const express = require('express');
const mysql = require('mysql2/promise');
const cors = require('cors');
const bcrypt = require('bcryptjs');
const jwt = require('jsonwebtoken');
require('dotenv').config();

const app = express();
const PORT = process.env.PORT || 5000;
const JWT_SECRET = 'weiMonkey2024_secret_key';

// 中间件
app.use(cors());
app.use(express.json());

// 数据库连接配置
const dbConfig = {
  host: 'localhost',
  port: 3306,
  user: 'root',
  password: '123456',
  database: 'myuser'
};

// 创建数据库连接池
const pool = mysql.createPool(dbConfig);

// 初始化数据库表
async function initDatabase() {
  try {
    const connection = await pool.getConnection();
    
    // 创建用户表
    await connection.execute(`
      CREATE TABLE IF NOT EXISTS users (
        id INT AUTO_INCREMENT PRIMARY KEY,
        username VARCHAR(64) NOT NULL UNIQUE,
        password VARCHAR(255) NOT NULL,
        is_admin BOOLEAN DEFAULT FALSE,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
      )
    `);
    
    // 创建待办事项表
    await connection.execute(`
      CREATE TABLE IF NOT EXISTS todos (
        id INT AUTO_INCREMENT PRIMARY KEY,
        title VARCHAR(255) NOT NULL,
        description TEXT,
        priority ENUM('low', 'medium', 'high', 'urgent') DEFAULT 'medium',
        completed BOOLEAN DEFAULT FALSE,
        suspended BOOLEAN DEFAULT FALSE,
        date DATE NOT NULL,
        suspended_date DATE NULL,
        user_id INT NOT NULL,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
        FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
      )
    `);
    
    // 添加user_id字段（如果表已存在但没有该字段）
    try {
      await connection.execute(`
        ALTER TABLE todos 
        ADD COLUMN user_id INT NOT NULL,
        ADD CONSTRAINT fk_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
      `);
    } catch (error) {
      // 字段可能已存在，忽略错误
      console.log('User_id column may already exist');
    }
    
    // 添加suspended字段（如果表已存在但没有该字段）
    try {
      await connection.execute(`
        ALTER TABLE todos 
        ADD COLUMN suspended BOOLEAN DEFAULT FALSE,
        ADD COLUMN suspended_date DATE NULL
      `);
    } catch (error) {
      // 字段可能已存在，忽略错误
      console.log('Suspended columns may already exist');
    }

    // 添加description字段（如果表已存在但没有该字段）
    try {
      await connection.execute(`
        ALTER TABLE todos 
        ADD COLUMN description TEXT
      `);
    } catch (error) {
      // 字段可能已存在，忽略错误
      console.log('Description column may already exist');
    }
    
    // 创建默认管理员用户
    const adminPassword = await bcrypt.hash('weiMonkey2024', 10);
    try {
      await connection.execute(`
        INSERT INTO users (username, password, is_admin) 
        VALUES ('admin', ?, TRUE)
      `, [adminPassword]);
      console.log('默认管理员用户创建成功');
    } catch (error) {
      // 用户可能已存在
      console.log('默认管理员用户可能已存在');
    }
    
    connection.release();
    console.log('数据库表初始化成功');
  } catch (error) {
    console.error('数据库初始化失败:', error);
  }
}

// 验证密码的中间件
const authenticatePassword = (req, res, next) => {
  const { password } = req.body;
  const correctPassword = 'weiMonkey2024';
  
  if (password !== correctPassword) {
    return res.status(401).json({ error: '密码错误' });
  }
  
  next();
};

// 验证token的中间件
const authenticateToken = (req, res, next) => {
  const authHeader = req.headers['authorization'];
  const token = authHeader && authHeader.split(' ')[1];

  if (!token) {
    return res.status(401).json({ error: '需要认证' });
  }

  jwt.verify(token, JWT_SECRET, (err, user) => {
    if (err) {
      return res.status(403).json({ error: '无效的token' });
    }
    req.user = user;
    next();
  });
};

// 验证管理员权限的中间件
const authenticateAdmin = (req, res, next) => {
  if (!req.user.is_admin) {
    return res.status(403).json({ error: '需要管理员权限' });
  }
  next();
};

