Example of cordova-plugin-googleplus `GooglePlus.java` that provides `accessToken` for Android

Firebase-Ready-GooglePlus.java

package nl.xservices.plugins;

import android.content.Intent;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.util.Log;

import com.google.android.gms.auth.api.Auth;
import com.google.android.gms.auth.GoogleAuthUtil;
import com.google.android.gms.auth.api.signin.GoogleSignInResult;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.api.ResultCallback;
import com.google.android.gms.common.api.Status;
import com.google.android.gms.common.api.Scope;

import org.apache.cordova.*;
import org.json.JSONException;
import org.json.JSONObject;

import java.security.MessageDigest;
import android.content.pm.Signature;
import android.os.AsyncTask;
import android.content.Context;

/**
 * Originally written by Eddy Verbruggen (http://github.com/EddyVerbruggen/cordova-plugin-googleplus)
 * Forked/Duplicated and Modified by PointSource, LLC, 2016.
 */
public class GooglePlus extends CordovaPlugin implements GoogleApiClient.OnConnectionFailedListener {

    public static final String ACTION_IS_AVAILABLE = "isAvailable";
    public static final String ACTION_LOGIN = "login";
    public static final String ACTION_TRY_SILENT_LOGIN = "trySilentLogin";
    public static final String ACTION_LOGOUT = "logout";
    public static final String ACTION_DISCONNECT = "disconnect";
    public static final String ACTION_GET_SIGNING_CERTIFICATE_FINGERPRINT = "getSigningCertificateFingerprint";

    //String options/config object names passed in to login and trySilentLogin
    public static final String ARGUMENT_WEB_CLIENT_ID = "webClientId";
    public static final String ARGUMENT_SCOPES = "scopes";
    public static final String ARGUMENT_OFFLINE_KEY = "offline";

    public static final String TAG = "GooglePlugin";
    public static final int RC_GOOGLEPLUS = 77552; // Request Code to identify our plugin's activities
    private String lastAccessToken = null;

    // Wraps our service connection to Google Play services and provides access to the users sign in state and Google APIs
    private GoogleApiClient mGoogleApiClient;
    private CallbackContext savedCallbackContext;

    @Override
    public void initialize(CordovaInterface cordova, CordovaWebView webView) {
        super.initialize(cordova, webView);
    }

    @Override
    public boolean execute(String action, CordovaArgs args, CallbackContext callbackContext) throws JSONException {
        this.savedCallbackContext = callbackContext;

        if (ACTION_IS_AVAILABLE.equals(action)) {
            final boolean avail = true;
            savedCallbackContext.success("" + avail);

        } else if (ACTION_LOGIN.equals(action)) {
            //pass args into api client build
            buildGoogleApiClient(args.optJSONObject(0));

            // Tries to Log the user in
            Log.i(TAG, "Trying to Log in!");
            cordova.setActivityResultCallback(this); //sets this class instance to be an activity result listener
            signIn();

        } else if (ACTION_TRY_SILENT_LOGIN.equals(action)) {
            //pass args into api client build
            buildGoogleApiClient(args.optJSONObject(0));

            Log.i(TAG, "Trying to do silent login!");
            trySilentLogin();

        } else if (ACTION_LOGOUT.equals(action)) {
            Log.i(TAG, "Trying to logout!");
            signOut();

        } else if (ACTION_DISCONNECT.equals(action)) {
            Log.i(TAG, "Trying to disconnect the user");
            disconnect();

        } else if (ACTION_GET_SIGNING_CERTIFICATE_FINGERPRINT.equals(action)) {
            getSigningCertificateFingerprint();

        } else {
            Log.i(TAG, "This action doesn't exist");
            return false;

        }
        return true;
    }

    /**
     * Set options for login and Build the GoogleApiClient if it has not already been built.
     * @param clientOptions - the options object passed in the login function
     */
    private synchronized void buildGoogleApiClient(JSONObject clientOptions) throws JSONException {
        if (clientOptions == null) {
            return;
        }

        //If options have been passed in, they could be different, so force a rebuild of the client
        // disconnect old client iff it exists
        if (this.mGoogleApiClient != null) this.mGoogleApiClient.disconnect();
        // nullify
        this.mGoogleApiClient = null;

        Log.i(TAG, "Building Google options");

        // Make our SignIn Options builder.
        GoogleSignInOptions.Builder gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN);

        // request the default scopes
        gso.requestEmail().requestProfile();

