const DAILY_GOAL = 5,
  ROUND_SIZE = 5;

// === AUDIO with mobile unlock ===
var AudioCtx = window.AudioContext || window.webkitAudioContext;
var audioCtx = null,
  audioUnlocked = false;
function unlockAudio() {
  if (audioUnlocked || !audioCtx) return;
  var buf = audioCtx.createBuffer(1, 1, 22050);
  var src = audioCtx.createBufferSource();
  src.buffer = buf;
  src.connect(audioCtx.destination);
  src.start(0);
  if (audioCtx.state === "suspended") audioCtx.resume();
  audioUnlocked = true;
}
function ensureAudio() {
  if (!audioCtx) audioCtx = new AudioCtx();
  unlockAudio();
}
document.addEventListener(
  "touchstart",
  function () {
    ensureAudio();
  },
  { once: true },
);
document.addEventListener(
  "click",
  function () {
    ensureAudio();
  },
  { once: true },
);
function playTone(f, d, t, v) {
  if (!state.sound) return;
  t = t || "sine";
  v = v || 0.3;
  try {
    ensureAudio();
    var o = audioCtx.createOscillator(),
      g = audioCtx.createGain();
    o.type = t;
    o.frequency.value = f;
    g.gain.setValueAtTime(v, audioCtx.currentTime);
    g.gain.exponentialRampToValueAtTime(0.001, audioCtx.currentTime + d);
    o.connect(g);
    g.connect(audioCtx.destination);
    o.start();
    o.stop(audioCtx.currentTime + d);
  } catch (e) {}
}
function sfxCorrect() {
  playTone(523, 0.12);
  setTimeout(function () {
    playTone(659, 0.12);
  }, 80);
  setTimeout(function () {
    playTone(784, 0.2);
  }, 160);
}
function sfxWrong() {
  playTone(200, 0.15, "square", 0.2);
  setTimeout(function () {
    playTone(160, 0.2, "square", 0.2);
  }, 120);
}
function sfxClick() {
  playTone(440, 0.06, "sine", 0.15);
}
function sfxCombo() {
  playTone(523, 0.1);
  setTimeout(function () {
    playTone(659, 0.1);
  }, 60);
  setTimeout(function () {
    playTone(784, 0.1);
  }, 120);
  setTimeout(function () {
    playTone(1047, 0.25);
  }, 180);
}
function sfxComplete() {
  [523, 587, 659, 784, 1047].forEach(function (n, i) {
    setTimeout(function () {
      playTone(n, 0.2, "sine", 0.25);
    }, i * 100);
  });
}

// === STATE ===
const APP_VERSION = 2;
var state = {
  sound: true,
  theme: "ink",
  difficulty: 1,
  score: 0,
  combo: 0,
  maxCombo: 0,
  todayCount: 0,
  totalCount: 0,
  streak: 0,
  checkinDays: [],
  round: 0,
  roundResults: [],
  currentIdiom: null,
  blankIndices: [],
  selectedBlank: -1,
  filledChars: {},
  hintUsed: false,
  answered: false,
  usedIdiomIndices: {},
  wrongBook: [],
  reviewMode: false,
};
var currentOptions = [];
function getToday() {
  return new Date().toISOString().slice(0, 10);
}
function saveState() {
  localStorage.setItem(
    "chengyu_s",
    JSON.stringify({
      sound: state.sound,
      theme: state.theme,
      difficulty: state.difficulty,
      totalCount: state.totalCount,
      streak: state.streak,
      checkinDays: state.checkinDays,
      maxCombo: state.maxCombo,
    }),
  );
}
function saveWrongBook() {
  localStorage.setItem("chengyu_wb", JSON.stringify(state.wrongBook));
}
function loadWrongBook() {
  try {
    state.wrongBook = JSON.parse(localStorage.getItem("chengyu_wb") || "[]");
  } catch (e) {
    state.wrongBook = [];
  }
}
function addToWrongBook(idiom) {
  var ex = null;
  for (var i = 0; i < state.wrongBook.length; i++) {
    if (state.wrongBook[i].w === idiom.w) {
      ex = state.wrongBook[i];
      break;
    }
  }
  if (ex) {
    ex.count++;
    ex.last = getToday();
  } else {
    state.wrongBook.push({
      w: idiom.w,
      p: idiom.p,
      e: idiom.e,
      l: idiom.l,
      count: 1,
      last: getToday(),
    });
  }
  saveWrongBook();
  renderWbBadge();
}
function removeFromWrongBook(w) {
  state.wrongBook = state.wrongBook.filter(function (x) {
