// CDN Integration Manager
// Multi-provider CDN with intelligent routing

import { EventEmitter } from 'events';

type CDNProvider = 'cloudflare' | 'aws_cloudfront' | 'fastly' | 'bunny' | 'custom';
type FileType = 'image' | 'video' | 'document' | 'script' | 'style' | 'font' | 'other';

interface CDNConfig {
  id: string;
  tenantId: string;
  provider: CDNProvider;
  name: string;
  enabled: boolean;
  credentials: {
    apiToken?: string;
    apiKey?: string;
    zoneId?: string;
    distributionId?: string;
  };
  settings: {
    originUrl: string;
    cdnDomain: string;
    ssl: boolean;
    http2: boolean;
    brotli: boolean;
    minify: {
      css: boolean;
      js: boolean;
      html: boolean;
    };
    caching: {
      browserTTL: number;
      edgeTTL: number;
      queryStringSort: boolean;
    };
    optimizations: {
      image: boolean;
      video: boolean;
      polish: boolean; // Cloudflare specific
    };
  };
  rules: Array<{
    pattern: string;
    fileType: FileType;
    cacheDuration: number;
    optimizations: string[];
  }>;
  status: 'active' | 'pending' | 'error';
  lastSyncAt?: Date;
}

interface CDNAsset {
  id: string;
  tenantId: string;
  originalUrl: string;
  cdnUrl: string;
  fileType: FileType;
  size: number;
  hash: string;
  metadata: {
    width?: number;
    height?: number;
    duration?: number;
    format?: string;
  };
  status: 'uploading' | 'uploaded' | 'processing' | 'ready' | 'error';
  cacheStatus: 'miss' | 'hit' | 'stale';
  lastAccessedAt?: Date;
  accessCount: number;
  createdAt: Date;
  variants?: Record<string, string>; // Different sizes/formats
}

interface CDNStats {
  totalRequests: number;
  cacheHitRate: number;
  bandwidthSaved: number; // GB
  averageResponseTime: number; // ms
  errors: number;
  byCountry: Record<string, { requests: number; bandwidth: number }>;
  topAssets: Array<{ url: string; requests: number }>;
}

// CDN Manager
export class CDNManager extends EventEmitter {
  private configs: Map<string, CDNConfig> = new Map();
  private assets: Map<string, CDNAsset> = new Map();
  private stats: Map<string, CDNStats> = new Map();

  // Register CDN provider
  registerConfig(config: Omit<CDNConfig, 'id' | 'status' | 'lastSyncAt'>): CDNConfig {
    const cdnConfig: CDNConfig = {
      ...config,
      id: crypto.randomUUID(),
      status: 'pending',
    };

    this.configs.set(cdnConfig.id, cdnConfig);
    this.emit('configCreated', cdnConfig);
    return cdnConfig;
  }

  // Upload asset to CDN
  async uploadAsset(
    tenantId: string,
    file: Buffer,
    options: {
      filename: string;
      contentType: string;
      fileType: FileType;
      optimize?: boolean;
      generateVariants?: boolean;
    }
  ): Promise<CDNAsset> {
    const config = this.getActiveConfig(tenantId);
    if (!config) throw new Error('No active CDN configured');

    const hash = await this.calculateHash(file);
    const assetId = crypto.randomUUID();
    const originalUrl = `${config.settings.originUrl}/${assetId}/${options.filename}`;

    const asset: CDNAsset = {
      id: assetId,
      tenantId,
      originalUrl,
      cdnUrl: `${config.settings.cdnDomain}/${assetId}/${options.filename}`,
      fileType: options.fileType,
      size: file.length,
      hash,
      metadata: {},
      status: 'uploading',
      cacheStatus: 'miss',
      accessCount: 0,
      createdAt: new Date(),
    };

    this.assets.set(asset.id, asset);
    this.emit('uploadStarted', asset);

    try {
      // Upload to CDN provider
      await this.uploadToCDN(config, file, asset);
      
      asset.status = 'uploaded';

      // Process optimizations
      if (options.optimize) {
        asset.status = 'processing';
        await this.optimizeAsset(config, asset);
      }

      // Generate variants for images
      if (options.generateVariants && options.fileType === 'image') {
        asset.variants = await this.generateVariants(config, asset);
      }

      asset.status = 'ready';
      this.emit('uploadCompleted', asset);

