const { ipcRenderer } = require('electron');

const POLL_INTERVAL_MS = 3000;
let lastSent = null;

function scrapeNowPlaying() {
  const titleEl =
    document.querySelector('ytmusic-player-bar .title') ||
    document.querySelector('.ytmusic-player-bar .title');
  const title = titleEl ? titleEl.textContent.trim() : null;

  const bylineEl =
    document.querySelector('ytmusic-player-bar .byline') ||
    document.querySelector('.ytmusic-player-bar .byline');
  const artist = bylineEl ? bylineEl.textContent.trim() : null;

  const artImg =
    document.querySelector('ytmusic-player-bar .middle-controls .thumbnail-image-wrapper img') ||
    document.querySelector('ytmusic-player-bar .image img') ||
    document.querySelector('ytmusic-player-bar img.image');
  const albumArt = artImg ? artImg.src : null;

  // The play/pause button's title indicates state: when music is playing the
  // button's action is "Pause", and vice versa.
  const playPauseBtn = document.querySelector('#play-pause-button');
  let isPlaying = false;
  if (playPauseBtn) {
    const btnTitle = (
      playPauseBtn.getAttribute('title') ||
      playPauseBtn.getAttribute('aria-label') ||
      ''
    ).toLowerCase();
    isPlaying = btnTitle.includes('pause');
  }

  if (!title) return null;
  return { title, artist, albumArt, isPlaying };
}

function changed(a, b) {
  if (a === null && b === null) return false;
  if (a === null || b === null) return true;
  return (
    a.title !== b.title ||
    a.artist !== b.artist ||
    a.albumArt !== b.albumArt ||
    a.isPlaying !== b.isPlaying
  );
}

function poll() {
  const data = scrapeNowPlaying();
  if (!changed(data, lastSent)) return;
  lastSent = data;
  ipcRenderer.send('wtm:state', data || { isPlaying: false });
}

setInterval(poll, POLL_INTERVAL_MS);
poll();

console.log('[wtm] yt-scraper preload loaded');