refactor: handle auto upgrade anonymous improvement

FirebaseSwiftUI/FirebaseAppleSwiftUI/Sources/Views/SignInWithAppleButton.swift

@@ -19,6 +19,7 @@ import SwiftUI
 @MainActor
 public struct SignInWithAppleButton {
   @Environment(AuthService.self) private var authService
+  @Environment(\.signInWithMergeConflictHandler) private var signInHandler
   let provider: AuthProviderSwift
   public init(provider: AuthProviderSwift) {
     self.provider = provider
@@ -29,7 +30,13 @@ extension SignInWithAppleButton: View {
   public var body: some View {
     Button(action: {
       Task {
-        try? await authService.signIn(provider)
+        if let handler = signInHandler {
+          try? await handler(authService) {
+            try await authService.signIn(provider)
+          }
+        } else {
+          try? await authService.signIn(provider)
+        }
       }
     }) {
       HStack {

FirebaseSwiftUI/FirebaseAuthSwiftUI/Sources/Services/AuthService.swift

@@ -177,6 +177,8 @@ public final class AuthService {
   public func signOut() async throws {
     do {
       try await auth.signOut()
+      // Cannot wait for auth listener to change, feedback needs to be immediate
+      currentUser = nil
       updateAuthenticationState()
     } catch {
       updateError(message: string.localizedErrorMessage(for: error))
@@ -202,7 +204,7 @@ public final class AuthService {
     }
   }
 
-  public func handleAutoUpgradeAnonymousUser(credentials: AuthCredential) async throws
+  private func handleAutoUpgradeAnonymousUser(credentials: AuthCredential) async throws
     -> SignInOutcome {
     if currentUser == nil {
       throw AuthServiceError.noCurrentUser
@@ -213,11 +215,27 @@ public final class AuthService {
       updateAuthenticationState()
       return .signedIn(result)
     } catch let error as NSError {
+      // Handle credentialAlreadyInUse error
+      if error.code == AuthErrorCode.credentialAlreadyInUse.rawValue {
+        // Extract the updated credential from the error
+        let updatedCredential = error.userInfo["FIRAuthUpdatedCredentialKey"] as? AuthCredential
+          ?? credentials
+
+        let context = AccountMergeConflictContext(
+          credential: updatedCredential,
+          underlyingError: error,
+          message: "Unable to merge accounts. The credential is already associated with a different account.",
+          uid: currentUser?.uid
+        )
+        throw AuthServiceError.accountMergeConflict(context: context)
+      }
+
+      // Handle emailAlreadyInUse error
       if error.code == AuthErrorCode.emailAlreadyInUse.rawValue {
         let context = AccountMergeConflictContext(
           credential: credentials,
           underlyingError: error,
-          message: "Unable to merge accounts. Use the credential in the context to resolve the conflict.",
+          message: "Unable to merge accounts. This email is already associated with a different account.",
           uid: currentUser?.uid
         )
         throw AuthServiceError.accountMergeConflict(context: context)

FirebaseSwiftUI/FirebaseAuthSwiftUI/Sources/Version.swift

@@ -16,4 +16,4 @@
 public enum FirebaseAuthSwiftUIVersion {
   // Use the release-swift.sh script to bump this version number, commit and push a new tag.
   public static let version = "15.1.0"
-}
+}

