var provider = new firebase.auth.GoogleAuthProvider();
document.getElementById('signIn').addEventListener('click', function (e) {
    firebase.auth().signInWithRedirect(provider);
});

document.getElementById('signOut').addEventListener('click', function (e) {
    firebase.auth().signOut()
        .then(function () {
            console.log('User signed out');
        }).catch(function (error) {
            console.error('Error while signing out: ', error);
        })
});

firebase.auth().getRedirectResult()
    .then(function (result) {
        if (result.credential) {
            console.log('Got Google Token');
        }
        var user = result.user;
        console.log(user);
    }).catch(function (error) {
        console.error('Error(code: ' + error.code + ', message: ' + error.message + ')');
    });

firebase.auth().onAuthStateChanged(function (user) {
    if (user) {
        document.getElementById('signedUserName').textContent = 'Signed in user: ' + user.displayName + '[email: ' + user.email + ']';
        document.getElementById('userImage').src = user.photoURL;
    } else {
        document.getElementById('signedUserName').textContent = 'Signed in user: NONE';
        document.getElementById('userImage').src = '';
    }
});