package router

import (
	"bookhoard/internal/database"
	"bookhoard/internal/handlers"
	"bookhoard/internal/services"
	"bookhoard/internal/sync"
	"bookhoard/internal/utils"
	"bookhoard/templates"
	"bytes"
	"encoding/json"
	"net/http"
	"strings"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgtype"
	"github.com/labstack/echo/v5"
)

func registerReaderRoutes(cfg *Config) {
	e := cfg.Echo

	// Create reader service and handler
	readerService := services.NewReaderService(cfg.Queries, cfg.Worker)
	cfg.ReaderHandler = handlers.NewReaderHandler(
		cfg.Queries,
		services.NewLibraryService(cfg.Queries),
		readerService,
		cfg.Worker,
	)

	jwtMiddleware := createJWTMiddleware(cfg)

	// Reader page routes (SSR + API)
	reader := e.Group("/readers", jwtMiddleware)

	// Reader page (SSR)
	reader.GET("/:mediaItemId", func(c *echo.Context) error {
		// Get user
		user, err := getTemplateUserWithTheme(c, cfg)
		if err != nil {
			return renderErrorPage(c, "Error loading user", "user_load_error")
		}
		// Parse mediaItemID
		mediaItemID := c.Param("mediaItemId")
		parsedUUID, err := uuid.Parse(mediaItemID)
		if err != nil {
			return renderErrorPage(c, "Invalid media item ID", "invalid_id")
		}
		// Fetch media item (directly, no handler)
		mediaItem, err := cfg.Queries.GetMediaItem(c.Request().Context(), pgtype.UUID{Bytes: parsedUUID, Valid: true})
		if err != nil {
			return renderErrorPage(c, "Media item not found", "not_found")
		}
		// Check library access (using pattern from opds.go)
		userUUID, _ := uuid.Parse(user.ID)
		libraries, err := cfg.Queries.GetUserVisibleLibraries(c.Request().Context(), uuidToPGType(userUUID))
		if err != nil {
			return renderErrorPage(c, "Failed to check access", "access_error")
		}

		visible := false
		for _, lib := range libraries {
			if lib.ID == mediaItem.LibraryID {
				visible = true
				break
			}
		}
		if !visible {
			return renderErrorPage(c, "Access denied", "access_denied")
		}
		// Library type decides comic reader treatment: fixed-layout items
		// (e.g. manga PDFs) shelved in comics/manga libraries are paged
		// through like comics — bookmarks only, no highlights or search.
		libraryWithType, err := cfg.Queries.GetLibraryWithType(c.Request().Context(), mediaItem.LibraryID)
		if err != nil {
			return renderErrorPage(c, "Failed to get library info", "library_error")
		}
		// Convert to template types. Reading state is deliberately NOT
		// fetched or embedded: the reader pulls position, bookmarks, and
		// annotations from the APIs at open time so the page can never
		// carry (nor write back) a stale snapshot.
		mediaUUID, _ := uuid.FromBytes(mediaItem.ID.Bytes[0:16])
		libUUID, _ := uuid.FromBytes(mediaItem.LibraryID.Bytes[0:16])
		metadata := templates.ReaderMetadata{
			MediaItemID: mediaUUID.String(),
			Title:       mediaItem.Title,
			Author:      utils.PgTextString(mediaItem.Author),
			// Sidecar covers store a raw library-relative path; resolve to
			// the cookie-authed /uploads URL (idempotent for items whose
			// stored value is already a servable path).
			CoverImagePath:   utils.ResolveMediaURL(mediaItem.LibraryID, mediaItem.CoverImagePath),
			LibraryType:      mediaItem.FormatGroup,
			MimeType:         utils.PgTextString(mediaItem.MimeType),
			FilePath:         mediaItem.FilePath,
			TotalPages:       int(mediaItem.PageCount.Int32),
			ChapterCount:     int(mediaItem.ChapterCount.Int32),
			FormatGroup:      mediaItem.FormatGroup,
			MangaType:        utils.PgTextString(mediaItem.MangaType),
			ReadingDirection: utils.PgTextString(mediaItem.ReadingDirection),
			LibraryID:        libUUID.String(),
			FileURL:          utils.ResolveMediaURL(mediaItem.LibraryID, pgtype.Text{String: mediaItem.FilePath, Valid: true}),
			TotalCharacters:  mediaItem.TotalCharacters.Int64,
			EstimatedPages:   sync.EstimatedPages(mediaItem.TotalCharacters.Int64),
			TreatAsComic:     handlers.ShouldTreatAsComic(libraryWithType.TypeName, mediaItem.FormatGroup),
			KeepScreenAwake:  user.KeepScreenAwake,
		}
		// Podcast chaining (plan D7): episodes render the audio reader
		// with sequence context — the neighboring DOWNLOADED episodes in
		// the caller's effective order (override applied). RLS already
		// scoped the episode read; the subscription predicate covers the
		// neighbors the same way. ?single=1 escapes chaining (the "play
		// single episode" affordance).
		if mediaItem.Source == "podcast_episode" && mediaItem.SourceFeedID.Valid && c.QueryParam("single") != "1" {
			userPG := uuidToPGType(userUUID)
			if seq := buildPodcastSequenceContext(c, cfg, &mediaItem, userPG, libraryWithType.TypeName); seq != nil {
				metadata.PodcastSequence = seq
			}
		}
		// Render template
		var buf bytes.Buffer
		// Audiobooks get the audio player page — the foliate document
		// engine is deliberately not involved (handoff item 3 Batch A).
		if mediaItem.FormatGroup == "audiobook" {
			err = templates.AudioReader(user, metadata).Render(c.Request().Context(), &buf)
		} else {
			err = templates.Reader(user, metadata).Render(c.Request().Context(), &buf)
		}
		if err != nil {
			return renderErrorPage(c, "Error rendering reader", "render_error")
		}
		return c.HTML(http.StatusOK, buf.String())
	})

