refactor: remove json_serializable

- Remove code generation
- Use manual json conversion
- Add json converters util

Author: fulleni

lib/src/models/feed/ad.dart

@@ -1,16 +1,13 @@
+import 'package:equatable/equatable.dart';
 import 'package:ht_shared/src/models/feed/ad_placement.dart';
 import 'package:ht_shared/src/models/feed/feed_item.dart';
-import 'package:ht_shared/src/models/feed/feed_item_action.dart'
-    show FeedItemAction, feedItemActionFromJson, feedItemActionToJson;
-import 'package:json_annotation/json_annotation.dart';
+import 'package:ht_shared/src/models/feed/feed_item_action.dart';
+import 'package:ht_shared/src/utils/json_converters.dart';
 import 'package:uuid/uuid.dart';
 
-part 'ad.g.dart';
-
 /// {@template ad_type}
 /// Defines the visual format or type of an advertisement in the feed.
 /// {@endtemplate}
-@JsonEnum(fieldRename: FieldRename.snake)
 enum AdType {
   /// A banner advertisement, typically a rectangular image.
   banner,
@@ -28,21 +25,31 @@ enum AdType {
 /// {@template ad}
 /// Represents an advertisement item that can appear in the feed.
 /// {@endtemplate}
-@JsonSerializable(explicitToJson: true, includeIfNull: false)
 class Ad extends FeedItem {
   /// {@macro ad}
   Ad({
     required this.imageUrl,
     required this.targetUrl,
     required this.adType,
-    required super.action,
+    required super.action, // Refactored to super.action
     this.placement,
     String? id,
   })  : id = id ?? const Uuid().v4(),
-        super(type: 'ad');
+        super(type: 'ad'); // Removed action from super constructor
 
   /// Factory method to create an [Ad] instance from a JSON map.
-  factory Ad.fromJson(Map<String, dynamic> json) => _$AdFromJson(json);
+  factory Ad.fromJson(Map<String, dynamic> json) {
+    return Ad(
+      id: json['id'] as String?,
+      imageUrl: json['imageUrl'] as String,
+      targetUrl: json['targetUrl'] as String,
+      adType: adTypeFromJson(json['adType'] as String),
+      placement: json['placement'] == null
+          ? null
+          : adPlacementFromJson(json['placement'] as String),
+      action: FeedItemAction.fromJson(json['action'] as Map<String, dynamic>),
+    );
+  }
 
   /// Unique identifier for the ad.
   final String id;
@@ -60,14 +67,20 @@ class Ad extends FeedItem {
   /// for this ad in the UI.
   final AdPlacement? placement;
 
-  /// The action to be performed when this feed item is interacted with.
-  @JsonKey(fromJson: feedItemActionFromJson, toJson: feedItemActionToJson)
-  @override
-  late final FeedItemAction action;
-
   /// Converts this [Ad] instance to a JSON map.
   @override
-  Map<String, dynamic> toJson() => _$AdToJson(this);
+  Map<String, dynamic> toJson() {
+    final Map<String, dynamic> json = {
+      'id': id,
+      'imageUrl': imageUrl,
+      'targetUrl': targetUrl,
+      'adType': adTypeToJson(adType),
+      'placement': placement == null ? null : adPlacementToJson(placement!),
+      'action': action.toJson(),
+      'type': type, // Inherited from FeedItem
+    };
+    return json..removeWhere((key, value) => value == null);
+  }
 
   @override
   List<Object?> get props => [

lib/src/models/feed/ad.g.dart

@@ -1,36 +1,44 @@
+import 'package:equatable/equatable.dart';
 import 'package:ht_shared/src/models/feed/engagement_content_type.dart';
 import 'package:ht_shared/src/models/feed/feed_item.dart';
-import 'package:ht_shared/src/models/feed/feed_item_action.dart'
-    show FeedItemAction, feedItemActionFromJson, feedItemActionToJson;
-import 'package:json_annotation/json_annotation.dart';
+import 'package:ht_shared/src/models/feed/feed_item_action.dart';
+import 'package:ht_shared/src/utils/json_converters.dart';
 import 'package:uuid/uuid.dart';
 
-part 'engagement_content.g.dart';
-
 /// {@template engagement_content}
 /// A generic model for in-feed calls-to-action or engagement prompts.
 ///
 /// This item encourages user interaction, such as signing up, upgrading,
 /// or providing feedback. The [engagementContentType] specifies the nature
 /// of the call-to-action.
 /// {@endtemplate}
-@JsonSerializable(explicitToJson: true, includeIfNull: false)
 class EngagementContent extends FeedItem {
   /// {@macro engagement_content}
   EngagementContent({
     required this.title,
     required this.engagementContentType,
-    required super.action,
+    required super.action, // Refactored to super.action
     this.description,
     this.callToActionText,
     this.callToActionUrl,
     String? id,
   })  : id = id ?? const Uuid().v4(),
-        super(type: 'engagement_content');
+        super(type: 'engagement_content'); // Removed action from super constructor
 
   /// Factory method to create an [EngagementContent] instance from a JSON map.
-  factory EngagementContent.fromJson(Map<String, dynamic> json) =>
-      _$EngagementContentFromJson(json);
+  factory EngagementContent.fromJson(Map<String, dynamic> json) {
+    return EngagementContent(
+      id: json['id'] as String?,
+      title: json['title'] as String,
+      description: json['description'] as String?,
+      engagementContentType: engagementContentTypeFromJson(
+        json['engagementContentType'] as String,
+      ),
+      callToActionText: json['callToActionText'] as String?,
+      callToActionUrl: json['callToActionUrl'] as String?,
+      action: FeedItemAction.fromJson(json['action'] as Map<String, dynamic>),
+    );
+  }
 
   /// Unique identifier for the engagement content.
   final String id;
@@ -50,14 +58,22 @@ class EngagementContent extends FeedItem {
   /// The URL to navigate to when the call-to-action is triggered.
   final String? callToActionUrl;
 
-  /// The action to be performed when this feed item is interacted with.
-  @JsonKey(fromJson: feedItemActionFromJson, toJson: feedItemActionToJson)
-  @override
-  late final FeedItemAction action;
-
   /// Converts this [EngagementContent] instance to a JSON map.
   @override
-  Map<String, dynamic> toJson() => _$EngagementContentToJson(this);
+  Map<String, dynamic> toJson() {
+    final Map<String, dynamic> json = {
+      'id': id,
+      'title': title,
+      'description': description,
+      'engagementContentType':
+          engagementContentTypeToJson(engagementContentType),
+      'callToActionText': callToActionText,
+      'callToActionUrl': callToActionUrl,
+      'action': action.toJson(),
+      'type': type, // Inherited from FeedItem
+    };
+    return json..removeWhere((key, value) => value == null);
+  }
 
   @override
   List<Object?> get props => [