    return x.w !== w;
  });
  saveWrongBook();
  renderWbBadge();
}
function renderWbBadge() {
  var b = document.getElementById("wbBadge");
  if (!b) return;
  b.textContent = state.wrongBook.length;
  b.className = "wb-badge" + (state.wrongBook.length === 0 ? " empty" : "");
}
function showWrongBookModal() {
  document.getElementById("wrongBookModal").classList.add("show");
  document.getElementById("wbCount").textContent = state.wrongBook.length;
  var list = document.getElementById("wbList");
  var startBtn = document.getElementById("btnStartReview");
  if (!state.wrongBook.length) {
    list.innerHTML = '<div class="wb-empty">🎉 暂无错题，梅子很棒！</div>';
    startBtn.style.display = "none";
  } else {
    startBtn.style.display = "";
    list.innerHTML = "";
    var sorted = state.wrongBook.slice().sort(function (a, b) {
      return b.count - a.count;
    });
    sorted.forEach(function (item) {
      var d = document.createElement("div");
      d.className = "wb-item";
      d.innerHTML =
        '<div class="wb-word">' +
        item.w +
        '</div><div class="wb-pinyin">' +
        item.p +
        '</div><div class="wb-explain">' +
        item.e +
        '</div><div class="wb-meta">错误 ' +
        item.count +
        " 次</div>";
      list.appendChild(d);
    });
  }
}
function startReview() {
  document.getElementById("wrongBookModal").classList.remove("show");
  state.reviewMode = true;
  state.usedIdiomIndices = {};
  startRound();
}
function checkWhatsNew() {
  var v = parseInt(localStorage.getItem("chengyu_v") || "0");
  if (v < APP_VERSION) {
    document.getElementById("whatsNewModal").classList.add("show");
  }
}
function saveTodayState() {
  localStorage.setItem(
    "chengyu_t",
    JSON.stringify({
      d: getToday(),
      s: state.score,
      c: state.todayCount,
      cb: state.combo,
    }),
  );
}
function loadState() {
  try {
    var s = JSON.parse(localStorage.getItem("chengyu_s") || "{}");
    state.sound = s.sound !== undefined ? s.sound : true;
    state.theme = s.theme || "ink";
    state.totalCount = s.totalCount || 0;
    state.streak = s.streak || 0;
    state.checkinDays = s.checkinDays || [];
    state.maxCombo = s.maxCombo || 0;
    state.difficulty = s.difficulty || 1;
    var t = JSON.parse(localStorage.getItem("chengyu_t") || "{}");
    if (t.d === getToday()) {
      state.score = t.s || 0;
      state.todayCount = t.c || 0;
      state.combo = t.cb || 0;
    }
    updateStreak();
  } catch (e) {}
}
function updateStreak() {
  var today = getToday(),
    days = state.checkinDays;
  if (!days.length) {
    state.streak = 0;
    return;
  }
  var sorted = days.slice().sort().reverse();
  var streak = 0,
    cd = new Date(today + "T00:00:00");
  if (sorted[0] === today) {
    for (var i = 0; i < sorted.length; i++) {
      var e = new Date(cd);
      e.setDate(e.getDate() - i);
      if (sorted[i] === e.toISOString().slice(0, 10)) streak++;
      else break;
    }
  } else {
    var y = new Date(cd);
    y.setDate(y.getDate() - 1);
    var ys = y.toISOString().slice(0, 10);
    if (sorted[0] === ys) {
      for (var i = 0; i < sorted.length; i++) {
        var e = new Date(y);
        e.setDate(e.getDate() - i);
        if (sorted[i] === e.toISOString().slice(0, 10)) streak++;
        else break;
      }
    }
  }
  state.streak = streak;
}
function tryCheckin() {
  var t = getToday();
  if (state.todayCount >= DAILY_GOAL && state.checkinDays.indexOf(t) === -1) {
    state.checkinDays.push(t);
    if (state.checkinDays.length > 60)
      state.checkinDays = state.checkinDays.slice(-60);
    updateStreak();
    saveState();
    return true;
  }
  return false;
}

// === GAME LOGIC ===
function pickIdiom() {