FirebaseSwiftUI/FirebaseAuthSwiftUI/Sources/Views/AuthPickerView.swift

@@ -15,6 +15,59 @@
 import FirebaseCore
 import SwiftUI
 
+// MARK: - Merge Conflict Handling
+
+/// Helper function to handle sign-in with automatic merge conflict resolution.
+///
+/// This function attempts to sign in with the provided action. If a merge conflict occurs
+/// (when an anonymous user is being upgraded and the credential is already associated with
+/// an existing account), it automatically signs out the anonymous user and signs in with
+/// the existing account's credential.
+///
+/// - Parameters:
+///   - authService: The AuthService instance to use for sign-in operations
+///   - signInAction: An async closure that performs the sign-in operation
+/// - Returns: The SignInOutcome from the successful sign-in
+/// - Throws: Re-throws any errors except accountMergeConflict (which is handled internally)
+@MainActor
+public func signInWithMergeConflictHandling(authService: AuthService,
+                                            signInAction: () async throws
+                                              -> SignInOutcome) async throws -> SignInOutcome {
+  do {
+    return try await signInAction()
+  } catch let error as AuthServiceError {
+    if case let .accountMergeConflict(context) = error {
+      // The anonymous account conflicts with an existing account
+      // Sign out the anonymous user
+      try await authService.signOut()
+
+      // Sign in with the existing account's credential
+      // This works because shouldHandleAnonymousUpgrade is now false after sign out
+      return try await authService.signIn(credentials: context.credential)
+    }
+    throw error
+  }
+}
+
+// MARK: - Environment Key for Sign-In Handler
+
+/// Environment key for a sign-in handler that includes merge conflict resolution
+private struct SignInHandlerKey: EnvironmentKey {
+  static let defaultValue: (@MainActor (AuthService, () async throws -> SignInOutcome) async throws
+    -> SignInOutcome)? = nil
+}
+
+public extension EnvironmentValues {
+  /// A sign-in handler that automatically handles merge conflicts for anonymous user upgrades.
+  /// When set in the environment, views should use this handler to wrap their sign-in calls.
+  var signInWithMergeConflictHandler: (@MainActor (AuthService,
+                                                   () async throws -> SignInOutcome) async throws
+      -> SignInOutcome)? {
+    get { self[SignInHandlerKey.self] }
+    set { self[SignInHandlerKey.self] = newValue }
+  }
+}
+
 @MainActor
 public struct AuthPickerView {
   @Environment(AuthService.self) private var authService
@@ -67,10 +120,13 @@ extension AuthPickerView: View {
                 .emailLoginFlowLabel : authService.string.emailSignUpFlowLabel)
               Divider()
               EmailAuthView()
+                .environment(\.signInWithMergeConflictHandler, signInWithMergeConflictHandling)
             }
             VStack {
               authService.renderButtons()
-            }.padding(.horizontal)
+            }
+            .padding(.horizontal)
+            .environment(\.signInWithMergeConflictHandler, signInWithMergeConflictHandling)
             if authService.emailSignInEnabled {
               Divider()
               HStack {

FirebaseSwiftUI/FirebaseAuthSwiftUI/Sources/Views/EmailAuthView.swift

@@ -31,6 +31,7 @@ private enum FocusableField: Hashable {
 @MainActor
 public struct EmailAuthView {
   @Environment(AuthService.self) private var authService
+  @Environment(\.signInWithMergeConflictHandler) private var signInHandler
 
   @State private var email = ""
   @State private var password = ""
@@ -49,11 +50,23 @@ public struct EmailAuthView {
   }
 
   private func signInWithEmailPassword() async {
-    try? await authService.signIn(email: email, password: password)
+    if let handler = signInHandler {
+      try? await handler(authService) {
+        try await authService.signIn(email: email, password: password)
+      }
+    } else {
+      try? await authService.signIn(email: email, password: password)
+    }
   }
 
   private func createUserWithEmailPassword() async {
-    try? await authService.createUser(email: email, password: password)
+    if let handler = signInHandler {
+      try? await handler(authService) {
+        try await authService.createUser(email: email, password: password)
+      }
+    } else {
+      try? await authService.createUser(email: email, password: password)
+    }
   }
 }
 

FirebaseSwiftUI/FirebaseFacebookSwiftUI/Sources/Views/SignInWithFacebookButton.swift

@@ -23,6 +23,7 @@ import SwiftUI
 @MainActor
 public struct SignInWithFacebookButton {
   @Environment(AuthService.self) private var authService
+  @Environment(\.signInWithMergeConflictHandler) private var signInHandler
   let facebookProvider: FacebookProviderSwift
   @State private var showCanceledAlert = false
   @State private var limitedLogin = true
@@ -67,7 +68,13 @@ extension SignInWithFacebookButton: View {
       Button(action: {
         Task {
           facebookProvider.isLimitedLogin = limitedLogin
-          try? await authService.signIn(facebookProvider)
+          if let handler = signInHandler {
+            try? await handler(authService) {
+              try await authService.signIn(facebookProvider)
+            }
+          } else {
+            try? await authService.signIn(facebookProvider)
+          }
         }
       }) {
         HStack {

