refactor(media): store filenames, use pre-signed s3/azure URLs, UUIDs

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

backend/src/media/media-upload.entity.ts

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2024 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
@@ -15,37 +15,49 @@ import { Note } from '../notes/note.entity';
 import { User } from '../users/user.entity';
 import { BackendType } from './backends/backend-type.enum';
 
-export type BackendData = string | null;
-
 @Entity()
 export class MediaUpload {
+  /** The unique identifier of a media upload */
   @PrimaryColumn()
-  id: string;
+  uuid: string;
 
+  /**
+   * The note where a media file was uploaded, required for the media browser in the note editor.
+   * Can be set to null after creation when the note was deleted without the associated uploads
+   */
   @ManyToOne((_) => Note, (note) => note.mediaUploads, {
     nullable: true,
   })
   note: Promise<Note | null>;
 
+  /** The user who uploaded the media file or {@code null} if uploaded by a guest user */
   @ManyToOne((_) => User, (user) => user.mediaUploads, {
     nullable: true,
   })
   user: Promise<User | null>;
 
+  /** The original filename of the media upload */
+  @Column()
+  fileName: string;
+
+  /** The backend type where this upload is stored */
   @Column({
     nullable: false,
   })
   backendType: string;
 
-  @Column()
-  fileUrl: string;
-
+  /**
+   * Additional data, depending on the backend type, serialized as JSON.
+   * This can include for example required additional identifiers for retrieving the file from the backend or to
+   * delete the file afterward again.
+   */
   @Column({
     nullable: true,
     type: 'text',
   })
-  backendData: BackendData | null;
+  backendData: string | null;
 
+  /** The date when the upload was created */
   @CreateDateColumn()
   createdAt: Date;
 
@@ -53,30 +65,30 @@ export class MediaUpload {
   private constructor() {}
 
   /**
-   * Create a new media upload enity
-   * @param id the id of the upload
+   * Create a new media upload entity
+   *
+   * @param uuid the unique identifier of the upload
+   * @param fileName the original filename of the uploaded file
    * @param note the note the upload should be associated with. This is required despite the fact the note field is optional, because it's possible to delete a note without also deleting the associated media uploads, but a note is required for the initial creation.
    * @param user the user that owns the upload
-   * @param extension which file extension the upload has
    * @param backendType on which type of media backend the upload is saved
    * @param backendData the backend data returned by the media backend
-   * @param fileUrl the url where the upload can be accessed
    */
   public static create(
-    id: string,
+    uuid: string,
+    fileName: string,
     note: Note,
     user: User | null,
-    extension: string,
     backendType: BackendType,
-    fileUrl: string,
+    backendData: string | null,
   ): Omit<MediaUpload, 'createdAt'> {
     const upload = new MediaUpload();
-    upload.id = id;
+    upload.uuid = uuid;
+    upload.fileName = fileName;
     upload.note = Promise.resolve(note);
     upload.user = Promise.resolve(user);
     upload.backendType = backendType;
-    upload.backendData = null;
-    upload.fileUrl = fileUrl;
+    upload.backendData = backendData;
     return upload;
   }
 }