const User = require('../models/User');
const jwt = require('jsonwebtoken');
const validator = require('validator');
const bcrypt = require('bcryptjs');

const generateToken = (userId) => {
  return jwt.sign({ userId }, process.env.JWT_SECRET || 'fallback-secret', { 
    expiresIn: process.env.JWT_EXPIRES_IN || '30d' 
  });
};

exports.register = async (req, res) => {
  try {
    const { username, email, password, displayName } = req.body;

    console.log('📝 Registration attempt:', { username, email, displayName });

    // Validation
    if (!username || !email || !password || !displayName) {
      return res.status(400).json({ error: 'All fields are required' });
    }

    if (!validator.isEmail(email)) {
      return res.status(400).json({ error: 'Invalid email format' });
    }

    if (password.length < 6) {
      return res.status(400).json({ error: 'Password must be at least 6 characters' });
    }

    if (username.length < 3 || username.length > 30) {
      return res.status(400).json({ error: 'Username must be between 3 and 30 characters' });
    }

    if (displayName.length < 2 || displayName.length > 50) {
      return res.status(400).json({ error: 'Display name must be between 2 and 50 characters' });
    }

    // Check if user exists
    const existingUser = await User.findOne({
      $or: [{ email }, { username }]
    });

    if (existingUser) {
      const field = existingUser.email === email ? 'email' : 'username';
      return res.status(400).json({ error: `User already exists with this ${field}` });
    }

    // Create user
    const user = await User.create({
      username,
      email,
      password,
      displayName,
      status: 'online'
    });

    // Generate token
    const token = generateToken(user._id);

    res.status(201).json({
      message: 'User registered successfully',
      user: {
        id: user._id,
        username: user.username,
        email: user.email,
        displayName: user.displayName,
        avatar: user.avatar,
        status: user.status,
        bio: user.bio,
        lastSeen: user.lastSeen
      },
      token
    });

  } catch (error) {
    console.error('❌ Registration error:', error);
    
    if (error.name === 'ValidationError') {
      const errors = Object.values(error.errors).map(err => err.message);
      return res.status(400).json({ error: errors.join(', ') });
    }
    
    if (error.code === 11000) {
      return res.status(400).json({ error: 'Username or email already exists' });
    }
    
    res.status(500).json({ error: 'Server error during registration' });
  }
};

exports.login = async (req, res) => {
  try {
    const { email, password } = req.body;

    console.log('🔐 Login attempt:', { email });

    if (!email || !password) {
      return res.status(400).json({ error: 'Email and password are required' });
    }

    // Find user and include password for comparison
    const user = await User.findOne({ email }).select('+password');
    
    if (!user) {
      return res.status(401).json({ error: 'Invalid credentials' });
    }

    // Check password
    const isPasswordValid = await user.comparePassword(password);
    if (!isPasswordValid) {
      return res.status(401).json({ error: 'Invalid credentials' });
    }

    // Update status to online
    user.status = 'online';
    user.lastSeen = new Date();
    await user.save();

    const token = generateToken(user._id);

    res.json({
      message: 'Login successful',
      user: {
        id: user._id,
        username: user.username,
        email: user.email,
        displayName: user.displayName,
        avatar: user.avatar,
        status: user.status,
        bio: user.bio,
        lastSeen: user.lastSeen,
        settings: user.settings
      },
      token
    });
  } catch (error) {
    console.error('❌ Login error:', error);
    res.status(500).json({ error: 'Server error during login' });
  }
};

exports.logout = async (req, res) => {
  try {
    // Update user status to offline
    if (req.user && req.user.userId) {
      await User.findByIdAndUpdate(req.user.userId, {
        status: 'offline',
        lastSeen: new Date()
      });
    }

    res.json({ message: 'Logged out successfully' });
  } catch (error) {
    console.error('❌ Logout error:', error);
    res.status(500).json({ error: 'Server error during logout' });
  }
};

exports.getMe = async (req, res) => {
  try {
    const user = await User.findById(req.user.userId);
    if (!user) {
      return res.status(404).json({ error: 'User not found' });
    }

    res.json({ 
      user: {
        id: user._id,
        username: user.username,
        email: user.email,
        displayName: user.displayName,
        avatar: user.avatar,
        status: user.status,
        bio: user.bio,
        lastSeen: user.lastSeen,
        settings: user.settings,
        createdAt: user.createdAt
      }
    });
  } catch (error) {
    console.error('❌ Get me error:', error);
    res.status(500).json({ error: 'Server error' });
  }
};

exports.updateProfile = async (req, res) => {
  try {
    const { displayName, bio, status } = req.body;
    const updateData = {};

    if (displayName) {
      if (displayName.length < 2 || displayName.length > 50) {
        return res.status(400).json({ error: 'Display name must be between 2 and 50 characters' });
      }
      updateData.displayName = displayName;
    }
    
    if (bio !== undefined) {
      if (bio.length > 500) {
        return res.status(400).json({ error: 'Bio must be less than 500 characters' });
      }
      updateData.bio = bio;
    }
    
    if (status && ['online', 'offline', 'away', 'busy'].includes(status)) {
      updateData.status = status;
    }

    const user = await User.findByIdAndUpdate(
      req.user.userId,
      updateData,
      { new: true, runValidators: true }
    );

    if (!user) {
      return res.status(404).json({ error: 'User not found' });
    }

    res.json({
      message: 'Profile updated successfully',
      user: {
        id: user._id,
        username: user.username,
        email: user.email,
        displayName: user.displayName,
        avatar: user.avatar,
        status: user.status,
        bio: user.bio,
        lastSeen: user.lastSeen
      }
    });
  } catch (error) {
    console.error('❌ Update profile error:', error);
    
    if (error.name === 'ValidationError') {
      const errors = Object.values(error.errors).map(err => err.message);
      return res.status(400).json({ error: errors.join(', ') });
    }
    
    res.status(500).json({ error: 'Server error during profile update' });
  }
};