// Package playback manages video playback, including episode sources and subtitle management.
package playback

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"io"
	"mal/integrations/jikan"
	"mal/internal/db"
	"mal/internal/domain"
	"mal/internal/observability"
	netutil "mal/pkg/net"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"github.com/google/uuid"
)

type playbackService struct {
	repo          domain.PlaybackRepository
	providers     []domain.Provider
	jikan         *jikan.Client
	episodes      domain.EpisodeService
	httpClient    *http.Client
	proxyTokenKey string
	proxyTokens   *proxyTokenStore
	auditSvc      domain.AuditService
}

type ProxyTokenKey string

func NewPlaybackService(repo domain.PlaybackRepository, providers []domain.Provider, jikan *jikan.Client, episodes domain.EpisodeService, auditSvc domain.AuditService, proxyTokenKey ProxyTokenKey) domain.PlaybackService {
	return &playbackService{
		repo:          repo,
		providers:     providers,
		jikan:         jikan,
		episodes:      episodes,
		auditSvc:      auditSvc,
		httpClient:    &http.Client{Timeout: 10 * time.Second},
		proxyTokenKey: string(proxyTokenKey),
		proxyTokens:   newProxyTokenStore(),
	}
}

func (s *playbackService) SignProxyToken(targetURL, referer, scope string) (string, error) {
	if s.proxyTokenKey == "" {
		return "", nil
	}
	return s.proxyTokens.create(targetURL, referer, scope, 2*time.Hour, time.Now())
}

func (s *playbackService) ResolveProxyToken(token string, scope string) (string, string, error) {
	if s.proxyTokenKey == "" {
		return "", "", fmt.Errorf("proxy token key not configured")
	}
	target, err := s.proxyTokens.resolve(token, time.Now())
	if err != nil {
		return "", "", err
	}
	if target.scope != scope {
		return "", "", fmt.Errorf("invalid proxy token scope")
	}
	return target.targetURL, target.referer, nil
}

func (s *playbackService) loadWatchProgress(ctx context.Context, userID string, animeID int, totalEpisodes int, episode string) (float64, string, []int64) {
	if userID == "" {
		return 0, "", nil
	}

	entry, err := s.repo.GetWatchListEntry(ctx, db.GetWatchListEntryParams{
		UserID:  userID,
		AnimeID: int64(animeID),
	})

	watchlistStatus := ""
	var watchlistIDs []int64
	startTime := 0.0
	if err == nil {
		watchlistStatus = entry.Status
		watchlistIDs = []int64{entry.AnimeID}
		if resumeTimeForEpisode(entry.CurrentEpisode, entry.CurrentTimeSeconds, totalEpisodes, episode) > 0 {
			startTime = entry.CurrentTimeSeconds
		}
	}

	if startTime > 0 {
		return startTime, watchlistStatus, watchlistIDs
	}

	cwEntry, err := s.repo.GetContinueWatchingEntry(ctx, db.GetContinueWatchingEntryParams{
		UserID:  userID,
		AnimeID: int64(animeID),
	})
	if err == nil {
		startTime = resumeTimeForEpisode(cwEntry.CurrentEpisode, cwEntry.CurrentTimeSeconds, totalEpisodes, episode)
	}

	return startTime, watchlistStatus, watchlistIDs
}

func resumeTimeForEpisode(currentEpisode sql.NullInt64, currentTimeSeconds float64, totalEpisodes int, requestedEpisode string) float64 {
	if !currentEpisode.Valid {
		return 0
	}

	if strconv.FormatInt(currentEpisode.Int64, 10) == requestedEpisode {
		return currentTimeSeconds
	}

	if totalEpisodes > 0 && requestedEpisode == strconv.Itoa(totalEpisodes) && currentEpisode.Int64 == int64(totalEpisodes) {
		return currentTimeSeconds
	}

	return 0
}

func (s *playbackService) CompleteAnime(ctx context.Context, userID string, animeID int64) error {
	if err := s.repo.InTx(ctx, func(txCtx context.Context, repo domain.PlaybackRepository) error {
		entry, err := repo.GetWatchListEntry(txCtx, db.GetWatchListEntryParams{
			UserID:  userID,
			AnimeID: animeID,
		})
		if err != nil || entry.Status != "completed" {
			_, err = repo.UpsertWatchListEntry(txCtx, db.UpsertWatchListEntryParams{
				ID:                 uuid.New().String(),
				UserID:             userID,
				AnimeID:            animeID,
				Status:             "completed",
				CurrentEpisode:     entry.CurrentEpisode,
				CurrentTimeSeconds: entry.CurrentTimeSeconds,
			})
			if err != nil {
				return err
			}
		}

