// ─── 常量定义 ──────────────────────────────────────
    const MONEY_DIGITS  = ['零', '壹', '贰', '叁', '肆', '伍', '陆', '柒', '捌', '玖'];
    const MONEY_UNITS   = ['', '拾', '佰', '仟'];
    const MONEY_BIG_UNITS = ['', '萬', '億']; // 分组单位：个、万、亿

    const SIMPLE_DIGITS = ['零', '一', '二', '三', '四', '五', '六', '七', '八', '九'];
    const SIMPLE_UNITS  = ['', '十', '百', '千'];
    const SIMPLE_BIG_UNITS = ['', '万', '亿'];

    // 中文 → 数字 映射
    const CAP_MAP = { '零':0,'壹':1,'贰':2,'叁':3,'肆':4,'伍':5,'陆':6,'柒':7,'捌':8,'玖':9 };
    const SIM_MAP = { '零':0,'一':1,'二':2,'三':3,'四':4,'五':5,'六':6,'七':7,'八':8,'九':9 };
    const U_MAP   = { '十':10,'拾':10,'百':100,'佰':100,'千':1000,'仟':1000 };

    // ─── 金额大写（财务） ───────────────────────────────
    function numberToMoney(numStr) {
      numStr = numStr.replace(/,/g, '').trim();
      let [intPart, decPart] = numStr.includes('.')
        ? numStr.split('.')
        : [numStr, ''];

      // 处理整数部分前导零，保留纯数字形式
      intPart = intPart.replace(/^0+(?=\d)/, '') || '0';

      // 特殊情况：整数部分为0且有分数
      if (intPart === '0') {
        if (decPart) {
          // 纯小数，如 0.53
          decPart = decPart.slice(0, 2).padEnd(2, '0');
          const jiao = parseInt(decPart[0] || 0);
          const fen  = parseInt(decPart[1] || 0);
          let decStr = '';
          if (jiao > 0) decStr += MONEY_DIGITS[jiao] + '角';
          if (fen > 0) decStr += MONEY_DIGITS[fen] + '分';
          return '零元' + (decStr || '整');
        }
        return '零元整';
      }

      // 每4位分组：从右往左
      const groups = [];
      let tmp = intPart;
      while (tmp.length > 0) {
        groups.unshift(tmp.slice(-4));
        tmp = tmp.slice(0, -4);
      }

      let res = '';
      let lastWasZero = false; // 上一个分组是否全零

      for (let gi = 0; gi < groups.length; gi++) {
        const group = groups[gi];
        const bigUnit = MONEY_BIG_UNITS[groups.length - 1 - gi] || ''; // 正确的单位索引

        if (group === '0000') {
          // 全零分组，标记需要补零（如果有后续非零分组）
          lastWasZero = true;
          continue;
        }

        let groupStr = '';

        for (let i = 0; i < group.length; i++) {
          const digit = parseInt(group[i]);
          const posFromRight = group.length - 1 - i; // 0=个位,1=拾位,2=佰位,3=仟位

          if (digit === 0) {
            // 只有当下一位非零时才补零
            if (i < group.length - 1 && parseInt(group[i + 1]) !== 0) {
              groupStr += '零';
            }
          } else {
            groupStr += MONEY_DIGITS[digit] + MONEY_UNITS[posFromRight];
          }
        }

        // 清理连续零
        groupStr = groupStr.replace(/零+/g, '零');

        // 如果前一个分组是全零，且当前分组开头不是零，需要补零
        if (lastWasZero && !groupStr.startsWith('零')) {
          groupStr = '零' + groupStr;
        }
        lastWasZero = false;

        // 添加分组单位
        res += groupStr + bigUnit;
      }

      // 财务规范：保留"壹拾"，不简化为"拾"
      // if (res.startsWith('壹拾')) res = res.slice(2);

      if (!res || res === '') res = '零';

      // 处理小数部分
      let decStr = '';
      if (decPart) {
        decPart = decPart.slice(0, 2).padEnd(2, '0');
        const jiao = parseInt(decPart[0] || 0);
        const fen  = parseInt(decPart[1] || 0);
        if (jiao > 0) decStr += MONEY_DIGITS[jiao] + '角';
        if (fen > 0) decStr += MONEY_DIGITS[fen] + '分';
        if (jiao === 0 && fen === 0) decStr = '整';
      } else {
        decStr = '整';
      }

      return res + '元' + decStr;
    }

    // ─── 中文小写 ───────────────────────────────────────
    function numberToSimple(numStr) {
      let [intPart, decPart] = numStr.includes('.')
        ? numStr.split('.')
        : [numStr, ''];

      // 处理整数部分前导零，保留纯数字形式
      intPart = intPart.replace(/^0+(?=\d)/, '') || '0';

