// AI助手 - 前端应用
// 使用智谱 GLM-4.5-Air 模型（流式输出 + 多对话管理）

const CONFIG = {
  apiUrl: 'https://open.bigmodel.cn/api/paas/v4/chat/completions',
  apiKey: '2259e33a1357460abe17919aaf81e73d.K44a8LPQTmFM5PKm',
  model: 'glm-4.5-air',
  maxTokens: 2048
};

// 数据结构
let conversations = [];  // 对话列表
let currentConversation = null;  // 当前对话
let isLoading = false;

// DOM 元素（初始为 null，在 openConversation 时重新获取）
let appContainer = null;
let messagesContainer = null;
let messagesDiv = null;
let userInput = null;
let sendBtn = null;
let welcome = null;

// 初始化
document.addEventListener('DOMContentLoaded', () => {
  // 初始化 appContainer
  appContainer = document.getElementById('app');
  
  // 从本地存储加载对话列表
  const saved = localStorage.getItem('conversations');
  if (saved) {
    conversations = JSON.parse(saved);
  }
  
  // 兼容旧数据格式（chat_history）
  const oldHistory = localStorage.getItem('chat_history');
  if (oldHistory && conversations.length === 0) {
    const oldMessages = JSON.parse(oldHistory);
    if (oldMessages.length > 0) {
      // 转换旧数据为新格式
      const convertedConv = {
        id: Date.now().toString(),
        title: oldMessages[0].content.slice(0, 30) + (oldMessages[0].content.length > 30 ? '...' : ''),
        messages: oldMessages,
        createdAt: Date.now(),
        updatedAt: Date.now()
      };
      conversations.push(convertedConv);
      saveConversations();
      localStorage.removeItem('chat_history');  // 清理旧数据
    }
  }
  
  // 显示对话列表页面
  showConversationList();
});

// ==================== 对话列表页面 ====================

function showConversationList() {
  currentConversation = null;
  
  // 渲染对话列表
  const listHtml = `
    <div class="conversation-list-page">
      <header class="list-header">
        <div class="header-title">
          <span class="logo">🤖</span>
          <h1>AI助手</h1>
        </div>
      </header>
      
      <div class="list-content">
        <button class="new-chat-btn" id="newChatBtn">
          <svg viewBox="0 0 24 24" width="20" height="20"><path fill="currentColor" d="M19 13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/></svg>
          新建对话
        </button>
        
        <div class="conversation-list" id="conversationList">
          ${conversations.length === 0 
            ? '<div class="empty-list">暂无对话记录</div>'
            : conversations.map(conv => `
              <div class="conversation-item" data-id="${conv.id}">
                <div class="conv-title">${escapeHtml(conv.title)}</div>
                <div class="conv-meta">${conv.messages.length} 条消息 · ${formatTime(conv.updatedAt)}</div>
                <button class="conv-delete-btn" data-id="${conv.id}" title="删除对话">
                  <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M6 19c0 1.1.9 2 2 2h8c1.1 0 2-.9 2-2V7H6v12zM19 4h-3.5l-1-1h-5l-1 1H5v2h14V4z"/></svg>
                </button>
              </div>
            `).join('')
          }
        </div>
      </div>
    </div>
  `;
  
  appContainer.innerHTML = listHtml;
  
  // 绑定事件
  const newChatBtn = document.getElementById('newChatBtn');
  if (newChatBtn) {
    newChatBtn.addEventListener('click', createNewConversation);
  }
  
  const conversationList = document.getElementById('conversationList');
  if (conversationList) {
    conversationList.addEventListener('click', (e) => {
      const item = e.target.closest('.conversation-item');
      const deleteBtn = e.target.closest('.conv-delete-btn');
      
      if (deleteBtn) {
        e.stopPropagation();
        const id = deleteBtn.getAttribute('data-id');
        deleteConversation(id);
      } else if (item) {
        const id = item.getAttribute('data-id');
        openConversation(id);
      }
    });
  }
}

// 创建新对话
function createNewConversation() {
  const newConv = {
    id: Date.now().toString(),
    title: '新对话',
    messages: [],
    createdAt: Date.now(),
    updatedAt: Date.now()
  };
  
  conversations.unshift(newConv);
  saveConversations();
  openConversation(newConv.id);
}

// 打开对话
function openConversation(id) {
  currentConversation = conversations.find(c => c.id === id);
  if (!currentConversation) {
    showConversationList();
    return;
  }
  
