Retrieves Firebase Project ID from the provided service credential file

README.md

@@ -26,45 +26,36 @@ A version of supported Ruby, currently:
 To use this gem, you need to instantiate a client with your firebase credentials:
 
 ```ruby
-fcm = FCM.new(
-  GOOGLE_APPLICATION_CREDENTIALS_PATH,
-  FIREBASE_PROJECT_ID
-)
+fcm = FCM.new(GOOGLE_APPLICATION_CREDENTIALS_PATH)
 ```
 
+**Note:** The Firebase project ID is automatically extracted from your Firebase service credentials file.
+
 ## About the `GOOGLE_APPLICATION_CREDENTIALS_PATH`
 The `GOOGLE_APPLICATION_CREDENTIALS_PATH` is meant to contain your firebase credentials.
 
 The easiest way to provide them is to pass here an absolute path to a file with your credentials:
 
 ```ruby
-fcm = FCM.new(
-  '/path/to/credentials.json',
-  FIREBASE_PROJECT_ID
-)
+fcm = FCM.new('/path/to/credentials.json')
 ```
 
 As per their secret nature, you might not want to have them in your repository. In that case, another supported solution is to pass a `StringIO` that contains your credentials:
 
 ```ruby
-fcm = FCM.new(
-  StringIO.new(ENV.fetch('FIREBASE_CREDENTIALS')),
-  FIREBASE_PROJECT_ID
-)
-
+fcm = FCM.new(StringIO.new(ENV.fetch('FIREBASE_CREDENTIALS')))
 ```
 
+The gem will automatically extract the `project_id` from your Firebase service credentials file.
+
 ## Usage
 
 ## HTTP v1 API
 
 To migrate to HTTP v1 see: https://firebase.google.com/docs/cloud-messaging/migrate-v1
 
 ```ruby
-fcm = FCM.new(
-  GOOGLE_APPLICATION_CREDENTIALS_PATH,
-  FIREBASE_PROJECT_ID
-)
+fcm = FCM.new(GOOGLE_APPLICATION_CREDENTIALS_PATH)
 message = {
   'token': "000iddqd", # send to a specific device
   # 'topic': "yourTopic",
@@ -108,8 +99,7 @@ https://firebase.google.com/docs/cloud-messaging/android/device-group#managing_d
 
 Then you will need a notification key which you can create for a particular `key_name` which needs to be uniquely named per app in case you have multiple apps for the same `project_id`. This ensures that notifications only go to the intended target app. The `create` method will do this and return the token `notification_key`, that represents the device group, in the response:
 
-`project_id` is the SENDER_ID in your cloud settings.
-https://firebase.google.com/docs/cloud-messaging/concept-options#senderid
+**Note:** The `project_id` parameter used in device group management is your Firebase project's sender ID, which can be found in your Firebase project settings under Cloud Messaging.
 
 ```ruby
 params = { key_name: "appUser-Chris",

lib/fcm.rb

@@ -12,13 +12,27 @@ class FCM
   INSTANCE_ID_API = "https://iid.googleapis.com"
   TOPIC_REGEX = /[a-zA-Z0-9\-_.~%]+/
 
-  def initialize(json_key_path = "", project_name = "", http_options = {})
+  # Service account credentials file schema (JSON format):
+  # {
+  #   "type": "service_account",
+  #   "project_id": "your-project-id",
+  #   "private_key_id": "key-id",
+  #   "private_key": "-----BEGIN PRIVATE KEY-----\n...\n-----END PRIVATE KEY-----\n",
+  #   "client_email": "firebase-adminsdk@your-project-id.iam.gserviceaccount.com",
+  #   "client_id": "client-id",
+  #   "auth_uri": "https://accounts.google.com/o/oauth2/auth",
+  #   "token_uri": "https://oauth2.googleapis.com/token",
+  #   "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
+  #   "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/firebase-adminsdk%40your-project-id.iam.gserviceaccount.com",
+  #   "universe_domain": "googleapis.com"
+  # }
+  # The project_id field is automatically extracted from this file for FCM API calls.
+  def initialize(json_key_path = '', http_options = {})
     @json_key_path = json_key_path
-    @project_name = project_name
     @http_options = http_options
   end
 