    } catch (error) {
      asset.status = 'error';
      this.emit('uploadFailed', { asset, error });
      throw error;
    }

    return asset;
  }

  // Get optimized URL with transformations
  getOptimizedUrl(
    assetId: string,
    transformations: {
      width?: number;
      height?: number;
      fit?: 'cover' | 'contain' | 'fill';
      quality?: number;
      format?: 'webp' | 'jpeg' | 'png' | 'avif';
    } = {}
  ): string {
    const asset = this.assets.get(assetId);
    if (!asset) throw new Error('Asset not found');

    // Update access stats
    asset.accessCount++;
    asset.lastAccessedAt = new Date();

    // Build transformation string
    const params = new URLSearchParams();
    
    if (transformations.width) params.set('w', String(transformations.width));
    if (transformations.height) params.set('h', String(transformations.height));
    if (transformations.fit) params.set('fit', transformations.fit);
    if (transformations.quality) params.set('q', String(transformations.quality));
    if (transformations.format) params.set('f', transformations.format);

    const queryString = params.toString();
    return queryString 
      ? `${asset.cdnUrl}?${queryString}` 
      : asset.cdnUrl;
  }

  // Purge cache
  async purgeCache(
    tenantId: string,
    options: {
      assetIds?: string[];
      pattern?: string;
      all?: boolean;
    }
  ): Promise<{
    purged: number;
    failed: number;
  }> {
    const config = this.getActiveConfig(tenantId);
    if (!config) throw new Error('No active CDN configured');

    let purged = 0;
    let failed = 0;

    if (options.all) {
      // Purge everything
      try {
        await this.purgeAllFromCDN(config);
        purged = this.assets.size;
        
        // Reset cache status
        for (const asset of this.assets.values()) {
          if (asset.tenantId === tenantId) {
            asset.cacheStatus = 'miss';
          }
        }
      } catch (error) {
        failed = this.assets.size;
      }
    } else if (options.assetIds) {
      for (const assetId of options.assetIds) {
        const asset = this.assets.get(assetId);
        if (asset && asset.tenantId === tenantId) {
          try {
            await this.purgeAssetFromCDN(config, asset);
            asset.cacheStatus = 'miss';
            purged++;
          } catch (error) {
            failed++;
          }
        }
      }
    } else if (options.pattern) {
      // Purge by pattern
      for (const asset of this.assets.values()) {
        if (asset.tenantId === tenantId && asset.cdnUrl.includes(options.pattern)) {
          try {
            await this.purgeAssetFromCDN(config, asset);
            asset.cacheStatus = 'miss';
            purged++;
          } catch (error) {
            failed++;
          }
        }
      }
    }

    this.emit('cachePurged', { tenantId, purged, failed });
    return { purged, failed };
  }

  // Get CDN stats
  async getStats(tenantId: string, period: { from: Date; to: Date }): Promise<CDNStats> {
    // In production, fetch from CDN provider analytics API
    const cached = this.stats.get(tenantId);
    
    if (cached) return cached;

    // Mock stats
    const stats: CDNStats = {
      totalRequests: 1250000,
      cacheHitRate: 94.5,
      bandwidthSaved: 850.5,
      averageResponseTime: 45,
      errors: 125,
      byCountry: {
        'TR': { requests: 450000, bandwidth: 300 },
        'DE': { requests: 250000, bandwidth: 180 },
        'US': { requests: 150000, bandwidth: 120 },
        'GB': { requests: 120000, bandwidth: 95 },
        'FR': { requests: 100000, bandwidth: 80 },
      },
      topAssets: [
        { url: '/assets/logo.png', requests: 50000 },
        { url: '/assets/banner.jpg', requests: 35000 },
        { url: '/assets/product-placeholder.png', requests: 25000 },
      ],
    };

    this.stats.set(tenantId, stats);
    return stats;
  }

  // Prefetch/warm cache
  async prefetch(
    tenantId: string,
    assetUrls: string[]
  ): Promise<{
    prefetched: number;
    failed: number;
  }> {
    const config = this.getActiveConfig(tenantId);
    if (!config) throw new Error('No active CDN configured');

    let prefetched = 0;
    let failed = 0;

    for (const url of assetUrls) {
      try {
        await this.prefetchToCDN(config, url);
        prefetched++;
      } catch (error) {
        failed++;
      }
    }

    return { prefetched, failed };
  }

  // Get asset by ID
  getAsset(assetId: string): CDNAsset | null {
    return this.assets.get(assetId) || null;
  }

