implementation 'com.google.android.gms:play-services-auth:19.2.0'

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

    <com.google.android.gms.common.SignInButton
                android:id="@+id/sign_in_button"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginBottom="8dp"
                app:layout_constraintBottom_toBottomOf="parent" android:layout_marginTop="8dp"
                app:layout_constraintTop_toTopOf="parent" app:layout_constraintStart_toStartOf="parent"
                android:layout_marginStart="8dp" app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"
                app:layout_constraintVertical_bias="0.665"
    />

class MainActivity : AppCompatActivity() {
    private val RC_SIGN_IN = 9001
    private var mGoogleSignInClient: GoogleSignInClient? = null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestIdToken(getString(R.string.server_client_id))
            .requestEmail()
            .build()
        mGoogleSignInClient = GoogleSignIn.getClient(this, gso);
    }
    public override fun onStart() {
        super.onStart()
        val mGmailSignIn = findViewById<SignInButton>(R.id.sign_in_button)
        val account = GoogleSignIn.getLastSignedInAccount(this)
        Log.w("Sign In: ", account.toString())
        mGmailSignIn.setOnClickListener {
                signIn()
        }
    }
    public override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        if (requestCode == RC_SIGN_IN) {
            val task = GoogleSignIn.getSignedInAccountFromIntent(data)
            handleSignInResult(task)
        }
    }
    private fun handleSignInResult(completedTask: Task<GoogleSignInAccount>) {
        Log.w("Sign In: ", completedTask.toString())
        try {
            val account = completedTask.getResult(ApiException::class.java)
            val idToken = account!!.idToken
            Log.w("Sign In: ", idToken.toString())
            authCheck(idToken.toString())
        } catch (e: ApiException) {
            Log.w("Sign In: ", "signInResult:failed code=" + e.statusCode)
        }
    }
    private fun signIn() {
        val signInIntent = mGoogleSignInClient!!.signInIntent
        startActivityForResult(signInIntent, RC_SIGN_IN)
    }
    private fun authCheck(token: String) {
        // Instantiate the RequestQueue.
        val queue = newRequestQueue(this)
        val url = "https://pubsub.pubnub.com/v1/blocks/sub-key/sub-c-87dbd99c-e470-11e8-8d80-3ee0fe19ec50/google?token=$token"
        // Request a string response from the provided URL.
        val stringRequest = StringRequest(
            Request.Method.GET, url,
            Response.Listener<String> { response ->
                // Display the first 500 characters of the response string.
                Log.d("Response: ", response)
            },
            Response.ErrorListener {Log.d("Response: ", "Didn't Work!")})
        // Add the request to the RequestQueue.
        queue.add(stringRequest)
    }
}

export default (request, response) => {
    const pubnub = require('pubnub');
    const xhr = require('xhr');
    let headersObject = request.headers;
    let paramsObject = request.params;
    let methodString = request.method;
    let bodyString = request.body;
    // Set the status code - by default it would return 200
    response.status = 200;
    // Set the headers the way you like

    var client_id = "your google client id"
    var client_secret = "your google client secret";
    var redirect = "https://pubsub.pubnub.com/v1/blocks/sub-key/sub-c-87dbd99c-e470-11e8-8d80-3ee0fe19ec50/Auth";

    response.headers['X-Custom-Header'] = 'CustomHeaderValue';
    var dataString = `client_id=${client_id}&client_secret=${client_secret}&redirect_uri=${redirect}&grant_type=authorization_code&code=CODE`;
    var url = `https://www.googleapis.com/oauth2/v4/token${dataString}`;
    var options = {
        "method": 'POST',
        "body": dataString,
    };

    console.log(dataString);
    return xhr.fetch(url, options).then((x) => {
        const body = JSON.parse(x.body);
        console.log(body);
         return response.send(body);
    }).catch((err) => {
        // console.log(err)
        return response.send("Malformed JSON body.");
    });
};

Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
try {
    GoogleSignInAccount account = task.getResult(ApiException.class);
    String authCode = account.getServerAuthCode();
    // Show signed-un UI
    updateUI(account);
    // TODO(developer): send code to server and exchange for access/refresh/ID tokens
} catch (ApiException e) {
    Log.w(TAG, "Sign-in failed", e);
    updateUI(null);
}