  if (state.reviewMode && state.wrongBook.length) {
    var pool = state.wrongBook.filter(function (x) {
      return !state.usedIdiomIndices[x.w];
    });
    if (!pool.length) {
      state.usedIdiomIndices = {};
      pool = state.wrongBook.slice();
    }
    var item = pool[Math.floor(Math.random() * pool.length)];
    state.usedIdiomIndices[item.w] = 1;
    return item;
  }
  var pool = IDIOMS.filter(function (i) {
    return i.l <= state.difficulty && !state.usedIdiomIndices[i.w];
  });
  if (!pool.length) {
    state.usedIdiomIndices = {};
    pool = IDIOMS.filter(function (i) { return i.l <= state.difficulty; });
  }
  var item = pool[Math.floor(Math.random() * pool.length)];
  state.usedIdiomIndices[item.w] = 1;
  return item;
}
function generateBlanks(w, d) {
  var n = d === 1 ? 1 : d === 2 ? 2 : 3;
  var idx = [0, 1, 2, 3];
  for (var i = 3; i > 0; i--) {
    var j = Math.floor(Math.random() * (i + 1));
    var tmp = idx[i];
    idx[i] = idx[j];
    idx[j] = tmp;
  }
  return idx.slice(0, n).sort();
}
function generateOptions(idiom, blanks) {
  var correct = blanks.map(function (i) {
    return idiom.w[i];
  });
  var decoyN = blanks.length <= 1 ? 3 : blanks.length === 2 ? 4 : 5;
  var allC = {};
  IDIOMS.forEach(function (it) {
    for (var i = 0; i < it.w.length; i++) allC[it.w[i]] = 1;
  });
  var pool = Object.keys(allC).filter(function (c) {
    return correct.indexOf(c) === -1;
  });
  var decoys = [],
    used = {};
  correct.forEach(function (c) {
    used[c] = 1;
  });
  while (decoys.length < decoyN && pool.length) {
    var i = Math.floor(Math.random() * pool.length);
    if (!used[pool[i]]) {
      decoys.push(pool[i]);
      used[pool[i]] = 1;
    }
    pool.splice(i, 1);
  }
  var opts = correct.concat(decoys);
  for (var i = opts.length - 1; i > 0; i--) {
    var j = Math.floor(Math.random() * (i + 1));
    var tmp = opts[i];
    opts[i] = opts[j];
    opts[j] = tmp;
  }
  return opts;
}

// === RENDER ===
function renderStats() {
  document.getElementById("statScore").textContent = state.score;
  document.getElementById("statCombo").textContent = state.combo;
  document.getElementById("statTotal").textContent = state.totalCount;
  document.getElementById("statStreak").textContent = state.streak;
  var flame = document.getElementById("flameIcon");
  flame.className = "";
  if (state.combo >= 8)      flame.className = "flame-high";
  else if (state.combo >= 5) flame.className = "flame-mid";
  else if (state.combo >= 3) flame.className = "flame-low";
}
function renderProgress() {
  var bar = document.getElementById("progressBar");
  bar.innerHTML = "";
  for (var i = 0; i < ROUND_SIZE; i++) {
    var d = document.createElement("div");
    d.className =
      "progress-dot" +
      (i < state.round
        ? state.roundResults[i]
          ? " done"
          : " skip"
        : i === state.round
          ? " current"
          : "");
    bar.appendChild(d);
  }
}
function renderIdiom() {
  var el = document.getElementById("idiomDisplay");
  el.innerHTML = "";
  var idiom = state.currentIdiom,
    pp = idiom.p.split(" ");
  for (var i = 0; i < idiom.w.length; i++) {
    var box = document.createElement("div");
    box.className = "char-box";
    if (state.blankIndices.indexOf(i) !== -1) {
      box.classList.add("blank");
      if (state.filledChars[i]) {
        box.classList.remove("blank");
        box.classList.add("filled");
        box.textContent = state.filledChars[i];
      } else {
        box.textContent = "?";
        if (state.selectedBlank === i) box.classList.add("selected");
      }
      (function (idx) {
        box.addEventListener("click", function () {
          selectBlank(idx);
        });
      })(i);
    } else {
