Implementing FCM sendAll and sendMulticast APIs (#247)

* Preliminary impl of FCM batch support

* Added BatchMessage class and tests

* Refactored the FCM send operation

* Added unit tests for sendBatch() API

* Refactored error handling

* Refactored FCM logic into a new FirebaseMessagingClient class

* Using a separate request factory for child requests

* Added the InstanceIdClient class for handling topic mgt ops

* Added license headers

* Renamed BatchResponse as SendResponse

* Added BatchResponse class; Renamed BatchMessage to MulticastMessage

* Updated tests and docs

* Updated documentation

* Added documentation and tests

* Updated docs, changelog and annotations

* Updated integration test to use multiple topics; Updated docs

* Removing a redundant whitespace

* Reduced FCM batch size to 100 (#250)

* Setting the X-Client-Version header for FCM (#252)

* Snippets for FCM sendAll() and sendMulticast() (#249)

* Snippets for FCM sendAll() and sendMulticast()

* Reduced batch size to 100 in snippets

* Addressing some documentation nits

Author: hiranya911

.gitignore

@@ -5,6 +5,8 @@ target/
 .classpath
 .project
 .checkstyle
+.factorypath
+.vscode/
 release.properties
 integration_cert.json
 integration_apikey.txt

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Unreleased
 
+- [added] Implemented new `sendAll()` and `sendMulticast()` APIs in
+  `FirebaseMessaging`.
 - [changed] Removed org.json dependency and replaced with com.google.code.gson.
 - [changed] Upgraded Mockito dependency, and fixed the build on Java 11.
 

src/main/java/com/google/firebase/internal/ApiClientUtils.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2019 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.firebase.internal;
+
+import com.google.api.client.http.HttpRequestFactory;
+import com.google.api.client.http.HttpResponse;
+import com.google.api.client.http.HttpTransport;
+import com.google.firebase.FirebaseApp;
+
+import java.io.IOException;
+
+/**
+ * A set of shared utilities for using the Google API client.
+ */
+public class ApiClientUtils {
+
+  public static HttpRequestFactory newAuthorizedRequestFactory(FirebaseApp app) {
+    HttpTransport transport = app.getOptions().getHttpTransport();
+    return transport.createRequestFactory(new FirebaseRequestInitializer(app));
+  }
+
+  public static HttpRequestFactory newUnauthorizedRequestFactory(FirebaseApp app) {
+    HttpTransport transport = app.getOptions().getHttpTransport();
+    return transport.createRequestFactory();
+  }
+
+  public static void disconnectQuietly(HttpResponse response) {
+    if (response != null) {
+      try {
+        response.disconnect();
+      } catch (IOException ignored) {
+        // ignored
+      }
+    }
+  }
+}

src/main/java/com/google/firebase/messaging/BatchResponse.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright  2019 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.firebase.messaging;
+
+import com.google.common.collect.ImmutableList;
+import com.google.firebase.internal.NonNull;
+import java.util.List;
+
+/**
+ * Response from an operation that sends FCM messages to multiple recipients.
+ * See {@link FirebaseMessaging#sendAll(List)} and {@link
+ * FirebaseMessaging#sendMulticast(MulticastMessage)}.
+ */
+public final class BatchResponse {
+
+  private final List<SendResponse> responses;
+  private final int successCount;
+
+  BatchResponse(List<SendResponse> responses) {
+    this.responses = ImmutableList.copyOf(responses);
+    int successCount = 0;
+    for (SendResponse response : this.responses) {
+      if (response.isSuccessful()) {
+        successCount++;
+      }
+    }
+    this.successCount = successCount;
+  }
+
+  @NonNull
+  public List<SendResponse> getResponses() {
+    return responses;
+  }
+
+  public int getSuccessCount() {
+    return successCount;
+  }
+
+  public int getFailureCount() {
+    return responses.size() - successCount;
+  }
+}