	// Content serving (lazy-loaded pages)
	reader.GET("/:mediaItemId/pages/:pageNumber", cfg.ReaderHandler.GetPage)

	// Chapter metadata
	reader.GET("/:mediaItemId/chapters", cfg.ReaderHandler.GetChapters)

	// Panel data (comics/manga)
	reader.GET("/:mediaItemId/panels/:pageNumber", cfg.ReaderHandler.GetPanels)
	reader.PUT("/:mediaItemId/panels/:pageNumber", cfg.ReaderHandler.UpdatePanels)

	// PDF outline/TOC
	reader.GET("/:mediaItemId/outline", cfg.ReaderHandler.GetPDFOutline)

	// PDF thumbnails (for mini-map)
	reader.GET("/:mediaItemId/thumbnails/:pageNumber", cfg.ReaderHandler.GetPDFThumbnail)

	// Reading speed
	reader.GET("/:mediaItemId/reading-speed", cfg.ReaderHandler.GetReadingSpeed)
	reader.POST("/:mediaItemId/reading-speed", cfg.ReaderHandler.UpdateReadingSpeed)

	// Dictionary lookup
	reader.GET("/dictionary/:word", cfg.ReaderHandler.LookupWord)

	// Reader settings
	reader.GET("/settings", cfg.ReaderHandler.GetSettings)
	reader.PUT("/settings", cfg.ReaderHandler.UpdateSettings)
}

// buildPodcastSequenceContext computes the episode chain payload (plan
// D7): effective order — the D5 override applied, feed-native fallback —
// DOWNLOADED episodes only (gaps never enter the queue), the current
// episode's index, and prev/next reader URLs. RLS scopes the episode
// reads; non-subscribers never reach this path in the first place.
func buildPodcastSequenceContext(c *echo.Context, cfg *Config, item *database.MediaItems, userID pgtype.UUID, libraryType string) *templates.PodcastSequenceContext {
	ctx := c.Request().Context()
	// Queue override (plan item 2.3): ?queue=collection:<id> plays the
	// episode inside an Up Next collection chain. Absent/malformed/
	// not-owned ids fall back to the feed queue — the reader page must
	// never hard-fail on a stale link.
	if q := c.QueryParam("queue"); strings.HasPrefix(q, "collection:") {
		if collID, err := uuid.Parse(strings.TrimPrefix(q, "collection:")); err == nil {
			if seq := buildCollectionSequenceContext(c, cfg, item, userID, collID); seq != nil {
				return seq
			}
		}
	}
	eps, err := cfg.Queries.ListPodcastEpisodes(ctx, item.SourceFeedID)
	if err != nil || len(eps) == 0 {
		return nil
	}
	feed, err := cfg.Queries.GetPodcastFeed(ctx, item.SourceFeedID)
	if err != nil {
		return nil
	}