  // 渲染对话页面
  const chatHtml = `
    <div id="chatPage">
      <header class="header">
        <button class="back-btn" id="backBtn">
          <svg viewBox="0 0 24 24" width="24" height="24"><path fill="currentColor" d="M20 11H7.83l5.59-5.59L12 4l-8 8 8 8 1.41-1.41L7.83 13H20v-2z"/></svg>
        </button>
        <div class="header-title">
          <span class="logo">🤖</span>
          <h1>${escapeHtml(currentConversation.title)}</h1>
        </div>
        <button class="clear-btn" id="clearBtn" title="清空对话">
          <svg viewBox="0 0 24 24" width="20" height="20"><path fill="currentColor" d="M19 6.41L17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12 19 6.41z"/></svg>
        </button>
      </header>

      <div class="messages-container" id="messagesContainer">
        <div class="welcome" id="welcome" style="${currentConversation.messages.length > 0 ? 'display:none' : ''}">
          <div class="welcome-icon">👋</div>
          <h2>你好！我是AI助手</h2>
          <p>有什么可以帮助你的吗？</p>
          <div class="quick-actions">
            <button class="quick-btn" data-text="介绍一下你自己">介绍一下你自己</button>
            <button class="quick-btn" data-text="帮我写一段代码">帮我写代码</button>
            <button class="quick-btn" data-text="解释一个概念">解释概念</button>
          </div>
        </div>
        <div class="messages" id="messages"></div>
      </div>

      <div class="input-area">
        <textarea 
          id="userInput" 
          placeholder="输入消息..." 
          rows="1"
        ></textarea>
        <button class="send-btn" id="sendBtn">
          <svg viewBox="0 0 24 24" width="24" height="24"><path fill="currentColor" d="M2.01 21L23 12 2.01 3 2 10l15 2-15 2z"/></svg>
        </button>
      </div>
    </div>
  `;
  
  appContainer.innerHTML = chatHtml;
  
  // 重新获取 DOM 元素
  messagesContainer = document.getElementById('messagesContainer');
  messagesDiv = document.getElementById('messages');
  userInput = document.getElementById('userInput');
  sendBtn = document.getElementById('sendBtn');
  welcome = document.getElementById('welcome');
  
  // 绑定按钮事件
  const backBtn = document.getElementById('backBtn');
  if (backBtn) backBtn.addEventListener('click', showConversationList);
  
  const clearBtn = document.getElementById('clearBtn');
  if (clearBtn) clearBtn.addEventListener('click', clearCurrentChat);
  
  // 绑定输入事件
  userInput.addEventListener('keydown', handleKeyDown);
  userInput.addEventListener('input', (e) => autoResize(e.target));
  sendBtn.addEventListener('click', sendMessage);
  
  // 绑定快捷按钮事件
  document.querySelectorAll('.quick-btn').forEach(btn => {
    btn.addEventListener('click', () => {
      const text = btn.getAttribute('data-text');
      userInput.value = text;
      sendMessage();
    });
  });
  
  // 渲染消息
  renderMessages();
  userInput.focus();
}

// 删除对话
function deleteConversation(id) {
  if (!confirm('确定要删除这个对话吗？')) return;
  
  conversations = conversations.filter(c => c.id !== id);
  saveConversations();
  showConversationList();
}

// ==================== 对话页面 ====================

// 自动调整输入框高度
function autoResize(textarea) {
  textarea.style.height = 'auto';
  textarea.style.height = Math.min(textarea.scrollHeight, 120) + 'px';
}

// 处理键盘事件
function handleKeyDown(event) {
  if (event.key === 'Enter' && !event.shiftKey) {
    event.preventDefault();
    sendMessage();
  }
}

// 发送快捷消息
function sendQuickMessage(text) {
  userInput.value = text;
  sendMessage();
}

// 发送消息（流式输出）
async function sendMessage() {
  if (!currentConversation) return;
  
  const text = userInput.value.trim();
  if (!text || isLoading) return;

  // 隐藏欢迎界面
  welcome.style.display = 'none';

  // 添加用户消息
  currentConversation.messages.push({ role: 'user', content: text });
  
  // 更新对话标题（第一条用户消息）
  if (currentConversation.title === '新对话') {
    currentConversation.title = text.slice(0, 30) + (text.length > 30 ? '...' : '');
    // 更新标题显示
    const titleEl = document.querySelector('.header h1');
    if (titleEl) {
      titleEl.textContent = currentConversation.title;
    }
  }
  
  currentConversation.updatedAt = Date.now();
  saveConversations();
  
  renderMessages();
  userInput.value = '';
  autoResize(userInput);

