Google Firebase Auth

AuthActivity.kt

package XXX

import android.content.Intent
import android.os.Bundle
import au.sjowl.base.basex.BaseActivity
import com.google.android.gms.auth.api.signin.GoogleSignIn
import com.google.android.gms.auth.api.signin.GoogleSignInClient
import io.michaelrocks.lightsaber.getInstance
import kotlinx.android.synthetic.main.activity_auth.*
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.launch

open class AuthActivity :
    BaseActivity<AuthPresenter, AuthView>(),
    AuthView {

    override val layoutId: Int get() = R.layout.activity_auth
    override fun providePresenter(): AuthPresenter = appInjector.getInstance()

    /* ********************       google sign in      *********************/

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        signInButton.setOnClickListener { presenter.onGoogleSignIn() }
    }

    public override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)

        when (requestCode) {
            RC_SIGN_IN -> {
                val task = GoogleSignIn.getSignedInAccountFromIntent(data)
                presenter.onSignedIn(task)
            }
        }
    }

    /* ********************       View      *********************/
    override suspend fun closeView() = GlobalScope.launch(uiDispatcher) {
        finish()
    }

    override suspend fun googleSignIn(googleSignInClient: GoogleSignInClient) = GlobalScope.launch(uiDispatcher) {
        val signInIntent = googleSignInClient.signInIntent
        startActivityForResult(signInIntent, RC_SIGN_IN)
    }

    companion object {
        private const val RC_SIGN_IN = 123
    }
}

AuthInteractor.kt

package xxx

import android.content.Context
import au.sjowl.base.utils.log
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.android.gms.tasks.Task
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.FirebaseUser
import com.google.firebase.auth.GoogleAuthProvider
import javax.inject.Inject

class AuthInteractor @Inject constructor(
    private val context: Context
) {
    private val googleSignInOptions = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
        .requestIdToken(BuildConfig.WEB_CLIENT_ID)
        .requestEmail()
        .build()

    val googleSignInClient: GoogleSignInClient = GoogleSignIn.getClient(context, googleSignInOptions)

    private val firebaseAuth = FirebaseAuth.getInstance()

    private var googleAccount: GoogleSignInAccount? = null

    fun isLogin() = FirebaseAuth.getInstance().currentUser != null

    val account get() = GoogleSignIn.getLastSignedInAccount(context)

    fun signInWithGoogle(task: Task<GoogleSignInAccount>) {
        task.getResult(ApiException::class.java)?.let { account ->
            googleAccount = account
            firebaseAuthWithGoogle(account)
        }
    }

    private fun firebaseAuthWithGoogle(account: GoogleSignInAccount) {
        log("Google token:" + account.idToken)

        val credential = GoogleAuthProvider.getCredential(account.idToken, null)
        firebaseAuth.signInWithCredential(credential)
            .addOnCompleteListener { task ->
                if (task.isSuccessful) {
                    val user = firebaseAuth.currentUser as FirebaseUser
                }
            }
    }

    fun signOut() {
        FirebaseAuth.getInstance().signOut()
    }
}

AuthPresenter.kt

package XXX

import android.content.Context
import au.sjowl.base.basex.BasePresenter
import au.sjowl.base.basex.BaseTiView
import au.sjowl.base.utils.SLog
import com.google.android.gms.auth.api.signin.GoogleSignInAccount
import com.google.android.gms.auth.api.signin.GoogleSignInClient
import com.google.android.gms.tasks.Task
import kotlinx.coroutines.CoroutineExceptionHandler
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.Job
import kotlinx.coroutines.launch
import javax.inject.Inject

class AuthPresenter @Inject constructor(
    val authInteractor: AuthInteractor,
    val context: Context
) : BasePresenter<AuthView>() {

    fun onGoogleSignIn() {
        GlobalScope.launch(bgDispatcher + exceptionHandler) {
            view?.googleSignIn(authInteractor.googleSignInClient)
        }
    }

    fun onSignedIn(task: Task<GoogleSignInAccount>) {
        GlobalScope.launch(bgDispatcher + exceptionHandler) {
            authInteractor.signInWithGoogle(task)
            view?.closeView()
        }
    }

    override val exceptionHandler = CoroutineExceptionHandler { coroutineContext, throwable ->
        SLog.e(throwable.message.orEmpty())
        throwable.printStackTrace()
    }
}

interface AuthView : BaseTiView {
    suspend fun googleSignIn(googleSignInClient: GoogleSignInClient): Job
    suspend fun closeView(): Job
}

build.gradle

// ...
android {
    defaultConfig {
       // ...
        buildConfigField "String", "WEB_CLIENT_ID", '"Place your project web-client id"'
    }
// ...
}

HomePresenter.kt

// launch activity
class HomePresenter @Inject constructor(
    private val authInteractor: AuthInteractor
) : BasePresenter<HomeView>() {
    
  override fun onCreate() {
        super.onCreate()
        if (authInteractor.isLogin()) {
        } else {
            sendToView { view?.showLogin() }
        }
    }
}

interface HomeView : BaseTiView {
    fun showLogin()
}