# Google Credential in Android
###### tags: `Android` `Google Credential`

[TOC]

## How to integrate Google Sign-In?

**Google Site Steps:**
URL: https://developers.google.com/identity/sign-in/android/start-integrating#next_steps

>**Note:**
Remember to always set Internet permission in Manifest![color=#187fce]

<uses-permission android:name="android.permission.INTERNET" />

### 1. Build Gradle (Project)

allprojects {
    repositories {
        google()
        jcenter()
        mavenCentral()
    }
}

### 2. Build Gradle (App)

dependencies {
    //Google Credential
    compile 'com.google.android.gms:play-services-auth:16.0.1'
}

### 3. Configure a Google API Console project

**Step 1:**

**Step 2:**

:::info
**SHA-1 signing certificate:**
1. Go to Gradle -> Android -> signing Report
2. Double Click *++Signing Report++* and you will get SHA1 in your **"Run Window"**.
:::

**Step 3:**
Download your client configuration(json file) and place it in your app folder.

### 4. Add Google Sign-In Button to XML
You can decide whether you want to use Google Default Button or other. It will not affect the google sign-in process.

Default Button Preview:

Default Button XML:

<com.google.android.gms.common.SignInButton
 android:id="@+id/sign_in_button"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content" />

### 5. Set up GoogleSignInOptions and GoogleSignInClient

**GoogleSignInOptions:**
Configures Google Sign-In to request users' ID and basic profile information.

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

this.mGoogleSignInClient = GoogleSignIn.getClient(this, gso);

//Check whether google account is signed or not
GoogleSignInAccount account = GoogleSignIn.getLastSignedInAccount(this);
if(account != null){
    //Get information
    setUpGLUser(account);
    logInSuccessful();
}

#### Check for an existing signed-in user:
Use the client made in onCreate to check whether there is an account already logged in.
>Note:
>GL_RC in this case is a final int I made to use as requestCode.[color=#55a6e8]

public void glSignIn(){
    Intent signInIntent = mGoogleSignInClient.getSignInIntent();
    startActivityForResult(signInIntent, GL_RC);
}

### 6. Handle Sign-In Result
We may be able to log in successfully but also fail. Therefore, we need to handle the possible error by using following code.

private void handleSignInResult(Task<GoogleSignInAccount> completedTask) {
    //Handles the error if Google Sign in was not successful;
    try {
        GoogleSignInAccount account = completedTask.getResult(ApiException.class);
        setUpGLUser(account);

        // Signed in successfully
        // Decide what to do next
        logInSuccessful();
    } catch (ApiException e) {
        Toast.makeText(LoginActivity.this, "GOOGLE SIGN IN FAILED", Toast.LENGTH_SHORT).show();
    }
}

### 7. Get User's information
We use GoogleSignInAccount, we obtained from ++*handleSignInResult*++ to get the information we need.
>Note:
>Some information like photoUrl may not be available if the user did not set any.[color=#55a6e8]

private void setUpGLUser(GoogleSignInAccount account){
    String img_url = "NULL";
    if(account.getPhotoUrl() != null){
        img_url = account.getPhotoUrl().toString();
    }
    userInfo.userProfile(account.getId(),account.getDisplayName(),img_url, account.getEmail());
}

## Google Log in Buttons
1. Default Button
2. Large rectangular round button
3. Rounded Buttons

Remember no matter which type you make, you must setOnClickListener to it.

### Large rectangular rounded corners button:
Preview:

Code:

<FrameLayout
    android:layout_width="250dp"
    android:layout_height="50dp"
    android:layout_marginTop="5dp"
    android:layout_gravity="center">

    <Button
        android:id="@+id/gl"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/button_rounded_gl"
        android:drawableStart="@drawable/gl_logo_25px"
        android:drawableLeft="@drawable/gl_logo_25px"
        android:paddingEnd="20dp"
        android:paddingStart="20dp"
        android:text="@string/gl"
        android:textAllCaps="false"
        android:textColor="#ffffff"
        android:textSize="14sp"
        android:textStyle="bold">
    </Button>

</FrameLayout>

### Rounded Button:

>Note:
>You can make it with or without FrameLayout. It is all up to you.[color=#55a6e8]

<FrameLayout
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_gravity="center">

    <ImageButton
        android:id="@+id/gl"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/button_rounded_fb"
        android:src="@drawable/gl_logo_25px"
        android:padding="8dp"
        android:scaleType="centerInside"/>
</FrameLayout>

## Google Account Sign-Out

private void signOut() {
    mGoogleSignInClient.signOut().addOnCompleteListener(this, new OnCompleteListener<Void>() {
        @Override
        public void onComplete(@NonNull Task<Void> task) {
            // Code you want to do when sign-out
            //Ex: Finish activity or intent, etc...
            finish();
        }
    });
}

## Google Account Revoke from App
Users will have the ability to remove their information from app.

private void revokeAccess() {
    mGoogleSignInClient.revokeAccess()
    .addOnCompleteListener(this, new OnCompleteListener<Void>() {
        @Override
        public void onComplete(@NonNull Task<Void> task) {
            // ...
        }
    });
}