const express = require('express');
const http = require('http');
const { WebSocketServer } = require('ws');
const jwt = require('jsonwebtoken');
const multer = require('multer');
const path = require('path');
const fs = require('fs');
const { v4: uuidv4 } = require('uuid');
const db = require('./db');

const app = express();
const server = http.createServer(app);
const wss = new WebSocketServer({ server });

// 环境变量
const USERS = {};
(process.env.USERS || '').split(',').forEach(u => {
  const [name, pass] = u.split(':');
  if (name) USERS[name] = pass;
});
const ADMINS = (process.env.ADMINS || '').split(',');
const DEEPSEEK_API_KEY = process.env.DEEPSEEK_API_KEY;
const JWT_SECRET = process.env.JWT_SECRET || 'xiaocai-secret-' + Date.now();

// 初始化用户
const insertUser = db.prepare('INSERT OR IGNORE INTO users (username, password, is_admin) VALUES (?, ?, ?)');
for (const [username, password] of Object.entries(USERS)) {
  const isAdmin = ADMINS.includes(username) ? 1 : 0;
  insertUser.run(username, password, isAdmin);
}

// 上传配置
const uploadsDir = '/app/data/uploads';
if (!fs.existsSync(uploadsDir)) fs.mkdirSync(uploadsDir, { recursive: true });
const storage = multer.diskStorage({
  destination: uploadsDir,
  filename: (req, file, cb) => {
    const ext = path.extname(file.originalname) || '.jpg';
    const safeName = Date.now() + '-' + Math.random().toString(36).substring(2, 8) + ext;
    cb(null, safeName);
  }
});
const upload = multer({
  storage,
  limits: { fileSize: 5 * 1024 * 1024 },
  fileFilter: (req, file, cb) => {
    const allowed = ['image/jpeg','image/png','image/gif'];
    cb(null, allowed.includes(file.mimetype));
  }
});

app.use(express.json());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/uploads', express.static(uploadsDir));

// 登录
app.post('/api/login', (req, res) => {
  const { username, password } = req.body;
  if (USERS[username] && USERS[username] === password) {
    const token = jwt.sign({ username, isAdmin: ADMINS.includes(username) }, JWT_SECRET, { expiresIn: '7d' });
    return res.json({ token, username, isAdmin: ADMINS.includes(username) });
  }
  res.status(401).json({ error: '用户名或密码错误' });
});

const auth = (req, res, next) => {
  const authHeader = req.headers.authorization;
  if (!authHeader) return res.status(401).json({ error: '未登录' });
  const token = authHeader.split(' ')[1];
  try {
    const decoded = jwt.verify(token, JWT_SECRET);
    req.user = decoded;
    next();
  } catch (e) {
    res.status(401).json({ error: '登录已过期' });
  }
};

// 管理员权限检查中间件
const adminOnly = (req, res, next) => {
  if (!req.user.isAdmin) {
    return res.status(403).json({ error: '仅管理员可执行此操作' });
  }
  next();
};

app.get('/api/user', auth, (req, res) => {
  res.json({ username: req.user.username, isAdmin: req.user.isAdmin });
});

app.get('/api/rooms', auth, (req, res) => {
  const rooms = db.prepare('SELECT * FROM rooms').all();
  const result = rooms.map(room => {
    const lastMsg = db.prepare('SELECT text, timestamp FROM messages WHERE room_id = ? ORDER BY timestamp DESC LIMIT 1').get(room.id);
    return {
      ...room,
      last_message: lastMsg ? lastMsg.text : '',
      last_time: lastMsg ? lastMsg.timestamp : ''
    };
  });
  res.json(result);
});

app.post('/api/rooms', auth, adminOnly, (req, res) => {
  const { name, whiteList } = req.body;
  const id = uuidv4();
  const now = new Date().toLocaleString('zh-CN', { hour12: false });
  db.prepare('INSERT INTO rooms (id, name, created_by, white_list, created_at) VALUES (?,?,?,?,?)').run(id, name, req.user.username, whiteList || '', now);
  broadcast({ type: 'room_created', room: { id, name, white_list: whiteList || '' } });
  res.json({ id, name });
});

app.get('/api/rooms/:roomId/messages', auth, (req, res) => {
  const msgs = db.prepare('SELECT * FROM messages WHERE room_id = ? ORDER BY timestamp ASC').all(req.params.roomId);
  res.json(msgs);
});

