refactor(firebaseui): move Firebase calls to ViewModel

Author: thatfiredev

auth/app/src/main/java/com/google/firebase/quickstart/auth/kotlin/FirebaseUIFragment.kt

@@ -5,18 +5,20 @@ import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
-import android.widget.Toast
+import androidx.core.view.isGone
 import androidx.fragment.app.Fragment
+import androidx.fragment.app.viewModels
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.lifecycleScope
+import androidx.lifecycle.repeatOnLifecycle
 import com.firebase.ui.auth.AuthUI
 import com.firebase.ui.auth.FirebaseAuthUIActivityResultContract
 import com.firebase.ui.auth.data.model.FirebaseAuthUIAuthenticationResult
-import com.google.firebase.auth.FirebaseAuth
-import com.google.firebase.auth.FirebaseUser
-import com.google.firebase.auth.ktx.auth
-import com.google.firebase.ktx.Firebase
+import com.google.android.material.snackbar.Snackbar
 import com.google.firebase.quickstart.auth.BuildConfig
 import com.google.firebase.quickstart.auth.R
 import com.google.firebase.quickstart.auth.databinding.FragmentFirebaseUiBinding
+import kotlinx.coroutines.launch
 
 /**
  * Demonstrate authentication using the FirebaseUI-Android library. This fragment demonstrates
@@ -26,7 +28,7 @@ import com.google.firebase.quickstart.auth.databinding.FragmentFirebaseUiBinding
  */
 class FirebaseUIFragment : Fragment() {
 
-    private lateinit var auth: FirebaseAuth
+    private val viewModel by viewModels<FirebaseUIViewModel>()
 
     private var _binding: FragmentFirebaseUiBinding? = null
     private val binding: FragmentFirebaseUiBinding
@@ -36,7 +38,7 @@ class FirebaseUIFragment : Fragment() {
     // possible customization see: https://github.com/firebase/firebaseui-android
     private val signInLauncher = registerForActivityResult(
         FirebaseAuthUIActivityResultContract()
-    ) { result -> this.onSignInResult(result)}
+    ) { result -> this.onSignInResult(result) }
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
         _binding = FragmentFirebaseUiBinding.inflate(inflater, container, false)
@@ -46,62 +48,42 @@ class FirebaseUIFragment : Fragment() {
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
 
-        // Initialize Firebase Auth
-        auth = Firebase.auth
-
         binding.signInButton.setOnClickListener { startSignIn() }
-        binding.signOutButton.setOnClickListener { signOut() }
-    }
-
-    override fun onStart() {
-        super.onStart()
-        updateUI(auth.currentUser)
+        binding.signOutButton.setOnClickListener { viewModel.signOut() }
+
+        lifecycleScope.launch {
+            viewLifecycleOwner.repeatOnLifecycle(Lifecycle.State.STARTED) {
+                viewModel.uiState.collect { uiState ->
+                    binding.status.text = uiState.status
+                    binding.detail.text = uiState.detail
+
+                    binding.signInButton.isGone = !uiState.isSignInVisible
+                    binding.signOutButton.isGone = uiState.isSignInVisible
+                }
+            }
+        }
     }
 
     private fun onSignInResult(result: FirebaseAuthUIAuthenticationResult) {
         if (result.resultCode == Activity.RESULT_OK) {
             // Sign in succeeded
-            updateUI(auth.currentUser)
         } else {
             // Sign in failed
-            Toast.makeText(context, "Sign In Failed", Toast.LENGTH_SHORT).show()
-            updateUI(null)
+            Snackbar.make(requireView(), "Sign In Failed", Snackbar.LENGTH_SHORT).show()
         }
+        viewModel.showSignedInUser()
     }
 
     private fun startSignIn() {
         val intent = AuthUI.getInstance().createSignInIntentBuilder()
-                .setIsSmartLockEnabled(!BuildConfig.DEBUG)
-                .setAvailableProviders(listOf(AuthUI.IdpConfig.EmailBuilder().build()))
-                .setLogo(R.mipmap.ic_launcher)
-                .build()
+            .setIsSmartLockEnabled(!BuildConfig.DEBUG)
+            .setAvailableProviders(listOf(AuthUI.IdpConfig.EmailBuilder().build()))
+            .setLogo(R.mipmap.ic_launcher)
+            .build()
 
         signInLauncher.launch(intent)
     }
 
-    private fun updateUI(user: FirebaseUser?) {
-        if (user != null) {
-            // Signed in
-            binding.status.text = getString(R.string.firebaseui_status_fmt, user.email)
-            binding.detail.text = getString(R.string.id_fmt, user.uid)
-
-            binding.signInButton.visibility = View.GONE
-            binding.signOutButton.visibility = View.VISIBLE
-        } else {
-            // Signed out
-            binding.status.setText(R.string.signed_out)
-            binding.detail.text = null
-
-            binding.signInButton.visibility = View.VISIBLE
-            binding.signOutButton.visibility = View.GONE
-        }
-    }
-
-    private fun signOut() {
-        AuthUI.getInstance().signOut(requireContext())
-        updateUI(null)
-    }
-
     override fun onDestroyView() {
         super.onDestroyView()
         _binding = null

auth/app/src/main/java/com/google/firebase/quickstart/auth/kotlin/FirebaseUIViewModel.kt

@@ -0,0 +1,61 @@
+package com.google.firebase.quickstart.auth.kotlin
+
+import androidx.lifecycle.ViewModel
+import com.google.firebase.auth.FirebaseAuth
+import com.google.firebase.auth.FirebaseUser
+import com.google.firebase.auth.ktx.auth
+import com.google.firebase.ktx.Firebase
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.update
+
+class FirebaseUIViewModel(
+    private val firebaseAuth: FirebaseAuth = Firebase.auth
+) : ViewModel() {
+    private val _uiState = MutableStateFlow(UiState())
+    val uiState: StateFlow<UiState> = _uiState
+
+    data class UiState(
+        var status: String = "",
+        var detail: String? = null,
+        var isSignInVisible: Boolean = true
+    )
+
+    init {
+        // Check if user is signed in (non-null) and update UI accordingly.
+        showSignedInUser()
+    }
+
+    fun showSignedInUser() {
+        val firebaseUser = firebaseAuth.currentUser
+        updateUiState(firebaseUser)
+    }
+
+    fun signOut() {
+        updateUiState(null)
+    }
+
+    private fun updateUiState(user: FirebaseUser?) {
+        if (user != null) {
+            _uiState.update { currentUiState ->
+                currentUiState.copy(
+                    status = "Firebase User: ${user.displayName}",
+                    detail = "Firebase UID: ${user.uid}",
+                    isSignInVisible = false
+                )
+            }
+        } else {
+            _uiState.update { currentUiState ->
+                currentUiState.copy(
+                    status = "Signed out",
+                    detail = null,
+                    isSignInVisible = true
+                )
+            }
+        }
+    }
+
+    companion object {
+        const val TAG = "FirebaseUIViewModel"
+    }
+}