      // 特殊情况：整数部分为0
      if (intPart === '0') {
        if (decPart) {
          decPart = decPart.slice(0, 2).padEnd(2, '0');
          const jiao = parseInt(decPart[0] || 0);
          const fen  = parseInt(decPart[1] || 0);
          let decStr = '';
          if (jiao > 0) decStr += SIMPLE_DIGITS[jiao] + '角';
          if (fen > 0) decStr += SIMPLE_DIGITS[fen] + '分';
          return '零元' + (decStr || '');
        }
        return '零';
      }

      if (intPart.length > 12) return '超出范围';

      const groups = [];
      let tmp = intPart;
      while (tmp.length > 0) {
        groups.unshift(tmp.slice(-4));
        tmp = tmp.slice(0, -4);
      }

      let res = '';
      let lastWasZero = false;

      for (let gi = 0; gi < groups.length; gi++) {
        const group = groups[gi];
        const bigUnit = SIMPLE_BIG_UNITS[groups.length - 1 - gi] || '';

        if (group === '0000') {
          lastWasZero = true;
          continue;
        }

        let groupStr = '';

        for (let i = 0; i < group.length; i++) {
          const digit = parseInt(group[i]);
          const pos = group.length - 1 - i;

          if (digit === 0) {
            if (i < group.length - 1 && parseInt(group[i + 1]) !== 0) {
              groupStr += '零';
            }
          } else {
            groupStr += SIMPLE_DIGITS[digit] + SIMPLE_UNITS[pos];
          }
        }

        groupStr = groupStr.replace(/零+/g, '零');

        if (lastWasZero && !groupStr.startsWith('零')) {
          groupStr = '零' + groupStr;
        }
        lastWasZero = false;

        res += groupStr + bigUnit;
      }

      // 10-19 的"一十"改为"十"
      if (res.startsWith('一十')) {
        res = res.slice(1);
      }

      if (!res) res = '零';

      let decStr = '';
      if (decPart) {
        decPart = decPart.slice(0, 2).padEnd(2, '0');
        const jiao = parseInt(decPart[0] || 0);
        const fen  = parseInt(decPart[1] || 0);
        if (jiao > 0) decStr += SIMPLE_DIGITS[jiao] + '角';
        if (fen > 0) decStr += SIMPLE_DIGITS[fen] + '分';
        // 如果有小数部分，加上"元"
        return res + '元' + decStr;
      }

      return res;
    }

    // ─── 中文 → 阿拉伯数字 ───────────────────────────────
    function chineseToArabic(str) {
      str = str.trim();
      const useCapital = /[壹贰叁肆伍陆柒捌玖]/.test(str);

      // 去掉"元整"等无关字符
      str = str.replace(/元|整|圆|角|分/g, '');

      let total = 0;

      // 按 亿 分割
      if (/[億亿]/.test(str)) {
        const idx = str.search(/[億亿]/);
        const yiPart = str.substring(0, idx);       // 亿位
        const rest = str.substring(idx + 1);        // 剩余部分
        
        total = parseChineseGroup(yiPart, useCapital) * 100000000;
        
        // 剩余部分再按万分割
        if (/[萬万]/.test(rest)) {
          const idx2 = rest.search(/[萬万]/);
          const wanPart = rest.substring(0, idx2);
          const gePart = rest.substring(idx2 + 1);
          total += parseChineseGroup(wanPart, useCapital) * 10000;
          total += parseChineseGroup(gePart, useCapital);
        } else {
          total += parseChineseGroup(rest, useCapital);
        }
        
        return total;
      }

      // 按 万 分割
      if (/[萬万]/.test(str)) {
        const idx = str.search(/[萬万]/);
        const wanPart = str.substring(0, idx);
        const gePart = str.substring(idx + 1);
        return parseChineseGroup(wanPart, useCapital) * 10000
             + parseChineseGroup(gePart, useCapital);
      }

      return parseChineseGroup(str, useCapital);
    }

    function parseChineseGroup(s, useCapital) {
      const digitMap = useCapital ? CAP_MAP : SIM_MAP;
      let total = 0;      // 最终结果
      let current = 0;    // 当前组内累积值
      let digitBuf = '';   // 连续数字字符缓冲区，拼成完整多位数

      for (let i = 0; i < s.length; i++) {
        const ch = s[i];

        if (digitMap[ch] !== undefined) {
          // 数字字符：拼接到缓冲区（构建多位数，如 "一二三" → 123）
          digitBuf += digitMap[ch];
        } else if (U_MAP[ch] !== undefined) {
          // 单位字符：将缓冲区数字转为整数后乘以单位
          const unitVal = U_MAP[ch];
          const num = parseInt(digitBuf || '0', 10);
          if (num === 0) {
            // 没有前置数字，如 "十"、"百" 开头（相当于 "一十"、"一百"）
            current += unitVal;
          } else {
            // 有前置数字，如 "二十"、"三百"
            current += num * unitVal;
          }
          digitBuf = '';
        }
        // 忽略其他字符（如 "零"）
      }

