Firebase Functions (tutorial for mac)

My notes below :)
Only me: Android Studio $cd /dev/Android_code/Functions_Firebase

1. Install Firebase CLI and install Node.js
2. $firebase login
3. Create a new directory

$cd /Users/andres/dev/firebase_Learning/functionsDemo/

4. Open terminal and enter command: $firebase init functions
Command installs functions dependencies
$cd /Users/andres/dev/firebase_Learning/functionsDemo/functions

5. Add your function to file index.js

Add this code to index.js

        var functions = require('firebase-functions');

        var admin = require('firebase-admin');

        admin.initializeApp(functions.config().firebase);

        exports.sendNotification = functions.database.ref('/articles/{articleId}')

        .onWrite(event => {

        // Grab the current value of what was written to the Realtime Database.

        var eventSnapshot = event.data;

        var str1 = "Author is ";

        var str = str1.concat(eventSnapshot.child("author").val());

        console.log(str);

        var topic = "android";

        var payload = {

            data: {

                title: eventSnapshot.child("title").val(),

                author: eventSnapshot.child("author").val()

            }

        };

        // Send a message to devices subscribed to the provided topic.

        return admin.messaging().sendToTopic(topic, payload)

            .then(function (response) {

                // See the MessagingTopicResponse reference documentation for the

                // contents of response.

                console.log("Successfully sent message:", response);

            })

            .catch(function (error) {

                console.log("Error sending message:", error);

            });

        });

To deploy run:

$firebase deploy --only functions

Part 2. Create Android App
1. Install Android Studio
2. Create new empty project
3. Below files that we need to create
Architecture:
Model - Article.java
Presenter - MainActivity.java
- MyFirebaseMessagingService.java

4. Open and add MainActivity.java

public class MainActivity extends AppCompatActivity {




    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        FirebaseMessaging.getInstance().subscribeToTopic("android");

        final FirebaseDatabase database = FirebaseDatabase.getInstance();




        final EditText titleEditText = (EditText) findViewById(R.id.et_title);

        final EditText authorEditText = (EditText) findViewById(R.id.et_author);

        Button submitButton = (Button) findViewById(R.id.btn_submit);

        submitButton.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View view) {

                DatabaseReference myRef = database.getReference("articles").push();

                Article article = new Article(titleEditText.getText().toString(),

                        authorEditText.getText().toString());

                myRef.setValue(article);

            }

        });

    }

}

4.5 Add this to main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context="code.andres.com.functions_firebase.MainActivity">

    <EditText        android:id="@+id/et_title"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:hint="Title" />

    <EditText        android:id="@+id/et_author"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:hint="Author" />

    <Button        android:id="@+id/btn_submit"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:hint="Submit" />
</LinearLayout>

5. Create new java class Article.java

public class Article {
    public String title;
    public String author;

    public Article() {
        // Default constructor required for calls to DataSnapshot.getValue(Article.class)    }

    public Article(String title, String author) {
        this.title = title;
        this.author = author;
    }
}

6. Create new java class Article.java

public class MyFirebaseMessagingService extends FirebaseMessagingService {

    @Override    public void onMessageReceived(RemoteMessage remoteMessage) {

        // Check if message contains a data payload.        if (remoteMessage.getData().size() > 0) {
            showNotification(remoteMessage.getData().get("title"), remoteMessage.getData().get("author"));
        }

        // Check if message contains a notification payload.        if (remoteMessage.getNotification() != null) {

        }
    }

    private void showNotification(String title, String author) {
        Intent intent = new Intent(this, MainActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0 /* Request code */, intent,
                PendingIntent.FLAG_ONE_SHOT);

        Uri defaultSoundUri= RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
                .setContentTitle("New Article: " + title)
                .setSmallIcon(R.mipmap.ic_launcher)
                .setContentText("By " + author)
                .setAutoCancel(true)
                .setSound(defaultSoundUri)
                .setContentIntent(pendingIntent);

        NotificationManager notificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        notificationManager.notify(0 /* ID of notification */, notificationBuilder.build());
    }
}

7. Add this to AndroidManifext.xml

<service    android:name=".MyFirebaseMessagingService">
    <intent-filter>
        <action android:name="com.google.firebase.MESSAGING_EVENT"/>
    </intent-filter>
</service>

8. Add to build.gradle

compile 'com.google.firebase:firebase-database:10.0.1'compile 'com.google.firebase:firebase-messaging:10.0.1'

refrenence:
https://code.tutsplus.com/tutorials/serverless-apps-with-firebase-cloud-functions--cms-28557