Add MediaService

This service is responsible for operations regarding uploaded media. It should perform save, get and delete operations with the configured backend.
The service also checks, if the mime type of the uploaded media is allowed.

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

src/media/media.service.ts

@@ -0,0 +1,52 @@
+import { Injectable } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import * as FileType from 'file-type';
+import { Repository } from 'typeorm';
+import { NotesService } from '../notes/notes.service';
+import { UsersService } from '../users/users.service';
+import { BackendType } from './backends/backend-type.enum';
+import { FilesystemBackend } from './backends/filesystem-backend';
+import { MediaUpload } from './media-upload.entity';
+import { MulterFile } from './multer-file.interface';
+
+@Injectable()
+export class MediaService {
+  constructor(
+    @InjectRepository(MediaUpload)
+    private mediaUploadRepository: Repository<MediaUpload>,
+    private notesService: NotesService,
+    private usersService: UsersService,
+  ) {}
+
+  public async saveFile(file: MulterFile, username: string, noteId: string) {
+    const note = await this.notesService.getNoteByIdOrAlias(noteId);
+    const user = await this.usersService.getUserByUsername(username);
+    const fileTypeResult = await FileType.fromBuffer(file.buffer);
+    if (!fileTypeResult) {
+      throw new Error('Could not detect file type.');
+    }
+    if (!MediaService.isAllowedMimeType(fileTypeResult.mime)) {
+      throw new Error('MIME type not allowed');
+    }
+    //TODO: Choose backend according to config
+    const mediaUpload = MediaUpload.create(
+      note,
+      user,
+      fileTypeResult.ext,
+      BackendType.FILEYSTEM,
+    );
+    const backend = new FilesystemBackend();
+    const [url, backendData] = await backend.saveFile(
+      file.buffer,
+      mediaUpload.id,
+    );
+    mediaUpload.backendData = backendData;
+    await this.mediaUploadRepository.save(mediaUpload);
+    return url;
+  }
+
+  private static isAllowedMimeType(mimeType: string): boolean {
+    //TODO: Which mimetypes are allowed?
+    return true;
+  }
+}