import crypto from 'crypto';
import path from 'path';
import fs from 'fs';

export class ThumbnailManager {
  private static readonly THUMBNAIL_WIDTH = 320;
  private static readonly HASH_ALGORITHM = 'md5';
  private static readonly THUMBNAIL_EXTENSION = '.png';

  /**
   * Generate MD5 hash for a file path
   */
  static generateHash(filePath: string): string {
    return crypto
      .createHash(this.HASH_ALGORITHM)
      .update(filePath)
      .digest('hex');
  }

  /**
   * Generate thumbnail filename based on hash and width
   */
  static getThumbnailFilename(hash: string, width: number = this.THUMBNAIL_WIDTH): string {
    return `${hash}_${width}${this.THUMBNAIL_EXTENSION}`;
  }

  /**
   * Get the folder structure for a given hash
   */
  static getFolderStructure(hash: string): { folder1: string; folder2: string } {
    return {
      folder1: hash.substring(0, 2),
      folder2: hash.substring(2, 4)
    };
  }

  /**
   * Get the complete thumbnail path information
   */
  static getThumbnailPath(filePath: string): {
    folderPath: string;
    filename: string;
    fullPath: string;
    url: string;
  } {
    const hash = this.generateHash(filePath);
    const { folder1, folder2 } = this.getFolderStructure(hash);
    const filename = this.getThumbnailFilename(hash);
    
    const folderPath = path.join('thumbnails', folder1, folder2);
    const fullPath = path.join(process.cwd(), 'public', folderPath, filename);
    const url = `/${folderPath}/${filename}`;
    
    return { folderPath, filename, fullPath, url };
  }

  /**
   * Ensure thumbnail directory exists
   */
  static ensureDirectory(folderPath: string): void {
    const fullPath = path.join(process.cwd(), 'public', folderPath);
    if (!fs.existsSync(fullPath)) {
      fs.mkdirSync(fullPath, { recursive: true });
    }
  }

  /**
   * Get the base thumbnails directory
   */
  static getThumbnailsBaseDir(): string {
    return path.join(process.cwd(), 'public', 'thumbnails');
  }

  /**
   * Check if a thumbnail exists
   */
  static thumbnailExists(filePath: string): boolean {
    const { fullPath } = this.getThumbnailPath(filePath);
    return fs.existsSync(fullPath);
  }

  /**
   * Get fallback thumbnail URL based on media type
   */
  static getFallbackThumbnailUrl(mediaType: 'video' | 'photo' | 'text'): string {
    switch (mediaType) {
      case 'video':
        return '/placeholder-video.svg';
      case 'photo':
        return '/placeholder-photo.svg';
      default:
        return '/placeholder.svg';
    }
  }
}