package navidrome

import (
	"context"
	"errors"
	"fmt"

	"naviwatcher/internal/database"
)

// SyncAlbums fetches all albums from Navidrome for each monitored artist and
// stores them in the local_albums table. For each artist, existing local albums
// are deleted before inserting the fresh set, so the table always reflects the
// current Navidrome state. Unmonitored artists are skipped.
// Context cancellation is checked before each artist's album fetch.
func SyncAlbums(ctx context.Context, client *NavidromeClient, db *database.DB) error {
	if err := ctx.Err(); err != nil {
		return fmt.Errorf("sync albums: %w", err)
	}

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

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

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

		albums, err := client.GetArtistAlbums(artist.ID)
		if err != nil {
			return fmt.Errorf("sync albums: get albums for artist %s: %w", artist.ID, err)
		}

		// Delete existing albums for this artist and insert fresh set within
		// a transaction to prevent partial sync state on failure.
		tx, err := db.Begin()
		if err != nil {
			return fmt.Errorf("sync albums: begin transaction for artist %s: %w", artist.ID, err)
		}
		if err := database.DeleteLocalAlbumsByArtistTx(tx, artist.ID); err != nil {
			tx.Rollback()
			return fmt.Errorf("sync albums: delete existing for artist %s: %w", artist.ID, err)
		}

		for _, album := range albums {
			if err := ctx.Err(); err != nil {
				tx.Rollback()
				return fmt.Errorf("sync albums: %w", err)
			}

			localAlbum := &database.LocalAlbum{
				ID:       album.ID,
				ArtistID: artist.ID,
				Title:    album.Name,
			}
			if err := database.SaveLocalAlbumTx(tx, localAlbum); err != nil {
				tx.Rollback()
				return fmt.Errorf("sync albums: save album %s: %w", album.ID, err)
			}
		}
		if err := tx.Commit(); err != nil {
			return fmt.Errorf("sync albums: commit for artist %s: %w", artist.ID, err)
		}
	}

	return nil
}

// SyncArtists fetches all artists from Navidrome and upserts them into the
// local artist_settings table. New artists are inserted with monitored=true.
// Existing artists have their name refreshed but their monitored/ignore
// settings are preserved.
// Context cancellation is checked before the API call and between individual
// artist upserts.
func SyncArtists(ctx context.Context, client *NavidromeClient, db *database.DB) error {
	// Check context before making the API call.
	if err := ctx.Err(); err != nil {
		return fmt.Errorf("sync artists: %w", err)
	}

	artists, err := client.GetArtists()
	if err != nil {
		return fmt.Errorf("sync artists: %w", err)
	}

	for _, artist := range artists {
		// Check context cancellation between each upsert to allow
		// graceful interruption on large libraries.
		if err := ctx.Err(); err != nil {
			return fmt.Errorf("sync artists: %w", err)
		}

		// Preserve existing user settings (monitored, ignore_singles,
		// ignore_compilations) if the row already exists.
		settings := &database.ArtistSettings{
			ID:        artist.ID,
			Name:      artist.Name,
			Monitored: true,
		}
		existing, err := database.GetArtistSettings(db, artist.ID)
		if err == nil {
			settings.MBID = existing.MBID
			settings.Monitored = existing.Monitored
			settings.IgnoreSingles = existing.IgnoreSingles
			settings.IgnoreCompilations = existing.IgnoreCompilations
			settings.LastSynced = existing.LastSynced
		} else if !errors.Is(err, database.ErrArtistNotFound) {
			return fmt.Errorf("sync artists: get settings for artist %s: %w", artist.ID, err)
		}

		if err := database.SaveArtistSettings(db, settings); err != nil {
			return fmt.Errorf("sync artists: save artist %s: %w", artist.ID, err)
		}
	}

	return nil
}