ImgurBackend: Add Imgur MediaBackend

Add node-fetch dependency.
This was chosen as other libs we use already use node-fetch.

Signed-off-by: Philip Molares <philip.molares@udo.edu>

src/media/backends/imgur-backend.ts

@@ -0,0 +1,83 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { Inject, Injectable } from '@nestjs/common';
+import mediaConfiguration from '../../config/media.config';
+import { ConsoleLoggerService } from '../../logger/console-logger.service';
+import { MediaBackend } from '../media-backend.interface';
+import { BackendData } from '../media-upload.entity';
+import { MediaConfig } from '../../config/media.config';
+import fetch from 'node-fetch';
+import { URLSearchParams } from 'url';
+import { MediaBackendError } from '../../errors/errors';
+
+@Injectable()
+export class ImgurBackend implements MediaBackend {
+  private config: MediaConfig['backend']['imgur'];
+
+  constructor(
+    private readonly logger: ConsoleLoggerService,
+    @Inject(mediaConfiguration.KEY)
+    private mediaConfig: MediaConfig,
+  ) {
+    this.logger.setContext(ImgurBackend.name);
+    this.config = mediaConfig.backend.imgur;
+  }
+
+  async saveFile(
+    buffer: Buffer,
+    fileName: string,
+  ): Promise<[string, BackendData]> {
+    const params = new URLSearchParams();
+    params.append('image', buffer.toString('base64'));
+    params.append('type', 'base64');
+    try {
+      const result = await fetch('https://api.imgur.com/3/image', {
+        method: 'POST',
+        body: params,
+        headers: { Authorization: `Client-ID ${this.config.clientID}` },
+      })
+        .then(ImgurBackend.checkStatus)
+        .then((res) => res.json());
+      this.logger.debug(`Response: ${JSON.stringify(result)}`, 'saveFile');
+      this.logger.log(`Uploaded ${fileName}`, 'saveFile');
+      return [result.data.link, result.data.deletehash];
+    } catch (e) {
+      this.logger.error(`error: ${e.message}`, e.stack, 'saveFile');
+      throw new MediaBackendError(`Could not save '${fileName}' on imgur`);
+    }
+  }
+
+  async deleteFile(fileName: string, backendData: BackendData): Promise<void> {
+    if (backendData === null) {
+      throw new Error();
+    }
+    try {
+      const result = await fetch(
+        `https://api.imgur.com/3/image/${backendData}`,
+        {
+          method: 'POST',
+          headers: { Authorization: `Client-ID ${this.config.clientID}` },
+        },
+      ).then(ImgurBackend.checkStatus);
+      this.logger.debug(`Response: ${result}`, 'saveFile');
+      this.logger.log(`Deleted ${fileName}`, 'deleteFile');
+      return;
+    } catch (e) {
+      this.logger.error(`error: ${e.message}`, e.stack, 'deleteFile');
+      throw new MediaBackendError(`Could not delete '${fileName}' on imgur`);
+    }
+  }
+
+  private static checkStatus(res) {
+    if (res.ok) {
+      // res.status >= 200 && res.status < 300
+      return res;
+    } else {
+      throw new MediaBackendError(res.statusText);
+    }
+  }
+}

src/media/media.module.ts

@@ -13,6 +13,7 @@ import { UsersModule } from '../users/users.module';
 import { FilesystemBackend } from './backends/filesystem-backend';
 import { MediaUpload } from './media-upload.entity';
 import { MediaService } from './media.service';
+import { ImgurBackend } from './backends/imgur-backend';
 
 @Module({
   imports: [
@@ -22,7 +23,7 @@ import { MediaService } from './media.service';
     LoggerModule,
     ConfigModule,
   ],
-  providers: [MediaService, FilesystemBackend],
+  providers: [MediaService, FilesystemBackend, ImgurBackend],
   exports: [MediaService],
 })
 export class MediaModule {}

src/media/media.service.ts

@@ -19,6 +19,7 @@ import { FilesystemBackend } from './backends/filesystem-backend';
 import { MediaBackend } from './media-backend.interface';
 import { MediaUpload } from './media-upload.entity';
 import { MediaUploadUrlDto } from './media-upload-url.dto';
+import { ImgurBackend } from './backends/imgur-backend';
 
 @Injectable()
 export class MediaService {
@@ -158,6 +159,8 @@ export class MediaService {
     switch (this.mediaConfig.backend.use) {
       case 'filesystem':
         return BackendType.FILESYSTEM;
+      case 'imgur':
+        return BackendType.IMGUR;
     }
   }
 
@@ -165,6 +168,8 @@ export class MediaService {
     switch (type) {
       case BackendType.FILESYSTEM:
         return this.moduleRef.get(FilesystemBackend);
+      case BackendType.IMGUR:
+        return this.moduleRef.get(ImgurBackend);
     }
   }