StartScreenActivity.java

package com.application.qatarmotorsports;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import android.accounts.Account;
import android.content.Intent;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.auth.api.Auth;
import com.google.android.gms.auth.api.signin.GoogleSignIn;
import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
import com.google.android.gms.auth.api.signin.GoogleSignInClient;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
import com.google.android.gms.common.AccountPicker;
import com.google.android.gms.common.SignInButton;
import com.google.android.gms.common.api.ApiException;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthCredential;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.auth.GoogleAuthProvider;
import com.squareup.picasso.Picasso;

public class StartScreenActivity extends AppCompatActivity {


    Button btn_logout;
    SignInButton signin;
    GoogleSignInClient mGoogleSignInClient;
    int RC_SIGN_IN = 0;
    FirebaseAuth mAuth;
    FirebaseUser firebaseUser;





    @Override
    protected void onCreate(Bundle savedInstanceState) {


        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_start_screen);

        mAuth = FirebaseAuth.getInstance();

        firebaseUser = mAuth.getCurrentUser();

        if(firebaseUser != null){
            startActivity(new Intent(this,MainActivity.class));
            finish();
        }

        // Configure Google Sign In
        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.default_web_client_id))
                .requestEmail()
                .build();




        mGoogleSignInClient = GoogleSignIn.getClient(this,gso);
        signin = (SignInButton) findViewById(R.id.sign_in_button);

        signin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

               /* Intent pickintent = AccountPicker.newChooseAccountIntent(null, null, new String[]{"com.google"},
                        false, null, null, null, null);
                startActivityForResult(pickintent, RC_SIGN_IN);*/
                mGoogleSignInClient.signOut();


                Intent signInIntent = mGoogleSignInClient.getSignInIntent();
                startActivityForResult(signInIntent, RC_SIGN_IN);

            }
        });
    }





    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
            try {
                // Google Sign In was successful, authenticate with Firebase
                GoogleSignInAccount account = task.getResult(ApiException.class);
                firebaseAuthWithGoogle(account);
            } catch (ApiException e) {
                // Google Sign In failed, update UI appropriately
                e.printStackTrace();
                // ...
            }
        }
    }



    private void firebaseAuthWithGoogle(GoogleSignInAccount acct) {


        AuthCredential credential =  GoogleAuthProvider.getCredential(acct.getIdToken(), null);
        mAuth.signInWithCredential(credential)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task< AuthResult> task) {
                        if (task.isSuccessful()) {
                            // Sign in success, update UI with the signed-in user's information

                            FirebaseUser user = mAuth.getCurrentUser();
                            Intent i = new Intent(getApplicationContext(),MainActivity.class);
                            startActivity(i);
                            finish();
                            Toast.makeText(getApplicationContext(),"User Logged In Successfully",Toast.LENGTH_SHORT).show();

                        } else {
                            // If sign in fails, display a message to the user.
                            Toast.makeText(getApplicationContext(),"Login Failed",Toast.LENGTH_SHORT).show();

                        }

                        // ...
                    }
                });
    }

}






/*
        signin = findViewById(R.id.sign_in_button);
        signin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                switch (v.getId()) {
                    case R.id.sign_in_button:
                        signIn();
                        break;
                }
            }
        });

        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestEmail()
                .build();

        // Configure Google Sign In
        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.default_web_client_id))
                .requestEmail()
                .build();

        mGoogleSignInClient = GoogleSignIn.getClient(this, gso);


    }

    private void signIn() {
        Intent signInIntent = mGoogleSignInClient.getSignInIntent();
        startActivityForResult(signInIntent, RC_SIGN_IN);
    }


    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        // Result returned from launching the Intent from GoogleSignInClient.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            // The Task returned from this call is always completed, no need to attach
            // a listener.
            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
            handleSignInResult(task);
        }
    }


    private void handleSignInResult(Task<GoogleSignInAccount> completedTask) {
        try {
            GoogleSignInAccount account = completedTask.getResult(ApiException.class);

            // Signed in successfully, show authenticated UI.
            Intent intent = new Intent(StartScreenActivity.this, MainActivity.class);
            startActivity(intent);
        } catch (ApiException e) {
            // The ApiException status code indicates the detailed failure reason.
            // Please refer to the GoogleSignInStatusCodes class reference for more information.
            Log.w("Error", "signInResult:failed code=" + e.getStatusCode());
        }


    }*/