feat(app_configuration): add feed decorator form widget

- Implement FeedDecoratorForm StatefulWidget for configuring feed decorators
- Add logic to handle different decorator types and user roles
- Include functionality to update remote config based on form input
- Create role-specific fields for customization

Author: fulleni

lib/app_configuration/widgets/feed_decorator_form.dart

@@ -0,0 +1,255 @@
+import 'package:core/core.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_news_app_web_dashboard_full_source_code/app_configuration/widgets/app_config_form_fields.dart';
+import 'package:flutter_news_app_web_dashboard_full_source_code/l10n/app_localizations.dart';
+import 'package:flutter_news_app_web_dashboard_full_source_code/l10n/l10n.dart';
+import 'package:flutter_news_app_web_dashboard_full_source_code/shared/extensions/app_user_role_l10n.dart';
+import 'package:ui_kit/ui_kit.dart';
+
+/// {@template feed_decorator_form}
+/// A form widget for configuring a single feed decorator's settings.
+/// {@endtemplate}
+class FeedDecoratorForm extends StatefulWidget {
+  /// {@macro feed_decorator_form}
+  const FeedDecoratorForm({
+    required this.decoratorType,
+    required this.remoteConfig,
+    required this.onConfigChanged,
+    super.key,
+  });
+
+  /// The specific type of decorator this form is configuring.
+  final FeedDecoratorType decoratorType;
+
+  /// The current [RemoteConfig] object.
+  final RemoteConfig remoteConfig;
+
+  /// Callback to notify parent of changes to the [RemoteConfig].
+  final ValueChanged<RemoteConfig> onConfigChanged;
+
+  @override
+  State<FeedDecoratorForm> createState() => _FeedDecoratorFormState();
+}
+
+class _FeedDecoratorFormState extends State<FeedDecoratorForm> {
+  AppUserRole _selectedUserRole = AppUserRole.guestUser;
+  late final TextEditingController _itemsToDisplayController;
+  late final Map<AppUserRole, TextEditingController> _roleControllers;
+
+  @override
+  void initState() {
+    super.initState();
+    _initializeControllers();
+  }
+
+  @override
+  void didUpdateWidget(covariant FeedDecoratorForm oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (widget.remoteConfig.feedDecoratorConfig[widget.decoratorType] !=
+        oldWidget.remoteConfig.feedDecoratorConfig[widget.decoratorType]) {
+      _updateControllers();
+    }
+  }
+
+  void _initializeControllers() {
+    final decoratorConfig =
+        widget.remoteConfig.feedDecoratorConfig[widget.decoratorType]!;
+    _itemsToDisplayController = TextEditingController(
+      text: decoratorConfig.itemsToDisplay?.toString() ?? '',
+    )..selection = TextSelection.collapsed(
+        offset: decoratorConfig.itemsToDisplay?.toString().length ?? 0,
+      );
+
+    _roleControllers = {
+      for (final role in AppUserRole.values)
+        role: TextEditingController(
+          text: decoratorConfig.visibleTo[role]?.daysBetweenViews.toString() ??
+              '',
+        )..selection = TextSelection.collapsed(
+            offset: decoratorConfig.visibleTo[role]?.daysBetweenViews
+                    .toString()
+                    .length ??
+                0,
+          ),
+    };
+  }
+
+  void _updateControllers() {
+    final decoratorConfig =
+        widget.remoteConfig.feedDecoratorConfig[widget.decoratorType]!;
+    _itemsToDisplayController.text =
+        decoratorConfig.itemsToDisplay?.toString() ?? '';
+    _itemsToDisplayController.selection = TextSelection.collapsed(
+      offset: _itemsToDisplayController.text.length,
+    );
+    for (final role in AppUserRole.values) {
+      _roleControllers[role]?.text =
+          decoratorConfig.visibleTo[role]?.daysBetweenViews.toString() ?? '';
+      _roleControllers[role]?.selection = TextSelection.collapsed(
+        offset: _roleControllers[role]?.text.length ?? 0,
+      );
+    }
+  }
+
+  @override
+  void dispose() {
+    _itemsToDisplayController.dispose();
+    for (final controller in _roleControllers.values) {
+      controller.dispose();
+    }
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final l10n = AppLocalizationsX(context).l10n;
+    final decoratorConfig =
+        widget.remoteConfig.feedDecoratorConfig[widget.decoratorType]!;
+
+    return Column(
+      children: [
+        SwitchListTile(
+          title: Text(l10n.enabledLabel),
+          value: decoratorConfig.enabled,
+          onChanged: (value) {
+            final newDecoratorConfig = decoratorConfig.copyWith(enabled: value);
+            final newFeedDecoratorConfig =
+                Map<FeedDecoratorType, FeedDecoratorConfig>.from(
+              widget.remoteConfig.feedDecoratorConfig,
+            )..[widget.decoratorType] = newDecoratorConfig;
+            widget.onConfigChanged(
+              widget.remoteConfig.copyWith(
+                feedDecoratorConfig: newFeedDecoratorConfig,
+              ),
+            );
+          },
+        ),
+        if (decoratorConfig.category == FeedDecoratorCategory.contentCollection)