  // List assets for tenant
  listAssets(tenantId: string, options: {
    fileType?: FileType;
    status?: CDNAsset['status'];
    limit?: number;
    offset?: number;
  } = {}): CDNAsset[] {
    let assets = Array.from(this.assets.values()).filter(a => a.tenantId === tenantId);

    if (options.fileType) {
      assets = assets.filter(a => a.fileType === options.fileType);
    }

    if (options.status) {
      assets = assets.filter(a => a.status === options.status);
    }

    assets.sort((a, b) => b.createdAt.getTime() - a.createdAt.getTime());

    const offset = options.offset || 0;
    const limit = options.limit || 50;
    return assets.slice(offset, offset + limit);
  }

  // Get best CDN for user location
  getOptimalCDN(userCountry: string, userRegion?: string): CDNProvider {
    // CDN selection based on geography and performance
    const regions: Record<string, CDNProvider> = {
      'TR': 'cloudflare',
      'DE': 'bunny',
      'US': 'aws_cloudfront',
      'GB': 'fastly',
      'default': 'cloudflare',
    };

    return regions[userCountry] || regions['default'];
  }

  // Private methods
  private getActiveConfig(tenantId: string): CDNConfig | null {
    return Array.from(this.configs.values()).find(
      c => c.tenantId === tenantId && c.enabled && c.status === 'active'
    ) || null;
  }

  private async calculateHash(buffer: Buffer): Promise<string> {
    // In production, use crypto module
    return 'mock-hash-' + buffer.length;
  }

  private async uploadToCDN(config: CDNConfig, file: Buffer, asset: CDNAsset): Promise<void> {
    // In production, call CDN provider API
    
    switch (config.provider) {
      case 'cloudflare':
        await this.uploadToCloudflare(config, file, asset);
        break;
      case 'aws_cloudfront':
        await this.uploadToCloudFront(config, file, asset);
        break;
      case 'bunny':
        await this.uploadToBunny(config, file, asset);
        break;
      default:
        throw new Error(`Provider ${config.provider} not implemented`);
    }

    await new Promise(resolve => setTimeout(resolve, 500));
  }

  private async uploadToCloudflare(config: CDNConfig, file: Buffer, asset: CDNAsset): Promise<void> {
    // Cloudflare Images API
    console.log('Uploading to Cloudflare:', asset.originalUrl);
  }

  private async uploadToCloudFront(config: CDNConfig, file: Buffer, asset: CDNAsset): Promise<void> {
    // AWS S3 + CloudFront
    console.log('Uploading to AWS:', asset.originalUrl);
  }

  private async uploadToBunny(config: CDNConfig, file: Buffer, asset: CDNAsset): Promise<void> {
    // BunnyCDN Storage API
    console.log('Uploading to BunnyCDN:', asset.originalUrl);
  }

  private async optimizeAsset(config: CDNConfig, asset: CDNAsset): Promise<void> {
    // In production:
    // - Compress images
    // - Transcode videos
    // - Minify JS/CSS
    
    await new Promise(resolve => setTimeout(resolve, 1000));
  }

  private async generateVariants(config: CDNConfig, asset: CDNAsset): Promise<Record<string, string>> {
    // Generate different sizes for responsive images
    const sizes = [100, 300, 600, 1200];
    const variants: Record<string, string> = {};

    for (const size of sizes) {
      variants[`w${size}`] = `${asset.cdnUrl}?w=${size}`;
    }

    return variants;
  }

  private async purgeAssetFromCDN(config: CDNConfig, asset: CDNAsset): Promise<void> {
    // Call CDN purge API
    await new Promise(resolve => setTimeout(resolve, 100));
  }

  private async purgeAllFromCDN(config: CDNConfig): Promise<void> {
    // Call CDN purge all API
    await new Promise(resolve => setTimeout(resolve, 500));
  }

  private async prefetchToCDN(config: CDNConfig, url: string): Promise<void> {
    // Request asset to warm CDN cache
    await new Promise(resolve => setTimeout(resolve, 50));
  }
}

// Image transformation presets
export const IMAGE_PRESETS: Record<string, {
  width?: number;
  height?: number;
  fit?: 'cover' | 'contain' | 'fill';
  quality: number;
  format: 'webp' | 'jpeg' | 'png';
}> = {
  thumbnail: {
    width: 150,
    height: 150,
    fit: 'cover',
    quality: 80,
    format: 'webp',
  },
  small: {
    width: 300,
    quality: 85,
    format: 'webp',
  },
  medium: {
    width: 600,
    quality: 85,
    format: 'webp',
  },
  large: {
    width: 1200,
    quality: 90,
    format: 'webp',
  },
  hero: {
    width: 1920,
    height: 600,
    fit: 'cover',
    quality: 90,
    format: 'jpeg',
  },
};

// Export singleton
export const cdnManager = new CDNManager();

export { CDNConfig, CDNAsset, CDNStats, CDNProvider, FileType };