      box.textContent = idiom.w[i];
      var py = document.createElement("span");
      py.className = "pinyin-hint";
      py.textContent = pp[i] || "";
      box.appendChild(py);
    }
    el.appendChild(box);
  }
}
function renderOptions(opts) {
  var grid = document.getElementById("optionsGrid");
  grid.innerHTML = "";
  var filled = Object.keys(state.filledChars).map(function (k) {
    return state.filledChars[k];
  });
  opts.forEach(function (ch) {
    var btn = document.createElement("button");
    btn.className = "option-btn";
    btn.textContent = ch;
    if (filled.indexOf(ch) !== -1) btn.classList.add("used");
    if (state.answered) btn.classList.add("disabled");
    btn.addEventListener("click", function () {
      selectOption(ch);
    });
    grid.appendChild(btn);
  });
}
function renderCombo() {
  var el = document.getElementById("comboDisplay");
  var toast = document.getElementById("comboToast");
  if (state.combo >= 3) {
    var msgs = [
      "梅子不错哦~",
      "太棒了梅子!",
      "梅子真厉害!",
      "学富五车!",
      "梅子无人能挡!",
      "登峰造极!",
      "出口成章!",
      "满腹经纶!",
      "博古通今!",
      "梅子开挂了!",
      "无可匹敌!",
      "梅子是成语王!",
    ];
    var i = Math.min(Math.floor((state.combo - 3) / 2), msgs.length - 1);
    var txt = "🔥 连击 ×" + state.combo + " " + msgs[i];
    el.innerHTML = '<span class="combo-text">' + txt + "</span>";
    if (toast) {
      toast.textContent = txt;
      toast.classList.add("show");
      clearTimeout(window._comboTimer);
      window._comboTimer = setTimeout(function () {
        toast.classList.remove("show");
      }, 2200);
    }
  } else {
    el.innerHTML = "";
    if (toast) toast.classList.remove("show");
  }
}

// === ACTIONS ===
function startRound() {
  state.round = 0;
  state.roundResults = [];
  state.usedIdiomIndices = {};
  nextQuestion();
}
function nextQuestion() {
  if (state.round >= ROUND_SIZE) {
    finishRound();
    return;
  }
  state.currentIdiom = pickIdiom();
  state.blankIndices = generateBlanks(state.currentIdiom.w, state.difficulty);
  state.selectedBlank = state.blankIndices[0];
  state.filledChars = {};
  state.hintUsed = false;
  state.answered = false;
  currentOptions = generateOptions(state.currentIdiom, state.blankIndices);
  document.getElementById("btnNext").style.display = "none";
  document.getElementById("btnHint").style.display = "";
  document.getElementById("btnHint").style.opacity = "1";
  document.getElementById("btnHint").style.pointerEvents = "";
  document.getElementById("btnSkip").style.display = "";
  document.getElementById("resultArea").innerHTML = "";
  document.getElementById("optLabel").style.display = "";
  renderProgress();
  renderIdiom();
  renderOptions(currentOptions);
  renderCombo();
  renderStats();
}
function selectBlank(i) {
  if (state.answered) return;
  if (state.filledChars[i]) {
    delete state.filledChars[i];
    state.selectedBlank = i;
    sfxClick();
    renderIdiom();
    renderOptions(currentOptions);
    return;
  }
  state.selectedBlank = i;
  sfxClick();
  renderIdiom();
}
function selectOption(ch) {
  if (state.answered || state.selectedBlank === -1) return;
  sfxClick();
  state.filledChars[state.selectedBlank] = ch;
  var next = -1;
  for (var j = 0; j < state.blankIndices.length; j++) {
    if (!state.filledChars[state.blankIndices[j]]) {
      next = state.blankIndices[j];
      break;
    }
  }
  state.selectedBlank = next;
  renderIdiom();
  renderOptions(currentOptions);
  var allFilled = true;
  for (var j = 0; j < state.blankIndices.length; j++) {
    if (!state.filledChars[state.blankIndices[j]]) {
      allFilled = false;
      break;
    }
  }
  if (allFilled) checkAnswer();
}
function checkAnswer() {
  state.answered = true;
