const express = require('express');
const { success } = require('../src/utils/responses');
const fs = require('fs');
const path = require('path');

const DEFAULT_BACKUP_DIR = process.env.BACKUP_DIR || path.join(__dirname, 'backups');

/**
 * Backups routes factory
 * @param {Object} deps - Explicit dependencies
 * @param {Object} deps.backupManager - Backup management module
 * @param {Object} deps.licenseManager - License manager for premium gating
 * @param {Function} deps.asyncHandler - Async route handler wrapper
 * @returns {express.Router}
 */
module.exports = function({ backupManager, licenseManager, asyncHandler }) {
  const router = express.Router();

  // ==================== SCHEDULE ENDPOINTS (PREMIUM) ====================

  // Apply premium gating to schedule-related routes
  const premiumGating = licenseManager.requirePremium('auto-backup');

  // Get all scheduled backup configs
  router.get('/backups/schedule', premiumGating, asyncHandler(async (req, res) => {
    const config = backupManager.getConfig();
    const backups = config.backups || {};
    
    // Calculate next run times based on schedule and last history entry
    const history = backupManager.getHistory(1000);
    const schedules = Object.entries(backups).map(([appId, backup]) => {
      const appHistory = history.filter(h => h.name === appId && h.status === 'success');
      const lastRun = appHistory.length > 0 ? new Date(appHistory[0].timestamp) : null;
      const nextRun = calculateNextRun(lastRun, backup.schedule);
      
      return {
        appId,
        enabled: backup.enabled || false,
        schedule: backup.schedule || 'daily',
        retention: backup.retention || { keep: 7, olderThan: null },
        runImmediately: backup.runImmediately || false,
        destination: backup.destination || 'local',
        destinationPath: backup.destinationPath || DEFAULT_BACKUP_DIR,
        lastRun: lastRun ? lastRun.toISOString() : null,
        nextRun: nextRun ? nextRun.toISOString() : null,
        lastBackupId: appHistory.length > 0 ? appHistory[0].id : null
      };
    });
    
    success(res, { schedules });
  }, 'backups-schedule-list'));

  // Create or update a scheduled backup for an app
  router.post('/backups/schedule', premiumGating, asyncHandler(async (req, res) => {
    const { appId, enabled, schedule, retention, runImmediately, destination, destinationPath } = req.body;
    
    if (!appId) {
      const { ValidationError } = require('../errors');
      throw new ValidationError('appId is required');
    }

    const config = backupManager.getConfig();
    if (!config.backups) config.backups = {};
    
    // Build the backup config for this app
    const backupConfig = {
      enabled: enabled !== undefined ? enabled : true,
      schedule: schedule || 'daily',
      retention: retention || { keep: 7, olderThan: null },
      runImmediately: runImmediately || false,
      destination: destination || 'local',
      destinationPath: destinationPath || DEFAULT_BACKUP_DIR,
      include: ['all'],
      destinations: [{ type: destination || 'local', path: destinationPath || DEFAULT_BACKUP_DIR }]
    };

    config.backups[appId] = backupConfig;
    backupManager.updateConfig(config);
    
    success(res, { 
      message: `Backup schedule ${enabled === false ? 'disabled' : 'updated'} for ${appId}`,
      schedule: {
        appId,
        ...backupConfig,
        retention: backupConfig.retention
      }
    });
  }, 'backups-schedule-update'));

  // Remove scheduled backup for an app
  router.delete('/backups/schedule/:appId', premiumGating, asyncHandler(async (req, res) => {
    const { appId } = req.params;
    const config = backupManager.getConfig();
    
    if (!config.backups || !config.backups[appId]) {
      const { NotFoundError } = require('../errors');
      throw new NotFoundError(`No backup schedule found for app: ${appId}`, 'DC-404');
    }

    delete config.backups[appId];
    backupManager.updateConfig(config);
    
    success(res, { message: `Backup schedule removed for ${appId}` });
  }, 'backups-schedule-delete'));

