document.addEventListener('DOMContentLoaded', () => {
  const form = document.getElementById('loginForm');
  const username = document.getElementById('username');
  const password = document.getElementById('password');
  const remember = document.getElementById('remember');
  const error = document.getElementById('error');

  function showError(msg){
    error.textContent = msg;
  }

  function validate() {
    if (!username.value || username.value.trim().length < 3) {
      showError('用户名至少 3 个字符');
      return false;
    }
    if (!password.value || password.value.length < 6) {
      showError('密码至少 6 个字符');
      return false;
    }
    return true;
  }

  form.addEventListener('submit', (e) => {
    e.preventDefault();
    showError('');
    if (!validate()) return;

    // 本地模拟认证：示例用户名/密码对
    const validUsers = { 'alice':'password123', 'bob':'secret123', 'beppeb':'demoPass' };
    const inputUser = username.value.trim();
    const inputPass = password.value;

    if (validUsers[inputUser] && validUsers[inputUser] === inputPass) {
      // 登录成功：写入本地 token（示例）并跳转首页
      const token = 'demo-token-' + Math.random().toString(36).slice(2);
      if (remember.checked) {
        localStorage.setItem('demo_auth_token', token);
      } else {
        sessionStorage.setItem('demo_auth_token', token);
        // keep a copy in localStorage to let index.html detect login; it's demo-only
        localStorage.setItem('demo_auth_token', token);
      }
      // 简短提示后跳转
      showError('登录成功，正在跳转……');
      setTimeout(() => { window.location.href = '/'; }, 700);
    } else {
      showError('用户名或密码不正确（此示例使用本地模拟账号）。');
    }
  });
});