feat: Email sign in link

Author: demolaf

auth/src/main/AndroidManifest.xml

@@ -83,8 +83,8 @@
 
         <activity
             android:name=".ui.email.EmailLinkCatcherActivity"
-            android:exported="false"
             android:label=""
+            android:exported="false"
             android:theme="@style/FirebaseUI.Transparent"
             android:windowSoftInputMode="adjustResize" />
 
@@ -119,6 +119,16 @@
             </intent-filter>
         </activity>
 
+        <!-- Email Link Sign-In Handler Activity for Compose -->
+        <!-- IMPORTANT: This activity is NOT exported by default -->
+        <!-- Users must declare this activity with an intent filter in their app's AndroidManifest.xml -->
+        <!-- See documentation for setup instructions -->
+        <activity
+            android:name=".compose.ui.screens.EmailSignInLinkHandlerActivity"
+            android:label=""
+            android:exported="false"
+            android:theme="@style/FirebaseUI.Transparent" />
+
         <provider
             android:name=".data.client.AuthUiInitProvider"
             android:authorities="${applicationId}.authuiinitprovider"

auth/src/main/java/com/firebase/ui/auth/compose/AuthState.kt

@@ -243,6 +243,15 @@ abstract class AuthState private constructor() {
         override fun toString(): String = "AuthState.PasswordResetLinkSent"
     }
 
+    /**
+     * Email sign in link has been sent to the user's email.
+     */
+    class EmailSignInLinkSent : AuthState() {
+        override fun equals(other: Any?): Boolean = other is EmailSignInLinkSent
+        override fun hashCode(): Int = javaClass.hashCode()
+        override fun toString(): String = "AuthState.EmailSignInLinkSent"
+    }
+
     companion object {
         /**
          * Creates an Idle state instance.

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

@@ -28,6 +28,10 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.callbackFlow
 import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.drop
+import kotlinx.coroutines.flow.merge
+import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.tasks.await
 import java.util.concurrent.ConcurrentHashMap
 

auth/src/main/java/com/firebase/ui/auth/compose/configuration/AuthUIConfiguration.kt

@@ -85,12 +85,7 @@ class AuthUIConfigurationBuilder {
         // Provider specific validations
         providers.forEach { provider ->
             when (provider) {
-                is AuthProvider.Email -> {
-                    provider.validate(
-                        isAnonymousUpgradeEnabled = isAnonymousUpgradeEnabled
-                    )
-                }
-
+                is AuthProvider.Email -> provider.validate(isAnonymousUpgradeEnabled)
                 is AuthProvider.Phone -> provider.validate()
                 is AuthProvider.Google -> provider.validate(context)
                 is AuthProvider.Facebook -> provider.validate(context)

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

@@ -675,7 +675,7 @@ internal suspend fun FirebaseAuthUI.sendSignInLinkToEmail(
         // Save Email to dataStore for use in signInWithEmailLink
         EmailLinkPersistenceManager.saveEmail(context, email, sessionId, anonymousUserId)
 