      // 处理末尾没有单位的数字，如 "一百二十三" 的 "三"
      if (digitBuf !== '') {
        current += parseInt(digitBuf, 10);
      }
      return current;
    }

    // ─── UI 逻辑 ───────────────────────────────────────
    let currentMode = 'money';

    // 使用事件委托处理模式切换
    document.querySelector('.mode-tabs').addEventListener('click', function(e) {
      if (e.target.classList.contains('mode-tab')) {
        const mode = e.target.dataset.mode;
        currentMode = mode;

        document.querySelectorAll('.mode-tab').forEach(t => t.classList.remove('active'));
        e.target.classList.add('active');

        document.getElementById('panel-arabic-to-chinese').style.display =
          (mode === 'money' || mode === 'capital') ? 'block' : 'none';
        document.getElementById('panel-chinese-to-arabic').style.display =
          mode === 'chinese' ? 'block' : 'none';

        clearResults();
      }
    });

    function fillInput(val) {
      document.getElementById('inputNum').value = val;
      convertToChinese();
    }

    function appendChar(ch) {
      const ta = document.getElementById('inputCN');
      ta.value += ch;
      ta.focus();
      // 触发自动转换
      clearTimeout(window.inputTimer);
      window.inputTimer = setTimeout(convertToArabic, 600);
    }

    function showError(id, msg) {
      const el = document.getElementById(id);
      el.textContent = msg;
      el.classList.add('show');
    }

    function hideError(id) {
      document.getElementById(id).classList.remove('show');
    }

    function setResult(id, val) {
      const el = document.getElementById(id);
      el.textContent = val;
      el.classList.remove('empty');
    }

    function clearResults() {
      ['resMoney', 'resSimple', 'resArabic'].forEach(id => {
        const el = document.getElementById(id);
        el.textContent = '等待转换…';
        el.classList.add('empty');
      });
      hideError('errorNum');
      hideError('errorCN');
    }

    function isValidNum(s) {
      return /^-?\d+(\.\d+)?$/.test(s.trim()) && !isNaN(parseFloat(s));
    }

    function convertToChinese() {
      hideError('errorNum');
      const raw = document.getElementById('inputNum').value.replace(/,/g, '').trim();

      if (!raw) { showError('errorNum', '请输入数字'); return; }
      if (!isValidNum(raw)) { showError('errorNum', '请输入有效的数字'); return; }

      const num = parseFloat(raw);
      if (Math.abs(num) > 999999999999) {
        showError('errorNum', '数字超出范围（最大 ±9999亿）');
        return;
      }

      const sign = raw.startsWith('-') ? '负' : '';
      const absStr = Math.abs(num).toString();

      setResult('resMoney', sign + numberToMoney(absStr));
      setResult('resSimple', sign + numberToSimple(absStr));
    }

    function convertToArabic() {
      hideError('errorCN');
      const raw = document.getElementById('inputCN').value.replace(/,/g, '').trim();

      if (!raw) { showError('errorCN', '请输入中文数字'); return; }

      const result = chineseToArabic(raw);
      if (result === 0 && !/零|〇/.test(raw)) {
        showError('errorCN', '无法识别的中文数字');
        return;
      }

      setResult('resArabic', result.toLocaleString('zh-CN'));
    }

    function copyText(elId, btn) {
      const text = document.getElementById(elId).textContent;
      if (!text || text.includes('等待转换')) return;
      navigator.clipboard.writeText(text).then(() => {
        const orig = btn.textContent;
        btn.textContent = '已复制 ✓';
        btn.classList.add('copied');
        setTimeout(() => {
          btn.textContent = orig;
          btn.classList.remove('copied');
        }, 1500);
      });
    }

    // 回车触发转换
    document.getElementById('inputNum').addEventListener('keydown', e => {
      if (e.key === 'Enter') convertToChinese();
    });

    // 自动转换（输入后稍等）
    window.inputTimer = null;

    document.getElementById('inputNum').addEventListener('input', () => {
      clearTimeout(window.inputTimer);
      window.inputTimer = setTimeout(convertToChinese, 600);
    });

    document.getElementById('inputCN').addEventListener('input', () => {
      clearTimeout(window.inputTimer);
      window.inputTimer = setTimeout(convertToArabic, 600);
    });

    // 初始化默认空状态
    ['resMoney', 'resSimple', 'resArabic'].forEach(id => {
      const el = document.getElementById(id);
      el.textContent = '等待转换…';
      el.classList.add('empty');
    });