  // List backup files on disk
  router.get('/backups/files', asyncHandler(async (req, res) => {
    const backupDir = DEFAULT_BACKUP_DIR;
    const files = [];

    try {
      if (fs.existsSync(backupDir)) {
        const entries = fs.readdirSync(backupDir, { withFileTypes: true });
        
        for (const entry of entries) {
          if (entry.isFile() && entry.name.endsWith('.backup')) {
            try {
              const filepath = path.join(backupDir, entry.name);
              const stats = fs.statSync(filepath);
              const nameWithoutExt = entry.name.replace('.backup', '');
              const parts = nameWithoutExt.split('-');
              const appId = parts[0];
              const timestamp = parts.length > 1 ? parseInt(parts[parts.length - 1]) : stats.mtimeMs;
              
              files.push({
                name: entry.name,
                appId,
                size: stats.size,
                sizeFormatted: formatBytes(stats.size),
                timestamp: new Date(timestamp).toISOString(),
                path: filepath
              });
            } catch (err) {
              // Skip malformed filenames
            }
          }
        }
      }
    } catch (err) {
      // Directory might not exist yet
    }

    // Sort by timestamp descending (newest first)
    files.sort((a, b) => new Date(b.timestamp) - new Date(a.timestamp));

    success(res, { files, total: files.length });
  }, 'backups-files-list'));

  // Trigger immediate backup for an app
  router.post('/backups/backup/:appId', asyncHandler(async (req, res) => {
    const { appId } = req.params;
    const config = backupManager.getConfig();
    
    const backupConfig = config.backups && config.backups[appId];
    if (!backupConfig) {
      const { NotFoundError } = require('../errors');
      throw new NotFoundError(`No backup schedule found for app: ${appId}`, 'DC-404');
    }

    const backup = await backupManager.executeBackup(appId, {
      ...backupConfig,
      destinations: backupConfig.destinations || [{ type: backupConfig.destination || 'local', path: backupConfig.destinationPath || DEFAULT_BACKUP_DIR }]
    });

    success(res, { 
      message: `Backup started for ${appId}`,
      backup: {
        id: backup.id,
        name: backup.name,
        timestamp: backup.timestamp,
        size: backup.size,
        status: backup.status
      }
    });
  }, 'backups-backup-trigger'));

  // List backup files for a specific app
  router.get('/backups/files/:appId', asyncHandler(async (req, res) => {
    const { appId } = req.params;
    const backupDir = DEFAULT_BACKUP_DIR;
    const files = [];

    try {
      if (fs.existsSync(backupDir)) {
        const entries = fs.readdirSync(backupDir, { withFileTypes: true });

        for (const entry of entries) {
          if (entry.isFile() && entry.name.endsWith('.backup')) {
            try {
              const nameWithoutExt = entry.name.replace('.backup', '');
              const parts = nameWithoutExt.split('-');
              const fileAppId = parts[0];

              // Only include files for the requested app
              if (fileAppId !== appId) continue;

              const filepath = path.join(backupDir, entry.name);
              const stats = fs.statSync(filepath);
              const timestamp = parts.length > 1 ? parseInt(parts[parts.length - 1]) : stats.mtimeMs;

              files.push({
                name: entry.name,
                appId: fileAppId,
                size: stats.size,
                sizeFormatted: formatBytes(stats.size),
                timestamp: new Date(timestamp).toISOString(),
                path: filepath
              });
            } catch (err) {
              // Skip malformed filenames
            }
          }
        }
      }
    } catch (err) {
      // Directory might not exist yet
    }

    // Sort by timestamp descending (newest first)
    files.sort((a, b) => new Date(b.timestamp) - new Date(a.timestamp));

    success(res, { files, total: files.length });
  }, 'backups-files-app'));

  // Restore from a specific backup file on disk
  router.post('/backups/restore-file/:filename', asyncHandler(async (req, res) => {
    const { filename } = req.params;
    const { encryptionKey, restartContainers } = req.body || {};

