how to implement firebase google sign to kotlin application

Question

I'm trying to implement google firebase sign in my kotlin application,

Here is what I did :

• Added SHA1 to my project's app in firebase.

• Implemented firebase to my project and it synced correctly.

here is the code I used:

class LoginActivity : AppCompatActivity() {

    val RC_SIGN_IN: Int = 1
    lateinit var mGoogleSignInClient: GoogleSignInClient
    lateinit var mGoogleSignInOptions: GoogleSignInOptions

    private lateinit var firebaseAuth: FirebaseAuth


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_login)
        setupUI()
        configureGoogleSignIn()
        firebaseAuth = FirebaseAuth.getInstance()

    }

    override fun onStart() {
        super.onStart()
        val user = FirebaseAuth.getInstance().currentUser
        if (user != null) {
            val mainActivityIntent = Intent(this, MainActivity::class.java)
            startActivity(mainActivityIntent)
            finish()
        }
    }

    private fun configureGoogleSignIn() {
        mGoogleSignInOptions = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestIdToken(getString(R.string.default_web_client_id))
            .requestEmail()
            .build()
        mGoogleSignInClient = GoogleSignIn.getClient(this, mGoogleSignInOptions)
    }

    private fun setupUI() {
        google_button.setOnClickListener {
            signIn()
        }
    }

    private fun signIn() {
        val signInIntent: Intent = mGoogleSignInClient.signInIntent
        startActivityForResult(signInIntent, RC_SIGN_IN)
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        if (requestCode == RC_SIGN_IN) {
            val task: Task<GoogleSignInAccount> = GoogleSignIn.getSignedInAccountFromIntent(data)
            try {
                val account = task.getResult(ApiException::class.java)
                if (account != null) {
                    firebaseAuthWithGoogle(account)
                }
            } catch (e: ApiException) {
                Toast.makeText(this, "Google sign in failed:(", Toast.LENGTH_LONG).show()
            }
        }
    }
    private fun firebaseAuthWithGoogle(acct: GoogleSignInAccount) {
        val credential = GoogleAuthProvider.getCredential(acct.idToken, null)
        firebaseAuth.signInWithCredential(credential).addOnCompleteListener {
            if (it.isSuccessful) {
                val mainActivityIntent = Intent(this, MainActivity::class.java)
                startActivity(mainActivityIntent)
            } else {
                Toast.makeText(this, "Google sign in failed:(", Toast.LENGTH_LONG).show()
            }
        }
    }

    companion object {
        fun getLaunchIntent(from: Context) = Intent(from, LoginActivity::class.java).apply {
            addFlags(Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK)
        }
    }

}

it stops at the line Toast.makeText(this, "Google sign in failed:(", Toast.LENGTH_LONG).show() which means something wrong with the auth request flow. any help ?

Answer 1

Solved it!

The whole problem is to add all the info in Google developer console

in the OAuth consent screen you will need :

• Application Homepage link

• Application Privacy Policy link

• Application Terms of Service link (Optional)

if one of them is missing, the login won't work.