  // 调用流式生成
  await streamGenerate(currentConversation.messages.length - 1);
}

// 流式生成 AI 回复
async function streamGenerate(userMsgIndex) {
  isLoading = true;
  sendBtn.disabled = true;

  const aiMessageIndex = currentConversation.messages.length;
  currentConversation.messages.push({ role: 'assistant', content: '' });
  renderMessages();
  
  const lastMessageEl = messagesDiv.lastElementChild;
  const contentEl = lastMessageEl.querySelector('.message-content');
  contentEl.innerHTML = '<span class="streaming-cursor">▌</span>';

  try {
    const response = await fetch(CONFIG.apiUrl, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${CONFIG.apiKey}`
      },
      body: JSON.stringify({
        model: CONFIG.model,
        messages: currentConversation.messages.slice(0, aiMessageIndex).map(m => ({
          role: m.role,
          content: m.content
        })),
        max_tokens: CONFIG.maxTokens,
        stream: true
      })
    });

    if (!response.ok) {
      throw new Error(`API 错误: ${response.status}`);
    }

    const reader = response.body.getReader();
    const decoder = new TextDecoder();
    let buffer = '';

    while (true) {
      const { done, value } = await reader.read();
      if (done) break;

      buffer += decoder.decode(value, { stream: true });
      const lines = buffer.split('\n');
      buffer = lines.pop() || '';

      for (const line of lines) {
        if (line.startsWith('data: ')) {
          const jsonStr = line.slice(6).trim();
          if (jsonStr === '[DONE]') continue;
          
          try {
            const data = JSON.parse(jsonStr);
            if (data.choices && data.choices[0]?.delta?.content) {
              currentConversation.messages[aiMessageIndex].content += data.choices[0].delta.content;
              contentEl.innerHTML = renderMarkdown(currentConversation.messages[aiMessageIndex].content) + '<span class="streaming-cursor">▌</span>';
              scrollToBottom();
            }
          } catch (e) {}
        }
      }
    }

    contentEl.innerHTML = renderMarkdown(currentConversation.messages[aiMessageIndex].content);

  } catch (error) {
    console.error('Error:', error);
    currentConversation.messages[aiMessageIndex].content = `抱歉，出现了错误：${error.message}\n\n请检查网络连接后重试。`;
    contentEl.innerHTML = renderMarkdown(currentConversation.messages[aiMessageIndex].content);
  } finally {
    isLoading = false;
    sendBtn.disabled = false;
    currentConversation.updatedAt = Date.now();
    saveConversations();
    renderMessages();
  }
}

// 重新生成 AI 回复
async function regenerate(index) {
  if (!currentConversation || isLoading || index < 1) return;
  
  const userMsgIndex = index - 1;
  if (currentConversation.messages[userMsgIndex].role !== 'user') return;
  
  currentConversation.messages.splice(index, 1);
  currentConversation.updatedAt = Date.now();
  saveConversations();
  
  await streamGenerate(userMsgIndex);
}

// 删除消息
function deleteMessage(index) {
  if (!currentConversation || isLoading) return;
  
  const msg = currentConversation.messages[index];
  
  if (msg.role === 'assistant') {
    if (index > 0 && currentConversation.messages[index - 1].role === 'user') {
      currentConversation.messages.splice(index - 1, 2);
    } else {
      currentConversation.messages.splice(index, 1);
    }
  } else {
    if (index < currentConversation.messages.length - 1 && currentConversation.messages[index + 1].role === 'assistant') {
      currentConversation.messages.splice(index, 2);
    } else {
      currentConversation.messages.splice(index, 1);
    }
  }
  
  currentConversation.updatedAt = Date.now();
  saveConversations();
  renderMessages();
  
  if (currentConversation.messages.length === 0) {
    welcome.style.display = 'block';
  }
}

// 复制消息（复制原文）
function copyMessage(index) {
  if (!currentConversation) return;
  
  const content = currentConversation.messages[index].content;
  
  navigator.clipboard.writeText(content).then(() => {
    showToast('已复制到剪贴板');
  }).catch(err => {
    const textarea = document.createElement('textarea');
    textarea.value = content;
    textarea.style.position = 'fixed';
    textarea.style.opacity = '0';
    document.body.appendChild(textarea);
    textarea.select();
    document.execCommand('copy');
    document.body.removeChild(textarea);
    showToast('已复制到剪贴板');
  });
}

// 清空当前对话
function clearCurrentChat() {
  if (!currentConversation) return;
  
  if (confirm('确定要清空当前对话吗？')) {
    currentConversation.messages = [];
    currentConversation.updatedAt = Date.now();
    saveConversations();
    renderMessages();
    welcome.style.display = 'block';
  }
}

// 渲染消息
function renderMessages() {
  if (!currentConversation) return;
  
