package subsonic

import (
	"database/sql"
	"os"
	"path/filepath"
	"sort"
	"strconv"
	"strings"

	"git.noroutes.net/NoRoutes/vibetunes/internal/database"
	"git.noroutes.net/NoRoutes/vibetunes/internal/similarity"
	"git.noroutes.net/NoRoutes/vibetunes/internal/streaming"
)

func handleGetVideos(rc *Context) *apiError {
	db := rc.Server.DB
	files, err := database.ListVideoMediaFiles(db)
	if err != nil {
		return newError(ErrGeneric, err.Error())
	}
	out := &Videos{}
	for _, mf := range files {
		if canSee, cerr := UserCanSeeMediaFile(db, rc.User, mf); cerr != nil || !canSee {
			continue
		}
		song, serr := database.GetSongByMediaFileID(db, mf.ID)
		if serr != nil {
			continue
		}
		out.Video = append(out.Video, childFromSong(db, song, mf, albumOfSong(db, song), rc.User.ID))
	}
	rc.Response = newResponse()
	rc.Response.Videos = out
	return nil
}

// sidecarCaptionExtensions are checked next to a video file for a
// same-basename subtitle track — the common convention most media
// managers and players use (movie.mp4 + movie.srt/.vtt/.ass).
var sidecarCaptionExtensions = []string{".srt", ".vtt", ".ass"}

func findSidecarCaptions(videoAbsPath string) []string {
	dir := filepath.Dir(videoAbsPath)
	base := strings.TrimSuffix(filepath.Base(videoAbsPath), filepath.Ext(videoAbsPath))
	var found []string
	for _, ext := range sidecarCaptionExtensions {
		p := filepath.Join(dir, base+ext)
		if _, err := os.Stat(p); err == nil {
			found = append(found, p)
		}
	}
	return found
}

func handleGetVideoInfo(rc *Context) *apiError {
	id, aerr := rc.Params.Required("id")
	if aerr != nil {
		return aerr
	}
	db := rc.Server.DB
	song, err := database.GetSong(db, id)
	if err != nil {
		return errNotFound("Video")
	}
	mf, err := database.GetMediaFile(db, song.MediaFileID)
	if err != nil {
		return errNotFound("Video")
	}
	if canSee, cerr := UserCanSeeMediaFile(db, rc.User, mf); cerr != nil || !canSee {
		return errUnauthorized("video")
	}
	folder, err := database.GetMusicFolder(db, mf.MusicFolderID)
	if err != nil {
		return newError(ErrGeneric, err.Error())
	}
	absPath, perr := streaming.ResolvePath(folder.Path, mf.RelativePath)
	if perr != nil {
		return newError(ErrGeneric, perr.Error())
	}

	info := &VideoInfo{ID: id, AudioTrack: []AudioTrack{{ID: id, Name: "Default"}}}
	for i, capPath := range findSidecarCaptions(absPath) {
		info.Captions = append(info.Captions, Captions{ID: id + ":cap:" + strconv.Itoa(i), Name: filepath.Base(capPath)})
	}
	rc.Response = newResponse()
	rc.Response.VideoInfo = info
	return nil
}

// --- Artist/album info: local data only (title/name, and a
// MusicBrainz ID if one was tagged), optionally enriched from
// MusicBrainz/Cover Art Archive when VIBESONIC_ENABLE_EXTERNAL_METADATA
// is set and the entity has a tagged MusicBrainz ID — see enrich.go.
// VibeSonic must work completely offline; enrichment is always
// best-effort and never blocks or fails the response. ---

func handleGetArtistInfo(rc *Context) *apiError {
	id, aerr := rc.Params.Required("id")
	if aerr != nil {
		return aerr
	}
	rc.Response = newResponse()
	rc.Response.ArtistInfo = &ArtistInfo{ArtistInfoBase: artistInfoBase(rc, id)}
	return nil
}

func handleGetArtistInfo2(rc *Context) *apiError {
	id, aerr := rc.Params.Required("id")
	if aerr != nil {
		return aerr
	}
	rc.Response = newResponse()
	rc.Response.ArtistInfo2 = &ArtistInfo2{ArtistInfoBase: artistInfoBase(rc, id)}
	return nil
}

func handleGetAlbumInfo(rc *Context) *apiError {
	id, aerr := rc.Params.Required("id")
	if aerr != nil {
		return aerr
	}
	rc.Response = newResponse()
	rc.Response.AlbumInfo = albumInfo(rc, id)
	return nil
}

func handleGetAlbumInfo2(rc *Context) *apiError {
	id, aerr := rc.Params.Required("id")
	if aerr != nil {
		return aerr
	}
	rc.Response = newResponse()
	rc.Response.AlbumInfo = albumInfo(rc, id)
	return nil
}

// --- Similar/top songs: a real, local, genre-based heuristic rather
// than a fabricated or hardcoded list. ---

func handleGetSimilarSongs(rc *Context) *apiError {
	id, aerr := rc.Params.Required("id")
	if aerr != nil {
		return aerr
	}
	count := rc.Params.Int("count", 50)
	db := rc.Server.DB

	songs, serr := similarSongsFor(db, id, count)
	if serr != nil {
		return errNotFound("Item")
	}
	out := &SimilarSongs{}
	for _, s := range songs {
		mf, merr := database.GetMediaFile(db, s.MediaFileID)
		if merr != nil {
			continue
		}
		out.Song = append(out.Song, childFromSong(db, s, mf, albumOfSong(db, s), rc.User.ID))
	}
	rc.Response = newResponse()
	rc.Response.SimilarSongs = out
	return nil
}

func handleGetSimilarSongs2(rc *Context) *apiError {
	id, aerr := rc.Params.Required("id")
	if aerr != nil {
		return aerr
	}
	count := rc.Params.Int("count", 50)
	db := rc.Server.DB