// 路由

// 用户登录
app.post('/api/auth/login', async (req, res) => {
  try {
    const { username, password } = req.body;
    
    if (!username || !password) {
      return res.status(400).json({ error: '用户名和密码是必需的' });
    }
    
    const connection = await pool.getConnection();
    
    // 查找用户
    const [users] = await connection.execute(
      'SELECT * FROM users WHERE username = ?',
      [username]
    );
    
    connection.release();
    
    if (users.length === 0) {
      return res.status(401).json({ error: '用户名或密码错误' });
    }
    
    const user = users[0];
    
    // 验证密码
    const isValidPassword = await bcrypt.compare(password, user.password);
    if (!isValidPassword) {
      return res.status(401).json({ error: '用户名或密码错误' });
    }
    
    // 生成token
    const token = jwt.sign(
      { 
        userId: user.id, 
        username: user.username, 
        is_admin: user.is_admin 
      }, 
      JWT_SECRET, 
      { expiresIn: '24h' }
    );
    
    res.json({ 
      success: true, 
      token,
      user: {
        id: user.id,
        username: user.username,
        is_admin: user.is_admin
      }
    });
  } catch (error) {
    console.error('登录失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 管理员添加用户
app.post('/api/auth/register', authenticateToken, authenticateAdmin, async (req, res) => {
  try {
    const { username, password } = req.body;
    
    if (!username || !password) {
      return res.status(400).json({ error: '用户名和密码是必需的' });
    }
    
    if (password.length < 6) {
      return res.status(400).json({ error: '密码长度至少6位' });
    }
    
    const connection = await pool.getConnection();
    
    // 检查用户名是否已存在
    const [existingUsers] = await connection.execute(
      'SELECT id FROM users WHERE username = ?',
      [username]
    );
    
    if (existingUsers.length > 0) {
      connection.release();
      return res.status(400).json({ error: '用户名已存在' });
    }
    
    // 创建新用户
    const hashedPassword = await bcrypt.hash(password, 10);
    const [result] = await connection.execute(
      'INSERT INTO users (username, password, is_admin) VALUES (?, ?, FALSE)',
      [username, hashedPassword]
    );
    
    connection.release();
    
    res.json({ 
      success: true, 
      message: '用户创建成功',
      userId: result.insertId 
    });
  } catch (error) {
    console.error('注册用户失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 获取所有用户（仅管理员）
app.get('/api/users', authenticateToken, authenticateAdmin, async (req, res) => {
  try {
    const connection = await pool.getConnection();
    
    const [users] = await connection.execute(
      'SELECT id, username, is_admin, created_at FROM users ORDER BY created_at DESC'
    );
    
    connection.release();
    res.json(users);
  } catch (error) {
    console.error('获取用户列表失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 获取历史待办事项（一周之前的）
app.get('/api/todos/history', authenticateToken, async (req, res) => {
  try {
    const connection = await pool.getConnection();
    
    // 获取一周之前的历史数据
    const today = new Date();
    const oneWeekAgo = new Date(today.getTime() - 7 * 24 * 60 * 60 * 1000);
    
    // 管理员可以查看所有用户的数据，普通用户只能查看自己的
    let       query = 'SELECT * FROM todos WHERE date < ? AND user_id = ? ORDER BY date DESC, priority DESC, created_at DESC';
    let params = [oneWeekAgo.toISOString().split('T')[0]];
    params.push(req.user.userId);
    
    
    const [rows] = await connection.execute(query, params);
    
    connection.release();
    res.json(rows);
  } catch (error) {
    console.error('获取历史待办事项失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 获取最近一周的待办事项（排除挂起的）
app.get('/api/todos', authenticateToken, async (req, res) => {
  try {
    const connection = await pool.getConnection();
    
    // 获取最近一周的日期范围
    const today = new Date();
    const oneWeekAgo = new Date(today.getTime() - 7 * 24 * 60 * 60 * 1000);
    