    // Security: prevent path traversal
    if (filename.includes('..') || filename.includes('/') || filename.includes('\\')) {
      const { ValidationError } = require('../errors');
      throw new ValidationError('Invalid filename');
    }

    const filepath = path.join(DEFAULT_BACKUP_DIR, filename);
    if (!fs.existsSync(filepath)) {
      const { NotFoundError } = require('../errors');
      throw new NotFoundError(`Backup file not found: ${filename}`, 'DC-404');
    }

    // Read the backup file
    let fileData = fs.readFileSync(filepath);

    // Decrypt if needed (format: iv:authTag:encrypted base64)
    if (encryptionKey) {
      try {
        fileData = await backupManager.decryptBackup(fileData, encryptionKey);
      } catch (err) {
        throw new Error('Failed to decrypt backup: ' + err.message);
      }
    }

    // Decompress
    const backupData = await backupManager.decompressBackup(fileData);

    // Extract to temp directory for inspection/restoration
    const os = require('os');
    const crypto = require('crypto');
    const tempDir = path.join(os.tmpdir(), `dashcaddy-restore-${Date.now()}-${crypto.randomBytes(4).toString('hex')}`);
    fs.mkdirSync(tempDir, { recursive: true });

    try {
      // Write the decompressed JSON as a tar.gz to extract
      const tarPath = path.join(tempDir, 'backup.tar.gz');
      fs.writeFileSync(tarPath, backupData);

      // Extract tar.gz
      const { execSync } = require('child_process');
      try {
        execSync(`cd "${tempDir}" && tar -xzf backup.tar.gz`, { stdio: 'pipe' });
      } catch (tarErr) {
        throw new Error('Failed to extract backup archive: ' + tarErr.message);
      }

      // Read manifest if present
      const manifestPath = path.join(tempDir, 'manifest.json');
      let manifest = null;
      if (fs.existsSync(manifestPath)) {
        try {
          manifest = JSON.parse(fs.readFileSync(manifestPath, 'utf8'));
        } catch (_) { /* ignore malformed manifest */ }
      }

      // Read extracted data files
      const restoreData = {
        services: null,
        config: null,
        credentials: null,
        volumes: null
      };

      const servicesPath = path.join(tempDir, 'services.json');
      if (fs.existsSync(servicesPath)) {
        try { restoreData.services = JSON.parse(fs.readFileSync(servicesPath, 'utf8')); } catch (_) {}
      }
      const configPath = path.join(tempDir, 'config.json');
      if (fs.existsSync(configPath)) {
        try { restoreData.config = JSON.parse(fs.readFileSync(configPath, 'utf8')); } catch (_) {}
      }
      const credsPath = path.join(tempDir, 'credentials.json');
      if (fs.existsSync(credsPath)) {
        try { restoreData.credentials = JSON.parse(fs.readFileSync(credsPath, 'utf8')); } catch (_) {}
      }
      const volumesPath = path.join(tempDir, 'volumes.json');
      if (fs.existsSync(volumesPath)) {
        try { restoreData.volumes = JSON.parse(fs.readFileSync(volumesPath, 'utf8')); } catch (_) {}
      }

      // If restartContainers is true, actually perform the restore
      if (restartContainers) {
        if (restoreData.services) {
          backupManager.restoreServices(restoreData.services);
        }
        if (restoreData.config) {
          backupManager.restoreConfig(restoreData.config);
        }
        if (restoreData.credentials) {
          backupManager.restoreCredentials(restoreData.credentials);
        }
        if (restoreData.volumes) {
          await backupManager.restoreVolumes(restoreData.volumes);
        }

