feat: add error builder to chat detail screen for failed to load messages

packages/chat_repository_interface/lib/chat_repository_interface.dart

@@ -1,15 +1,14 @@
+// exceptions
+export "src/exceptions/chat.dart";
 // Interfaces
 export "src/interfaces/chat_repostory_interface.dart";
 export "src/interfaces/user_repository_interface.dart";
-
 // Local implementations
 export "src/local/local_chat_repository.dart";
 export "src/local/local_user_repository.dart";
-
 // Models
 export "src/models/chat_model.dart";
 export "src/models/message_model.dart";
 export "src/models/user_model.dart";
-
 // Services
 export "src/services/chat_service.dart";

packages/chat_repository_interface/lib/src/exceptions/chat.dart

@@ -0,0 +1,23 @@
+/// An exception that is used to indicate the failure to load a chat for given
+/// [chatId]
+class ChatNotFoundException implements Exception {
+  /// Create an instance of the chat not found exception
+  const ChatNotFoundException({
+    required this.chatId,
+  });
+
+  /// The chat that was attempted to load, but never found.
+  final String chatId;
+}
+
+/// An exception that is used to indicate the failure to load the messages for a
+/// given [chatId]
+class ChatMessagesNotFoundException implements Exception {
+  /// Create an instance of the chatmessages not found exception
+  const ChatMessagesNotFoundException({
+    required this.chatId,
+  });
+
+  /// The chat for which messages were attempted to load, but never found.
+  final String chatId;
+}

packages/flutter_chat/lib/src/config/chat_builders.dart

@@ -1,17 +1,15 @@
 import "dart:typed_data";
 
-import "package:chat_repository_interface/chat_repository_interface.dart";
 import "package:flutter/material.dart";
-import "package:flutter_chat/src/config/chat_translations.dart";
-import "package:flutter_chat/src/config/screen_types.dart";
+import "package:flutter_chat/flutter_chat.dart";
 import "package:flutter_chat/src/screens/chat_detail/widgets/default_loader.dart";
-import "package:flutter_chat/src/screens/chat_detail/widgets/default_message_builder.dart";
 import "package:flutter_chat/src/screens/creation/widgets/default_image_picker.dart";
 
 /// The chat builders
 class ChatBuilders {
   /// The chat builders constructor
   const ChatBuilders({
+    this.chatMessagesErrorBuilder,
     this.baseScreenBuilder,
     this.chatScreenBuilder,
     this.messageInputBuilder,
@@ -99,6 +97,10 @@ class ChatBuilders {
   /// This is displayed in the list of chat messages when loading more messages
   /// can be above and below the list
   final WidgetBuilder loadingChatMessageBuilder;
+
+  /// Errorbuilder for when messages are not loading correctly on the detail
+  /// screen of a chat.
+  final ChatErrorBuilder? chatMessagesErrorBuilder;
 }
 
 /// The button builder
@@ -189,3 +191,11 @@ typedef NoUsersPlaceholderBuilder = Widget Function(
   BuildContext context,
   ChatTranslations translations,
 );
+
+/// Builder for when there is an error on a chatscreen
+typedef ChatErrorBuilder = Widget Function(
+  BuildContext context,
+  Object error,
+  StackTrace stackTrace,
+  ChatOptions options,
+);

packages/flutter_chat/lib/src/config/chat_translations.dart

@@ -48,6 +48,7 @@ class ChatTranslations {
     required this.selectedMembersHeader,
     required this.createGroupChatButton,
     required this.groupNameEmpty,
+    required this.messagesLoadingError,
     required this.next,
   });
 
@@ -92,6 +93,7 @@ class ChatTranslations {
     this.selectedMembersHeader = "Members: ",
     this.createGroupChatButton = "Create groupchat",
     this.groupNameEmpty = "Group",
+    this.messagesLoadingError = "Error loading messages, you can reload below:",
     this.next = "Next",
   });
 
