const express = require('express');
const router = express.Router();
const { db } = require('../database/db');
const { authenticate } = require('../middleware/auth');
const { backupLimiter, heavyLimiter, readLimiter } = require('../middleware/rateLimiter');
const fs = require('fs').promises;
const path = require('path');
const archiver = require('archiver');
const unzipper = require('unzipper');
const { promisify } = require('util');

const dbAll = promisify(db.all.bind(db));
const dbRun = promisify(db.run.bind(db));

const BACKUP_DIR = path.join(__dirname, '../../data/backups');

// Ensure backup directory exists
const ensureBackupDir = async () => {
  try {
    await fs.mkdir(BACKUP_DIR, { recursive: true });
  } catch (error) {
    console.error('Failed to create backup directory:', error);
  }
};

/**
 * GET /api/backup/list
 * List all backups for the current user
 */
router.get('/list', authenticate, readLimiter, async (req, res) => {
  try {
    await ensureBackupDir();
    const userId = req.user.id;
    const username = req.user.username;
    
    const files = await fs.readdir(BACKUP_DIR);
    const userBackups = files.filter(f => 
      (f.startsWith(`StreamFlow_Backup_${username}_`) || f.startsWith(`backup_user${userId}_`)) && f.endsWith('.zip')
    );
    
    const backupList = await Promise.all(
      userBackups.map(async (filename) => {
        const filePath = path.join(BACKUP_DIR, filename);
        const stats = await fs.stat(filePath);
        
        // Parse filename: StreamFlow_Backup_{username}_{timestamp}.zip or old format backup_user{id}_{timestamp}.zip
        let match = filename.match(/StreamFlow_Backup_[^_]+_(\d+)\.zip/);
        if (!match) {
          match = filename.match(/backup_user\d+_(\d+)\.zip/);
        }
        const filenameTimestamp = match ? parseInt(match[1]) : 0;
        
        // Use file's actual mtime (modification time) which is more reliable
        const actualTimestamp = stats.mtimeMs;
        
        return {
          filename,
          size: stats.size,
          created: new Date(actualTimestamp).toISOString(),
          timestamp: actualTimestamp
        };
      })
    );
    
    // Sort by timestamp descending (newest first)
    backupList.sort((a, b) => b.timestamp - a.timestamp);
    
    res.json(backupList);
  } catch (error) {
    console.error('Failed to list backups:', error);
    res.status(500).json({ error: 'Failed to list backups' });
  }
});

/**
 * POST /api/backup/create
 * Create a new backup of user data
 */
router.post('/create', authenticate, backupLimiter, async (req, res) => {
  try {
    await ensureBackupDir();
    const userId = req.user.id;
    const username = req.user.username;
    const timestamp = Date.now();
    const filename = `StreamFlow_Backup_${username}_${timestamp}.zip`;
    const backupPath = path.join(BACKUP_DIR, filename);
    
    // Create write stream for zip
    const output = require('fs').createWriteStream(backupPath);
    const archive = archiver('zip', { zlib: { level: 9 } });
    
    output.on('close', () => {
      res.json({
        success: true,
        filename,
        size: archive.pointer(),
        created: new Date(timestamp).toISOString()
      });
    });
    
    archive.on('error', (err) => {
      throw err;
    });
    
    archive.pipe(output);
    
    // Export user data - CWE-532: Exclude password and sensitive fields
    const userData = await dbAll(
      `SELECT id, username, email, role, two_factor_enabled, is_active, 
              created_at, updated_at, last_login_at, last_login_ip, 
              password_changed_at, password_expires_at 
       FROM users WHERE id = ?`, 
      [userId]
    );
    archive.append(JSON.stringify(userData, null, 2), { name: 'user.json' });
    
    // Export playlists
    const playlists = await dbAll('SELECT * FROM playlists WHERE user_id = ?', [userId]);
    archive.append(JSON.stringify(playlists, null, 2), { name: 'playlists.json' });
    
