fix(authenticator): move username selection state to authenticator state

packages/amplify_authenticator/lib/src/mixins/authenticator_username_field.dart

@@ -16,6 +16,7 @@
 import 'package:amplify_auth_cognito/amplify_auth_cognito.dart';
 import 'package:amplify_authenticator/src/l10n/auth_strings_resolver.dart';
 import 'package:amplify_authenticator/src/models/username_input.dart';
+import 'package:amplify_authenticator/src/state/authenticator_state.dart';
 import 'package:amplify_authenticator/src/utils/validators.dart';
 import 'package:amplify_authenticator/src/widgets/component.dart';
 import 'package:amplify_authenticator/src/widgets/form.dart';
@@ -129,19 +130,29 @@ mixin AuthenticatorUsernameField<FieldType,
               return ToggleButtons(
                 borderWidth: buttonBorderWidth,
                 constraints: buttonConstraints,
-                isSelected: [useEmail.value, !useEmail.value],
+                isSelected: [
+                  state.usernameSelection == UsernameSelection.email,
+                  state.usernameSelection == UsernameSelection.phoneNumber,
+                ],
                 onPressed: (int index) {
-                  bool useEmail = index == 0;
-                  setState(() {
-                    this.useEmail.value = useEmail;
-                  });
+                  final newUsernameSelection = index == 0
+                      ? UsernameSelection.email
+                      : UsernameSelection.phoneNumber;
+                  final oldUsernameSelection = state.usernameSelection;
+                  if (oldUsernameSelection == newUsernameSelection) {
+                    return;
+                  }
+                  state.usernameSelection = newUsernameSelection;
                   // Reset current username value to align with the current switch state.
-                  String newUsername = useEmail
+                  String newUsername = newUsernameSelection ==
+                          UsernameSelection.email
                       ? state.getAttribute(CognitoUserAttributeKey.email) ?? ''
                       : state.getAttribute(
                               CognitoUserAttributeKey.phoneNumber) ??
                           '';
                   state.username = newUsername;
+                  // Clear attributes on switch
+                  state.authAttributes.clear();
                 },
                 children: [
                   Text(emailTitle),
@@ -219,7 +230,7 @@ mixin AuthenticatorUsernameField<FieldType,
         validator: _validator,
         enabled: enabled,
         errorMaxLines: errorMaxLines,
-        initialValue: state.getAttribute(CognitoUserAttributeKey.phoneNumber),
+        initialValue: state.username,
       );
     }
     return TextFormField(
@@ -253,9 +264,6 @@ mixin UsernameAttributes<T extends AuthenticatorForm>
     return <CognitoUserAttributeKey>{...?authConfig?.usernameAttributes};
   }();
 
-  /// Toggle value for the email or phone number case.
-  final ValueNotifier<bool> useEmail = ValueNotifier(true);
-
   UsernameConfigType get usernameType {
     if (usernameAttributes.isEmpty) {
       return UsernameConfigType.username;
@@ -283,7 +291,7 @@ mixin UsernameAttributes<T extends AuthenticatorForm>
       case UsernameConfigType.phoneNumber:
         return UsernameType.phoneNumber;
       case UsernameConfigType.emailOrPhoneNumber:
-        if (useEmail.value) {
+        if (state.usernameSelection == UsernameSelection.email) {
           return UsernameType.email;
         }
         return UsernameType.phoneNumber;

packages/amplify_authenticator/lib/src/state/authenticator_state.dart

@@ -21,6 +21,12 @@ import 'package:amplify_authenticator/src/state/auth_state.dart';
 import 'package:amplify_authenticator/src/utils/country_code.dart';
 import 'package:flutter/material.dart';
 
+/// {@macro amplify_authenticator.authenticator_state.username_selection}
+enum UsernameSelection {
+  email,
+  phoneNumber,
+}
+
 @visibleForTesting
 typedef BlocEventPredicate = bool Function(AuthState state);
 
@@ -98,6 +104,21 @@ class AuthenticatorState extends ChangeNotifier {
 
   String _username = '';
 
+  /// {@template amplify_authenticator.authenticator_state.username_selection}
+  /// The username type to use during sign up and sign in.
+  ///
+  /// For auth configurations that allow sign up via username or email,
+  /// this will determine which option is currently selected.
+  /// {@endtemplate}
+  UsernameSelection get usernameSelection => _usernameSelection;
+
+  set usernameSelection(UsernameSelection value) {
+    _usernameSelection = value;
+    notifyListeners();
+  }
+
+  UsernameSelection _usernameSelection = UsernameSelection.email;
+
   /// The value for the password form field
   ///
   /// This value will be used during sign up, sign in, or other actions

packages/amplify_authenticator/lib/src/widgets/form.dart

@@ -142,26 +142,6 @@ class AuthenticatorFormState<T extends AuthenticatorForm>
 
   final ValueNotifier<bool> obscureTextToggleValue = ValueNotifier(true);
 
-  @override
-  void initState() {
-    super.initState();
-    useEmail.addListener(_updateUseEmail);
-  }
-
-  @override
-  void dispose() {
-    useEmail.removeListener(_updateUseEmail);
-    super.dispose();
-  }
-
-  void _updateUseEmail() {
-    // Clear attributes on switch
-    state.authAttributes.clear();
-
-    // Refresh state
-    setState(() {});
-  }
-
   /// Controls optional visibility of the field.
   Widget get obscureTextToggle {
     return ValueListenableBuilder<bool>(

packages/amplify_authenticator/lib/src/widgets/form_field.dart

@@ -140,10 +140,6 @@ abstract class AuthenticatorFormFieldState<FieldType, FieldValue,
   UsernameType get selectedUsernameType =>
       AuthenticatorFormState.of(context).selectedUsernameType;
 
-  @nonVirtual
-  ValueNotifier<bool> get useEmail =>
-      AuthenticatorFormState.of(context).useEmail;
-
   /// Callback for when `onChanged` is triggered on the [FormField].
   ValueChanged<FieldValue> get onChanged => (_) {};
 
@@ -255,8 +251,6 @@ abstract class AuthenticatorFormFieldState<FieldType, FieldValue,
         .add(EnumProperty<UsernameConfigType>('usernameType', usernameType));
     properties.add(EnumProperty<UsernameType>(
         'selectedUsernameType', selectedUsernameType));
-    properties
-        .add(DiagnosticsProperty<ValueNotifier<bool>>('useEmail', useEmail));
     properties.add(IntProperty('maxLength', maxLength));
     properties.add(DiagnosticsProperty<bool>('isOptional', isOptional));
     properties.add(StringProperty('labelText', labelText));