File Storage Architecture: Local and Cloud Providers

interface StorageProvider {
  /**
   * Upload a file and return the public-accessible URL or storage path.
   * @param file  The incoming multipart file from Multer
   * @param path  The desired storage path (e.g. "media/images/2024/photo.jpg")
   */
  upload(file: Express.Multer.File, path: string): Promise<string>;

  /**
   * Permanently delete a file from the storage backend.
   * @param path  The storage path returned by upload()
   */
  delete(path: string): Promise<void>;

  /**
   * Resolve a storage path to a publicly accessible URL.
   * @param path  The storage path returned by upload()
   */
  getUrl(path: string): string;
}

# ── Local filesystem ────────────────────────────────────────────
STORAGE_DRIVER=local
STORAGE_LOCAL_PATH=./uploads

# ── Amazon S3 ───────────────────────────────────────────────────
STORAGE_DRIVER=s3
STORAGE_S3_BUCKET=ssa-media
STORAGE_S3_REGION=us-east-1
STORAGE_S3_ACCESS_KEY=...
STORAGE_S3_SECRET_KEY=...

# ── Azure Blob Storage ──────────────────────────────────────────
STORAGE_DRIVER=azure
STORAGE_AZURE_CONTAINER=ssa-media
STORAGE_AZURE_CONNECTION_STRING=...

# ── Google Cloud Storage ────────────────────────────────────────
STORAGE_DRIVER=gcs
STORAGE_GCS_BUCKET=ssa-media
STORAGE_GCS_KEY_FILE=/path/to/service-account.json

// Example: using StorageProvider inside a service
@Injectable()
export class MultimediaService {
  constructor(
    private readonly storageProvider: StorageProvider,
    private readonly mediaAssetRepository: MediaAssetRepository,
  ) {}

  async uploadFile(file: Express.Multer.File): Promise<MediaAsset> {
    // Deduplication check happens here before calling storageProvider
    const storagePath = await this.storageProvider.upload(file, `media/${file.originalname}`);
    return this.mediaAssetRepository.create({ path: storagePath });
  }
}