// narrator.js — 旁白系统
// 全程语音播报：场景描述、操作提示、状态反馈。
// 这是无障碍核心：玩家闭眼也能完全掌握游戏状态。

const Narrator = (() => {
  let _voice   = null;
  let _busy    = false;
  let _queue   = [];      // [{ text, resolve }]
  let _repTimer = null;
  let _repFn    = null;

  // ── 初始化：找最佳中文语音 ──
  function init() {
    return new Promise(resolve => {
      if (!window.speechSynthesis) { resolve(); return; }
      const load = () => {
        const vs = speechSynthesis.getVoices();
        _voice = vs.find(v => v.lang === 'zh-CN')
              || vs.find(v => v.lang.startsWith('zh'))
              || vs[0] || null;
        resolve();
      };
      if (speechSynthesis.getVoices().length > 0) load();
      else speechSynthesis.addEventListener('voiceschanged', load, { once: true });
    });
  }

  // ── 底层单句播放 ──
  function _speak(text) {
    return new Promise(resolve => {
      if (!window.speechSynthesis) { resolve(); return; }
      const u = new SpeechSynthesisUtterance(text);
      u.lang   = 'zh-CN';
      u.rate   = 0.88;
      u.pitch  = 1.0;
      u.volume = 1.0;
      if (_voice) u.voice = _voice;
      u.onend  = resolve;
      u.onerror = resolve;
      speechSynthesis.speak(u);
    });
  }

  // ── 推进队列 ──
  async function _next() {
    if (_busy || _queue.length === 0) return;
    _busy = true;
    const item = _queue.shift();
    dbg(`[N] ${item.text.slice(0, 40)}`);
    await _speak(item.text);
    _busy = false;
    if (item.resolve) item.resolve();
    _next();
  }

  // ── 排队说（fire-and-forget）──
  function say(text, onDone) {
    _queue.push({ text, resolve: onDone || null });
    _next();
  }

  // ── 说完再继续（await 用）──
  function sayAndWait(text) {
    return new Promise(resolve => {
      _queue.push({ text, resolve });
      _next();
    });
  }

  // ── 立刻打断当前语音，说新内容 ──
  function interrupt(text, onDone) {
    if (window.speechSynthesis) speechSynthesis.cancel();
    _queue = [];
    _busy  = false;
    say(text, onDone);
  }

  // ── 宣告操作选项 + 每12秒自动重复 ──
  function options(tapLabel, dtLabel) {
    clearTimeout(_repTimer);
    let tip = '';
    if (tapLabel && dtLabel) tip = `单击${tapLabel}，双击${dtLabel}。`;
    else if (tapLabel)       tip = `单击${tapLabel}。`;
    else if (dtLabel)        tip = `双击${dtLabel}。`;

    _repFn = () => {
      interrupt(`——还在等你。${tip}`);
      _repTimer = setTimeout(_repFn, 14000);
    };
    say(tip);
    _repTimer = setTimeout(_repFn, 14000);
  }

  // ── 清除重复定时器（选择后调用）──
  function clearOptions() {
    clearTimeout(_repTimer);
    _repFn = null;
  }

  // ── 停止一切 ──
  function stop() {
    if (window.speechSynthesis) speechSynthesis.cancel();
    _queue = [];
    _busy  = false;
    clearOptions();
  }

  return { init, say, sayAndWait, interrupt, options, clearOptions, stop };
})();