// Package library turns parsed file metadata into the relational tag
// model (artists, albums, songs, genres, credits) that both filesystem-
// style and ID3-style Subsonic browsing will read from in later phases.
package library

import (
	"database/sql"

	"git.noroutes.net/NoRoutes/vibetunes/internal/database"
	"git.noroutes.net/NoRoutes/vibetunes/internal/metadata"
)

// IndexFile creates or updates the songs row (and its album/artist/genre
// relations) for a scanned media file, given its parsed tags. It is
// idempotent: rerunning it for the same file converges to the same rows,
// reusing existing artist/album/genre IDs via their natural keys so IDs
// stay stable across rescans.
func IndexFile(db *sql.DB, mediaFile *database.MediaFile, absPath string, tags *metadata.Tags) (*database.Song, error) {
	title := tags.Title
	if title == "" {
		title = mediaFile.RelativePath
	}

	primaryArtistID, err := resolvePrimaryAlbumArtist(db, tags)
	if err != nil {
		return nil, err
	}

	var albumID sql.NullString
	if tags.Album != "" {
		album, err := database.FindOrCreateAlbum(db, tags.Album, primaryArtistID, tags.SortAlbum,
			intToNull(tags.Year), intToNull(tags.OriginalYear), tags.RecordLabel, tags.MusicBrainzAlbumID)
		if err != nil {
			return nil, err
		}
		albumID = sql.NullString{String: album.ID, Valid: true}

		if err := linkAlbumArtists(db, album.ID, tags, primaryArtistID); err != nil {
			return nil, err
		}
		for _, name := range tags.Genres {
			genre, err := database.FindOrCreateGenre(db, name)
			if err != nil {
				return nil, err
			}
			if err := database.LinkAlbumGenre(db, album.ID, genre.ID); err != nil {
				return nil, err
			}
		}
	}

	song, err := database.UpsertSong(db, database.UpsertSongInput{
		MediaFileID:            mediaFile.ID,
		AlbumID:                albumID,
		Title:                  title,
		SortTitle:              tags.SortTitle,
		TrackNumber:            intToNull(tags.TrackNumber),
		TrackTotal:             intToNull(tags.TrackTotal),
		DiscNumber:             intToNull(tags.DiscNumber),
		DiscTotal:              intToNull(tags.DiscTotal),
		DiscSubtitle:           tags.DiscSubtitle,
		Composer:               tags.Composer,
		Conductor:              tags.Conductor,
		Comment:                tags.Comment,
		ISRC:                   tags.ISRC,
		BPM:                    intToNull(tags.BPM),
		MusicBrainzTrackID:     tags.MusicBrainzTrackID,
		MusicBrainzRecordingID: tags.MusicBrainzRecordingID,
		ReplayGainTrackGainDB:  floatPtrToNull(tags.ReplayGainTrackGainDB),
		ReplayGainTrackPeak:    floatPtrToNull(tags.ReplayGainTrackPeak),
		ReplayGainAlbumGainDB:  floatPtrToNull(tags.ReplayGainAlbumGainDB),
		ReplayGainAlbumPeak:    floatPtrToNull(tags.ReplayGainAlbumPeak),
	})
	if err != nil {
		return nil, err
	}

	if err := database.ClearSongArtists(db, song.ID); err != nil {
		return nil, err
	}
	for i, name := range tags.Artists {
		artist, err := database.FindOrCreateArtist(db, name, "", "")
		if err != nil {
			return nil, err
		}
		if err := database.LinkSongArtist(db, song.ID, artist.ID, "artist", i); err != nil {
			return nil, err
		}
	}

	if err := database.ClearContributors(db, song.ID); err != nil {
		return nil, err
	}
	for i, c := range tags.Contributors {
		artist, err := database.FindOrCreateArtist(db, c.Name, "", "")
		if err != nil {
			return nil, err
		}
		if err := database.LinkContributor(db, song.ID, artist.ID, c.Role, i); err != nil {
			return nil, err
		}
	}

	if err := database.ClearSongGenres(db, song.ID); err != nil {
		return nil, err
	}
	for _, name := range tags.Genres {
		genre, err := database.FindOrCreateGenre(db, name)
		if err != nil {
			return nil, err
		}
		if err := database.LinkSongGenre(db, song.ID, genre.ID); err != nil {
			return nil, err
		}
	}

	if err := IndexLyrics(db, song.ID, absPath, tags.EmbeddedLyrics); err != nil {
		return nil, err
	}

	return song, nil
}

// resolvePrimaryAlbumArtist picks the artist an album groups under:
// the explicit album artist tag if present, otherwise the first
// performer credited on the track.
func resolvePrimaryAlbumArtist(db *sql.DB, tags *metadata.Tags) (sql.NullString, error) {
	name := tags.AlbumArtist
	sortName := tags.SortAlbumArtist
	if name == "" && len(tags.Artists) > 0 {
		name = tags.Artists[0]
	}
	if name == "" {
		return sql.NullString{}, nil
	}
	artist, err := database.FindOrCreateArtist(db, name, sortName, "")
	if err != nil {
		return sql.NullString{}, err
	}
	return sql.NullString{String: artist.ID, Valid: true}, nil
}

func linkAlbumArtists(db *sql.DB, albumID string, tags *metadata.Tags, primaryArtistID sql.NullString) error {
	if tags.AlbumArtist != "" {
		if primaryArtistID.Valid {
			return database.LinkAlbumArtist(db, albumID, primaryArtistID.String, 0)
		}
		return nil
	}
	// No explicit album artist: treat every track performer as an album artist.
	for i, name := range tags.Artists {
		artist, err := database.FindOrCreateArtist(db, name, "", "")
		if err != nil {
			return err
		}
		if err := database.LinkAlbumArtist(db, albumID, artist.ID, i); err != nil {
			return err
		}
	}
	return nil
}

func intToNull(n int) sql.NullInt64 {
	if n == 0 {
		return sql.NullInt64{}
	}
	return sql.NullInt64{Int64: int64(n), Valid: true}
}

func floatPtrToNull(f *float64) sql.NullFloat64 {
	if f == nil {
		return sql.NullFloat64{}
	}
	return sql.NullFloat64{Float64: *f, Valid: true}
}