const express = require('express');
const sqlite3 = require('sqlite3').verbose();
const cors = require('cors');
const bodyParser = require('body-parser');
const { v4: uuidv4 } = require('uuid');
const path = require('path');

const app = express();
const PORT = process.env.PORT || 3000;

// 中间件
app.use(cors());
app.use(bodyParser.json());
app.use(express.static('public'));

// 初始化数据库
const db = new sqlite3.Database('./agent_tasks.db', (err) => {
  if (err) {
    console.error('数据库连接失败:', err.message);
  } else {
    console.log('✅ 已连接到 SQLite 数据库');
    initDatabase();
  }
});

// 创建表结构
function initDatabase() {
  db.serialize(() => {
    // 智能体表
    db.run(`CREATE TABLE IF NOT EXISTS agents (
      id TEXT PRIMARY KEY,
      name TEXT NOT NULL,
      type TEXT,
      capabilities TEXT,
      status TEXT DEFAULT 'idle',
      registered_at INTEGER,
      last_heartbeat INTEGER
    )`);

    // 任务表
    db.run(`CREATE TABLE IF NOT EXISTS tasks (
      id TEXT PRIMARY KEY,
      title TEXT NOT NULL,
      description TEXT,
      priority TEXT DEFAULT 'normal',
      status TEXT DEFAULT 'pending',
      created_by TEXT,
      assigned_to TEXT,
      created_at INTEGER,
      updated_at INTEGER,
      completed_at INTEGER,
      result TEXT
    )`);

    console.log('✅ 数据库表已初始化');
  });
}

// ==================== API 路由 ====================

// 1. 智能体注册
app.post('/api/agents/register', (req, res) => {
  const { name, type, capabilities } = req.body;
  
  if (!name) {
    return res.status(400).json({ error: '智能体名称不能为空' });
  }

  const id = uuidv4();
  const now = Date.now();

  db.run(
    `INSERT INTO agents (id, name, type, capabilities, status, registered_at, last_heartbeat) 
     VALUES (?, ?, ?, ?, 'idle', ?, ?)`,
    [id, name, type || 'general', JSON.stringify(capabilities || []), now, now],
    function(err) {
      if (err) {
        return res.status(500).json({ error: err.message });
      }
      res.json({ 
        id, 
        name, 
        type: type || 'general',
        status: 'idle',
        message: '智能体注册成功' 
      });
    }
  );
});

// 2. 获取所有智能体
app.get('/api/agents', (req, res) => {
  db.all('SELECT * FROM agents ORDER BY registered_at DESC', [], (err, rows) => {
    if (err) {
      return res.status(500).json({ error: err.message });
    }
    res.json(rows.map(row => ({
      ...row,
      capabilities: JSON.parse(row.capabilities || '[]')
    })));
  });
});

// 3. 更新智能体状态（心跳）
app.post('/api/agents/:id/heartbeat', (req, res) => {
  const { id } = req.params;
  const { status } = req.body;
  
  db.run(
    'UPDATE agents SET status = ?, last_heartbeat = ? WHERE id = ?',
    [status || 'idle', Date.now(), id],
    function(err) {
      if (err) {
        return res.status(500).json({ error: err.message });
      }
      if (this.changes === 0) {
        return res.status(404).json({ error: '智能体不存在' });
      }
      res.json({ message: '心跳更新成功' });
    }
  );
});

// 4. 创建任务
app.post('/api/tasks', (req, res) => {
  const { title, description, priority, created_by } = req.body;
  
  if (!title) {
    return res.status(400).json({ error: '任务标题不能为空' });
  }

  const id = uuidv4();
  const now = Date.now();

  db.run(
    `INSERT INTO tasks (id, title, description, priority, status, created_by, created_at, updated_at) 
     VALUES (?, ?, ?, ?, 'pending', ?, ?, ?)`,
    [id, title, description || '', priority || 'normal', created_by || 'human', now, now],
    function(err) {
      if (err) {
        return res.status(500).json({ error: err.message });
      }
      res.json({ 
        id, 
        title,
        status: 'pending',
        message: '任务创建成功' 
      });
    }
  );
});

// 5. 获取所有任务
app.get('/api/tasks', (req, res) => {
  const { status } = req.query;
  
  let query = 'SELECT * FROM tasks';
  let params = [];
  
  if (status) {
    query += ' WHERE status = ?';
    params.push(status);
  }
  
  query += ' ORDER BY created_at DESC';
  
  db.all(query, params, (err, rows) => {
    if (err) {
      return res.status(500).json({ error: err.message });
    }
    res.json(rows);
  });
});