  var idiom = state.currentIdiom,
    ok = true;
  state.blankIndices.forEach(function (i) {
    if (state.filledChars[i] !== idiom.w[i]) ok = false;
  });
  var boxes = document.querySelectorAll(".char-box");
  state.blankIndices.forEach(function (i) {
    boxes[i].classList.remove("filled");
    boxes[i].classList.add(
      state.filledChars[i] === idiom.w[i] ? "correct" : "wrong",
    );
  });
  if (ok) {
    state.combo++;
    if (state.combo > state.maxCombo) state.maxCombo = state.combo;
    state.score += Math.round(
      state.difficulty *
        10 *
        (state.hintUsed ? 0.5 : 1) *
        (1 + state.combo * 0.1),
    );
    state.todayCount++;
    state.totalCount++;
    state.roundResults.push(true);
    state.combo >= 5 ? sfxCombo() : sfxCorrect();
    if (state.reviewMode) removeFromWrongBook(idiom.w);
    var nc = tryCheckin();
    showResult(true, nc);
  } else {
    state.combo = 0;
    state.roundResults.push(false);
    sfxWrong();
    addToWrongBook(idiom);
    setTimeout(function () {
      state.blankIndices.forEach(function (i) {
        boxes[i].textContent = idiom.w[i];
        boxes[i].classList.remove("wrong");
        boxes[i].classList.add("correct");
      });
    }, 800);
    showResult(false, false);
  }
  renderOptions(currentOptions);
  renderCombo();
  renderStats();
  renderProgress();
  saveTodayState();
  saveState();
  document.getElementById("btnNext").style.display = "";
  document.getElementById("btnHint").style.display = "none";
  document.getElementById("btnSkip").style.display = "none";
}
function showResult(ok, nc) {
  var idiom = state.currentIdiom,
    a = document.getElementById("resultArea");
  var ch = "";
  if (nc)
    ch =
      '<div style="margin-top:12px;padding:10px;background:linear-gradient(135deg,#FFF8E1,#FFECB3);border-radius:10px;text-align:center"><span style="font-size:1.2rem">🎉</span> <b>梅子今日打卡成功！</b> 连续 ' +
      state.streak +
      " 天</div>";
  var pg = "";
  if (!nc && state.todayCount < DAILY_GOAL)
    pg =
      '<div style="margin-top:8px;font-size:.8rem;color:var(--text2)">今日进度：' +
      state.todayCount +
      "/" +
      DAILY_GOAL +
      " 题（完成" +
      DAILY_GOAL +
      "题即可打卡）</div>";
  a.innerHTML =
    '<div class="result-card' +
    (ok ? "" : " wrong-result") +
    '"><h3 style="color:' +
    (ok ? "var(--green)" : "var(--red)") +
    '">' +
    (ok ? [
      "✅ 回答正确！",
      "✅ 太棒了！",
      "✅ 梅子答对了！",
      "✅ 完全正确！",
      "✅ 厉害！",
      "✅ 对！梅子真棒！",
    ][Math.floor(Math.random() * 6)] : [
      "❌ 答错了~",
      "❌ 没关系，记住它！",
      "❌ 这次没中，下次加油！",
      "❌ 差一点点~",
    ][Math.floor(Math.random() * 4)]) +
    (ok && state.combo >= 3 ? " 🔥" : "") +
    '</h3><div class="idiom-word">' +
    idiom.w +
    '</div><div class="idiom-pinyin">' +
    idiom.p +
    '</div><div class="idiom-explain"><b>释义：</b>' +
    idiom.e +
    "</div>" +
    ch +
    pg +
    "</div>";
}
function finishRound() {
  var c = state.roundResults.filter(function (r) {
    return r;
  }).length;
  sfxComplete();
  var wasReview = state.reviewMode;
  state.reviewMode = false;
  var msg =
    c === ROUND_SIZE
      ? [
          "满分！梅子太厉害了！🎉",
          "完美！梅子真是成语达人！✨",
          "全对！梅子今天状态绝佳！🌟",
          "漂亮！一题不差，梅子威武！👏",
        ][Math.floor(Math.random() * 4)]
      : c >= 3
        ? [
            "梅子表现不错！继续加油~",
            "答得很好，梅子越来越厉害了！",
            "不错不错，梅子进步了！🌸",
            "梅子答题越来越顺了，加油！",
          ][Math.floor(Math.random() * 4)]
        : [
            "没关系梅子，多练习就会进步！💪",
            "继续努力，梅子肯定能行！",
            "不怕不怕，熟能生巧！加油梅子~",
            "错了没关系，下次梅子一定更好！",
          ][Math.floor(Math.random() * 4)];
  var reviewBtn =
    wasReview && state.wrongBook.length