        // Cleanup temp dir
        fs.rmSync(tempDir, { recursive: true, force: true });

        success(res, {
          restored: {
            services: !!restoreData.services,
            config: !!restoreData.config,
            credentials: !!restoreData.credentials,
            volumes: !!restoreData.volumes
          },
          message: 'Backup restored successfully'
        });
      } else {
        // Preview mode: return what would be restored
        fs.rmSync(tempDir, { recursive: true, force: true });
        success(res, {
          preview: true,
          filename,
          size: fs.statSync(filepath).size,
          sizeFormatted: formatBytes(fs.statSync(filepath).size),
          manifest,
          restoreData: {
            hasServices: !!restoreData.services,
            hasConfig: !!restoreData.config,
            hasCredentials: !!restoreData.credentials,
            hasVolumes: !!restoreData.volumes
          }
        });
      }
    } catch (err) {
      // Cleanup on error
      try { fs.rmSync(tempDir, { recursive: true, force: true }); } catch (_) {}
      throw err;
    }
  }, 'backups-restore-file'));

  // Compare a backup file against current state
  router.post('/backups/compare/:filename', asyncHandler(async (req, res) => {
    const { filename } = req.params;
    const { encryptionKey } = req.body || {};

    // Security: prevent path traversal
    if (filename.includes('..') || filename.includes('/') || filename.includes('\\')) {
      const { ValidationError } = require('../errors');
      throw new ValidationError('Invalid filename');
    }

    const filepath = path.join(DEFAULT_BACKUP_DIR, filename);
    if (!fs.existsSync(filepath)) {
      const { NotFoundError } = require('../errors');
      throw new NotFoundError(`Backup file not found: ${filename}`, 'DC-404');
    }

    // Read the backup file
    let fileData = fs.readFileSync(filepath);

    // Decrypt if needed
    if (encryptionKey) {
      try {
        fileData = await backupManager.decryptBackup(fileData, encryptionKey);
      } catch (err) {
        throw new Error('Failed to decrypt backup: ' + err.message);
      }
    }

    // Decompress
    const backupData = await backupManager.decompressBackup(fileData);

    // Extract to temp directory
    const os = require('os');
    const crypto = require('crypto');
    const tempDir = path.join(os.tmpdir(), `dashcaddy-compare-${Date.now()}-${crypto.randomBytes(4).toString('hex')}`);
    fs.mkdirSync(tempDir, { recursive: true });

    try {
      const tarPath = path.join(tempDir, 'backup.tar.gz');
      fs.writeFileSync(tarPath, backupData);

      const { execSync } = require('child_process');
      try {
        execSync(`cd "${tempDir}" && tar -xzf backup.tar.gz`, { stdio: 'pipe' });
      } catch (tarErr) {
        throw new Error('Failed to extract backup archive: ' + tarErr.message);
      }

      // Build diff
      const diff = {
        filename,
        timestamp: fs.statSync(filepath).mtime.toISOString(),
        size: fs.statSync(filepath).size,
        sizeFormatted: formatBytes(fs.statSync(filepath).size),
        services: null,
        config: null
      };

      // Compare services.json
      const servicesPath = path.join(tempDir, 'services.json');
      if (fs.existsSync(servicesPath)) {
        try {
          const backupServices = JSON.parse(fs.readFileSync(servicesPath, 'utf8'));
          const currentServicesPath = process.env.SERVICES_FILE || path.join(__dirname, 'services.json');
          let currentServices = null;
          if (fs.existsSync(currentServicesPath)) {
            currentServices = JSON.parse(fs.readFileSync(currentServicesPath, 'utf8'));
          }
          diff.services = {
            backup: backupServices,
            current: currentServices,
            hasChanges: JSON.stringify(backupServices) !== JSON.stringify(currentServices),
            backupCount: Array.isArray(backupServices) ? backupServices.length : 0,
            currentCount: Array.isArray(currentServices) ? currentServices.length : 0
          };
        } catch (_) {}
      }