	// id here names an artist (ID3 context).
	songs, err := database.SimilarSongsByArtist(db, id, count)
	if err != nil {
		return newError(ErrGeneric, err.Error())
	}
	out := &SimilarSongs2{}
	for _, s := range songs {
		mf, merr := database.GetMediaFile(db, s.MediaFileID)
		if merr != nil {
			continue
		}
		out.Song = append(out.Song, childFromSong(db, s, mf, albumOfSong(db, s), rc.User.ID))
	}
	rc.Response = newResponse()
	rc.Response.SimilarSongs2 = out
	return nil
}

// similarSongsFor resolves id as a song, album, or artist (getSimilarSongs's
// "id" can be any of the three in real Subsonic usage), finds
// genre-similar songs for it, and — when the seed song has been sonic-
// analyzed — re-ranks that genre-matched candidate set by actual sonic
// distance rather than leaving it in the database's random order. This
// never replaces the genre filter with pure sonic search (that's what
// getSonicSimilarTracks is for); it just makes "similar" among
// genre-mates mean something more concrete when the data exists to
// back it up.
func similarSongsFor(db *sql.DB, id string, count int) ([]*database.Song, error) {
	if song, err := database.GetSong(db, id); err == nil {
		songs, err := database.SimilarSongsByGenre(db, song.ID, count)
		if err != nil {
			return nil, err
		}
		return reorderBySonicSimilarity(db, song.ID, songs), nil
	}
	if _, err := database.GetAlbum(db, id); err == nil {
		songs, err := database.ListSongsByAlbum(db, id)
		if err != nil || len(songs) == 0 {
			return nil, err
		}
		similar, err := database.SimilarSongsByGenre(db, songs[0].ID, count)
		if err != nil {
			return nil, err
		}
		return reorderBySonicSimilarity(db, songs[0].ID, similar), nil
	}
	if _, err := database.GetArtist(db, id); err == nil {
		return database.SimilarSongsByArtist(db, id, count)
	}
	return nil, database.ErrNotFound
}

// reorderBySonicSimilarity sorts songs by real sonic distance from
// seedSongID when both the seed and (some of) the candidates have
// stored audio_features; candidates without analysis data are left in
// their existing relative order at the end, never dropped and never
// assigned a fabricated distance.
func reorderBySonicSimilarity(db *sql.DB, seedSongID string, songs []*database.Song) []*database.Song {
	if len(songs) < 2 {
		return songs
	}
	seed, err := database.GetAudioFeatures(db, seedSongID)
	if err != nil || seed == nil {
		return songs
	}

	items := []similarity.Item{{ID: seedSongID, Vector: seed.Vector()}}
	analyzed := map[string]bool{}
	for _, s := range songs {
		f, err := database.GetAudioFeatures(db, s.ID)
		if err != nil || f == nil {
			continue
		}
		items = append(items, similarity.Item{ID: s.ID, Vector: f.Vector()})
		analyzed[s.ID] = true
	}
	if len(items) < 2 {
		return songs
	}
	idx := similarity.Build(items)

	sorted := make([]*database.Song, len(songs))
	copy(sorted, songs)
	sort.SliceStable(sorted, func(i, j int) bool {
		ai, aj := analyzed[sorted[i].ID], analyzed[sorted[j].ID]
		if ai != aj {
			return ai // analyzed songs sort before unanalyzed ones
		}
		if !ai {
			return false // preserve relative order among unanalyzed songs
		}
		return idx.DistanceBetween(seedSongID, sorted[i].ID) < idx.DistanceBetween(seedSongID, sorted[j].ID)
	})
	return sorted
}

func handleGetTopSongs(rc *Context) *apiError {
	count := rc.Params.Int("count", 50)
	db := rc.Server.DB

	// topSongsByArtistId: an explicit artist ID (the canonical internal
	// ID, same as everywhere else) takes priority over the legacy
	// name-based lookup when both are given, since it's unambiguous
	// where a name match can collide.
	var artistID string
	if id := rc.Params.Get("id"); id != "" {
		artist, err := database.GetArtist(db, id)
		if err != nil {
			rc.Response = newResponse()
			rc.Response.TopSongs = &TopSongs{}
			return nil
		}
		artistID = artist.ID
	} else {
		artistName, aerr := rc.Params.Required("artist")
		if aerr != nil {
			return aerr
		}
		artist, err := database.FindArtistByName(db, artistName)
		if err != nil {
			rc.Response = newResponse()
			rc.Response.TopSongs = &TopSongs{}
			return nil
		}
		artistID = artist.ID
	}

	songs, err := database.TopSongsByArtist(db, artistID, count)
	if err != nil {
		return newError(ErrGeneric, err.Error())
	}
	out := &TopSongs{}
	for _, s := range songs {
		mf, merr := database.GetMediaFile(db, s.MediaFileID)
		if merr != nil {
			continue
		}
		out.Song = append(out.Song, childFromSong(db, s, mf, albumOfSong(db, s), rc.User.ID))
	}
	rc.Response = newResponse()
	rc.Response.TopSongs = out
	return nil
}