    // Export channels
    const channels = await dbAll(
      `SELECT DISTINCT c.* FROM channels c
       JOIN playlists p ON c.playlist_id = p.id
       WHERE p.user_id = ?`,
      [userId]
    );
    archive.append(JSON.stringify(channels, null, 2), { name: 'channels.json' });
    
    // Export favorites
    const favorites = await dbAll('SELECT * FROM favorites WHERE user_id = ?', [userId]);
    archive.append(JSON.stringify(favorites, null, 2), { name: 'favorites.json' });
    
    // Export custom channel logos
    const customLogos = await dbAll(
      `SELECT c.id, c.name, c.custom_logo FROM channels c
       JOIN playlists p ON c.playlist_id = p.id
       WHERE p.user_id = ? AND c.custom_logo IS NOT NULL`,
      [userId]
    );
    
    // Add custom logo files
    for (const channel of customLogos) {
      if (channel.custom_logo) {
        const logoPath = path.join(__dirname, '../../data/logos', channel.custom_logo);
        try {
          const logoExists = await fs.access(logoPath).then(() => true).catch(() => false);
          if (logoExists) {
            archive.file(logoPath, { name: `logos/${channel.custom_logo}` });
          }
        } catch (err) {
          console.error(`Failed to add logo ${channel.custom_logo}:`, err);
        }
      }
    }
    
    // Export m3u files
    const m3uFiles = await dbAll('SELECT * FROM m3u_files WHERE user_id = ?', [userId]);
    archive.append(JSON.stringify(m3uFiles, null, 2), { name: 'm3u_files.json' });
    
    // Add actual m3u files
    for (const m3uFile of m3uFiles) {
      if (m3uFile.file_path) {
        const m3uPath = path.join(__dirname, '../../data/playlists', m3uFile.file_path);
        try {
          const m3uExists = await fs.access(m3uPath).then(() => true).catch(() => false);
          if (m3uExists) {
            archive.file(m3uPath, { name: `m3u_files/${m3uFile.file_path}` });
          }
        } catch (err) {
          console.error(`Failed to add m3u file ${m3uFile.file_path}:`, err);
        }
      }
    }
    
    // Export user settings (stream settings, preferences)
    const settings = {
      created: new Date(timestamp).toISOString(),
      version: '1.0',
      userId: userId,
      username: req.user.username
    };
    archive.append(JSON.stringify(settings, null, 2), { name: 'backup_info.json' });
    
    // Finalize the archive
    await archive.finalize();
    
  } catch (error) {
    console.error('Failed to create backup:', error);
    res.status(500).json({ error: 'Failed to create backup' });
  }
});

/**
 * GET /api/backup/download/:filename
 * Download a backup file
 */
router.get('/download/:filename', authenticate, heavyLimiter, async (req, res) => {
  try {
    const userId = req.user.id;
    const username = req.user.username;
    const { filename } = req.params;
    
    // Validate filename belongs to user (support both old and new format)
    const isOldFormat = filename.startsWith(`backup_user${userId}_`);
    const isNewFormat = filename.startsWith(`StreamFlow_Backup_${username}_`);
    if ((!isOldFormat && !isNewFormat) || !filename.endsWith('.zip')) {
      return res.status(403).json({ error: 'Unauthorized' });
    }
    
    const filePath = path.join(BACKUP_DIR, filename);
    
    // Check if file exists
    try {
      await fs.access(filePath);
    } catch (err) {
      return res.status(404).json({ error: 'Backup not found' });
    }
    
    res.download(filePath, filename);
  } catch (error) {
    console.error('Failed to download backup:', error);
    res.status(500).json({ error: 'Failed to download backup' });
  }
});

/**
 * DELETE /api/backup/:filename
 * Delete a backup file
 */
router.delete('/:filename', authenticate, readLimiter, async (req, res) => {
  try {
    const userId = req.user.id;
    const username = req.user.username;
    const { filename } = req.params;
    