      // Compare config.json
      const configPath = path.join(tempDir, 'config.json');
      if (fs.existsSync(configPath)) {
        try {
          const backupConfig = JSON.parse(fs.readFileSync(configPath, 'utf8'));
          const currentConfigPath = process.env.CONFIG_FILE || path.join(__dirname, 'config.json');
          let currentConfig = null;
          if (fs.existsSync(currentConfigPath)) {
            currentConfig = JSON.parse(fs.readFileSync(currentConfigPath, 'utf8'));
          }
          diff.config = {
            backup: backupConfig,
            current: currentConfig,
            hasChanges: JSON.stringify(backupConfig) !== JSON.stringify(currentConfig)
          };
        } catch (_) {}
      }

      fs.rmSync(tempDir, { recursive: true, force: true });
      success(res, { diff });
    } catch (err) {
      try { fs.rmSync(tempDir, { recursive: true, force: true }); } catch (_) {}
      throw err;
    }
  }, 'backups-compare'));

  // ==================== EXISTING ENDPOINTS ====================

  // Get backup configuration
  router.get('/backups/config', asyncHandler(async (req, res) => {
    const config = backupManager.getConfig();
    success(res, { config });
  }, 'backups-config-get'));

  // Update backup configuration
  router.post('/backups/config', asyncHandler(async (req, res) => {
    backupManager.updateConfig(req.body);
    success(res, { message: 'Backup configuration updated' });
  }, 'backups-config-update'));

  // Execute manual backup
  router.post('/backups/execute', asyncHandler(async (req, res) => {
    const backup = await backupManager.executeBackup('manual', req.body);
    success(res, { backup });
  }, 'backups-execute'));

  // Get backup history
  router.get('/backups/history', asyncHandler(async (req, res) => {
    const limit = parseInt(req.query.limit) || 50;
    const history = backupManager.getHistory(limit);
    success(res, { history });
  }, 'backups-history'));

  // Restore from backup
  router.post('/backups/restore/:backupId', asyncHandler(async (req, res) => {
    const result = await backupManager.restoreBackup(req.params.backupId, req.body);
    success(res, { result });
  }, 'backups-restore'));

  // ==================== CLOUD DESTINATIONS ====================

  // Test a destination (write+read+delete probe)
  router.post('/backups/test-destination', asyncHandler(async (req, res) => {
    const destination = req.body;
    if (!destination || !destination.type) {
      const { ValidationError } = require('../errors');
      throw new ValidationError('destination.type is required');
    }
    const result = await backupManager.testDestination(destination);
    success(res, result);
  }, 'backups-test-destination'));

  // Get cloud credentials (masked) for a provider
  // Provider: dropbox | webdav | sftp
  router.get('/backups/credentials/:provider', asyncHandler(async (req, res) => {
    const credentialManager = require('../credential-manager');
    const provider = req.params.provider;
    if (!['dropbox', 'webdav', 'sftp'].includes(provider)) {
      const { ValidationError } = require('../errors');
      throw new ValidationError('Invalid provider');
    }

    const mask = (val) => val ? '***' : null;
    let creds = {};
    if (provider === 'dropbox') {
      const token = await credentialManager.retrieve('backup.dropbox.token');
      creds = { token: mask(token) };
    } else if (provider === 'webdav') {
      creds = {
        url: (await credentialManager.retrieve('backup.webdav.url')) || null,
        username: (await credentialManager.retrieve('backup.webdav.username')) || null,
        password: mask(await credentialManager.retrieve('backup.webdav.password'))
      };
    } else if (provider === 'sftp') {
      creds = {
        host: (await credentialManager.retrieve('backup.sftp.host')) || null,
        port: (await credentialManager.retrieve('backup.sftp.port')) || '22',
        username: (await credentialManager.retrieve('backup.sftp.username')) || null,
        password: mask(await credentialManager.retrieve('backup.sftp.password')),
        privateKey: mask(await credentialManager.retrieve('backup.sftp.privateKey'))
      };
    }
    success(res, { provider, credentials: creds });
  }, 'backups-credentials-get'));