// 6. 领取任务
app.post('/api/tasks/:id/claim', (req, res) => {
  const { id } = req.params;
  const { agent_id } = req.body;
  
  if (!agent_id) {
    return res.status(400).json({ error: '需要提供智能体ID' });
  }

  db.get('SELECT status FROM tasks WHERE id = ?', [id], (err, task) => {
    if (err) {
      return res.status(500).json({ error: err.message });
    }
    if (!task) {
      return res.status(404).json({ error: '任务不存在' });
    }
    if (task.status !== 'pending') {
      return res.status(400).json({ error: '任务已被领取或已完成' });
    }

    db.run(
      'UPDATE tasks SET status = ?, assigned_to = ?, updated_at = ? WHERE id = ?',
      ['in_progress', agent_id, Date.now(), id],
      function(err) {
        if (err) {
          return res.status(500).json({ error: err.message });
        }
        
        // 同时更新智能体状态
        db.run('UPDATE agents SET status = ? WHERE id = ?', ['busy', agent_id]);
        
        res.json({ message: '任务领取成功' });
      }
    );
  });
});

// 7. 更新任务状态
app.put('/api/tasks/:id', (req, res) => {
  const { id } = req.params;
  const { status, result } = req.body;
  
  const now = Date.now();
  const updates = [];
  const params = [];
  
  if (status) {
    updates.push('status = ?');
    params.push(status);
  }
  if (result !== undefined) {
    updates.push('result = ?');
    params.push(result);
  }
  if (status === 'completed') {
    updates.push('completed_at = ?');
    params.push(now);
  }
  
  updates.push('updated_at = ?');
  params.push(now);
  params.push(id);
  
  db.run(
    `UPDATE tasks SET ${updates.join(', ')} WHERE id = ?`,
    params,
    function(err) {
      if (err) {
        return res.status(500).json({ error: err.message });
      }
      if (this.changes === 0) {
        return res.status(404).json({ error: '任务不存在' });
      }
      
      // 如果任务完成，将智能体状态改为 idle
      if (status === 'completed') {
        db.get('SELECT assigned_to FROM tasks WHERE id = ?', [id], (err, task) => {
          if (task && task.assigned_to) {
            db.run('UPDATE agents SET status = ? WHERE id = ?', ['idle', task.assigned_to]);
          }
        });
      }
      
      res.json({ message: '任务状态更新成功' });
    }
  );
});

// 8. 获取单个任务详情
app.get('/api/tasks/:id', (req, res) => {
  db.get('SELECT * FROM tasks WHERE id = ?', [req.params.id], (err, row) => {
    if (err) {
      return res.status(500).json({ error: err.message });
    }
    if (!row) {
      return res.status(404).json({ error: '任务不存在' });
    }
    res.json(row);
  });
});

// 9. 统计信息
app.get('/api/stats', (req, res) => {
  const stats = {
    total_agents: 0,
    active_agents: 0,
    total_tasks: 0,
    pending_tasks: 0,
    in_progress_tasks: 0,
    completed_tasks: 0
  };
  
  db.get('SELECT COUNT(*) as total FROM agents', [], (err, row) => {
    if (!err && row) stats.total_agents = row.total;
    
    db.get('SELECT COUNT(*) as active FROM agents WHERE status = "busy"', [], (err, row) => {
      if (!err && row) stats.active_agents = row.active;
      
      db.get('SELECT COUNT(*) as total FROM tasks', [], (err, row) => {
        if (!err && row) stats.total_tasks = row.total;
        
        db.get('SELECT COUNT(*) as pending FROM tasks WHERE status = "pending"', [], (err, row) => {
          if (!err && row) stats.pending_tasks = row.pending;
          
          db.get('SELECT COUNT(*) as in_progress FROM tasks WHERE status = "in_progress"', [], (err, row) => {
            if (!err && row) stats.in_progress_tasks = row.in_progress;
            
            db.get('SELECT COUNT(*) as completed FROM tasks WHERE status = "completed"', [], (err, row) => {
              if (!err && row) stats.completed_tasks = row.completed;
              res.json(stats);
            });
          });
        });
      });
    });
  });
});

// 启动服务器
app.listen(PORT, () => {
  console.log(`🚀 多智能体任务服务已启动: http://localhost:${PORT}`);
});

// 优雅关闭
process.on('SIGINT', () => {
  db.close((err) => {
    if (err) {
      console.error(err.message);
    }
    console.log('数据库连接已关闭');
    process.exit(0);
  });
});