _, err := h.Bot.SendDocument(ctx, &tgbot.SendDocumentParams{
		ChatID:   chatID,
		Document: doc,
	}); err != nil {
		slog.Error("send document failed", "error", err)
	}
}

// handleCancelDownload cancels the current download for a user.
func (h *Handler) handleCancelDownload(ctx context.Context, chatID int64, msgID int, cbID string, userID int64) {
	defer h.answerCb(ctx, cbID)

	job := h.getActiveJob(userID)
	if job != nil {
		dl.CancelDownload(job)
		h.mu.Lock()
		delete(h.activeJobs, userID)
		h.mu.Unlock()
		h.editText(ctx, chatID, msgID, "Download cancelled.", nil)
		return
	}
	h.clearStepState(chatID)
	h.editText(ctx, chatID, msgID, "Cancelled.", nil)
}

// handleBackStep goes back one step in the download flow.
func (h *Handler) handleBackStep(ctx context.Context, chatID int64, msgID int, cbID string, userID int64) {
	defer h.answerCb(ctx, cbID)
	ss := h.getUserStepState(chatID)
	if ss == nil {
		return
	}

	ss.Step--
	switch ss.Step {
	case -1:
		h.clearStepState(chatID)
		h.handleDownloadPrompt(ctx, chatID, msgID, cbID, userID)
	case 0:
		// Re-show format list
		deduped := dl.DeduplicateResolutions(ss.MediaInfo.Formats)
		var videoFmts, audioFmts []domain.Format
		for _, f := range deduped {
			if f.HasVideo {
				videoFmts = append(videoFmts, f)
			} else {
				audioFmts = append(audioFmts, f)
			}
		}
		ss.FormatIDs = []string{"best"}
		labels := []string{"Best"}
		for _, f := range videoFmts {
			ss.FormatIDs = append(ss.FormatIDs, f.ID)
			labels = append(labels, formatLabelForDisplay(f))
		}
		for _, f := range audioFmts {
			ss.FormatIDs = append(ss.FormatIDs, f.ID)
			labels = append(labels, formatLabelForDisplay(f))
		}
		h.setUserStepState(chatID, ss)
		kb := formatKeyboard("format_", labels, ss.FormatIDs)
		h.editText(ctx, chatID, msgID, "Select format:", &kb)
	case 1:
		// Re-show secondary format list or main format with secondary info cleared
		ss.SecondaryFmt = nil
		ss.SecondaryID = ""
		if ss.MainFormat != nil && ss.MainFormat.HasVideo && !ss.MainFormat.HasAudio {
			h.showSecondaryFormats(ctx, chatID, msgID, userID, ss, "audio")
		} else {
			h.advanceToLanguage(ctx, chatID, msgID, userID, ss)
		}
	case 2:
		if len(ss.MediaInfo.Languages) > 1 {
			kb := languageKeyboard(ss.MediaInfo.Languages)
			h.editText(ctx, chatID, msgID, "Select language:", &kb)
		} else {
			ss.Step = 1
			h.handleBackStep(ctx, chatID, msgID, cbID, userID)
		}
	}
}

// handleDownloadCommand handles the /download command, prompting for a URL.
func (h *Handler) handleDownloadCommand(ctx context.Context, msg *models.Message, userID int64) {
	h.promptForInput(ctx, msg.Chat.ID, 0, userID, PendingURL,
		"Send me the URL to download:", nil)
}

// handleDownloadPrompt shows the download prompt (asks for URL).
func (h *Handler) handleDownloadPrompt(ctx context.Context, chatID int64, msgID int, cbID string, userID int64) {
	h.promptForInput(ctx, chatID, msgID, userID, PendingURL,
		"Send me the URL to download:", nil)
}

func formatLabelForDisplay(f domain.Format) string {
	if f.Resolution != "" {
		label := f.Resolution
		if f.Filesize > 0 {
			label += fmt.Sprintf(" (%s)", formatBytes(f.Filesize))
		}
		return label
	}
	if f.Bitrate != "" {
		label := f.Bitrate
		if f.Filesize > 0 {
			label += fmt.Sprintf(" (%s)", formatBytes(f.Filesize))
		}
		return label
	}
	// Audio-only with no bitrate: show format ID + extension
	if f.IsAudioOnly {
		label := f.ID
		if f.Extension != "" {
			label += " (" + f.Extension + ")"
		}
		if f.Filesize > 0 {
			label += fmt.Sprintf(" (%s)", formatBytes(f.Filesize))
		}
		return label
	}
	return f.ID
}

// sendMediaPreview sends a thumbnail and metadata info before the selection flow.
func (h *Handler) sendMediaPreview(ctx context.Context, chatID int64, info *domain.MediaInfo) {
	caption := info.Title
	if info.Uploader != "" || info.Duration > 0 {
		caption += "\n"
		if info.Uploader != "" {
			caption += fmt.Sprintf("Channel: %s", info.Uploader)
		}
		if info.Duration > 0 {
			if info.Uploader != "" {
				caption += " | "
			}
			caption += fmt.Sprintf("Duration: %s", formatDuration(info.Duration))
		}
	}

	if info.Thumbnail != "" {
		photo := &models.InputFileString{Data: info.Thumbnail}
		_, err := h.Bot.SendPhoto(ctx, &tgbot.SendPhotoParams{
			ChatID:  chatID,
			Photo:   photo,
			Caption: caption,
		})
		if err == nil {
			return
		}
		slog.Warn("send thumbnail failed, falling back to text", "error", err)
	}

	h.sendText(ctx, chatID, caption)
}

func formatDuration(seconds float64) string {
	if seconds <= 0 {
		return "0:00"
	}
	d := time.Duration(seconds) * time.Second
	h := int(d.Hours())
	m := int(math.Mod(d.Minutes(), 60))
	s := int(math.Mod(d.Seconds(), 60))
	if h > 0 {
		return fmt.Sprintf("%d:%02d:%02d", h, m, s)
	}
	return fmt.Sprintf("%d:%02d", m, s)
}