-        updateAuthState(AuthState.Idle)
+        updateAuthState(AuthState.EmailSignInLinkSent())
     } catch (e: CancellationException) {
         val cancelledException = AuthException.AuthCancelledException(
             message = "Send sign in link to email was cancelled",
@@ -727,7 +727,8 @@ internal suspend fun FirebaseAuthUI.sendSignInLinkToEmail(
  *
  * @see sendSignInLinkToEmail for sending the initial email link
  */
-internal suspend fun FirebaseAuthUI.signInWithEmailLink(
+// TODO(demolaf: make this internal when done testing email link sign in with composeapp
+suspend fun FirebaseAuthUI.signInWithEmailLink(
     context: Context,
     config: AuthUIConfiguration,
     provider: AuthProvider.Email,
@@ -792,7 +793,10 @@ internal suspend fun FirebaseAuthUI.signInWithEmailLink(
         // Validate anonymous user ID matches (same-device flow)
         if (!anonymousUserIdFromLink.isNullOrEmpty()) {
             val currentUser = auth.currentUser
-            if (currentUser == null || !currentUser.isAnonymous || currentUser.uid != anonymousUserIdFromLink) {
+            if (currentUser == null
+                || !currentUser.isAnonymous
+                || currentUser.uid != anonymousUserIdFromLink
+            ) {
                 throw AuthException.EmailLinkDifferentAnonymousUserException()
             }
         }
@@ -804,7 +808,6 @@ internal suspend fun FirebaseAuthUI.signInWithEmailLink(
         val result = if (storedCredentialForLink == null) {
             // Normal Flow: Just sign in with email link
             signInAndLinkWithCredential(config, emailLinkCredential)
-                ?: throw AuthException.UnknownException("Sign in failed")
         } else {
             // Linking Flow: Sign in with email link, then link the social credential
             if (canUpgradeAnonymous(config, auth)) {
@@ -818,54 +821,39 @@ internal suspend fun FirebaseAuthUI.signInWithEmailLink(
                     .getInstance(appExplicitlyForValidation)
 
                 // Safe link: Validate that both credentials can be linked
-                val emailResult = authExplicitlyForValidation
+                val result = authExplicitlyForValidation
                     .signInWithCredential(emailLinkCredential).await()
-
-                val linkResult = emailResult.user
-                    ?.linkWithCredential(storedCredentialForLink)?.await()
-
-                // If safe link succeeds, emit merge conflict for UI to handle
-                if (linkResult?.user != null) {
-                    updateAuthState(
-                        AuthState.MergeConflict(
-                            storedCredentialForLink
+                    .user?.linkWithCredential(storedCredentialForLink)?.await()
+                    .also { result ->
+                        // If safe link succeeds, emit merge conflict for UI to handle
+                        updateAuthState(
+                            AuthState.MergeConflict(
+                                storedCredentialForLink
+                            )
                         )
-                    )
-                }
-
-                // Return the link result (will be non-null if successful)
-                linkResult
+                    }
+                return result
             } else {
                 // Non-upgrade: Sign in with email link, then link social credential
-                val emailLinkResult = auth.signInWithCredential(emailLinkCredential).await()
-
-                // Link the social credential
-                val linkResult = emailLinkResult.user
-                    ?.linkWithCredential(storedCredentialForLink)?.await()
-
-                // Merge profile from the linked social credential
-                linkResult?.user?.let { user ->
-                    mergeProfile(auth, user.displayName, user.photoUrl)
-                }
-
-                // Update to success state
-                if (linkResult?.user != null) {
-                    updateAuthState(
-                        AuthState.Success(
-                            result = linkResult,
-                            user = linkResult.user!!,
-                            isNewUser = linkResult.additionalUserInfo?.isNewUser ?: false
-                        )
-                    )
-                }
-
-                linkResult
+                val result = auth.signInWithCredential(emailLinkCredential).await()
+                    // Link the social credential
+                    .user?.linkWithCredential(storedCredentialForLink)?.await()
+                    .also { result ->
+                        result?.user?.let { user ->
+                            // Merge profile from the linked social credential
+                            mergeProfile(
+                                auth,
+                                user.displayName,
+                                user.photoUrl
+                            )
+                        }
+                    }
+                return result
             }
         }
-
         // Clear DataStore after success
         EmailLinkPersistenceManager.clear(context)
-
+        updateAuthState(AuthState.Idle)
         return result
     } catch (e: CancellationException) {
         val cancelledException = AuthException.AuthCancelledException(

auth/src/main/java/com/firebase/ui/auth/compose/ui/screens/EmailAuthScreen.kt

@@ -33,8 +33,10 @@ import com.firebase.ui.auth.compose.configuration.auth_provider.createOrLinkUser
 import com.firebase.ui.auth.compose.configuration.auth_provider.sendPasswordResetEmail
 import com.firebase.ui.auth.compose.configuration.auth_provider.sendSignInLinkToEmail
 import com.firebase.ui.auth.compose.configuration.auth_provider.signInWithEmailAndPassword
+import com.firebase.ui.auth.compose.configuration.auth_provider.signInWithEmailLink
 import com.firebase.ui.auth.compose.configuration.string_provider.DefaultAuthUIStringProvider
 import com.firebase.ui.auth.compose.ui.components.ErrorRecoveryDialog
+import com.firebase.ui.auth.compose.util.EmailLinkPersistenceManager
 import com.google.firebase.auth.AuthResult
 import kotlinx.coroutines.launch
 