    // 管理员可以查看所有用户的数据，普通用户只能查看自己的
    let query = 'SELECT * FROM todos WHERE date >= ? AND date <= ? AND suspended = FALSE AND user_id = ? ORDER BY date DESC, priority DESC, created_at DESC';

    let params = [oneWeekAgo.toISOString().split('T')[0], today.toISOString().split('T')[0]];
    params.push(req.user.userId);
    const [rows] = await connection.execute(query, params);
    
    connection.release();
    res.json(rows);
  } catch (error) {
    console.error('获取待办事项失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 创建新的待办事项
app.post('/api/todos', authenticateToken, async (req, res) => {
  try {
    const { title, priority, date, description } = req.body;
    
    if (!title || !date) {
      return res.status(400).json({ error: '标题和日期是必需的' });
    }
    
    const connection = await pool.getConnection();
    
    const [result] = await connection.execute(
      'INSERT INTO todos (title, description, priority, date, user_id) VALUES (?, ?, ?, ?, ?)',
      [title, description || null, priority || 'medium', date, req.user.userId]
    );
    
    const [newTodo] = await connection.execute(
      'SELECT * FROM todos WHERE id = ?',
      [result.insertId]
    );
    
    connection.release();
    res.status(201).json(newTodo[0]);
  } catch (error) {
    console.error('创建待办事项失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 更新待办事项状态
app.put('/api/todos/:id', authenticateToken, async (req, res) => {
  try {
    const { id } = req.params;
    const { completed, title, priority, date, description } = req.body;
    
    const connection = await pool.getConnection();
    
    // 检查待办事项是否存在且属于当前用户（管理员可以修改所有）
    let checkQuery = 'SELECT * FROM todos WHERE id = ?';
    let checkParams = [id];
    
    if (!req.user.is_admin) {
      checkQuery = 'SELECT * FROM todos WHERE id = ? AND user_id = ?';
      checkParams.push(req.user.userId);
    }
    
    const [existingTodos] = await connection.execute(checkQuery, checkParams);
    
    if (existingTodos.length === 0) {
      connection.release();
      return res.status(404).json({ error: '待办事项不存在或无权限访问' });
    }
    
    // 构建更新字段和值
    const updates = [];
    const values = [];
    
    if (completed !== undefined) {
      updates.push('completed = ?');
      values.push(completed);
    }
    
    if (title !== undefined) {
      updates.push('title = ?');
      values.push(title);
    }
    
    if (priority !== undefined) {
      updates.push('priority = ?');
      values.push(priority);
    }
    
    if (date !== undefined) {
      updates.push('date = ?');
      values.push(date);
    }
    
    if (description !== undefined) {
      updates.push('description = ?');
      values.push(description || null);
    }
    
    if (updates.length === 0) {
      connection.release();
      return res.status(400).json({ error: '没有提供要更新的字段' });
    }
    
    // 添加 id 到值数组
    values.push(id);
    
    // 执行更新
    await connection.execute(
      `UPDATE todos SET ${updates.join(', ')} WHERE id = ?`,
      values
    );
    
    // 获取更新后的待办事项
    const [updatedTodo] = await connection.execute(
      'SELECT * FROM todos WHERE id = ?',
      [id]
    );
    
    connection.release();
    res.json(updatedTodo[0]);
  } catch (error) {
    console.error('更新待办事项失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 删除待办事项
app.delete('/api/todos/:id', authenticateToken, async (req, res) => {
  try {
    const { id } = req.params;
    
    const connection = await pool.getConnection();
    
    // 检查待办事项是否存在且属于当前用户（管理员可以删除所有）
    let checkQuery = 'SELECT * FROM todos WHERE id = ?';
    let checkParams = [id];
    
    if (!req.user.is_admin) {
      checkQuery = 'SELECT * FROM todos WHERE id = ? AND user_id = ?';
      checkParams.push(req.user.userId);
    }
    
    const [existingTodos] = await connection.execute(checkQuery, checkParams);
    
    if (existingTodos.length === 0) {
      connection.release();
      return res.status(404).json({ error: '待办事项不存在或无权限访问' });
    }
    
    await connection.execute('DELETE FROM todos WHERE id = ?', [id]);
    
    connection.release();
    res.json({ success: true });
  } catch (error) {
    console.error('删除待办事项失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 挂起今天的待办事项
app.put('/api/todos/:id/suspend', authenticateToken, async (req, res) => {
  try {
    const { id } = req.params;
    const today = new Date().toISOString().split('T')[0];
    
    const connection = await pool.getConnection();
    