+          AppConfigIntField(
+            label: l10n.itemsToDisplayLabel,
+            description: l10n.itemsToDisplayDescription,
+            value: decoratorConfig.itemsToDisplay ?? 0,
+            onChanged: (value) {
+              final newDecoratorConfig = decoratorConfig.copyWith(
+                itemsToDisplay: value,
+              );
+              final newFeedDecoratorConfig =
+                  Map<FeedDecoratorType, FeedDecoratorConfig>.from(
+                widget.remoteConfig.feedDecoratorConfig,
+              )..[widget.decoratorType] = newDecoratorConfig;
+              widget.onConfigChanged(
+                widget.remoteConfig.copyWith(
+                  feedDecoratorConfig: newFeedDecoratorConfig,
+                ),
+              );
+            },
+            controller: _itemsToDisplayController,
+          ),
+        const SizedBox(height: AppSpacing.lg),
+        Center(
+          child: SegmentedButton<AppUserRole>(
+            segments: AppUserRole.values
+                .map(
+                  (role) => ButtonSegment<AppUserRole>(
+                    value: role,
+                    label: Text(role.l10n(context)),
+                  ),
+                )
+                .toList(),
+            selected: {_selectedUserRole},
+            onSelectionChanged: (newSelection) {
+              setState(() {
+                _selectedUserRole = newSelection.first;
+              });
+            },
+          ),
+        ),
+        const SizedBox(height: AppSpacing.lg),
+        _buildRoleSpecificFields(context, l10n, _selectedUserRole, decoratorConfig),
+      ],
+    );
+  }
+
+  Widget _buildRoleSpecificFields(
+    BuildContext context,
+    AppLocalizations l10n,
+    AppUserRole role,
+    FeedDecoratorConfig decoratorConfig,
+  ) {
+    final roleConfig = decoratorConfig.visibleTo[role];
+    final isLinkAccountForStandardOrPremium =
+        widget.decoratorType == FeedDecoratorType.linkAccount &&
+            (role == AppUserRole.standardUser ||
+                role == AppUserRole.premiumUser);
+
+    return Column(
+      children: [
+        CheckboxListTile(
+          title: Text(l10n.visibleToRoleLabel(role.l10n(context))),
+          value: roleConfig != null,
+          onChanged: isLinkAccountForStandardOrPremium
+              ? null // Disable for standard and premium users for linkAccount
+              : (value) {
+                  final newVisibleTo =
+                      Map<AppUserRole, FeedDecoratorRoleConfig>.from(
+                    decoratorConfig.visibleTo,
+                  );
+                  if (value ?? false) {
+                    newVisibleTo[role] = const FeedDecoratorRoleConfig(
+                      daysBetweenViews: 7,
+                    );
+                  } else {
+                    newVisibleTo.remove(role);
+                  }
+                  final newDecoratorConfig = decoratorConfig.copyWith(
+                    visibleTo: newVisibleTo,
+                  );
+                  final newFeedDecoratorConfig =
+                      Map<FeedDecoratorType, FeedDecoratorConfig>.from(
+                    widget.remoteConfig.feedDecoratorConfig,
+                  )..[widget.decoratorType] = newDecoratorConfig;
+                  widget.onConfigChanged(
+                    widget.remoteConfig.copyWith(
+                      feedDecoratorConfig: newFeedDecoratorConfig,
+                    ),
+                  );
+                },
+        ),
+        if (roleConfig != null)
+          Padding(
+            padding: const EdgeInsets.symmetric(
+              horizontal: AppSpacing.lg,
+              vertical: AppSpacing.sm,
+            ),
+            child: AppConfigIntField(
+              label: l10n.daysBetweenViewsLabel,
+              description: l10n.daysBetweenViewsDescription,
+              value: roleConfig.daysBetweenViews,
+              onChanged: (value) {
+                final newRoleConfig = roleConfig.copyWith(
+                  daysBetweenViews: value,
+                );
+                final newVisibleTo =
+                    Map<AppUserRole, FeedDecoratorRoleConfig>.from(
+                  decoratorConfig.visibleTo,
+                )..[role] = newRoleConfig;
+                final newDecoratorConfig = decoratorConfig.copyWith(
+                  visibleTo: newVisibleTo,
+                );
+                final newFeedDecoratorConfig =
+                    Map<FeedDecoratorType, FeedDecoratorConfig>.from(
+                  widget.remoteConfig.feedDecoratorConfig,
+                )..[widget.decoratorType] = newDecoratorConfig;
+                widget.onConfigChanged(
+                  widget.remoteConfig.copyWith(
+                    feedDecoratorConfig: newFeedDecoratorConfig,
+                  ),
+                );
+              },
+              controller: _roleControllers[role],
+            ),
+          ),
+      ],
+    );
+  }
+}