		return nil
	}); err != nil {
		return err
	}

	if err := s.auditSvc.Record(ctx, domain.AuditEvent{
		UserID:       userID,
		Action:       "watch_completed",
		ResourceType: "anime",
		ResourceID:   strconv.FormatInt(animeID, 10),
	}); err != nil {
		observability.Warn(
			"audit_record_failed",
			"playback",
			"",
			map[string]any{"user_id": userID, "anime_id": animeID, "action": "watch_completed"},
			err,
		)
	}
	return nil
}

func (s *playbackService) SaveProgress(ctx context.Context, userID string, animeID int64, episode int, timeSeconds float64) error {
	_, err := s.repo.UpsertContinueWatchingEntry(ctx, db.UpsertContinueWatchingEntryParams{
		ID:                 uuid.New().String(),
		UserID:             userID,
		AnimeID:            animeID,
		CurrentEpisode:     sql.NullInt64{Int64: int64(episode), Valid: true},
		CurrentTimeSeconds: timeSeconds,
		DurationSeconds:    sql.NullFloat64{Valid: false},
	})
	if err != nil {
		return err
	}

	metadataBytes, marshalErr := json.Marshal(struct {
		Episode     int     `json:"episode"`
		TimeSeconds float64 `json:"time_seconds"`
	}{Episode: episode, TimeSeconds: timeSeconds})
	if marshalErr == nil {
		_ = s.auditSvc.Record(ctx, domain.AuditEvent{
			UserID:       userID,
			Action:       "watch_progress_saved",
			ResourceType: "anime",
			ResourceID:   strconv.FormatInt(animeID, 10),
			MetadataJSON: metadataBytes,
		})
	} else {
		_ = s.auditSvc.Record(ctx, domain.AuditEvent{
			UserID:       userID,
			Action:       "watch_progress_saved",
			ResourceType: "anime",
			ResourceID:   strconv.FormatInt(animeID, 10),
		})
	}
	observability.Info("watch_progress_saved", "playback", "", map[string]any{
		"anime_id":     animeID,
		"episode":      episode,
		"time_seconds": timeSeconds,
		"user_id":      userID,
	})
	return nil
}

func normalizeSkipType(skipType string) (string, error) {
	switch strings.ToLower(strings.TrimSpace(skipType)) {
	case "op", "opening", "intro":
		return "op", nil
	case "ed", "ending", "outro":
		return "ed", nil
	default:
		return "", fmt.Errorf("invalid skip_type")
	}
}

func (s *playbackService) UpsertSkipSegmentOverride(ctx context.Context, userID string, animeID int64, episode int, skipType string, startTime, endTime float64) error {
	if userID == "" {
		return fmt.Errorf("not authenticated")
	}
	if animeID <= 0 || episode <= 0 {
		return fmt.Errorf("invalid anime/episode")
	}
	t, err := normalizeSkipType(skipType)
	if err != nil {
		return err
	}
	if !(startTime >= 0) || !(endTime > startTime) {
		return fmt.Errorf("invalid interval")
	}
	// let the player-side filters ignore obviously wrong durations, but keep some sanity.
	if endTime-startTime < 5 || endTime-startTime > 10*60 {
		return fmt.Errorf("interval duration out of range")
	}
	return s.repo.UpsertSkipSegmentOverride(ctx, db.SkipSegmentOverrideRow{
		ID:        uuid.New().String(),
		UserID:    userID,
		AnimeID:   animeID,
		Episode:   int64(episode),
		SkipType:  t,
		StartTime: startTime,
		EndTime:   endTime,
	})
}

func (s *playbackService) fetchSkipSegments(ctx context.Context, userID string, malID int, episode string) []domain.SkipSegment {
	if malID <= 0 || strings.TrimSpace(episode) == "" {
		return []domain.SkipSegment{}
	}

	segments := s.fetchAniSkipSegments(ctx, malID, episode)
	return s.applySkipSegmentOverrides(ctx, segments, userID, malID, episode)
}

func (s *playbackService) warmStreamURL(targetURL, referer string) {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, targetURL, nil)
	if err != nil {
		return
	}
	if referer != "" {
		req.Header.Set("Referer", referer)
	}
	req.Header.Set("User-Agent", netutil.Firefox121)