    // 检查是否是今天的待办事项且属于当前用户
    let checkQuery = 'SELECT * FROM todos WHERE id = ? AND date = ? AND user_id = ?';
    let checkParams = [id, today];
    checkParams.push(req.user.userId);
    
    
    const [todoCheck] = await connection.execute(checkQuery, checkParams);
    
    if (todoCheck.length === 0) {
      connection.release();
      return res.status(400).json({ error: '只能挂起今天的待办事项或无权限访问' });
    }
    
    // 更新挂起状态
    await connection.execute(
      'UPDATE todos SET suspended = TRUE, suspended_date = ? WHERE id = ?',
      [today, id]
    );
    
    const [updatedTodo] = await connection.execute(
      'SELECT * FROM todos WHERE id = ?',
      [id]
    );
    
    connection.release();
    res.json(updatedTodo[0]);
  } catch (error) {
    console.error('挂起待办事项失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 获取所有挂起的待办事项
app.get('/api/todos/suspended', authenticateToken, async (req, res) => {
  try {
    const connection = await pool.getConnection();
    
    // 管理员可以查看所有用户的挂起待办，普通用户只能查看自己的
    let query = 'SELECT * FROM todos WHERE suspended = TRUE AND user_id = ? ORDER BY suspended_date DESC, priority DESC, created_at DESC';
    let params = [];
    params.push(req.user.userId);
    
    
    const [rows] = await connection.execute(query, params);
    
    connection.release();
    res.json(rows);
  } catch (error) {
    console.error('获取挂起待办事项失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 恢复挂起的待办事项到今天
app.put('/api/todos/:id/resume', authenticateToken, async (req, res) => {
  try {
    const { id } = req.params;
    const today = new Date().toISOString().split('T')[0];
    
    const connection = await pool.getConnection();
    
    // 检查是否是挂起的待办事项且属于当前用户
    let checkQuery = 'SELECT * FROM todos WHERE id = ? AND suspended = TRUE AND user_id = ?';
    let checkParams = [id];
    checkParams.push(req.user.userId);
    
    
    const [todoCheck] = await connection.execute(checkQuery, checkParams);
    
    if (todoCheck.length === 0) {
      connection.release();
      return res.status(400).json({ error: '待办事项未处于挂起状态或无权限访问' });
    }
    
    // 恢复待办事项到今天
    await connection.execute(
      'UPDATE todos SET suspended = FALSE, suspended_date = NULL, date = ?, completed = FALSE WHERE id = ?',
      [today, id]
    );
    
    const [updatedTodo] = await connection.execute(
      'SELECT * FROM todos WHERE id = ?',
      [id]
    );
    
    connection.release();
    res.json(updatedTodo[0]);
  } catch (error) {
    console.error('恢复待办事项失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 将历史未完成待办迁移到今天
app.post('/api/todos/migrate-pending', authenticateToken, async (req, res) => {
  try {
    const connection = await pool.getConnection();
    
    // 获取今天的日期
    const today = new Date().toISOString().split('T')[0];
    
    // 查找今天之前所有未完成且未挂起的待办事项
    let query = 'SELECT * FROM todos WHERE date < ? AND completed = FALSE AND suspended = FALSE AND user_id = ? ORDER BY date DESC, priority DESC';
    let params = [today];
    params.push(req.user.userId);
    
    const [pendingTodos] = await connection.execute(query, params);
    
    let migratedCount = 0;
    
    // 将每个未完成的待办事项迁移到今天
    for (const todo of pendingTodos) {
      await connection.execute(
        'UPDATE todos SET date = ? WHERE id = ?',
        [today, todo.id]
      );
      migratedCount++;
    }
    
    connection.release();
    res.json({ 
      success: true, 
      migratedCount,
      message: `已迁移 ${migratedCount} 个未完成的待办事项到今天`
    });
  } catch (error) {
    console.error('迁移待办事项失败:', error);
    res.status(500).json({ error: '服务器错误' });
  }
});

// 启动服务器
app.listen(PORT, async () => {
  console.log(`服务器运行在端口 ${PORT}`);
  await initDatabase();
});