        // We're building the scopes on the Options object instead of the API Client
        // b/c of what was said under the "addScope" method here:
        // https://developers.google.com/android/reference/com/google/android/gms/common/api/GoogleApiClient.Builder.html#public-methods
        String scopes = clientOptions.optString(ARGUMENT_SCOPES, null);

        if (scopes != null && !scopes.isEmpty()) {
            // We have a string of scopes passed in. Split by space and request
            for (String scope : scopes.split(" ")) {
                gso.requestScopes(new Scope(scope));
            }
        }

        // Try to get web client id
        String webClientId = clientOptions.optString(ARGUMENT_WEB_CLIENT_ID, null);

        // if webClientId included, we'll request an idToken
        if (webClientId != null && !webClientId.isEmpty()) {
            gso.requestIdToken(webClientId);

            // if webClientId is included AND offline is true, we'll request the serverAuthCode
            if (clientOptions.optBoolean(ARGUMENT_OFFLINE_KEY, false)) {
                gso.requestServerAuthCode(webClientId, false);
            }
        }

        //Now that we have our options, let's build our Client
        Log.i(TAG, "Building GoogleApiClient");

        GoogleApiClient.Builder builder = new GoogleApiClient.Builder(webView.getContext())
            .addOnConnectionFailedListener(this)
            .addApi(Auth.GOOGLE_SIGN_IN_API, gso.build());

        this.mGoogleApiClient = builder.build();

        Log.i(TAG, "GoogleApiClient built");
    }

    // The Following functions were implemented in reference to Google's example here:
    // https://github.com/googlesamples/google-services/blob/master/android/signin/app/src/main/java/com/google/samples/quickstart/signin/SignInActivity.java

    /**
     * Starts the sign in flow with a new Intent, which should respond to our activity listener here.
     */
    private void signIn() {
        Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(this.mGoogleApiClient);
        cordova.getActivity().startActivityForResult(signInIntent, RC_GOOGLEPLUS);
    }

    /**
     * Tries to log the user in silently using existing sign in result information
     */
    private void trySilentLogin() {
        ConnectionResult apiConnect =  mGoogleApiClient.blockingConnect();

        if (apiConnect.isSuccess()) {
            handleSignInResult(Auth.GoogleSignInApi.silentSignIn(this.mGoogleApiClient).await());
        }
    }

    /**
     * Signs the user out from the client
     */
    private void signOut() {
        if (this.mGoogleApiClient == null) {
            savedCallbackContext.error("Please use login or trySilentLogin before logging out");
            return;
        }

        ConnectionResult apiConnect = mGoogleApiClient.blockingConnect();

        if (apiConnect.isSuccess()) {
            Auth.GoogleSignInApi.signOut(this.mGoogleApiClient).setResultCallback(
                    new ResultCallback<Status>() {
                        @Override
                        public void onResult(Status status) {
                            //on success, tell cordova
                            if (status.isSuccess()) {
                                savedCallbackContext.success("Logged user out");
                            } else {
                                savedCallbackContext.error(status.getStatusCode());
                            }
                        }
                    }
            );
        }
    }

    /**
     * Disconnects the user and revokes access
     */
    private void disconnect() {
        if (this.mGoogleApiClient == null) {
            savedCallbackContext.error("Please use login or trySilentLogin before disconnecting");
            return;
        }

        ConnectionResult apiConnect = mGoogleApiClient.blockingConnect();

        if (apiConnect.isSuccess()) {
            Auth.GoogleSignInApi.revokeAccess(this.mGoogleApiClient).setResultCallback(
                    new ResultCallback<Status>() {
                        @Override
                        public void onResult(Status status) {
                            if (status.isSuccess()) {
                                savedCallbackContext.success("Disconnected user");
                            } else {
                                savedCallbackContext.error(status.getStatusCode());
                            }
                        }
                    }
            );
        }
    }

    /**
     * Handles failure in connecting to google apis.
     *
     * @param result is the ConnectionResult to potentially catch
     */
    @Override
    public void onConnectionFailed(ConnectionResult result) {
        Log.i(TAG, "Unresolvable failure in connecting to Google APIs");
        savedCallbackContext.error(result.getErrorCode());
    }

    /**
     * Listens for and responds to an activity result. If the activity result request code matches our own,
     * we know that the sign in Intent that we started has completed.
     *
     * The result is retrieved and send to the handleSignInResult function.
     *
     * @param requestCode The request code originally supplied to startActivityForResult(),
     * @param resultCode The integer result code returned by the child activity through its setResult().
     * @param intent Information returned by the child activity
     */
    @Override
    public void onActivityResult(int requestCode, final int resultCode, final Intent intent) {
        super.onActivityResult(requestCode, resultCode, intent);