	resp, err := s.httpClient.Do(req)
	if err != nil {
		return
	}
	_ = resp.Body.Close()
}

func (s *playbackService) fetchAniSkipSegments(ctx context.Context, malID int, episode string) []domain.SkipSegment {
	endpoint := fmt.Sprintf("https://api.aniskip.com/v1/skip-times/%s/%s?types=op&types=ed", url.PathEscape(strconv.Itoa(malID)), url.PathEscape(episode))
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
	if err != nil {
		return nil
	}
	req.Header.Set("User-Agent", netutil.Generic)

	resp, err := s.httpClient.Do(req)
	if err != nil {
		return nil
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode != http.StatusOK {
		return nil
	}

	body, err := io.ReadAll(io.LimitReader(resp.Body, netutil.KiB512))
	if err != nil {
		return nil
	}

	return parseAniSkipSegments(body)
}

func parseAniSkipSegments(body []byte) []domain.SkipSegment {
	type resultItem struct {
		SkipType string `json:"skip_type"`
		Interval struct {
			StartTime float64 `json:"start_time"`
			EndTime   float64 `json:"end_time"`
		} `json:"interval"`
	}
	type apiResponse struct {
		Found  bool         `json:"found"`
		Result []resultItem `json:"results"`
	}

	var parsed apiResponse
	if err := json.Unmarshal(body, &parsed); err != nil || !parsed.Found || len(parsed.Result) == 0 {
		return nil
	}

	segments := make([]domain.SkipSegment, 0, len(parsed.Result))
	for _, item := range parsed.Result {
		segments = append(segments, domain.SkipSegment{
			Type:   normalizeSkipSegmentLabel(item.SkipType),
			Start:  item.Interval.StartTime,
			End:    item.Interval.EndTime,
			Source: "aniskip",
		})
	}

	return segments
}

func normalizeSkipSegmentLabel(skipType string) string {
	switch strings.ToLower(strings.TrimSpace(skipType)) {
	case "op":
		return "opening"
	case "ed":
		return "ending"
	default:
		return strings.ToLower(strings.TrimSpace(skipType))
	}
}

func (s *playbackService) applySkipSegmentOverrides(ctx context.Context, segments []domain.SkipSegment, userID string, malID int, episode string) []domain.SkipSegment {
	epNum, err := strconv.ParseInt(strings.TrimSpace(episode), 10, 64)
	if userID == "" || err != nil || epNum <= 0 {
		return segments
	}

	ok, err := s.repo.HasSkipSegmentOverrideTable(ctx)
	if err != nil || !ok {
		return segments
	}

	overrides, err := s.repo.ListSkipSegmentOverrides(ctx, userID, int64(malID), epNum)
	if err != nil {
		return segments
	}

	overrideByType := buildOverrideSegments(overrides)
	if len(overrideByType) == 0 {
		return segments
	}

	return mergeSkipSegments(segments, overrideByType)
}

func buildOverrideSegments(overrides []db.SkipSegmentOverrideRow) map[string]domain.SkipSegment {
	byType := make(map[string]domain.SkipSegment, len(overrides))
	for _, override := range overrides {
		skipType, ok := normalizeOverrideSkipType(override.SkipType)
		if !ok {
			continue
		}

		byType[skipType] = domain.SkipSegment{
			Type:   skipType,
			Start:  override.StartTime,
			End:    override.EndTime,
			Source: "override",
		}
	}

	return byType
}

func normalizeOverrideSkipType(skipType string) (string, bool) {
	switch strings.ToLower(strings.TrimSpace(skipType)) {
	case "op", "opening", "intro":
		return "opening", true
	case "ed", "ending", "outro":
		return "ending", true
	default:
		return "", false
	}
}

func mergeSkipSegments(segments []domain.SkipSegment, overrides map[string]domain.SkipSegment) []domain.SkipSegment {
	merged := make([]domain.SkipSegment, 0, len(segments)+len(overrides))
	seen := make(map[string]bool, len(segments))

	for _, segment := range segments {
		if override, ok := overrides[segment.Type]; ok {
			merged = append(merged, override)
		} else {
			merged = append(merged, segment)
		}
		seen[segment.Type] = true
	}

	for skipType, override := range overrides {
		if !seen[skipType] {
			merged = append(merged, override)
		}
	}

	return merged
}