feat(storage): Add getDownloadUrl method to the Storage API

src/storage/cloud-extensions.ts

@@ -0,0 +1,89 @@
+import {
+  Bucket,
+  BucketOptions,
+  File,
+  FileOptions,
+  Storage as StorageClient,
+} from "@google-cloud/storage";
+interface FirebaseMetadata {
+  name: string;
+  bucket: string;
+  generation: string;
+  metageneration: string;
+  contentType: string;
+  timeCreated: string;
+  updated: string;
+  storageClass: string;
+  size: string;
+  md5Hash: string;
+  contentEncoding: string;
+  contentDisposition: string;
+  crc32c: string;
+  etag: string;
+  downloadTokens: string;
+}
+export class FirebaseStorageFile extends File {
+  // Gets metadata from firebase backend instead of GCS
+  getFirebaseMetadata(): Promise<FirebaseMetadata> {
+    // We need to talk to the firebase storage endpoints instead of the google cloud bucket endpoint
+    const endpoint = "https://firebasestorage.googleapis.com/v0";
+    // Build any custom headers based on the defined interceptors on the parent
+    // storage object and this object
+    const storageInterceptors = this.storage?.interceptors || [];
+    const fileInterceptors = this.interceptors || [];
+    const allInterceptors = storageInterceptors.concat(fileInterceptors);
+    const uri = `${endpoint}/b/${this.bucket.name}/o/${encodeURIComponent(
+      this.name
+    )}`;
+    console.log(uri);
+
+    const headers = allInterceptors.reduce((acc, curInterceptor) => {
+      const currentHeaders = curInterceptor.request({
+        uri,
+      });
+
+      Object.assign(acc, currentHeaders.headers);
+      return acc;
+    }, {});
+    return new Promise((resolve, reject) => {
+      this.storage.makeAuthenticatedRequest(
+        {
+          method: "GET",
+          uri,
+          headers,
+        },
+        (err, body) => {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(body);
+          }
+        }
+      );
+    });
+  }
+
+
+  async getDownloadUrl(): Promise<string> {
+    const { downloadTokens } = await this.getFirebaseMetadata();
+    const [token] = downloadTokens.split(",");
+    const baseUrl =
+      process.env.STORAGE_EMULATOR_HOST ||
+      "https://firebasestorage.googleapis.com";
+    return `${baseUrl}/v0/b/${this.bucket.name}/o/${encodeURIComponent(
+      this.name
+    )}?alt=media&token=${token}`;
+  }
+}
+
+export class FirebaseStorageBucket extends Bucket {
+  file(name: string, options?: FileOptions): FirebaseStorageFile {
+    return new FirebaseStorageFile(this, name, options);
+  }
+}
+
+export class FirebaseStorageClient extends StorageClient {
+  bucket(bucketName: string, options?: BucketOptions): FirebaseStorageBucket {
+    return new FirebaseStorageBucket(this, bucketName, options);
+  }
+}

src/storage/storage.ts

@@ -17,14 +17,9 @@
 
 import { App } from '../app';
 import { FirebaseError } from '../utils/error';
+import { FirebaseStorageClient, FirebaseStorageBucket } from './cloud-extensions';
 import { ServiceAccountCredential, isApplicationDefault } from '../app/credential-internal';
-import {
-  Bucket,
-  BucketOptions,
-  File,
-  FileOptions,
-  Storage as StorageClient,
-} from '@google-cloud/storage';
+
 import * as utils from '../utils/index';
 import * as validator from '../utils/validator';
 
@@ -134,29 +129,3 @@ export class Storage {
   }
 }
 
-class FirebaseStorageFile extends File{
-  async getDownloadUrl(): Promise<string> {
-    const [metadata] = await this.getMetadata();
-    if (!metadata?.metadata?.firebaseStorageDownloadTokens) {
-      throw new FirebaseError({
-        code: 'storage/no-download-token',
-        message: 'No download token available. Please create one in the Firebase Console.',
-      });
-    }
-    const [token] = metadata.metadata.firebaseStorageDownloadTokens.split(',');
-    const baseUrl = process.env.STORAGE_EMULATOR_HOST || 'https://firebasestorage.googleapis.com';
-    return `${baseUrl}/v0/b/${this.bucket.name}/o/${encodeURIComponent(this.name)}?alt=media&token=${token}`;
-  }
-}
-
-class FirebaseStorageBucket extends Bucket {
-  file(name: string, options?: FileOptions): FirebaseStorageFile {
-    return new FirebaseStorageFile(this, name, options);
-  }
-}
-
-class FirebaseStorageClient extends StorageClient {
-  bucket(bucketName: string, options?: BucketOptions): FirebaseStorageBucket {
-    return new FirebaseStorageBucket(this, bucketName, options);
-  }
-}