	// Effective order override (D5): reader_settings KV.
	order := "native"
	if row, err := cfg.Queries.GetUserSettingByKey(ctx, database.GetUserSettingByKeyParams{
		UserID:     userID,
		SettingKey: "podcast_order:" + uuid.UUID(item.SourceFeedID.Bytes).String(),
	}); err == nil {
		var v struct {
			Order string `json:"order"`
		}
		if json.Unmarshal(row, &v) == nil && services.ValidPodcastEpisodeOrder(v.Order) {
			order = v.Order
		}
	}

	type seqEp struct {
		id    string
		title string
		date  string
		pos   int32
	}
	ordered := make([]seqEp, 0, len(eps))
	currentID := uuid.UUID(item.ID.Bytes).String()
	for i := range eps {
		ep := eps[i]
		if ep.DownloadState != "downloaded" {
			continue // un-downloaded episodes are skipped, not tracked (invariant 6)
		}
		date := ""
		if ep.DatePublished.Valid {
			date = ep.DatePublished.Time.Format("2006-01-02")
		}
		ordered = append(ordered, seqEp{
			id:    uuid.UUID(ep.ID.Bytes).String(),
			title: ep.Title,
			date:  date,
			pos:   ep.FeedPosition.Int32,
		})
	}
	// Effective listening order (order consolidation §0 item 5a).
	services.OrderEpisodes(ordered, order,
		func(e seqEp) int32 { return e.pos },
		func(e seqEp) string { return e.date },
	)

	idx := -1
	for i, ep := range ordered {
		if ep.id == currentID {
			idx = i
			break
		}
	}
	if idx < 0 {
		return nil // current episode not downloaded (or not in sequence)
	}

	seq := &templates.PodcastSequenceContext{
		FeedURL:      "/podcasts/" + uuid.UUID(item.SourceFeedID.Bytes).String(),
		FeedTitle:    feed.Title,
		// R2: this producer is the feed queue. The player's order
		// control renders only for this source.
		Source:      "feed",
		FeedID:      uuid.UUID(item.SourceFeedID.Bytes).String(),
		Order:       order,
		EpisodeIndex: idx + 1,
		IndexTotal:   len(ordered),
	}
	if idx > 0 {
		seq.PrevURL = "/readers/" + ordered[idx-1].id
	}
	if idx < len(ordered)-1 {
		seq.NextURL = "/readers/" + ordered[idx+1].id
		seq.NextTitle = ordered[idx+1].title
	}
	return seq
}

// buildCollectionSequenceContext is the COLLECTION queue producer (plan
// item 2.3, §10 R2: same context shape, different owner). The queue is
// the collection's ordered downloaded episodes — the collection's
// order IS content (R1), so no feed-order override applies here and
// the player's order control stays hidden (source=collection).
// Ownership gates the chain: collections are user-scoped app state
// (no RLS on the table), and a foreign or deleted collection id falls
// back to the feed queue. Prev/next URLs carry ?queue=collection:<id>
// so the chain survives hops; backToDetail lands on the collection.
func buildCollectionSequenceContext(c *echo.Context, cfg *Config, item *database.MediaItems, userID pgtype.UUID, collID uuid.UUID) *templates.PodcastSequenceContext {
	ctx := c.Request().Context()
	owns, err := cfg.CollectionHandler.CollectionService().UserOwnsCollection(ctx, collID, uuid.UUID(userID.Bytes))
	if err != nil || !owns {
		return nil
	}
	coll, err := cfg.Queries.GetCollection(ctx, pgtype.UUID{Bytes: collID, Valid: true})
	if err != nil {
		return nil
	}
	// Smart collections compute their membership live (R1: computed
	// order, never written back) — evaluate the rules for THIS viewer
	// and chain the downloaded episode matches in native feed order
	// (R3: every listening order routes through OrderEpisodes).
	if services.IsCollectionSmart(coll) {
		return buildSmartCollectionSequenceContext(c, cfg, item, userID, coll)
	}
	// Downloaded episodes in collection order (SQL orders; RLS scopes
	// the join — unsubscribed feeds drop out and the chain skips them).
	eps, err := cfg.Queries.GetCollectionEpisodesOrdered(ctx, pgtype.UUID{Bytes: collID, Valid: true})
	if err != nil || len(eps) == 0 {
		return nil
	}