@@ -74,6 +76,8 @@ enum class EmailAuthMode {
  * send a password reset email.
  * @param resetLinkSent (Mode: [EmailAuthMode.ResetPassword]) true after the password reset link
  * has been successfully sent.
+ * @param emailSignInLinkSent (Mode: [EmailAuthMode.SignIn]) true after the email sign in link has
+ * been successfully sent.
  * @param onGoToSignUp A callback to switch the UI to the SignUp mode.
  * @param onGoToSignIn A callback to switch the UI to the SignIn mode.
  * @param onGoToResetPassword A callback to switch the UI to the ResetPassword mode.
@@ -94,6 +98,7 @@ class EmailAuthContentState(
     val onSignUpClick: () -> Unit,
     val onSendResetLinkClick: () -> Unit,
     val resetLinkSent: Boolean = false,
+    val emailSignInLinkSent: Boolean = false,
     val onGoToSignUp: () -> Unit,
     val onGoToSignIn: () -> Unit,
     val onGoToResetPassword: () -> Unit,
@@ -104,8 +109,7 @@ class EmailAuthContentState(
  * including sign-in, sign-up, and password reset. It exposes the state for the current mode to
  * a custom UI via a trailing lambda (slot), allowing for complete visual customization.
  *
- * @param provider The configuration object contains rules for email auth, such as whether a
- * display name is required.
+ * @param configuration
  * @param onSuccess
  * @param onError
  * @param onCancel
@@ -116,12 +120,12 @@ fun EmailAuthScreen(
     context: Context,
     configuration: AuthUIConfiguration,
     authUI: FirebaseAuthUI,
-    provider: AuthProvider.Email,
     onSuccess: (AuthResult) -> Unit,
     onError: (AuthException) -> Unit,
     onCancel: () -> Unit,
     content: @Composable ((EmailAuthContentState) -> Unit)? = null,
 ) {
+    val provider = configuration.providers.filterIsInstance<AuthProvider.Email>().first()
     val stringProvider = DefaultAuthUIStringProvider(context)
     val coroutineScope = rememberCoroutineScope()
 
@@ -144,6 +148,7 @@ fun EmailAuthScreen(
     val errorMessage =
         if (authState is AuthState.Error) (authState as AuthState.Error).exception.message else null
     val resetLinkSent = authState is AuthState.PasswordResetLinkSent
+    val emailSignInLinkSent = authState is AuthState.EmailSignInLinkSent
 
     val isErrorDialogVisible =
         remember(authState) { mutableStateOf(authState is AuthState.Error) }
@@ -178,6 +183,7 @@ fun EmailAuthScreen(
         isLoading = isLoading,
         error = errorMessage,
         resetLinkSent = resetLinkSent,
+        emailSignInLinkSent = emailSignInLinkSent,
         onEmailChange = { email ->
             emailTextValue.value = email
         },
@@ -260,25 +266,15 @@ fun EmailAuthScreen(
     if (isErrorDialogVisible.value) {
         ErrorRecoveryDialog(
             error = when ((authState as AuthState.Error).exception) {
-                is AuthException -> {
-                    (authState as AuthState.Error).exception as AuthException
-                }
-
-                else -> {
-                    AuthException
-                        .from((authState as AuthState.Error).exception)
-                }
+                is AuthException -> (authState as AuthState.Error).exception as AuthException
+                else -> AuthException
+                    .from((authState as AuthState.Error).exception)
             },
             stringProvider = stringProvider,
             onRetry = { exception ->
                 when (exception) {
-                    is AuthException.InvalidCredentialsException -> {
-                        state.onSignInClick()
-                    }
-
-                    is AuthException.EmailAlreadyInUseException -> {
-                        state.onGoToSignIn()
-                    }
+                    is AuthException.InvalidCredentialsException -> state.onSignInClick()
+                    is AuthException.EmailAlreadyInUseException -> state.onGoToSignIn()
                 }
                 isErrorDialogVisible.value = false
             },
@@ -290,102 +286,3 @@ fun EmailAuthScreen(
 