@@ -134,6 +136,10 @@ class ChatTranslations {
   final String groupBioValidatorEmpty;
   final String groupNameEmpty;
 
+  /// message shown in the default chat screen when the chat messages are unable
+  /// to be loaded.
+  final String messagesLoadingError;
+
   final String next;
 
   // copyWith method to override the default values
@@ -174,6 +180,7 @@ class ChatTranslations {
     String? selectedMembersHeader,
     String? createGroupChatButton,
     String? groupNameEmpty,
+    String? messagesLoadingError,
     String? next,
   }) =>
       ChatTranslations(
@@ -225,6 +232,7 @@ class ChatTranslations {
         createGroupChatButton:
             createGroupChatButton ?? this.createGroupChatButton,
         groupNameEmpty: groupNameEmpty ?? this.groupNameEmpty,
+        messagesLoadingError: messagesLoadingError ?? this.messagesLoadingError,
         next: next ?? this.next,
       );
 }

packages/flutter_chat/lib/src/screens/chat_detail/chat_detail_screen.dart

@@ -3,6 +3,7 @@ import "dart:typed_data";
 
 import "package:chat_repository_interface/chat_repository_interface.dart";
 import "package:flutter/material.dart";
+import "package:flutter_chat/src/config/chat_options.dart";
 import "package:flutter_chat/src/config/screen_types.dart";
 import "package:flutter_chat/src/screens/chat_detail/widgets/chat_bottom.dart";
 import "package:flutter_chat/src/screens/chat_detail/widgets/chat_widgets.dart";
@@ -393,6 +394,41 @@ class _ChatBody extends HookWidget {
       [autoScrollEnabled.value],
     );
 
+    var chatBottomInputSection = ChatBottomInputSection(
+      chat: chat,
+      isLoading: chatIsLoading && !messagesSnapshot.hasData,
+      onPressSelectImage: () async => onPressSelectImage(
+        context,
+        options,
+        onUploadImage,
+      ),
+      onMessageSubmit: onMessageSubmit,
+    );
+
+    if (messagesSnapshot.hasError) {
+      var errorBuilder = options.builders.chatMessagesErrorBuilder;
+      if (errorBuilder != null) {
+        return Column(
+          children: [
+            Expanded(
+              child: errorBuilder(
+                context,
+                messagesSnapshot.error!,
+                messagesSnapshot.stackTrace!,
+                options,
+              ),
+            ),
+            chatBottomInputSection,
+          ],
+        );
+      }
+
+      return ErrorLoadingMessages(
+        options: options,
+        chatBottomInputSection: chatBottomInputSection,
+      );
+    }
+
     var userMap = <String, UserModel>{};
     for (var u in chatUsers) {
       userMap[u.id] = u;
@@ -449,17 +485,43 @@ class _ChatBody extends HookWidget {
             ),
           ),
         ],
-        ChatBottomInputSection(
-          chat: chat,
-          isLoading: chatIsLoading,
-          onPressSelectImage: () async => onPressSelectImage(
-            context,
-            options,
-            onUploadImage,
-          ),
-          onMessageSubmit: onMessageSubmit,
-        ),
+        chatBottomInputSection,
       ],
     );
   }
 }
+
+/// Default widget used when displaying an error for chats.
+class ErrorLoadingMessages extends StatelessWidget {
+  /// Create default error displaying widget for error in loading messages
+  const ErrorLoadingMessages({
+    required this.options,
+    required this.chatBottomInputSection,
+    super.key,
+  });
+
+  /// the options of the current chat userstory
+  final ChatOptions options;
+
+  /// The widget
+  final ChatBottomInputSection chatBottomInputSection;
+
+  @override
+  Widget build(BuildContext context) => Column(
+        children: [
+          Expanded(
+            child: Center(
+              child: Column(
+                mainAxisSize: MainAxisSize.min,
+                children: [
+                  Text(
+                    options.translations.messagesLoadingError,
+                  ),
+                ],
+              ),
+            ),
+          ),
+          chatBottomInputSection,
+        ],
+      );
+}