[WIP] move firebase auth calls to ViewModels

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

@@ -1,26 +1,22 @@
 package com.google.firebase.quickstart.auth.kotlin
 
 import android.os.Bundle
-import android.text.TextUtils
-import android.util.Log
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
-import android.widget.Toast
-import com.google.firebase.auth.EmailAuthProvider
-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.firebase.quickstart.auth.R
+import androidx.fragment.app.viewModels
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.lifecycleScope
+import androidx.lifecycle.repeatOnLifecycle
 import com.google.firebase.quickstart.auth.databinding.FragmentAnonymousAuthBinding
+import kotlinx.coroutines.launch
 
 class AnonymousAuthFragment : BaseFragment() {
     private var _binding: FragmentAnonymousAuthBinding? = null
     private val binding: FragmentAnonymousAuthBinding
         get() = _binding!!
 
-    private lateinit var auth: FirebaseAuth
+    private val viewModel by viewModels<AnonymousAuthViewModel>()
 
     override fun onCreateView(
             inflater: LayoutInflater,
@@ -35,134 +31,50 @@ class AnonymousAuthFragment : BaseFragment() {
         super.onViewCreated(view, savedInstanceState)
         setProgressBar(binding.progressBar)
 
-        // Initialize Firebase Auth
-        auth = Firebase.auth
-
-        // Click listeners
         binding.buttonAnonymousSignIn.setOnClickListener {
-            signInAnonymously()
+            viewModel.signInAnonymously()
         }
+
         binding.buttonAnonymousSignOut.setOnClickListener {
-            signOut()
-        }
-        binding.buttonLinkAccount.setOnClickListener {
-            linkAccount()
+            viewModel.signOut()
         }
-    }
-
-    override fun onStart() {
-        super.onStart()
-        // Check if user is signed in (non-null) and update UI accordingly.
-        val currentUser = auth.currentUser
-        updateUI(currentUser)
-    }
 
-    private fun signInAnonymously() {
-        showProgressBar()
-        auth.signInAnonymously()
-                .addOnCompleteListener(requireActivity()) { task ->
-                    if (task.isSuccessful) {
-                        // Sign in success, update UI with the signed-in user's information
-                        Log.d(TAG, "signInAnonymously:success")
-                        val user = auth.currentUser
-                        updateUI(user)
-                    } else {
-                        // If sign in fails, display a message to the user.
-                        Log.w(TAG, "signInAnonymously:failure", task.exception)
-                        Toast.makeText(context, "Authentication failed.",
-                                Toast.LENGTH_SHORT).show()
-                        updateUI(null)
-                    }
-
-                    hideProgressBar()
-                }
-    }
-
-    private fun signOut() {
-        auth.signOut()
-        updateUI(null)
-    }
+        binding.buttonLinkAccount.setOnClickListener {
+            val email = binding.fieldEmail.text.toString()
+            val password = binding.fieldPassword.text.toString()
 
-    private fun linkAccount() {
-        // Make sure form is valid
-        if (!validateLinkForm()) {
-            return
+            viewModel.linkAccount(email, password)
         }
 
-        // Get email and password from the form
-        val email = binding.fieldEmail.text.toString()
-        val password = binding.fieldPassword.text.toString()
+        lifecycleScope.launch {
+            viewLifecycleOwner.repeatOnLifecycle(Lifecycle.State.STARTED) {
+                viewModel.uiState.collect { uiState ->
+                    // Handle errors
+                    binding.fieldEmail.error = uiState.emailError
+                    binding.fieldPassword.error = uiState.passwordError
 
-        // Create EmailAuthCredential with email and password
-        val credential = EmailAuthProvider.getCredential(email, password)
+                    // Display texts
+                    binding.anonymousStatusId.text = uiState.userId
+                    binding.anonymousStatusEmail.text = uiState.userEmail
 
-        // Link the anonymous user to the email credential
-        showProgressBar()
-
-        auth.currentUser!!.linkWithCredential(credential)
-                .addOnCompleteListener(requireActivity()) { task ->
-                    if (task.isSuccessful) {
-                        Log.d(TAG, "linkWithCredential:success")
-                        val user = task.result?.user
-                        updateUI(user)
+                    // Toggle progress bar
+                    if (uiState.isProgressBarVisible) {
+                        showProgressBar()
                     } else {
-                        Log.w(TAG, "linkWithCredential:failure", task.exception)
-                        Toast.makeText(context, "Authentication failed.",
-                                Toast.LENGTH_SHORT).show()
-                        updateUI(null)
+                        hideProgressBar()
                     }
 
