Define a MediaBackend interface

This interface defines the functionality that all media backends (like S3 or Azure) must implement.

Signed-off-by: David Mehren <git@herrmehren.de>

src/media/media-backend.interface.ts

@@ -0,0 +1,25 @@
+import { BackendData } from './media-upload.entity';
+
+export interface MediaBackend {
+  /**
+   * Saves a file according to backend internals.
+   * @param buffer File data
+   * @param fileName Name of the file to save. Can include a file extension.
+   * @return Tuple of file URL and internal backend data, which should be saved.
+   */
+  saveFile(buffer: Buffer, fileName: string): Promise<[string, BackendData]>;
+
+  /**
+   * Retrieve the URL of a previously saved file.
+   * @param fileName String to identify the file
+   * @param backendData Internal backend data
+   */
+  getFileURL(fileName: string, backendData: BackendData): Promise<string>;
+
+  /**
+   * Delete a file from the backend
+   * @param fileName String to identify the file
+   * @param backendData Internal backend data
+   */
+  deleteFile(fileName: string, backendData: BackendData): Promise<void>;
+}