feat: add Facebook sign-out functionality

Author: demolaf

app/src/main/res/values/strings.xml

@@ -1,10 +1,10 @@
 <resources>
     <string name="app_name">FirebaseUI Demo</string>
 
-    <string name="firebase_web_host" translatable="false">flutterfire-e2e-tests.firebaseapp.com</string>
+    <string name="firebase_web_host" translatable="false">temp-test-aa342.firebaseapp.com</string>
 
     <!-- Facebook SDK Configuration -->
-    <string name="facebook_application_id" translatable="false">128693022464535</string>
-    <string name="facebook_login_protocol_scheme" translatable="false">fb128693022464535</string>
-    <string name="facebook_client_token" translatable="false">16dbbdf0cfb309034a6ad98ac2a21688</string>
+    <string name="facebook_application_id" translatable="false">879782018043124</string>
+    <string name="facebook_login_protocol_scheme" translatable="false">fb879782018043124</string>
+    <string name="facebook_client_token" translatable="false">3f03c9e0b3b4e084636d7bebd5f3633a</string>
 </resources>

auth/src/main/java/com/firebase/ui/auth/FirebaseAuthUI.kt

@@ -19,6 +19,7 @@ import android.content.Intent
 import androidx.annotation.RestrictTo
 import com.firebase.ui.auth.configuration.AuthUIConfiguration
 import com.firebase.ui.auth.configuration.auth_provider.AuthProvider
+import com.firebase.ui.auth.configuration.auth_provider.signOutFromFacebook
 import com.firebase.ui.auth.configuration.auth_provider.signOutFromGoogle
 import com.google.firebase.FirebaseApp
 import com.google.firebase.auth.FirebaseAuth
@@ -367,6 +368,7 @@ class FirebaseAuthUI private constructor(
             auth.signOut()
                 .also {
                     signOutFromGoogle(context)
+                    signOutFromFacebook()
                 }
 
             // Update state to idle (user signed out)

auth/src/main/java/com/firebase/ui/auth/configuration/auth_provider/FacebookAuthProvider+FirebaseAuthUI.kt

@@ -192,3 +192,21 @@ internal suspend fun FirebaseAuthUI.signInWithFacebook(
     }
 }
 
+/**
+ * Signs out the current user from Facebook.
+ *
+ * Invokes Facebook's LoginManager to log out the user from their Facebook session.
+ * This method silently catches and ignores any exceptions that may occur during the
+ * logout process to ensure the sign-out flow continues even if Facebook logout fails.
+ *
+ * This is typically called as part of the overall sign-out flow when a user signs out
+ * from Firebase Authentication.
+ */
+internal fun FirebaseAuthUI.signOutFromFacebook() {
+    try {
+        if (Provider.fromId(getCurrentUser()?.providerId) != Provider.FACEBOOK) return
+        LoginManager.getInstance().logOut()
+    } catch (e: Exception) {
+        Log.e("FacebookAuthProvider", "Error during Facebook sign out", e)
+    }
+}

auth/src/main/java/com/firebase/ui/auth/configuration/auth_provider/GoogleAuthProvider+FirebaseAuthUI.kt

@@ -1,6 +1,7 @@
 package com.firebase.ui.auth.configuration.auth_provider
 
 import android.content.Context
+import android.util.Log
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
@@ -198,13 +199,12 @@ internal suspend fun FirebaseAuthUI.signInWithGoogle(
  *
  * @param context Android context for Credential Manager
  */
-internal suspend fun signOutFromGoogle(context: Context) {
+internal suspend fun FirebaseAuthUI.signOutFromGoogle(context: Context) {
     try {
+        if (Provider.fromId(getCurrentUser()?.providerId) != Provider.GOOGLE) return
         val credentialManager = CredentialManager.create(context)
-        credentialManager.clearCredentialState(
-            ClearCredentialStateRequest()
-        )
-    } catch (_: Exception) {
-
+        credentialManager.clearCredentialState(ClearCredentialStateRequest())
+    } catch (e: Exception) {
+        Log.e("GoogleAuthProvider", "Error during Google sign out", e)
     }
 }