  // 根据消息数量显示/隐藏欢迎界面
  if (welcome) {
    welcome.style.display = currentConversation.messages.length > 0 ? 'none' : 'block';
  }
  
  messagesDiv.innerHTML = currentConversation.messages.map((msg, index) => {
    const isUser = msg.role === 'user';
    const avatar = isUser ? '👤' : '🤖';
    const content = renderMarkdown(msg.content);
    
    const copyIcon = `<svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M16 1H4c-1.1 0-2 .9-2 2v14h2V3h12V1zm3 4H8c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h11c1.1 0 2-.9 2-2V7c0-1.1-.9-2-2-2zm0 16H8V7h11v14z"/></svg>`;
    
    const actions = isUser 
      ? `<div class="message-actions">
          <button class="action-btn copy-btn" data-index="${index}" title="复制">${copyIcon}</button>
          <button class="action-btn delete-btn" data-index="${index}" title="删除">
            <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M6 19c0 1.1.9 2 2 2h8c1.1 0 2-.9 2-2V7H6v12zM19 4h-3.5l-1-1h-5l-1 1H5v2h14V4z"/></svg>
          </button>
        </div>`
      : `<div class="message-actions">
          <button class="action-btn copy-btn" data-index="${index}" title="复制">${copyIcon}</button>
          <button class="action-btn regenerate-btn" data-index="${index}" title="重新生成">
            <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M17.65 6.35C16.2 4.9 14.21 4 12 4c-4.42 0-7.99 3.58-7.99 8s3.57 8 7.99 8c3.73 0 6.84-2.55 7.73-6h-2.08c-.82 2.33-3.04 4-5.65 4-3.31 0-6-2.69-6-6s2.69-6 6-6c1.66 0 3.14.69 4.22 1.78L13 11h7V4l-2.35 2.35z"/></svg>
          </button>
          <button class="action-btn delete-btn" data-index="${index}" title="删除">
            <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M6 19c0 1.1.9 2 2 2h8c1.1 0 2-.9 2-2V7H6v12zM19 4h-3.5l-1-1h-5l-1 1H5v2h14V4z"/></svg>
          </button>
        </div>`;
    
    return `
      <div class="message ${msg.role}" data-index="${index}">
        <div class="message-avatar">${avatar}</div>
        <div class="message-body">
          <div class="message-content">${content}</div>
          ${actions}
        </div>
      </div>
    `;
  }).join('');

  // 绑定消息操作按钮事件（事件委托）
  messagesDiv.querySelectorAll('.copy-btn').forEach(btn => {
    btn.addEventListener('click', () => copyMessage(parseInt(btn.dataset.index)));
  });
  messagesDiv.querySelectorAll('.regenerate-btn').forEach(btn => {
    btn.addEventListener('click', () => regenerate(parseInt(btn.dataset.index)));
  });
  messagesDiv.querySelectorAll('.delete-btn').forEach(btn => {
    btn.addEventListener('click', () => deleteMessage(parseInt(btn.dataset.index)));
  });

  scrollToBottom();
}

// ==================== 工具函数 ====================

// 渲染 Markdown
function renderMarkdown(text) {
  if (!text) return '';
  
  marked.setOptions({
    breaks: true,
    gfm: true
  });
  
  return marked.parse(text);
}

// 滚动到底部
function scrollToBottom() {
  if (messagesContainer) {
    messagesContainer.scrollTop = messagesContainer.scrollHeight;
  }
}

// 保存对话列表
function saveConversations() {
  localStorage.setItem('conversations', JSON.stringify(conversations));
}

// 显示提示
function showToast(message) {
  const toast = document.createElement('div');
  toast.className = 'toast';
  toast.textContent = message;
  document.body.appendChild(toast);
  
  setTimeout(() => toast.classList.add('show'), 10);
  setTimeout(() => {
    toast.classList.remove('show');
    setTimeout(() => document.body.removeChild(toast), 300);
  }, 2000);
}

// HTML转义
function escapeHtml(text) {
  const div = document.createElement('div');
  div.textContent = text;
  return div.innerHTML;
}

// 格式化时间
function formatTime(timestamp) {
  const date = new Date(timestamp);
  const now = new Date();
  const diff = now - date;
  
  if (diff < 60000) return '刚刚';
  if (diff < 3600000) return Math.floor(diff / 60000) + '分钟前';
  if (diff < 86400000) return Math.floor(diff / 3600000) + '小时前';
  if (diff < 604800000) return Math.floor(diff / 86400000) + '天前';
  
  return date.toLocaleDateString('zh-CN');
}

// PWA 注册
if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('sw.js').catch(() => {});
}