     content?.invoke(state)
 }
-
-//@Preview
-//@Composable
-//internal fun PreviewEmailAuthScreen() {
-//    val applicationContext = LocalContext.current
-//    val provider = AuthProvider.Email(
-//        isDisplayNameRequired = true,
-//        isEmailLinkSignInEnabled = false,
-//        isEmailLinkForceSameDeviceEnabled = true,
-//        actionCodeSettings = null,
-//        isNewAccountsAllowed = true,
-//        minimumPasswordLength = 8,
-//        passwordValidationRules = listOf()
-//    )
-//
-//    AuthUITheme {
-//        EmailAuthScreen(
-//            context = applicationContext,
-//            configuration = authUIConfiguration {
-//                context = applicationContext
-//                providers { provider(provider) }
-//                tosUrl = ""
-//                privacyPolicyUrl = ""
-//            },
-//            authUI = null,
-//            provider = provider,
-//            onSuccess = {
-//
-//            },
-//            onError = {
-//
-//            },
-//            onCancel = {
-//
-//            },
-//        ) { state ->
-//            when (state.mode) {
-//                EmailAuthMode.SignIn -> {
-//                    SignInUI(
-//                        configuration = authUIConfiguration {
-//                            context = applicationContext
-//                            providers { provider(provider) }
-//                            tosUrl = ""
-//                            privacyPolicyUrl = ""
-//                        },
-//                        provider = provider,
-//                        email = state.email,
-//                        isLoading = false,
-//                        password = state.password,
-//                        onEmailChange = state.onEmailChange,
-//                        onPasswordChange = state.onPasswordChange,
-//                        onSignInClick = state.onSignInClick,
-//                        onGoToSignUp = state.onGoToSignUp,
-//                        onGoToResetPassword = state.onGoToResetPassword,
-//                    )
-//                }
-//
-//                EmailAuthMode.SignUp -> {
-//                    SignUpUI(
-//                        configuration = authUIConfiguration {
-//                            context = applicationContext
-//                            providers { provider(provider) }
-//                            tosUrl = ""
-//                            privacyPolicyUrl = ""
-//                        },
-//                        isLoading = state.isLoading,
-//                        displayName = state.displayName,
-//                        email = state.email,
-//                        password = state.password,
-//                        confirmPassword = state.confirmPassword,
-//                        onDisplayNameChange = state.onDisplayNameChange,
-//                        onEmailChange = state.onEmailChange,
-//                        onPasswordChange = state.onPasswordChange,
-//                        onConfirmPasswordChange = state.onConfirmPasswordChange,
-//                        onSignUpClick = state.onSignUpClick,
-//                        onGoToSignIn = state.onGoToSignIn,
-//                    )
-//                }
-//
-//                EmailAuthMode.ResetPassword -> {
-//                    ResetPasswordUI(
-//                        configuration = authUIConfiguration {
-//                            context = applicationContext
-//                            providers { provider(provider) }
-//                            tosUrl = ""
-//                            privacyPolicyUrl = ""
-//                        },
-//                        isLoading = state.isLoading,
-//                        email = state.email,
-//                        resetLinkSent = state.resetLinkSent,
-//                        onEmailChange = state.onEmailChange,
-//                        onSendResetLink = state.onSendResetLinkClick,
-//                        onGoToSignIn = state.onGoToSignIn
-//                    )
-//                }
-//            }
-//        }
-//    }
-//}