    // Validate filename belongs to user (support both old and new format)
    const isOldFormat = filename.startsWith(`backup_user${userId}_`);
    const isNewFormat = filename.startsWith(`StreamFlow_Backup_${username}_`);
    if ((!isOldFormat && !isNewFormat) || !filename.endsWith('.zip')) {
      return res.status(403).json({ error: 'Unauthorized' });
    }
    
    const filePath = path.join(BACKUP_DIR, filename);
    await fs.unlink(filePath);
    
    res.json({ success: true, message: 'Backup deleted' });
  } catch (error) {
    console.error('Failed to delete backup:', error);
    res.status(500).json({ error: 'Failed to delete backup' });
  }
});

/**
 * POST /api/backup/upload
 * Upload a backup file for restoration
 */
router.post('/upload', authenticate, heavyLimiter, async (req, res) => {
  try {
    await ensureBackupDir();
    
    if (!req.files || !req.files.backup) {
      return res.status(400).json({ error: 'No backup file provided' });
    }
    
    const userId = req.user.id;
    const username = req.user.username;
    const backupFile = req.files.backup;
    const timestamp = Date.now();
    const filename = `StreamFlow_Backup_${username}_${timestamp}.zip`;
    const uploadPath = path.join(BACKUP_DIR, filename);
    
    await backupFile.mv(uploadPath);
    
    const stats = await fs.stat(uploadPath);
    
    res.json({
      success: true,
      filename,
      size: stats.size,
      created: new Date(timestamp).toISOString()
    });
  } catch (error) {
    console.error('Failed to upload backup:', error);
    res.status(500).json({ error: 'Failed to upload backup' });
  }
});

/**
 * POST /api/backup/restore/:filename
 * Restore data from a backup file
 */
router.post('/restore/:filename', authenticate, backupLimiter, async (req, res) => {
  try {
    const userId = req.user.id;
    const username = req.user.username;
    const { filename } = req.params;
    
    // Validate filename belongs to user (support both old and new format)
    const isOldFormat = filename.startsWith(`backup_user${userId}_`);
    const isNewFormat = filename.startsWith(`StreamFlow_Backup_${username}_`);
    if ((!isOldFormat && !isNewFormat) || !filename.endsWith('.zip')) {
      return res.status(403).json({ error: 'Unauthorized' });
    }
    
    const backupPath = path.join(BACKUP_DIR, filename);
    const extractPath = path.join(BACKUP_DIR, `extract_${userId}_${Date.now()}`);
    
    // Check if backup exists
    try {
      await fs.access(backupPath);
    } catch (err) {
      return res.status(404).json({ error: 'Backup not found' });
    }
    
    // Extract backup
    await fs.mkdir(extractPath, { recursive: true });
    
    await require('fs')
      .createReadStream(backupPath)
      .pipe(unzipper.Extract({ path: extractPath }))
      .promise();
    
    // Read backup data
    const playlistsData = JSON.parse(await fs.readFile(path.join(extractPath, 'playlists.json'), 'utf8'));
    const channelsData = JSON.parse(await fs.readFile(path.join(extractPath, 'channels.json'), 'utf8'));
    const favoritesData = JSON.parse(await fs.readFile(path.join(extractPath, 'favorites.json'), 'utf8'));
    
    // Start transaction-like operations
    let restoredPlaylists = 0;
    let restoredChannels = 0;
    let restoredFavorites = 0;
    
    // Restore playlists
    for (const playlist of playlistsData) {
      try {
        await dbRun(
          `INSERT OR IGNORE INTO playlists (name, url, username, password, user_id, created_at)
           VALUES (?, ?, ?, ?, ?, ?)`,
          [playlist.name, playlist.url, playlist.username, playlist.password, userId, playlist.created_at]
        );
        restoredPlaylists++;
      } catch (err) {
        console.error('Failed to restore playlist:', err);
      }
    }
    
    // Get new playlist IDs mapping
    const newPlaylists = await dbAll('SELECT id, name FROM playlists WHERE user_id = ?', [userId]);
    const playlistMap = {};
    playlistsData.forEach((oldP, idx) => {
      const newP = newPlaylists.find(p => p.name === oldP.name);
      if (newP) playlistMap[oldP.id] = newP.id;
    });
    