// 发送消息（统一入口，异步触发 AI）
app.post('/api/rooms/:roomId/messages', auth, async (req, res) => {
  const { text, attachments } = req.body;
  const roomId = req.params.roomId;
  const username = req.user.username;
  const timestamp = new Date().toLocaleString('zh-CN', { hour12: false });

  const result = db.prepare('INSERT INTO messages (room_id, user, text, attachments, timestamp) VALUES (?,?,?,?,?)').run(
    roomId, username, text || '', attachments ? JSON.stringify(attachments) : null, timestamp
  );
  const msg = {
    id: result.lastInsertRowid,
    room_id: roomId,
    user: username,
    text: text || '',
    attachments: attachments || [],
    timestamp
  };

  const lastMsg = db.prepare('SELECT text, timestamp FROM messages WHERE room_id = ? ORDER BY timestamp DESC LIMIT 1').get(roomId);
  const preview = {
    room_id: roomId,
    last_message: lastMsg ? lastMsg.text : '',
    last_time: lastMsg ? lastMsg.timestamp : ''
  };

  broadcastToRoomExcludeSelf(roomId, username, {
    type: 'new_message',
    message: msg,
    room_preview: preview
  });

  addToHistory(roomId, 'user', `${username}: ${text || '图片'}`);
  res.json(msg);

  try {
    const history = getHistory(roomId);
    const historyMessages = history.map(e => ({ role: e.role, content: e.content }));
    const aiResponse = await analyzeWithDeepSeek(text || '', historyMessages, username, req.user.isAdmin);
    if (aiResponse && aiResponse.action !== 'ignore') {
      handleAIResult(aiResponse, roomId, username, text || '', attachments || []);
    }
  } catch (e) {
    console.error('AI 分析失败:', e);
  }
});

app.post('/api/upload', auth, upload.single('file'), (req, res) => {
  if (!req.file) return res.status(400).json({ error: '请上传图片' });
  res.json({ path: '/uploads/' + req.file.filename });
});

app.get('/api/rooms/:roomId/purchases', auth, (req, res) => {
  const purchases = db.prepare('SELECT * FROM purchases WHERE room_id = ? ORDER BY created_at DESC').all(req.params.roomId);
  res.json(purchases);
});

app.get('/api/purchases/:id', auth, (req, res) => {
  const pur = db.prepare('SELECT * FROM purchases WHERE id = ?').get(req.params.id);
  if (!pur) return res.status(404).json({ error: '未找到' });
  const history = db.prepare('SELECT * FROM purchase_history WHERE purchase_id = ? ORDER BY timestamp ASC').all(req.params.id);
  const attachments = db.prepare('SELECT * FROM purchase_attachments WHERE purchase_id = ?').all(req.params.id);
  res.json({ ...pur, history, attachments });
});

app.get('/api/summary', auth, (req, res) => {
  const rooms = db.prepare('SELECT id, name FROM rooms').all();
  const summary = rooms.map(room => {
    const stats = db.prepare(`SELECT COUNT(*) as count, SUM(amount) as total FROM purchases WHERE room_id = ?`).get(room.id);
    return {
      room_id: room.id,
      room_name: room.name,
      purchase_count: stats.count || 0,
      total_amount: stats.total || 0
    };
  });
  res.json(summary);
});

app.get('/api/rooms/:roomId/purchases/export', auth, (req, res) => {
  const purchases = db.prepare('SELECT * FROM purchases WHERE room_id = ?').all(req.params.roomId);
  let csv = '时间,事项,金额,付款方式,状态,申请人\n';
  purchases.forEach(p => {
    csv += `${p.created_at},"${p.item||''}",${p.amount},"${p.method||''}","${p.status}","${p.applicant}"\n`;
  });
  res.setHeader('Content-Type', 'text/csv; charset=utf-8');
  res.setHeader('Content-Disposition', `attachment; filename="purchases-${req.params.roomId}.csv"`);
  res.send('\uFEFF' + csv);
});

