GoogleSignInActivity.kt

package com.google.firebase.quickstart.auth.kotlin

import android.content.Intent
import android.os.Bundle
import com.google.android.material.snackbar.Snackbar
import android.util.Log
import android.view.View
import com.google.android.gms.auth.api.signin.GoogleSignIn
import com.google.android.gms.auth.api.signin.GoogleSignInAccount
import com.google.android.gms.auth.api.signin.GoogleSignInClient
import com.google.android.gms.auth.api.signin.GoogleSignInOptions
import com.google.android.gms.common.api.ApiException
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.FirebaseUser
import com.google.firebase.auth.GoogleAuthProvider
import com.google.firebase.quickstart.auth.R
import kotlinx.android.synthetic.main.activity_google.detail
import kotlinx.android.synthetic.main.activity_google.disconnectButton
import kotlinx.android.synthetic.main.activity_google.main_layout
import kotlinx.android.synthetic.main.activity_google.signInButton
import kotlinx.android.synthetic.main.activity_google.signOutAndDisconnect
import kotlinx.android.synthetic.main.activity_google.signOutButton
import kotlinx.android.synthetic.main.activity_google.status

/**
 * Demonstrate Firebase Authentication using a Google ID Token.
 */
class GoogleSignInActivity : BaseActivity(), View.OnClickListener {

    // [START declare_auth]
    private lateinit var auth: FirebaseAuth
    // [END declare_auth]

    private lateinit var googleSignInClient: GoogleSignInClient

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_google)

        // Button listeners
        signInButton.setOnClickListener(this)
        signOutButton.setOnClickListener(this)
        disconnectButton.setOnClickListener(this)

        // [START config_signin]
        // Configure Google Sign In
        val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.default_web_client_id))
                .requestEmail()
                .build()
        // [END config_signin]

        googleSignInClient = GoogleSignIn.getClient(this, gso)

        // [START initialize_auth]
        // Initialize Firebase Auth
        auth = FirebaseAuth.getInstance()
        // [END initialize_auth]
    }

    // [START on_start_check_user]
    public override fun onStart() {
        super.onStart()
        // Check if user is signed in (non-null) and update UI accordingly.
        val currentUser = auth.currentUser
        updateUI(currentUser)
    }
    // [END on_start_check_user]

    // [START onactivityresult]
    public override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)

        // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            val task = GoogleSignIn.getSignedInAccountFromIntent(data)
            try {
                // Google Sign In was successful, authenticate with Firebase
                val account = task.getResult(ApiException::class.java)
                firebaseAuthWithGoogle(account!!)
            } catch (e: ApiException) {
                // Google Sign In failed, update UI appropriately
                Log.w(TAG, "Google sign in failed", e)
                // [START_EXCLUDE]
                updateUI(null)
                // [END_EXCLUDE]
            }
        }
    }
    // [END onactivityresult]

    // [START auth_with_google]
    private fun firebaseAuthWithGoogle(acct: GoogleSignInAccount) {
        Log.d(TAG, "firebaseAuthWithGoogle:" + acct.id!!)
        // [START_EXCLUDE silent]
        showProgressDialog()
        // [END_EXCLUDE]

        val credential = GoogleAuthProvider.getCredential(acct.idToken, null)
        auth.signInWithCredential(credential)
                .addOnCompleteListener(this) { task ->
                    if (task.isSuccessful) {
                        // Sign in success, update UI with the signed-in user's information
                        Log.d(TAG, "signInWithCredential:success")
                        val user = auth.currentUser
                        updateUI(user)
                    } else {
                        // If sign in fails, display a message to the user.
                        Log.w(TAG, "signInWithCredential:failure", task.exception)
                        Snackbar.make(main_layout, "Authentication Failed.", Snackbar.LENGTH_SHORT).show()
                        updateUI(null)
                    }

                    // [START_EXCLUDE]
                    hideProgressDialog()
                    // [END_EXCLUDE]
                }
    }
    // [END auth_with_google]

    // [START signin]
    private fun signIn() {
        val signInIntent = googleSignInClient.signInIntent
        startActivityForResult(signInIntent, RC_SIGN_IN)
    }
    // [END signin]

    private fun signOut() {
        // Firebase sign out
        auth.signOut()

        // Google sign out
        googleSignInClient.signOut().addOnCompleteListener(this) {
            updateUI(null)
        }
    }

    private fun revokeAccess() {
        // Firebase sign out
        auth.signOut()

        // Google revoke access
        googleSignInClient.revokeAccess().addOnCompleteListener(this) {
            updateUI(null)
        }
    }

    private fun updateUI(user: FirebaseUser?) {
        hideProgressDialog()
        if (user != null) {
            status.text = getString(R.string.google_status_fmt, user.email)
            detail.text = getString(R.string.firebase_status_fmt, user.uid)

            signInButton.visibility = View.GONE
            signOutAndDisconnect.visibility = View.VISIBLE
        } else {
            status.setText(R.string.signed_out)
            detail.text = null

            signInButton.visibility = View.VISIBLE
            signOutAndDisconnect.visibility = View.GONE
        }
    }

    override fun onClick(v: View) {
        val i = v.id
        when (i) {
            R.id.signInButton -> signIn()
            R.id.signOutButton -> signOut()
            R.id.disconnectButton -> revokeAccess()
        }
    }

    companion object {
        private const val TAG = "GoogleActivity"
        private const val RC_SIGN_IN = 9001
    }
}