// Entry point for Plants vs Zombies game
document.addEventListener('DOMContentLoaded', () => {
  const startModal = document.getElementById('start-modal');
  const btnStart = document.getElementById('btn-start');

  const engine = new window.GameEngine('gameCanvas');

  function startGame() {
    if (startModal) {
      startModal.classList.add('hidden');
    }
    // Initialize Web Audio on user gesture
    if (window.PvZAudio) {
      window.PvZAudio.init();
    }
    engine.init();
  }

  if (btnStart) {
    btnStart.addEventListener('click', startGame);
  } else {
    startGame();
  }

  // Register PWA Service Worker for offline play
  if ('serviceWorker' in navigator) {
    window.addEventListener('load', () => {
      navigator.serviceWorker.register('./sw.js')
        .then((reg) => {
          console.log('PvZ ServiceWorker registered:', reg.scope);
        })
        .catch((err) => {
          console.warn('PvZ ServiceWorker registration failed:', err);
        });
    });
  }
});