feat: link preview v2 (#784)

* Rename LinkPreview class and prop to LinkPreviewData

* Add image height and width

* Update tests

* Add linkPreviewBuilder

* Add linkPreview to SimpleTextMessage and FlyerChatTextMessage

* Allow positioning of the preview

* Fix alignement when linkPreview is bigger than text

Author: nicolasbraun

packages/flutter_chat_core/lib/flutter_chat_core.dart

@@ -7,7 +7,7 @@ export 'src/chat_controller/in_memory_chat_controller.dart';
 export 'src/chat_controller/scroll_to_message_mixin.dart';
 export 'src/chat_controller/upload_progress_mixin.dart';
 export 'src/models/builders.dart';
-export 'src/models/link_preview.dart';
+export 'src/models/link_preview_data.dart';
 export 'src/models/message.dart';
 export 'src/models/message_group_status.dart';
 export 'src/models/user.dart';

packages/flutter_chat_core/lib/src/models/builders.dart

@@ -75,6 +75,9 @@ typedef LoadMoreBuilder = Widget Function(BuildContext);
 /// Signature for building the empty chat list widget.
 typedef EmptyChatListBuilder = Widget Function(BuildContext);
 
+/// Signature for building the link preview widget.
+typedef LinkPreviewBuilder = Widget? Function(BuildContext, TextMessage);
+
 /// A collection of builder functions used to customize the UI components
 /// of the chat interface.
 @Freezed(fromJson: false, toJson: false)
@@ -128,6 +131,9 @@ abstract class Builders with _$Builders {
 
     /// Custom builder for the empty chat list.
     EmptyChatListBuilder? emptyChatListBuilder,
+
+    /// Custom builder for the link preview widget.
+    LinkPreviewBuilder? linkPreviewBuilder,
   }) = _Builders;
 
   const Builders._();

packages/flutter_chat_core/lib/src/models/builders.freezed.dart

@@ -0,0 +1,54 @@
+import 'package:freezed_annotation/freezed_annotation.dart';
+
+part 'link_preview_data.freezed.dart';
+part 'link_preview_data.g.dart';
+
+/// Represents the data extracted for a link preview.
+@freezed
+abstract class LinkPreviewData with _$LinkPreviewData {
+  /// Creates a [LinkPreviewData] instance.
+  const factory LinkPreviewData({
+    /// The original URL link.
+    required String link,
+
+    /// A description extracted from the link source.
+    String? description,
+
+    /// The preview data of an image extracted from the link
+    ImagePreviewData? image,
+
+    /// The title extracted from the link source.
+    String? title,
+
+  }) = _LinkPreviewData;
+
+  const LinkPreviewData._();
+
+  /// Creates a [LinkPreviewData] instance from a JSON map.
+  factory LinkPreviewData.fromJson(Map<String, dynamic> json) =>
+      _$LinkPreviewDataFromJson(json);
+}
+
+/// Represents the data extracted for a link preview image.
+@freezed
+abstract class ImagePreviewData with _$ImagePreviewData {
+  /// Creates a [ImagePreviewData] instance.
+  const factory ImagePreviewData({
+
+    /// The URL of an image associated with the link.
+    required String url,
+
+    /// The image width.
+    required double width,
+
+    /// The image height.
+    required double height,
+
+  }) = _ImagePreviewData;
+
+  const ImagePreviewData._();
+
+  /// Creates a [ImagePreviewData] instance from a JSON map.
+  factory ImagePreviewData.fromJson(Map<String, dynamic> json) =>
+      _$ImagePreviewDataFromJson(json);
+}