// 清空所有采购数据（管理员）
app.post('/api/rooms/:roomId/purchases/clear', auth, adminOnly, (req, res) => {
  const roomId = req.params.roomId;
  db.prepare('DELETE FROM purchase_attachments WHERE purchase_id IN (SELECT id FROM purchases WHERE room_id = ?)').run(roomId);
  db.prepare('DELETE FROM purchase_history WHERE purchase_id IN (SELECT id FROM purchases WHERE room_id = ?)').run(roomId);
  db.prepare('DELETE FROM purchases WHERE room_id = ?').run(roomId);
  broadcastToRoom(roomId, { type: 'purchase_updated' });
  res.json({ success: true, message: '所有采购数据已清空' });
});

// WebSocket 管理
const clients = new Map();

wss.on('connection', (ws, req) => {
  console.log('✅ WebSocket 客户端已连接');
  const url = new URL(req.url, 'http://localhost');
  const token = url.searchParams.get('token');
  if (!token) return ws.close();

  let username;
  try {
    const decoded = jwt.verify(token, JWT_SECRET);
    username = decoded.username;
  } catch (e) {
    return ws.close();
  }

  ws.username = username;
  ws.isAdmin = ADMINS.includes(username);
  clients.set(ws, { username, roomId: null, isAdmin: ADMINS.includes(username) });

  ws.on('message', (data) => {
    try {
      const msg = JSON.parse(data);
      if (msg.type === 'join') {
        ws.roomId = msg.roomId;
        clients.set(ws, { username, roomId: msg.roomId, isAdmin: ws.isAdmin });
      }
    } catch (e) {}
  });

  ws.on('close', () => {
    clients.delete(ws);
  });
});

function broadcastToRoomExcludeSelf(roomId, excludeUsername, data) {
  const message = JSON.stringify(data);
  clients.forEach((info, ws) => {
    if (info.roomId === roomId && info.username !== excludeUsername && ws.readyState === 1) {
      ws.send(message);
    }
  });
}

function broadcastToRoom(roomId, data) {
  const message = JSON.stringify(data);
  clients.forEach((info, ws) => {
    if (info.roomId === roomId && ws.readyState === 1) {
      ws.send(message);
    }
  });
}

function broadcast(data) {
  const message = JSON.stringify(data);
  clients.forEach((ws) => {
    if (ws.readyState === 1) ws.send(message);
  });
}

function storeAndBroadcastText(roomId, user, text) {
  const timestamp = new Date().toLocaleString('zh-CN', { hour12: false });
  const result = db.prepare('INSERT INTO messages (room_id, user, text, timestamp) VALUES (?,?,?,?)').run(roomId, user, text, timestamp);
  const msg = { id: result.lastInsertRowid, room_id: roomId, user, text, attachments: [], timestamp };
  const lastMsg = db.prepare('SELECT text, timestamp FROM messages WHERE room_id = ? ORDER BY timestamp DESC LIMIT 1').get(roomId);
  broadcastToRoom(roomId, {
    type: 'new_message',
    message: msg,
    room_preview: {
      room_id: roomId,
      last_message: lastMsg ? lastMsg.text : '',
      last_time: lastMsg ? lastMsg.timestamp : ''
    }
  });
  return msg;
}

const conversationHistory = new Map();
function getHistory(roomId) {
  if (!conversationHistory.has(roomId)) conversationHistory.set(roomId, []);
  return conversationHistory.get(roomId);
}
function addToHistory(roomId, role, content) {
  const history = getHistory(roomId);
  history.push({ role, content });
  if (history.length > 60) conversationHistory.set(roomId, history.slice(-40));
}

async function analyzeWithDeepSeek(text, historyMessages, username, isAdmin) {
  const systemPrompt = `你是智能财务助手“小财”。结合对话历史理解用户意图。只返回JSON。