    // Restore channels
    for (const channel of channelsData) {
      const newPlaylistId = playlistMap[channel.playlist_id];
      if (!newPlaylistId) continue;
      
      try {
        await dbRun(
          `INSERT OR IGNORE INTO channels 
           (name, url, logo, group_name, playlist_id, custom_logo, is_radio, tvg_id, tvg_name)
           VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)`,
          [
            channel.name, channel.url, channel.logo, channel.group_name, 
            newPlaylistId, channel.custom_logo, channel.is_radio,
            channel.tvg_id, channel.tvg_name
          ]
        );
        restoredChannels++;
      } catch (err) {
        console.error('Failed to restore channel:', err);
      }
    }
    
    // Restore custom logos
    const logosDir = path.join(extractPath, 'logos');
    try {
      const logoFiles = await fs.readdir(logosDir);
      const targetLogosDir = path.join(__dirname, '../../data/logos');
      await fs.mkdir(targetLogosDir, { recursive: true });
      
      for (const logoFile of logoFiles) {
        const src = path.join(logosDir, logoFile);
        const dest = path.join(targetLogosDir, logoFile);
        await fs.copyFile(src, dest);
      }
    } catch (err) {
      // Logos directory might not exist in older backups
      console.log('No custom logos to restore');
    }
    
    // Restore favorites (map to new channel IDs)
    const newChannels = await dbAll(
      `SELECT c.id, c.name, c.url FROM channels c
       JOIN playlists p ON c.playlist_id = p.id
       WHERE p.user_id = ?`,
      [userId]
    );
    
    for (const fav of favoritesData) {
      const oldChannel = channelsData.find(c => c.id === fav.channel_id);
      if (!oldChannel) continue;
      
      const newChannel = newChannels.find(c => c.name === oldChannel.name && c.url === oldChannel.url);
      if (!newChannel) continue;
      
      try {
        await dbRun(
          `INSERT OR IGNORE INTO favorites (user_id, channel_id, custom_logo, is_radio)
           VALUES (?, ?, ?, ?)`,
          [userId, newChannel.id, fav.custom_logo, fav.is_radio]
        );
        restoredFavorites++;
      } catch (err) {
        console.error('Failed to restore favorite:', err);
      }
    }
    
    // Restore M3U files
    try {
      const m3uFilesData = JSON.parse(await fs.readFile(path.join(extractPath, 'm3u_files.json'), 'utf8'));
      const m3uFilesDir = path.join(extractPath, 'm3u_files');
      const targetM3uDir = path.join(__dirname, '../../data/playlists');
      await fs.mkdir(targetM3uDir, { recursive: true });
      
      for (const m3uFile of m3uFilesData) {
        try {
          // Copy physical file
          if (m3uFile.file_path) {
            const src = path.join(m3uFilesDir, m3uFile.file_path);
            const dest = path.join(targetM3uDir, m3uFile.file_path);
            await fs.copyFile(src, dest);
          }
          
          // Insert database record
          await dbRun(
            `INSERT OR IGNORE INTO m3u_files (user_id, name, file_path, uploaded_at)
             VALUES (?, ?, ?, ?)`,
            [userId, m3uFile.name, m3uFile.file_path, m3uFile.uploaded_at]
          );
        } catch (err) {
          console.error('Failed to restore m3u file:', err);
        }
      }
    } catch (err) {
      console.log('No M3U files to restore');
    }
    
    // Cleanup extraction directory
    await fs.rm(extractPath, { recursive: true, force: true });
    
    res.json({
      success: true,
      message: 'Backup restored successfully',
      stats: {
        playlists: restoredPlaylists,
        channels: restoredChannels,
        favorites: restoredFavorites
      }
    });
    
  } catch (error) {
    console.error('Failed to restore backup:', error);
    res.status(500).json({ error: 'Failed to restore backup' });
  }
});

module.exports = router;