FirebaseSwiftUI/FirebaseGoogleSwiftUI/Sources/Views/SignInWithGoogleButton.swift

@@ -26,6 +26,7 @@ import SwiftUI
 @MainActor
 public struct SignInWithGoogleButton {
   @Environment(AuthService.self) private var authService
+  @Environment(\.signInWithMergeConflictHandler) private var signInHandler
   let googleProvider: AuthProviderSwift
 
   public init(googleProvider: AuthProviderSwift) {
@@ -43,7 +44,13 @@ extension SignInWithGoogleButton: View {
   public var body: some View {
     GoogleSignInButton(viewModel: customViewModel) {
       Task {
-        try? await authService.signIn(googleProvider)
+        if let handler = signInHandler {
+          try? await handler(authService) {
+            try await authService.signIn(googleProvider)
+          }
+        } else {
+          try? await authService.signIn(googleProvider)
+        }
       }
     }
     .accessibilityIdentifier("sign-in-with-google-button")

FirebaseSwiftUI/FirebaseOAuthSwiftUI/Sources/Views/GenericOAuthButton.swift

@@ -19,6 +19,7 @@ import SwiftUI
 @MainActor
 public struct GenericOAuthButton {
   @Environment(AuthService.self) private var authService
+  @Environment(\.signInWithMergeConflictHandler) private var signInHandler
   let provider: AuthProviderSwift
   public init(provider: AuthProviderSwift) {
     self.provider = provider
@@ -36,7 +37,13 @@ extension GenericOAuthButton: View {
     return AnyView(
       Button(action: {
         Task {
-          try await authService.signIn(provider)
+          if let handler = signInHandler {
+            try? await handler(authService) {
+              try await authService.signIn(provider)
+            }
+          } else {
+            try? await authService.signIn(provider)
+          }
         }
       }) {
         HStack {

FirebaseSwiftUI/FirebasePhoneAuthSwiftUI/Sources/Views/PhoneAuthButtonView.swift

@@ -19,6 +19,7 @@ import SwiftUI
 @MainActor
 public struct PhoneAuthButtonView {
   @Environment(AuthService.self) private var authService
+  @Environment(\.signInWithMergeConflictHandler) private var signInHandler
   let phoneProvider: PhoneAuthProviderSwift
 
   public init(phoneProvider: PhoneAuthProviderSwift) {
@@ -30,7 +31,13 @@ extension PhoneAuthButtonView: View {
   public var body: some View {
     Button(action: {
       Task {
-        try await authService.signIn(phoneProvider)
+        if let handler = signInHandler {
+          try? await handler(authService) {
+            try await authService.signIn(phoneProvider)
+          }
+        } else {
+          try? await authService.signIn(phoneProvider)
+        }
       }
     }) {
       Label("Sign in with Phone", systemImage: "phone.fill")

FirebaseSwiftUI/FirebaseTwitterSwiftUI/Sources/Views/SignInWithTwitterButton.swift

@@ -19,6 +19,7 @@ import SwiftUI
 @MainActor
 public struct SignInWithTwitterButton {
   @Environment(AuthService.self) private var authService
+  @Environment(\.signInWithMergeConflictHandler) private var signInHandler
   let provider: AuthProviderSwift
   public init(provider: AuthProviderSwift) {
     self.provider = provider
@@ -29,7 +30,13 @@ extension SignInWithTwitterButton: View {
   public var body: some View {
     Button(action: {
       Task {
-        try? await authService.signIn(provider)
+        if let handler = signInHandler {
+          try? await handler(authService) {
+            try await authService.signIn(provider)
+          }
+        } else {
+          try? await authService.signIn(provider)
+        }
       }
     }) {
       HStack {

samples/swiftui/FirebaseSwiftUIExample/FirebaseSwiftUIExample/ContentView.swift

@@ -33,13 +33,15 @@ struct ContentView: View {
   let authService: AuthService
 
   init() {
+    Auth.auth().signInAnonymously()
     let actionCodeSettings = ActionCodeSettings()
     actionCodeSettings.handleCodeInApp = true
     actionCodeSettings
       .url = URL(string: "https://flutterfire-e2e-tests.firebaseapp.com")
     actionCodeSettings.linkDomain = "flutterfire-e2e-tests.firebaseapp.com"
     actionCodeSettings.setIOSBundleID(Bundle.main.bundleIdentifier!)
     let configuration = AuthConfiguration(
+      shouldAutoUpgradeAnonymousUsers: true,
       tosUrl: URL(string: "https://example.com/tos"),
       privacyPolicyUrl: URL(string: "https://example.com/privacy"),
       emailLinkSignInActionCodeSettings: actionCodeSettings,