      ? '<button class="action-btn secondary" onclick="showWrongBookModal()" style="margin-top:8px;width:100%">再次练习错题 📖</button>'
      : "";
  document.getElementById("resultArea").innerHTML =
    '<div class="result-card" style="border-top-color:var(--gold);text-align:center"><h3 style="color:var(--gold)">' +
    (wasReview ? "📖 错题练习结束!" : "🏆 本轮结束!") +
    '</h3><div style="font-size:2rem;font-weight:900;color:var(--accent);margin:12px 0;font-family:ZCOOL KuaiLe,cursive">' +
    c +
    " / " +
    ROUND_SIZE +
    '</div><div style="color:var(--text2);margin-bottom:16px">' +
    msg +
    '</div><button class="action-btn primary" onclick="startRound()" style="font-size:1rem;padding:12px 0;width:100%">再来一轮 →</button>' +
    reviewBtn +
    "</div>";
  document.getElementById("btnNext").style.display = "none";
  document.getElementById("btnHint").style.display = "none";
  document.getElementById("btnSkip").style.display = "none";
  document.getElementById("idiomDisplay").innerHTML = "";
  document.getElementById("optionsGrid").innerHTML = "";
  document.getElementById("optLabel").style.display = "none";
}
function useHint() {
  if (state.answered || state.hintUsed) return;
  state.hintUsed = true;
  var ub = [];
  for (var j = 0; j < state.blankIndices.length; j++) {
    if (!state.filledChars[state.blankIndices[j]])
      ub.push(state.blankIndices[j]);
  }
  if (!ub.length) return;
  var hi = ub[0],
    pp = state.currentIdiom.p.split(" "),
    boxes = document.querySelectorAll(".char-box"),
    py = document.createElement("span");
  py.className = "pinyin-hint";
  py.textContent = pp[hi] || "";
  py.style.color = "var(--accent)";
  boxes[hi].appendChild(py);
  sfxClick();
  document.getElementById("btnHint").style.opacity = ".5";
  document.getElementById("btnHint").style.pointerEvents = "none";
}
function skipQuestion() {
  if (state.answered) return;
  state.combo = 0;
  state.roundResults.push(false);
  state.round++;
  renderCombo();
  renderProgress();
  nextQuestion();
}
function showCheckinModal() {
  document.getElementById("checkinModal").classList.add("show");
  document.getElementById("modalStreak").textContent = state.streak;
  var tc = document.getElementById("modalTodayCount");
  var gf = document.getElementById("modalGoalFill");
  if (tc) tc.textContent = state.todayCount;
  if (gf)
    gf.style.width =
      Math.min(100, Math.round((state.todayCount / DAILY_GOAL) * 100)) + "%";
  var cal = document.getElementById("modalCalendar");
  cal.innerHTML = "";
  var today = new Date(),
    ts = getToday();
  ["一", "二", "三", "四", "五", "六", "日"].forEach(function (l) {
    var d = document.createElement("div");
    d.style.cssText =
      "font-size:.65rem;color:#8B6914;display:flex;align-items:center;justify-content:center";
    d.textContent = l;
    cal.appendChild(d);
  });
  var start = new Date(today);
  start.setDate(start.getDate() - 27);
  while (start.getDay() !== 1) start.setDate(start.getDate() - 1);
  var end = new Date(today);
  end.setDate(end.getDate() + ((7 - today.getDay()) % 7));
  var cur = new Date(start);
  while (cur <= end) {
    var ds = cur.toISOString().slice(0, 10),
      d = document.createElement("div");
    d.className = "cal-day";
    d.textContent = cur.getDate();
    if (state.checkinDays.indexOf(ds) !== -1) d.classList.add("checked");
    if (ds === ts) d.classList.add("today");
    if (cur > today) d.style.opacity = ".3";
    cal.appendChild(d);
    cur.setDate(cur.getDate() + 1);
  }
}

// === INIT ===
function init() {
  loadState();
  loadWrongBook();
  renderWbBadge();
  document.documentElement.setAttribute("data-theme", state.theme);
  document.getElementById("btnSound").classList.toggle("active", state.sound);
