apply plugin: 'com.android.application'

    android {
        compileSdkVersion 25
        buildToolsVersion "25.0.2"
        defaultConfig {
            applicationId "com.example.test.restaurant_app"
            minSdkVersion 19
            targetSdkVersion 25
            versionCode 1
            versionName "1.0"
            testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        }
        buildTypes {
            release {
                minifyEnabled false
                proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'

     }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })

    compile 'com.google.firebase:firebase-core:10.2.0'
    compile 'com.android.support:appcompat-v7:25.2.0'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    compile 'com.google.firebase:firebase-auth:10.2.0'
    compile 'com.google.firebase:firebase-database:10.2.0'
    testCompile 'junit:junit:4.12'
}




apply plugin: 'com.google.gms.google-services'

package com.example.test.restaurant_app;

import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private FirebaseAuth.AuthStateListener mAuthListener;

    private Button registerButton;
    private EditText editTextEmail;
    private EditText editTextPassword;
    private TextView textViewSignIn;

    private ProgressDialog progressDialog;

    private FirebaseAuth mAuth;

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

        setContentView(R.layout.activity_main);


        registerButton = (Button) findViewById(R.id.registerButton);
        editTextEmail = (EditText) findViewById(R.id.editTextEmail);
        editTextPassword = (EditText) findViewById(R.id.editTextPassword);

        textViewSignIn = (TextView)findViewById(R.id.textViewSignIn);
        progressDialog = new ProgressDialog(this);

        registerButton.setOnClickListener(this);
        textViewSignIn.setOnClickListener(this);

        mAuth = FirebaseAuth.getInstance();

    }

    private void registerUser(){
        String email = editTextEmail.getText().toString().trim();
        String password = editTextPassword.getText().toString().trim();

        if (TextUtils.isEmpty(email)){
            Toast.makeText(this, "Please enter an email address", Toast.LENGTH_SHORT).show();
            return;
        }

        if (TextUtils.isEmpty(password)){
            Toast.makeText(this, "Please enter a password", Toast.LENGTH_SHORT).show();
            return;
        }

        progressDialog.setMessage("Registering User...");
        progressDialog.show();

        mAuth.createUserWithEmailAndPassword(email, password)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()) {
                            progressDialog.dismiss();
                            Toast.makeText(MainActivity.this, "Registered Successfully",
                                    Toast.LENGTH_SHORT).show();
                            finish();
                           startActivity(new Intent(getApplicationContext(), MainPage.class));

                        } else {
                            Toast.makeText(MainActivity.this, "Could not Register...Please try again.",
                                    Toast.LENGTH_SHORT).show();
                            progressDialog.dismiss();
                        }
                    }
                });
    }

    @Override
    public void onClick(View view) {
        if (view == registerButton){
            registerUser();
        }
        if (view == textViewSignIn){
            startActivity(new Intent(this, LoginActivity.class));
        }
    }
}

package com.example.test.restaurant_app;

import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;

public class LoginActivity extends AppCompatActivity implements View.OnClickListener {

    private Button signInButton;
    private EditText editTextEmail;
    private EditText editTextPassword;
    private TextView textViewSignUp;
    private FirebaseAuth mAuth;
    private ProgressDialog progressDialog;

    private GoogleApiClient client;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        signInButton = (Button) findViewById(R.id.signInButton);
        editTextEmail = (EditText) findViewById(R.id.editTextEmail);
        editTextPassword = (EditText) findViewById(R.id.editTextPassword);
        textViewSignUp = (TextView) findViewById(R.id.textViewSignUp);
        progressDialog = new ProgressDialog(this);

        mAuth = FirebaseAuth.getInstance();

        signInButton.setOnClickListener(this);
        textViewSignUp.setOnClickListener(this);
    }

    private void signInUser() {
        String email = editTextEmail.getText().toString().trim();
        String password = editTextPassword.getText().toString().trim();

        if (TextUtils.isEmpty(email)) {
            Toast.makeText(this, "Please enter an email address", Toast.LENGTH_SHORT).show();
            return;
        }

        if (TextUtils.isEmpty(password)) {
            Toast.makeText(this, "Please enter a password", Toast.LENGTH_SHORT).show();
            return;
        }

        progressDialog.setMessage("Logging in...");
        progressDialog.show();

        mAuth.signInWithEmailAndPassword(email, password)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()) {
                            progressDialog.dismiss();
                            Toast.makeText(LoginActivity.this, "Signed in Successfully",
                                    Toast.LENGTH_SHORT).show();
                            finish();
                            startActivity(new Intent(getApplicationContext(), MainPage.class));

                        } else {
                            Toast.makeText(LoginActivity.this, "Could not Sign in...Please try again.",
                                    Toast.LENGTH_SHORT).show();
                            progressDialog.dismiss();

                        }
                    }
                });
    }

    @Override
    public void onClick (View view){
        if (view == signInButton) {
            signInUser();
        }
        if (view == textViewSignUp) {
            finish();
            startActivity(new Intent(this, MainActivity.class));
        }
    }
}

package com.example.test.restaurant_app;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;

public class MainPage extends AppCompatActivity implements View.OnClickListener {

    private FirebaseAuth mAuth;
    private FirebaseUser user;
    private TextView textViewEmail;
    private Button logoutButton;

    private EditText editTextName, editTextAddress, editTextAge;
    private Button saveInfo;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        mAuth = FirebaseAuth.getInstance();


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

        logoutButton = (Button) findViewById(R.id.logoutButton);
        textViewEmail = (TextView) findViewById(R.id.userEmail);
        findViewById(R.id.addressTextField);

        FirebaseUser user = mAuth.getCurrentUser();
        String name = user.getEmail().toString().trim();
        String welcomeMessage = "Hello, " + name;
        textViewEmail.setText(welcomeMessage);

        logoutButton.setOnClickListener(this);

    }

    public void onClick(View view) {
        if (view == logoutButton) {
            finish();
            startActivity(new Intent(getApplicationContext(), LoginActivity.class));
        }
        }
    }