  // Save cloud credentials for a provider
  router.post('/backups/credentials/:provider', asyncHandler(async (req, res) => {
    const credentialManager = require('../credential-manager');
    const { ValidationError } = require('../errors');
    const provider = req.params.provider;

    if (!['dropbox', 'webdav', 'sftp'].includes(provider)) {
      throw new ValidationError('Invalid provider');
    }

    const body = req.body || {};
    const storeIfPresent = async (key, val) => {
      if (val !== undefined && val !== null && val !== '' && val !== '***') {
        await credentialManager.store(key, String(val));
      }
    };

    if (provider === 'dropbox') {
      if (!body.token || body.token === '***') {
        const existing = await credentialManager.retrieve('backup.dropbox.token');
        if (!existing) {
          throw new ValidationError('Dropbox token required');
        }
      } else {
        await credentialManager.store('backup.dropbox.token', body.token);
      }
    } else if (provider === 'webdav') {
      await storeIfPresent('backup.webdav.url', body.url);
      await storeIfPresent('backup.webdav.username', body.username);
      await storeIfPresent('backup.webdav.password', body.password);
    } else if (provider === 'sftp') {
      await storeIfPresent('backup.sftp.host', body.host);
      await storeIfPresent('backup.sftp.port', body.port);
      await storeIfPresent('backup.sftp.username', body.username);
      await storeIfPresent('backup.sftp.password', body.password);
      await storeIfPresent('backup.sftp.privateKey', body.privateKey);
    }

    success(res, { message: `${provider} credentials saved` });
  }, 'backups-credentials-set'));

  // Delete cloud credentials for a provider
  router.delete('/backups/credentials/:provider', asyncHandler(async (req, res) => {
    const credentialManager = require('../credential-manager');
    const { ValidationError } = require('../errors');
    const provider = req.params.provider;

    if (!['dropbox', 'webdav', 'sftp'].includes(provider)) {
      throw new ValidationError('Invalid provider');
    }

    const keys = {
      dropbox: ['backup.dropbox.token'],
      webdav: ['backup.webdav.url', 'backup.webdav.username', 'backup.webdav.password'],
      sftp: ['backup.sftp.host', 'backup.sftp.port', 'backup.sftp.username', 'backup.sftp.password', 'backup.sftp.privateKey']
    };

    for (const k of keys[provider]) {
      try { await credentialManager.delete(k); } catch (_) { /* ignore */ }
    }

    success(res, { message: `${provider} credentials deleted` });
  }, 'backups-credentials-delete'));

  return router;
};

// Helper functions

/**
 * Calculate next run time based on schedule and last run
 */
function calculateNextRun(lastRun, schedule) {
  if (!lastRun) return null;
  
  const intervals = {
    'hourly': 60 * 60 * 1000,
    'daily': 24 * 60 * 60 * 1000,
    'weekly': 7 * 24 * 60 * 60 * 1000,
    'monthly': 30 * 24 * 60 * 60 * 1000
  };

  const baseInterval = intervals[schedule];
  
  if (baseInterval) {
    return new Date(lastRun.getTime() + baseInterval);
  }

  // Custom interval (e.g., "6h", "30m", "6" for 6 minutes)
  const match = schedule.match(/^(\d+)([mh])?$/);
  if (match) {
    const value = parseInt(match[1]);
    const unit = match[2] || 'm'; // default to minutes
    const ms = unit === 'h' ? value * 60 * 60 * 1000 : value * 60 * 1000;
    return new Date(lastRun.getTime() + ms);
  }

  // Default to daily
  return new Date(lastRun.getTime() + intervals.daily);
}

/**
 * Format bytes to human readable string
 */
function formatBytes(bytes) {
  if (bytes === 0) return '0 B';
  const k = 1024;
  const sizes = ['B', 'KB', 'MB', 'GB', 'TB'];
  const i = Math.floor(Math.log(bytes) / Math.log(k));
  return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i];
}