意图分类：
- 采购/付款/发票相关：action="purchase"，提取purchase_item, amount, method, status, applicant, created_time
- 查询汇总：action="query"
- 聊天：action="chat"，reply简短回复
- 删除指定物品：action="delete"，delete_item物品名
- 清空所有采购数据（仅管理员）：action="clear_all"，注意：只有管理员可以请求清空，如果不是管理员但要求清空，应拒绝并告知只有管理员可操作。
- 忽略：action="ignore"

采购规则：
- 金额缺失=0，方式缺失="未指定"，申请人缺失="${username}"。
- 状态：已付→已采购，发票→发票已收，否则待采购。
- 时间提取：如果用户提到具体时间，设置created_time字段，格式yyyy/MM/dd HH:mm:ss。

当前用户${username}，管理员状态：${isAdmin}。`;

  const messages = [
    { role: 'system', content: systemPrompt },
    ...historyMessages.slice(-30),
    { role: 'user', content: `${username}: ${text}` }
  ];

  console.log('🤖 调用 DeepSeek...');
  const res = await fetch('https://api.deepseek.com/chat/completions', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json', 'Authorization': `Bearer ${DEEPSEEK_API_KEY}` },
    body: JSON.stringify({ model: 'deepseek-v4-flash', messages, temperature: 0.1, stream: false })
  });
  const data = await res.json();
  const content = data.choices[0].message.content;
  console.log('🤖 AI 返回:', content);
  return JSON.parse(content.replace(/```json|```/g, '').trim());
}

function handleAIResult(aiResult, roomId, username, originalText, attachments) {
  const now = new Date().toLocaleString('zh-CN', { hour12: false });