  document.getElementById("btnSound").textContent = state.sound ? "🔊" : "🔇";
  document.getElementById("btnTheme").textContent = state.theme === "ink" ? "🌙" : "☀️";
  showThemeTooltip();
  document.querySelectorAll(".diff-btn").forEach(function (b) {
    b.classList.toggle("active", +b.dataset.diff === state.difficulty);
  });
  renderStats();
  startRound();
  setTimeout(checkWhatsNew, 800);
}
document.getElementById("btnSound").addEventListener("click", function () {
  state.sound = !state.sound;
  this.classList.toggle("active", state.sound);
  this.textContent = state.sound ? "🔊" : "🔇";
  saveState();
});
function showThemeTooltip() {
  if (localStorage.getItem("chengyu_theme_tip")) return;
  var tip = document.getElementById("themeTooltip");
  if (!tip) return;
  setTimeout(function () {
    tip.classList.add("show");
    var timer = setTimeout(dismissThemeTooltip, 5000);
    tip.addEventListener("click", function () {
      clearTimeout(timer);
      dismissThemeTooltip();
    }, { once: true });
  }, 1200);
}
function dismissThemeTooltip() {
  var tip = document.getElementById("themeTooltip");
  if (tip) tip.classList.remove("show");
  localStorage.setItem("chengyu_theme_tip", "1");
}
document.getElementById("btnTheme").addEventListener("click", function () {
  dismissThemeTooltip();
  state.theme = state.theme === "ink" ? "paper" : "ink";
  document.documentElement.setAttribute("data-theme", state.theme);
  this.textContent = state.theme === "ink" ? "🌙" : "☀️";
  saveState();
});
document
  .getElementById("btnCheckin")
  .addEventListener("click", showCheckinModal);
document.getElementById("closeModal").addEventListener("click", function () {
  document.getElementById("checkinModal").classList.remove("show");
});
document.getElementById("checkinModal").addEventListener("click", function (e) {
  if (e.target === document.getElementById("checkinModal"))
    document.getElementById("checkinModal").classList.remove("show");
});
document
  .getElementById("btnWrongBook")
  .addEventListener("click", showWrongBookModal);
document
  .getElementById("closeWrongBook")
  .addEventListener("click", function () {
    document.getElementById("wrongBookModal").classList.remove("show");
  });
document
  .getElementById("wrongBookModal")
  .addEventListener("click", function (e) {
    if (e.target === document.getElementById("wrongBookModal"))
      document.getElementById("wrongBookModal").classList.remove("show");
  });
document
  .getElementById("btnStartReview")
  .addEventListener("click", startReview);
document.getElementById("closeWhatsNew").addEventListener("click", function () {
  document.getElementById("whatsNewModal").classList.remove("show");
  localStorage.setItem("chengyu_v", APP_VERSION);
});
document
  .getElementById("whatsNewModal")
  .addEventListener("click", function (e) {
    if (e.target === document.getElementById("whatsNewModal")) {
      document.getElementById("whatsNewModal").classList.remove("show");
      localStorage.setItem("chengyu_v", APP_VERSION);
    }
  });
document.querySelectorAll(".diff-btn").forEach(function (b) {
  b.addEventListener("click", function () {
    document.querySelectorAll(".diff-btn").forEach(function (x) {
      x.classList.remove("active");
    });
    this.classList.add("active");
    state.difficulty = +this.dataset.diff;
    state.combo = 0;
    saveState();
    startRound();
  });
});
document.getElementById("btnHint").addEventListener("click", useHint);
document.getElementById("btnSkip").addEventListener("click", skipQuestion);
document.getElementById("btnNext").addEventListener("click", function () {
  state.round++;
  document.getElementById("optLabel").style.display = "";
  nextQuestion();
});
init();