-                    hideProgressBar()
+                    // Toggle button visibility
+                    binding.buttonAnonymousSignIn.isEnabled = uiState.isSignInEnabled
+                    binding.buttonLinkAccount.isEnabled = uiState.isLinkAccountEnabled
+                    binding.buttonAnonymousSignOut.isEnabled = uiState.isSignOutEnabled
                 }
-    }
-
-    private fun validateLinkForm(): Boolean {
-        var valid = true
-
-        val email = binding.fieldEmail.text.toString()
-        if (TextUtils.isEmpty(email)) {
-            binding.fieldEmail.error = "Required."
-            valid = false
-        } else {
-            binding.fieldEmail.error = null
-        }
-
-        val password = binding.fieldPassword.text.toString()
-        if (TextUtils.isEmpty(password)) {
-            binding.fieldPassword.error = "Required."
-            valid = false
-        } else {
-            binding.fieldPassword.error = null
-        }
-
-        return valid
-    }
-
-    private fun updateUI(user: FirebaseUser?) {
-        hideProgressBar()
-        val isSignedIn = user != null
-
-        // Status text
-        if (isSignedIn) {
-            binding.anonymousStatusId.text = getString(R.string.id_fmt, user!!.uid)
-            binding.anonymousStatusEmail.text = getString(R.string.email_fmt, user.email)
-        } else {
-            binding.anonymousStatusId.setText(R.string.signed_out)
-            binding.anonymousStatusEmail.text = null
+            }
         }
-
-        // Button visibility
-        binding.buttonAnonymousSignIn.isEnabled = !isSignedIn
-        binding.buttonAnonymousSignOut.isEnabled = isSignedIn
-        binding.buttonLinkAccount.isEnabled = isSignedIn
     }
 
     override fun onDestroyView() {
         super.onDestroyView()
         _binding = null
     }
-
-    companion object {
-        private const val TAG = "AnonymousAuth"
-    }
 }

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

@@ -0,0 +1,143 @@
+package com.google.firebase.quickstart.auth.kotlin
+
+import android.util.Log
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.google.firebase.auth.EmailAuthProvider
+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
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.tasks.await
+
+class AnonymousAuthViewModel(
+    private val firebaseAuth: FirebaseAuth = Firebase.auth
+) : ViewModel() {
+
+    private val _uiState = MutableStateFlow(UiState())
+    val uiState: StateFlow<UiState> = _uiState
+
+    data class UiState(
+        var userId: String? = null,
+        var userEmail: String? = null,
+        var isSignInEnabled: Boolean = true,
+        var isSignOutEnabled: Boolean = false,
+        var isLinkAccountEnabled: Boolean = false,
+        var isProgressBarVisible: Boolean = false,
+        var emailError: String? = null,
+        var passwordError: String?= null,
+    )
+
+    init {
+        // Check if there's a user signed in and update UI State accordingly
+        val firebaseUser = firebaseAuth.currentUser
+        updateUiState(firebaseUser)
+    }
+
+    fun signInAnonymously() {
+        viewModelScope.launch {
+            toggleProgressbar(true)
+            try {
+                val authResult = firebaseAuth.signInAnonymously().await()
+                // Sign in was successful, update UI State with the signed-in user's information
+                Log.d(TAG, "signInAnonymously:success")
+                updateUiState(authResult.user)
+            } catch (e: Exception) {
+                Log.e(TAG, "signInAnonymously:failure", e)
+                // TODO(thatfiredev): Display "Authentication failed" snackbar
+                updateUiState(null)
+            } finally {
+                toggleProgressbar(false)
+            }
+        }
+    }
+
+    fun linkAccount(email: String, password: String) {
+        // Make sure entered data is valid
+        if (!validateEmailAndPassword(email, password)) {
+            return
+        }
+        val credential = EmailAuthProvider.getCredential(email, password)
+
+        viewModelScope.launch {
+            toggleProgressbar(true)
+            val firebaseUser = firebaseAuth.currentUser!!
+
+            try {
+                val authResult = firebaseUser.linkWithCredential(credential).await()
+                // Account Link was successful, update UI State with the signed-in user's information
+                Log.d(TAG, "linkWithCredential:success")
+                updateUiState(authResult.user)
+            } catch (e: Exception) {
+                Log.e(TAG, "linkWithCredential:failure", e)
+                // TODO(thatfiredev): Display "Authentication failed" snackbar
+                updateUiState(null)
+            } finally {
+                toggleProgressbar(false)
+            }
+        }
+    }
+
+    fun signOut() {
+        firebaseAuth.signOut()
+        updateUiState(null)
+    }
+
+    private fun updateUiState(user: FirebaseUser?) {
+        if (user == null) {
+            _uiState.update { currentUiState ->
+                currentUiState.copy(
+                    userId = "Signed Out",
+                    userEmail = null,
+                    isSignInEnabled = true,
+                    isSignOutEnabled = false,
+                    isLinkAccountEnabled = false,
+                    isProgressBarVisible = false
+                )
+            }
+        } else {
+            _uiState.update { currentUiState ->
+                currentUiState.copy(
+                    userId = "User ID: ${user.uid}",
+                    userEmail = "Email: ${user.email}",
+                    isSignInEnabled = false,
+                    isSignOutEnabled = true,
+                    isLinkAccountEnabled = true,
+                    isProgressBarVisible = false
+                )
+            }
+        }
+    }
+
+    private fun validateEmailAndPassword(email: String, password: String): Boolean {
+        var isValid = true
+
+        if (email.isBlank()) {
+            _uiState.update { it.copy(emailError = "Required.") }
+            isValid = false
+        } else {
+            _uiState.update { it.copy(emailError = null) }
+        }
+
+        if (password.isBlank()) {
+            _uiState.update { it.copy(passwordError = "Required.") }
+            isValid = false
+        } else {
+            _uiState.update { it.copy(passwordError = null) }
+        }
+
+        return isValid
+    }
+
+    private fun toggleProgressbar(isVisible: Boolean) {
+        _uiState.update { it.copy(isProgressBarVisible = isVisible) }
+    }
+
+    companion object {
+        const val TAG = "AnonymousAuthViewModel"
+    }
+}