-  # See https://firebase.google.com/docs/cloud-messaging/send-message
+  # See https://firebase.google.com/docs/cloud-messaging/send/v1-api
   # {
   #   "token": "4sdsx",
   #   "notification": {
@@ -42,17 +56,17 @@ def initialize(json_key_path = "", project_name = "", http_options = {})
   #     }
   #   }
   # }
-  # fcm = FCM.new(json_key_path, project_name)
+  # fcm = FCM.new(json_key_path)
   # fcm.send_v1(
   #    { "token": "4sdsx",, "to" : "notification": {}.. }
   # )
   def send_notification_v1(message)
-    return if @project_name.empty?
+    return if firebase_project_id.empty?
 
     post_body = { 'message': message }
     for_uri(BASE_URI_V1) do |connection|
       response = connection.post(
-        "#{@project_name}/messages:send", post_body.to_json
+        "#{firebase_project_id}/messages:send", post_body.to_json
       )
       build_response(response)
     end
@@ -168,7 +182,7 @@ def send_to_topic(topic, options = {})
 
       for_uri(BASE_URI_V1) do |connection|
         response = connection.post(
-          "#{@project_name}/messages:send", body.to_json
+          "#{firebase_project_id}/messages:send", body.to_json
         )
         build_response(response)
       end
@@ -181,7 +195,7 @@ def send_to_topic_condition(condition, options = {})
 
       for_uri(BASE_URI_V1) do |connection|
         response = connection.post(
-          "#{@project_name}/messages:send", body.to_json
+          "#{firebase_project_id}/messages:send", body.to_json
         )
         build_response(response)
       end
@@ -298,4 +312,23 @@ def json_key
                     File.open(@json_key_path)
                   end
   end
+
+  def firebase_project_id
+    @firebase_project_id ||= extract_project_id
+  end
+
+  def extract_project_id
+    return '' if @json_key_path.nil? || @json_key_path == ''
+
+    json_content = if @json_key_path.respond_to?(:read)
+                     @json_key_path.read.tap { @json_key_path.rewind }
+                   else
+                     File.read(@json_key_path)
+                   end
+
+    credentials = JSON.parse(json_content)
+    credentials['project_id'] || ''
+  rescue JSON::ParserError, Errno::ENOENT
+    ''
+  end
 end

spec/fcm_spec.rb

@@ -1,7 +1,7 @@
 require "spec_helper"
 
 describe FCM do
-  let(:project_name) { 'test-project' }
+  let(:firebase_project_id) { 'test-project' }
   let(:json_key_path) { 'path/to/json/key.json' }
   let(:client) { FCM.new(json_key_path) }
 
@@ -15,6 +15,8 @@
 
   before do
     allow(client).to receive(:json_key)
+    allow(client).to receive(:extract_project_id)
+      .and_return(firebase_project_id)
 
     # Mock the Google::Auth::ServiceAccountCredentials
     allow(Google::Auth::ServiceAccountCredentials).to receive(:make_creds).
@@ -38,9 +40,9 @@
   end
 
   describe "#send_v1 or #send_notification_v1" do
-    let(:client) { FCM.new(json_key_path, project_name) }
+    let(:client) { FCM.new(json_key_path) }
 
-    let(:uri) { "#{FCM::BASE_URI_V1}#{project_name}/messages:send" }
+    let(:uri) { "#{FCM::BASE_URI_V1}#{firebase_project_id}/messages:send" }
     let(:status_code) { 200 }
 
     let(:stub_fcm_send_v1_request) do
@@ -177,8 +179,8 @@
       include_examples 'succesfuly send notification'
     end
 
-    context 'when project_name is empty' do
-      let(:project_name) { '' }
+    context 'when firebase_project_id is empty' do
+      let(:firebase_project_id) { '' }
       let(:send_v1_params) do
         {
           'token' => '4sdsx',
@@ -249,9 +251,9 @@
   end
 
   describe '#send_to_topic' do
-    let(:client) { FCM.new(json_key_path, project_name) }
+    let(:client) { FCM.new(json_key_path) }
 
-    let(:uri) { "#{FCM::BASE_URI_V1}#{project_name}/messages:send" }
+    let(:uri) { "#{FCM::BASE_URI_V1}#{firebase_project_id}/messages:send" }
 
     let(:topic) { 'news' }
     let(:params) do
@@ -300,9 +302,9 @@
   end
 
   describe "#send_to_topic_condition" do
-    let(:client) { FCM.new(json_key_path, project_name) }
+    let(:client) { FCM.new(json_key_path) }
 
-    let(:uri) { "#{FCM::BASE_URI_V1}#{project_name}/messages:send" }
+    let(:uri) { "#{FCM::BASE_URI_V1}#{firebase_project_id}/messages:send" }
 
     let(:topic_condition) { "'foo' in topics" }
     let(:params) do