// Entry point. Owns the frame loop, the button wiring, and the fallback for
// machines without WebGL.

import { Game } from './game.js';
import { Hud } from './hud.js';
import { Input } from './input.js';
import { AudioKit } from './audio.js';

const MAX_FRAME_DT = 1 / 20;

function hasWebGL() {
  try {
    const canvas = document.createElement('canvas');
    return !!(canvas.getContext('webgl2') || canvas.getContext('webgl'));
  } catch {
    return false;
  }
}

if (!hasWebGL()) {
  document.getElementById('unsupported').hidden = false;
  document.getElementById('menu').hidden = true;
} else {
  boot();
}

function boot() {
  const hud = new Hud();
  const input = new Input();
  const audio = new AudioKit();

  const game = new Game(document.getElementById('scene'), {
    hud,
    input,
    audio,
    onStateChange: () => {},
  });

  input.onFirstGesture = () => audio.unlock();

  const buttons = {
    start: document.getElementById('start-btn'),
    retry: document.getElementById('retry-btn'),
    resume: document.getElementById('resume-btn'),
  };

  buttons.start.addEventListener('click', () => {
    audio.ui();
    game.start();
  });
  buttons.retry.addEventListener('click', () => {
    audio.ui();
    game.restart();
  });
  buttons.resume.addEventListener('click', () => game.resume());

  // Enter starts and restarts, which is what a keyboard player expects from an
  // arcade game. Escape only goes back to the menu from the game over screen.
  addEventListener('keydown', (e) => {
    if (e.code === 'Enter' || e.code === 'NumpadEnter') {
      if (game.state === 'menu') game.start();
      else if (game.state === 'gameover') game.restart();
      else if (game.state === 'paused') game.resume();
    }
    if (e.code === 'Escape' && game.state === 'gameover') game.toMenu();
  });

  hud.show('menu');
  hud.showHud(false);

  let last = performance.now();
  function frame(now) {
    requestAnimationFrame(frame);
    const dt = Math.min(MAX_FRAME_DT, (now - last) / 1000);
    last = now;
    game.tick(dt);
    game.render();
  }
  requestAnimationFrame(frame);

  window.__game = game;
}