import {
  player,
  togglePlay,
  skipNext,
  skipPrev,
  seekTo
} from './store.svelte';

export function useMediaSession(): void {
  if (typeof navigator === 'undefined' || !('mediaSession' in navigator)) return;
  const ms = navigator.mediaSession;

  $effect(() => {
    const t = player.current;
    if (!t) {
      ms.metadata = null;
      return;
    }
    ms.metadata = new MediaMetadata({
      title: t.title,
      artist: t.artist_name,
      album: t.album_title,
      artwork: [{
        src: `/api/albums/${t.album_id}/cover`,
        sizes: '512x512',
        type: 'image/jpeg'
      }]
    });
  });

  ms.setActionHandler('play',  () => togglePlay());
  ms.setActionHandler('pause', () => togglePlay());
  ms.setActionHandler('previoustrack', () => skipPrev());
  ms.setActionHandler('nexttrack',     () => skipNext());
  ms.setActionHandler('seekto', (e) => {
    if (typeof e.seekTime === 'number') seekTo(e.seekTime);
  });

  $effect(() => {
    if (player.duration > 0 && 'setPositionState' in ms) {
      try {
        ms.setPositionState({
          duration: player.duration,
          position: Math.min(player.position, player.duration),
          playbackRate: 1
        });
      } catch {
        // setPositionState can throw on NaN/Infinity briefly between tracks.
      }
    }
  });

  $effect(() => {
    ms.playbackState = player.isPlaying ? 'playing' : 'paused';
  });
}