generate parse session token from google id token

function getRandomString()

{
    var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZ";
    var string_length = 10;
    var randomstring = '';

    for (var i=0; i<string_length; i++) {
        var rnum = Math.floor(Math.random() * chars.length);
        randomstring += chars.substring(rnum,rnum + 1);
    }
    return randomstring;
}

Parse.Cloud.define("getSessionToken", function(request, response) {
    //console.log(request);
    //console.log(request.params.accessToken);
    //console.log(request.params.GClientId);
    Parse.Cloud.useMasterKey();

    //Verifying token (id Token)
    var authTokenVerificationURL = "https://www.googleapis.com/oauth2/v3/tokeninfo?id_token=" + request.params.idToken;
    //console.log(authTokenVerificationURL);
    Parse.Cloud.httpRequest({
        url:authTokenVerificationURL
    }).then(function(httpResponse){
        //Success
        //console.log("success httpResponse: " + httpResponse.text);

        //Verify if token is generated from our client
        var gAudience = httpResponse.data.aud;
        if(gAudience == request.params.GClientId) {
            console.log("Verified: Token is generated from our app");

            var user_emailId = httpResponse.data.email;
            //console.log(user_emailId);

            //Check if User account exists for the emailId
            var query = new Parse.Query(Parse.User);
            query.equalTo("email",user_emailId);
            query.first({
                success: function(user) {

                    if(user) {
                        console.log("User found with Username: " + user.getUsername() + ", objectId: " + user.id);

                        //Generate the Session Token
                        var sessionToken = user.getSessionToken();
                        if(sessionToken) {
                            console.log("SessionToken: " + sessionToken);
                            response.success(sessionToken);
                        }else {
                            console.log("Unable to generate session token");
                            response.error('Unable to generate Session Token');
                        }

                    }else {
                        console.log("User not found, Creating new account for user with emailId: " + user_emailId);

                        //Create New Account
                        var nUser = new Parse.User();
                        nUser.set("username",user_emailId);
                        nUser.set("password",getRandomString());
                        nUser.set("email",user_emailId);
                        nUser.signUp(null,{
                            success: function(user) {
                                console.log("New account created for user with emailID: " + user_emailId);

                                //Generate the Session Token
                                var sessionToken = user.getSessionToken();
                                console.log("SessionToken: " + sessionToken);
                                response.success(sessionToken);
                            },
                            error: function(user, error) {
                                console.log("Failed to create a new account for emailID: " + user_emailId);
                                console.log("User: " + user + ", Error: " + error);
                                response.error(error);
                            }
                        });
                    }


                },
                error: function(user, error) {
                    console.log("Query to fetch user failed");
                    console.log("User: " + user + ", Error: " + error);;

                    response.error(error);
                },
                userMasterKey:true
            });



        }else { //Client has not login from our app
            console.log("Google AudienceID: " + gAudience + "\n AppClientId: " + request.params.GClientId);
            response.error('Invalid Audience');
        }

    },function(httpResponse) {
        //Error
        console.log("Failed httpResponse: " + httpResponse.text);
        console.error('Request Failed with response code' + httpResponse.status);
        response.error('Failed to verify access token');
    });

});