	currentID := uuid.UUID(item.ID.Bytes).String()
	idx := -1
	for i, ep := range eps {
		if uuid.UUID(ep.ID.Bytes).String() == currentID {
			idx = i
			break
		}
	}
	if idx < 0 {
		return nil // current episode not downloaded (or not in sequence)
	}

	queueParam := "?queue=collection:" + collID.String()
	seq := &templates.PodcastSequenceContext{
		FeedURL:      "/collections/" + collID.String(),
		FeedTitle:    coll.Name,
		Source:       "collection",
		EpisodeIndex: idx + 1,
		IndexTotal:   len(eps),
	}
	if idx > 0 {
		seq.PrevURL = "/readers/" + uuid.UUID(eps[idx-1].ID.Bytes).String() + queueParam
	}
	if idx < len(eps)-1 {
		seq.NextURL = "/readers/" + uuid.UUID(eps[idx+1].ID.Bytes).String() + queueParam
		seq.NextTitle = eps[idx+1].Title
	}
	return seq
}

// buildSmartCollectionSequenceContext chains a SMART collection's live
// membership (plan item 2.5 acceptance: "Daily Fiction" → Play =
// today's episodes back-to-back). The rules evaluate for the requesting
// user (mode from the collection; family lens via the visible set);
// episode matches that are downloaded chain in native feed order.
// Books and un-downloaded matches never enter the queue (invariant 6).
func buildSmartCollectionSequenceContext(c *echo.Context, cfg *Config, item *database.MediaItems, userID pgtype.UUID, coll database.Collections) *templates.PodcastSequenceContext {
	ctx := c.Request().Context()
	colService := cfg.CollectionHandler.CollectionService()
	visibleIDs, err := cfg.CollectionHandler.UserVisibleLibraryIDs(c)
	if err != nil {
		visibleIDs = nil
	}
	matches, err := colService.EvaluateSmartMembership(ctx, coll, services.SmartEvalOptions{
		VisibleIDs:   visibleIDs,
		MatchMode:    coll.RuleMatchMode,
		ViewerUserID: userID,
	})
	if err != nil {
		return nil
	}

	type seqEp struct {
		id    string
		title string
		date  string
		pos   int32
	}
	ordered := make([]seqEp, 0, len(matches))
	currentID := uuid.UUID(item.ID.Bytes).String()
	for _, m := range matches {
		if m.Source != "podcast_episode" || m.DownloadState != "downloaded" {
			continue
		}
		date := ""
		if m.DatePublished.Valid {
			date = m.DatePublished.Time.Format("2006-01-02")
		}
		ordered = append(ordered, seqEp{
			id:    uuid.UUID(m.ID.Bytes).String(),
			title: m.Title,
			date:  date,
			pos:   m.FeedPosition.Int32,
		})
	}
	if len(ordered) == 0 {
		return nil
	}
	services.OrderEpisodes(ordered, "native",
		func(e seqEp) int32 { return e.pos },
		func(e seqEp) string { return e.date },
	)

	idx := -1
	for i, ep := range ordered {
		if ep.id == currentID {
			idx = i
			break
		}
	}
	if idx < 0 {
		return nil
	}

	collID := uuid.UUID(coll.ID.Bytes).String()
	queueParam := "?queue=collection:" + collID
	seq := &templates.PodcastSequenceContext{
		FeedURL:      "/collections/" + collID,
		FeedTitle:    coll.Name,
		Source:       "collection",
		EpisodeIndex: idx + 1,
		IndexTotal:   len(ordered),
	}
	if idx > 0 {
		seq.PrevURL = "/readers/" + ordered[idx-1].id + queueParam
	}
	if idx < len(ordered)-1 {
		seq.NextURL = "/readers/" + ordered[idx+1].id + queueParam
		seq.NextTitle = ordered[idx+1].title
	}
	return seq
}