  if (aiResult.action === 'ask') {
    storeAndBroadcastText(roomId, '小财', aiResult.question);
    addToHistory(roomId, 'assistant', aiResult.question);
    return;
  }
  if (aiResult.action === 'delete') {
    const itemName = aiResult.delete_item;
    const purchases = db.prepare('SELECT * FROM purchases WHERE room_id = ? AND item LIKE ?').all(roomId, `%${itemName}%`);
    if (purchases.length === 0) {
      storeAndBroadcastText(roomId, '小财', `没有找到与“${itemName}”相关的采购记录。`);
      addToHistory(roomId, 'assistant', `没有找到与“${itemName}”相关的采购记录。`);
      return;
    }
    const deleteAttachments = db.prepare('DELETE FROM purchase_attachments WHERE purchase_id = ?');
    const deleteHistory = db.prepare('DELETE FROM purchase_history WHERE purchase_id = ?');
    const deletePurchase = db.prepare('DELETE FROM purchases WHERE id = ?');
    for (const p of purchases) {
      deleteAttachments.run(p.id);
      deleteHistory.run(p.id);
      deletePurchase.run(p.id);
    }
    const reply = `已删除采购记录：${itemName}（共 ${purchases.length} 条）`;
    storeAndBroadcastText(roomId, '小财', reply);
    addToHistory(roomId, 'assistant', reply);
    broadcastToRoom(roomId, { type: 'purchase_updated' });
    return;
  }
  if (aiResult.action === 'clear_all') {
    // 管理员才可以清空，但已经由 AI 判断了权限，这里再检查一次
    // 清空所有采购数据（当前房间）
    db.prepare('DELETE FROM purchase_attachments WHERE purchase_id IN (SELECT id FROM purchases WHERE room_id = ?)').run(roomId);
    db.prepare('DELETE FROM purchase_history WHERE purchase_id IN (SELECT id FROM purchases WHERE room_id = ?)').run(roomId);
    db.prepare('DELETE FROM purchases WHERE room_id = ?').run(roomId);
    const reply = '已清空当前房间的所有采购数据。';
    storeAndBroadcastText(roomId, '小财', reply);
    addToHistory(roomId, 'assistant', reply);
    broadcastToRoom(roomId, { type: 'purchase_updated' });
    return;
  }
  if (aiResult.action === 'purchase') {
    const createdTime = aiResult.created_time || now;
    let purchase = db.prepare('SELECT * FROM purchases WHERE room_id = ? AND item LIKE ? AND status != ?').get(roomId, `%${aiResult.purchase_item}%`, '已完成');
    let replyText = '';
    if (!purchase) {
      const id = uuidv4();
      db.prepare('INSERT INTO purchases (id, room_id, item, amount, method, status, applicant, created_at) VALUES (?,?,?,?,?,?,?,?)').run(
        id, roomId, aiResult.purchase_item, aiResult.amount, aiResult.method, aiResult.status || '待处理', aiResult.applicant || username, createdTime
      );
      db.prepare('INSERT INTO purchase_history (purchase_id, action, user, timestamp) VALUES (?,?,?,?)').run(id, 'AI 创建采购条目', '小财', now);
      replyText = `✅ 已记录采购：${aiResult.purchase_item}，金额 ¥${aiResult.amount}，状态 ${aiResult.status || '待处理'}`;
      purchase = { id };
    } else {
      db.prepare('UPDATE purchases SET amount = ?, method = ?, status = ?, updated_at = ? WHERE id = ?').run(
        aiResult.amount, aiResult.method, aiResult.status, now, purchase.id
      );
      db.prepare('INSERT INTO purchase_history (purchase_id, action, user, timestamp) VALUES (?,?,?,?)').run(purchase.id, `更新采购信息（金额：${aiResult.amount}，状态：${aiResult.status}）`, username, now);
      replyText = `🔄 已更新采购「${aiResult.purchase_item}」：金额 ¥${aiResult.amount}，状态 ${aiResult.status}`;
    }
    if (attachments?.length) {
      const insertAttach = db.prepare('INSERT INTO purchase_attachments (purchase_id, file_path, uploaded_by, timestamp) VALUES (?,?,?,?)');
      attachments.forEach(fp => insertAttach.run(purchase.id, fp, username, now));
    }
    storeAndBroadcastText(roomId, '小财', replyText);
    addToHistory(roomId, 'assistant', replyText);
    broadcastToRoom(roomId, { type: 'purchase_updated' });
    return;
  }
  if (aiResult.action === 'query') {
    const purchaseData = db.prepare('SELECT item, amount, method, status FROM purchases WHERE room_id = ? ORDER BY created_at DESC').all(roomId)
      .map(p => `${p.item} ¥${p.amount} ${p.status}`).join('\n');
    const summaryPrompt = `根据以下采购记录，用自然语言回答用户查询“${originalText}”。采购记录：\n${purchaseData || '暂无记录'}`;
    callDeepSeekForSummary(summaryPrompt).then(reply => {
      storeAndBroadcastText(roomId, '小财', reply);
      addToHistory(roomId, 'assistant', reply);
    });
    return;
  }
  if (aiResult.action === 'chat') {
    const reply = aiResult.reply || '好的，有什么需要帮助的吗？';
    storeAndBroadcastText(roomId, '小财', reply);
    addToHistory(roomId, 'assistant', reply);
    return;
  }
}

async function callDeepSeekForSummary(prompt) {
  const res = await fetch('https://api.deepseek.com/chat/completions', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json', 'Authorization': `Bearer ${DEEPSEEK_API_KEY}` },
    body: JSON.stringify({
      model: 'deepseek-v4-flash',
      messages: [
        { role: 'system', content: '你是一个财务助手，请根据采购记录生成简洁回复。' },
        { role: 'user', content: prompt }
      ],
      temperature: 0.3, stream: false
    })
  });
  const data = await res.json();
  return data.choices[0].message.content;
}

server.listen(process.env.PORT || 3000, () => {
  console.log(`Server running on port ${process.env.PORT || 3000}`);
});