const express = require('express');
const router = express.Router();
const User = require('../models/User');
const crypto = require('crypto');
const bcrypt = require('bcryptjs');

// Login page
router.get('/login', (req, res) => {
  if (req.session.isAuthenticated) {
    return res.redirect('/admin/dashboard');
  }
  
  res.render('auth/login', {
    title: 'Login',
    layout: false
  });
});

// Login handle
router.post('/login', async (req, res) => {
  const { username, password } = req.body;
  
  try {
        // Check database user
        const user = await User.findOne({ username });
    
    if (!user) {
      req.flash('error_msg', 'Invalid username or password');
      return res.redirect('/auth/login');
    }

    const isMatch = await user.comparePassword(password);
    
    if (!isMatch) {
      req.flash('error_msg', 'Invalid username or password');
      return res.redirect('/auth/login');
    }

    // Login success
    req.session.user = {
      id: user._id,
      username: user.username,
      email: user.email,
      name: user.name,
      role: user.role
    };
    req.session.isAuthenticated = true;
    req.flash('success_msg', 'Login successful');
    res.redirect('/admin/dashboard');

  } catch (err) {
    console.error(err);
    req.flash('error_msg', 'An error occurred during login');
    res.redirect('/auth/login');
  }
});

// Register page
router.get('/register', (req, res) => {
    if (req.session.isAuthenticated) {
        return res.redirect('/admin/dashboard');
    }
    res.render('auth/register', {
        title: 'Create Account',
        layout: false
    });
});

// Register handle
router.post('/register', async (req, res) => {
    const { username, email, password, confirm_password, name } = req.body;
    let errors = [];

    if (!username || !email || !password || !confirm_password || !name) {
        errors.push({ msg: 'Please enter all fields' });
    }

    if (password !== confirm_password) {
        errors.push({ msg: 'Passwords do not match' });
    }

    if (password.length < 6) {
        errors.push({ msg: 'Password must be at least 6 characters' });
    }

    if (errors.length > 0) {
        res.render('auth/register', {
            errors,
            username,
            email,
            name,
            title: 'Create Account',
            layout: false
        });
    } else {
        try {
            // Check if user exists
            const existingUser = await User.findOne({ $or: [{ email }, { username }] });
            
            if (existingUser) {
                errors.push({ msg: 'Email or Username already exists' });
                return res.render('auth/register', {
                    errors,
                    username,
                    email,
                    name,
                    title: 'Create Account',
                    layout: false
                });
            }

            const newUser = new User({
                username,
                email,
                name,
                password
            });

            await newUser.save();
            req.flash('success_msg', 'You are now registered and can log in');
            res.redirect('/auth/login');
        } catch (err) {
            console.error(err);
            errors.push({ msg: 'An error occurred during registration' });
            res.render('auth/register', {
                errors,
                username,
                email,
                name,
                title: 'Create Account',
                layout: false
            });
        }
    }
});

// Change Password Page
router.get('/change-password', (req, res) => {
    res.render('auth/change-password', {
        title: 'Change Password',
        layout: false
    });
});

// Change Password Handle
router.post('/change-password', async (req, res) => {
    const { email } = req.body;
    try {
        const user = await User.findOne({ email });
        if (!user) {
            req.flash('error_msg', 'No account with that email address exists.');
            return res.redirect('/auth/change-password');
        }

        const token = crypto.randomBytes(20).toString('hex');

        user.resetPasswordToken = token;
        user.resetPasswordExpires = Date.now() + 3600000; // 1 hour

        await user.save();

        // Direct flow as requested: Enter email -> Submit -> Enter new password
        // Redirect directly to the reset password page with the generated token
        res.redirect(`/auth/reset-password/${token}`);

    } catch (err) {
        console.error(err);
        req.flash('error_msg', 'Error processing request');
        res.redirect('/auth/change-password');
    }
});

// Reset Password Page
router.get('/reset-password/:token', async (req, res) => {
    try {
        const user = await User.findOne({ 
            resetPasswordToken: req.params.token, 
            resetPasswordExpires: { $gt: Date.now() } 
        });

        if (!user) {
            req.flash('error_msg', 'Password reset token is invalid or has expired.');
            return res.redirect('/auth/change-password');
        }

        res.render('auth/reset-password', {
            title: 'Reset Password',
            layout: false,
            token: req.params.token
        });
    } catch (err) {
        console.error(err);
        res.redirect('/auth/change-password');
    }
});

// Reset Password Handle
router.post('/reset-password/:token', async (req, res) => {
    try {
        const user = await User.findOne({ 
            resetPasswordToken: req.params.token, 
            resetPasswordExpires: { $gt: Date.now() } 
        });

        if (!user) {
            req.flash('error_msg', 'Password reset token is invalid or has expired.');
            return res.redirect('/auth/change-password');
        }

        if (req.body.password !== req.body.confirm_password) {
            req.flash('error_msg', 'Passwords do not match.');
            return res.redirect('back');
        }

        user.password = req.body.password;
        user.resetPasswordToken = undefined;
        user.resetPasswordExpires = undefined;

        await user.save();
        
        req.flash('success_msg', 'Success! Your password has been changed.');
        res.redirect('/auth/login');
    } catch (err) {
        console.error(err);
        res.redirect('back');
    }
});

router.get('/logout', (req, res) => {
  req.session.destroy((err) => {
    if (err) {
      console.error('Error when logout:', err);
    }
    res.redirect('/');
  });
});

module.exports = router;