        Log.i(TAG, "In onActivityResult");

        if (requestCode == RC_GOOGLEPLUS) {
            Log.i(TAG, "One of our activities finished up");
            //Call handleSignInResult passing in sign in result object
            handleSignInResult(Auth.GoogleSignInApi.getSignInResultFromIntent(intent));
        }
        else {
            Log.i(TAG, "This wasn't one of our activities");
        }
    }

    /**
     * Function for handling the sign in result
     * Handles the result of the authentication workflow.
     *
     * If the sign in was successful, we build and return an object containing the users email, id, displayname,
     * id token, and (optionally) the server authcode.
     *
     * If sign in was not successful, for some reason, we return the status code to web app to be handled.
     * Some important Status Codes:
     *      SIGN_IN_CANCELLED = 12501 -> cancelled by the user, flow exited, oauth consent denied
     *      SIGN_IN_FAILED = 12500 -> sign in attempt didn't succeed with the current account
     *      SIGN_IN_REQUIRED = 4 -> Sign in is needed to access API but the user is not signed in
     *      INTERNAL_ERROR = 8
     *      NETWORK_ERROR = 7
     *
     * @param signInResult - the GoogleSignInResult object retrieved in the onActivityResult method.
     */
    private void handleSignInResult(final GoogleSignInResult signInResult) {
        if (this.mGoogleApiClient == null) {
            savedCallbackContext.error("GoogleApiClient was never initialized");
            return;
        }

        if (signInResult == null) {
          savedCallbackContext.error("SignInResult is null");
          return;
        }

        Log.i(TAG, "Handling SignIn Result");

        if (!signInResult.isSuccess()) {
            Log.i(TAG, "Wasn't signed in");

            //Return the status code to be handled client side
            savedCallbackContext.error(signInResult.getStatus().getStatusCode());
        } else {

            AsyncTask<Void, Void, String> task = new AsyncTask<Void, Void, String>() {
                @Override
                protected String doInBackground(Void... params) {
                    JSONObject result = new JSONObject();
                    GoogleSignInAccount acct = signInResult.getSignInAccount();
                    Context context = cordova.getActivity().getApplicationContext();
                    String accessToken = null;
                    try {
                        Log.i(TAG, "trying to get account information");
                        try {
                            if (lastAccessToken != null) {
                                GoogleAuthUtil.clearToken (context, lastAccessToken);
                                lastAccessToken = null;
                            }

                            accessToken = GoogleAuthUtil.getToken(context, acct.getEmail(), "oauth2:profile email");
                        } catch (Exception e) {
                            Log.e(TAG, "getToken Error: " + e.toString());
                        }

                        if (accessToken != null) {
                            lastAccessToken = accessToken;
                        }
                        result.put("email", acct.getEmail());
                        result.put("accessToken", accessToken);

                        //only gets included if requested (See Line 164).
                        result.put("idToken", acct.getIdToken());

                        //only gets included if requested (See Line 166).
                        result.put("serverAuthCode", acct.getServerAuthCode());

                        result.put("userId", acct.getId());
                        result.put("displayName", acct.getDisplayName());
                        result.put("familyName", acct.getFamilyName());
                        result.put("givenName", acct.getGivenName());
                        result.put("imageUrl", acct.getPhotoUrl());

                        savedCallbackContext.success(result);
                    } catch (JSONException e) {
                        savedCallbackContext.error("Trouble parsing result, error: " + e.getMessage());
                    }

                    return accessToken;
                }

                @Override
                protected void onPostExecute(String token) {
                    Log.i(TAG, "Access token retrieved:" + token);
                }

            };

            task.execute();
        }


    }



    private void getSigningCertificateFingerprint() {
        String packageName = webView.getContext().getPackageName();
        int flags = PackageManager.GET_SIGNATURES;
        PackageManager pm = webView.getContext().getPackageManager();
        try {
            PackageInfo packageInfo = pm.getPackageInfo(packageName, flags);
            Signature[] signatures = packageInfo.signatures;
            byte[] cert = signatures[0].toByteArray();

            String strResult = "";
            MessageDigest md;
            md = MessageDigest.getInstance("SHA1");
            md.update(cert);
            for (byte b : md.digest()) {
                String strAppend = Integer.toString(b & 0xff, 16);
                if (strAppend.length() == 1) {
                    strResult += "0";
                }
                strResult += strAppend;
                strResult += ":";
            }
            // strip the last ':'
            strResult = strResult.substring(0, strResult.length()-1);
            strResult = strResult.toUpperCase();
            this.savedCallbackContext.success(strResult);

        } catch (Exception e) {
            e.printStackTrace();
            savedCallbackContext.error(e.getMessage());
        }
    }
}