package musicbrainz

import (
	"context"
	"fmt"
	"time"

	"naviwatcher/internal/database"
)

// MBIDResolver resolves a MusicBrainz artist ID for an artist name.
// The real *MusicBrainzClient satisfies this interface.
type MBIDResolver interface {
	ResolveArtistMBID(ctx context.Context, name string) (string, error)
}

// ArtistDiscographySyncer syncs one artist's MusicBrainz discography into the
// external_releases table. The real implementation (musicbrainz.SyncArtistDiscography)
// is wrapped by discographySyncer so the concrete *MusicBrainzClient dependency
// is injectable in tests.
type ArtistDiscographySyncer interface {
	SyncArtistDiscography(ctx context.Context, db *database.DB, artistID, artistMBID string, ttl time.Duration) ([]database.ExternalRelease, error)
}

// discographySyncer adapts the package-level SyncArtistDiscography function to
// the ArtistDiscographySyncer interface, binding a concrete *MusicBrainzClient.
type discographySyncer struct {
	client *MusicBrainzClient
}

// NewDiscographySyncer wraps a *MusicBrainzClient as an ArtistDiscographySyncer.
func NewDiscographySyncer(client *MusicBrainzClient) ArtistDiscographySyncer {
	return &discographySyncer{client: client}
}

func (s *discographySyncer) SyncArtistDiscography(
	ctx context.Context,
	db *database.DB,
	artistID, artistMBID string,
	ttl time.Duration,
) ([]database.ExternalRelease, error) {
	return SyncArtistDiscography(ctx, s.client, db, artistID, artistMBID, ttl)
}

// AlbumSyncer copies each monitored artist's albums from Navidrome into the
// local_albums table. The real implementation (navidrome.SyncAlbums) is wrapped
// so the concrete *navidrome.NavidromeClient dependency is injectable in tests.
type AlbumSyncer interface {
	SyncAlbums(ctx context.Context, db *database.DB) error
}

// albumSyncer adapts navidrome.SyncAlbums to the AlbumSyncer interface.
type albumSyncer struct {
	syncAlbums func(ctx context.Context, db *database.DB) error
}

func (s *albumSyncer) SyncAlbums(ctx context.Context, db *database.DB) error {
	return s.syncAlbums(ctx, db)
}

// NewAlbumSyncer adapts the given SyncAlbums function (typically
// navidrome.SyncAlbums) into an AlbumSyncer for injection into SyncAll.
func NewAlbumSyncer(syncAlbums func(ctx context.Context, db *database.DB) error) AlbumSyncer {
	return &albumSyncer{syncAlbums: syncAlbums}
}

// SyncAll orchestrates the data pipeline for every monitored artist:
//  1. MusicBrainz artist-ID resolution — for each artist with no cached MBID,
//     resolve it by name and persist it on the artist_settings row. Artists that
//     already have an MBID reuse it (no extra rate-limited MusicBrainz call).
//  2. MusicBrainz discography sync into external_releases.
//  3. Navidrome album sync into local_albums.
//
// Ordering matters: Navidrome's artist/album tables are populated by the caller
// before SyncAll (via navidrome.SyncArtists / SyncAlbums as appropriate); here we
// focus on the per-artist MBID + discography + album refresh. Unmonitored artists
// are skipped.
//
// Resolution failures for a single artist are logged and skipped (the artist is
// left for the next sync) rather than aborting the whole run; the error is still
// returned so the caller can decide whether to surface it.
func SyncAll(
	ctx context.Context,
	db *database.DB,
	resolver MBIDResolver,
	discography ArtistDiscographySyncer,
	albums AlbumSyncer,
	ttl time.Duration,
) error {
	if err := ctx.Err(); err != nil {
		return fmt.Errorf("sync all: %w", err)
	}

	artists, err := database.GetAllArtistSettings(db)
	if err != nil {
		return fmt.Errorf("sync all: get artists: %w", err)
	}

	var resolutionErr error
	for _, artist := range artists {
		if err := ctx.Err(); err != nil {
			return fmt.Errorf("sync all: %w", err)
		}

		// Skip unmonitored artists entirely.
		if !artist.Monitored {
			continue
		}

		// Ensure we have an MBID; resolve and persist if missing.
		mbid := artist.MBID
		if mbid == "" {
			resolved, rerr := resolver.ResolveArtistMBID(ctx, artist.Name)
			if rerr != nil {
				// Skip this artist but remember the first resolution error.
				if resolutionErr == nil {
					resolutionErr = fmt.Errorf("resolve MBID for artist %q: %w", artist.Name, rerr)
				}
				continue
			}
			mbid = resolved
			if perr := database.UpdateArtistSettings(db, artist.ID, map[string]interface{}{"mbid": mbid}); perr != nil {
				if resolutionErr == nil {
					resolutionErr = fmt.Errorf("persist MBID for artist %q: %w", artist.Name, perr)
				}
				continue
			}
		}

		// Sync the artist's MusicBrainz discography.
		if _, derr := discography.SyncArtistDiscography(ctx, db, artist.ID, mbid, ttl); derr != nil {
			if resolutionErr == nil {
				resolutionErr = fmt.Errorf("sync discography for artist %q: %w", artist.Name, derr)
			}
			continue
		}
	}

	// Album sync operates over all monitored artists in one pass.
	if aerr := albums.SyncAlbums(ctx, db); aerr != nil {
		if resolutionErr == nil {
			resolutionErr = fmt.Errorf("sync albums: %w", aerr)
		}
	}

	return resolutionErr
}