OC - P7: Go4Lunch - MVVM Example for DispatcherActivity

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest
    xmlns:android="http://schemas.android.com/apk/res/android"
    package="fr.delcey.go4lunch">

    <application
        ...
        >
        <activity
            android:name=".view.dispatcher.DispatcherActivity"
            android:theme="@style/Theme.Go4Lunch.NoActionBar.Transparent">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
      
        ...
      
    </application>
</manifest>

DispatcherActivity.java

import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;
import androidx.lifecycle.ViewModelProvider;

import fr.delcey.go4lunch.view.ViewModelFactory;

public class DispatcherActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // No "setContentView(int)" to have a fully transparent and performant Activity

        DispatcherViewModel viewModel = new ViewModelProvider(this, ViewModelFactory.getInstance()).get(DispatcherViewModel.class);

        viewModel.getViewActionSingleLiveEvent().observe(this, dispatcherViewAction -> {
            switch (dispatcherViewAction) {
                case GO_TO_CONNECT_SCREEN:
                    startActivity(new Intent(DispatcherActivity.this, OAuthActivity.class));
                    finish();
                    break;
                case GO_TO_MAIN_SCREEN:
                    startActivity(new Intent(DispatcherActivity.this, MainActivity.class));
                    finish();
                    break;
            }
        });
    }
}

DispatcherViewAction.java

public enum DispatcherViewAction {
    GO_TO_CONNECT_SCREEN,
    GO_TO_MAIN_SCREEN
}

DispatcherViewModel.java

import androidx.annotation.NonNull;
import androidx.lifecycle.ViewModel;

import com.google.firebase.auth.FirebaseAuth;

import fr.delcey.go4lunch.view.utils.SingleLiveEvent;

public class DispatcherViewModel extends ViewModel {

    @NonNull
    private final SingleLiveEvent<DispatcherViewAction> viewActionSingleLiveEvent = new SingleLiveEvent<>();

    public DispatcherViewModel(@NonNull FirebaseAuth firebaseAuth) {
        // User not connected
        if (firebaseAuth.getCurrentUser() == null) {
            viewActionSingleLiveEvent.setValue(DispatcherViewAction.GO_TO_CONNECT_SCREEN);
        } else {
            viewActionSingleLiveEvent.setValue(DispatcherViewAction.GO_TO_MAIN_SCREEN);
        }
    }

    @NonNull
    public SingleLiveEvent<DispatcherViewAction> getViewActionSingleLiveEvent() {
        return viewActionSingleLiveEvent;
    }
}