Manage prompts as a "messages" object during prompt lifecycle

Before, our prompts were just a string like "Translate this text:
user text" and just before being sent to the backend, it was
converted to an "messages" object compatible with OpenAI API like [{
"role": "user", "content": "Translate this text: user text"}].

Now, we use "messages" object directly when building the prompt
because in the near future we will create more complex prompts with
system content and user content so we will need "messages" object
dirrectly.

scribe/lib/scribe/ai/data/datasource/ai_datasource.dart

@@ -1,5 +1,6 @@
+import 'package:scribe/scribe/ai/data/model/ai_message.dart';
 import 'package:scribe/scribe/ai/domain/model/ai_response.dart';
 
 abstract class AIDataSource {
-  Future<AIResponse> generateMessage(String prompt);
+  Future<AIResponse> generateMessage(List<AIMessage> messages);
 }

scribe/lib/scribe/ai/data/datasource_impl/ai_datasource_impl.dart

@@ -1,5 +1,6 @@
 import 'package:dio/dio.dart';
 import 'package:scribe/scribe/ai/data/datasource/ai_datasource.dart';
+import 'package:scribe/scribe/ai/data/model/ai_message.dart';
 import 'package:scribe/scribe/ai/data/network/ai_api.dart';
 import 'package:scribe/scribe/ai/domain/model/ai_response.dart';
 
@@ -9,9 +10,9 @@ class AIDataSourceImpl implements AIDataSource {
   AIDataSourceImpl(this._aiApi);
 
   @override
-  Future<AIResponse> generateMessage(String prompt) async {
+  Future<AIResponse> generateMessage(List<AIMessage> messages) async {
     try {
-      final apiResponse = await _aiApi.generateMessage(prompt);
+      final apiResponse = await _aiApi.generateMessage(messages);
       return AIResponse(result: apiResponse.content);
     } on DioException catch (e) {
       throw Exception('Failed to generate AI text: ${e.message}');

scribe/lib/scribe/ai/data/model/ai_message.dart

@@ -5,6 +5,7 @@ part 'ai_message.g.dart';
 @JsonSerializable()
 class AIMessage {
   static const String aiUserRole = 'user';
+  static const String aiSystemRole = 'system';
 
   final String role;
   final String content;
@@ -23,4 +24,9 @@ class AIMessage {
         role: aiUserRole,
         content: content,
       );
+
+  factory AIMessage.ofSystem(String content) => AIMessage(
+        role: aiSystemRole,
+        content: content,
+      );
 }

scribe/lib/scribe/ai/data/network/ai_api.dart

@@ -9,8 +9,8 @@ class AIApi {
 
   AIApi(this._dioClient, this.aiEndpoint);
 
-  Future<AIApiResponse> generateMessage(String prompt) async {
-    final aiRequest = _generateRequest(prompt);
+  Future<AIApiResponse> generateMessage(List<AIMessage> messages) async {
+    final aiRequest = AIAPIRequest(messages: messages);
 
     final response = await _dioClient.post(
       aiEndpoint,
@@ -20,8 +20,4 @@ class AIApi {
 
     return AIApiResponse.fromJson(response);
   }
-
-  AIAPIRequest _generateRequest(String prompt) {
-    return AIAPIRequest(messages: [AIMessage.ofUser(prompt)]);
-  }
 }

scribe/lib/scribe/ai/data/repository/ai_repository_impl.dart

@@ -1,4 +1,5 @@
 import 'package:scribe/scribe/ai/data/datasource/ai_datasource.dart';
+import 'package:scribe/scribe/ai/data/model/ai_message.dart';
 import 'package:scribe/scribe/ai/domain/model/ai_response.dart';
 import 'package:scribe/scribe/ai/domain/repository/ai_scribe_repository.dart';
 
@@ -8,7 +9,7 @@ class AIScribeRepositoryImpl implements AIScribeRepository {
   AIScribeRepositoryImpl(this._aiDataSource);
 
   @override
-  Future<AIResponse> generateMessage(String prompt) {
-    return _aiDataSource.generateMessage(prompt);
+  Future<AIResponse> generateMessage(List<AIMessage> messages) {
+    return _aiDataSource.generateMessage(messages);
   }
 }

scribe/lib/scribe/ai/domain/constants/ai_prompts.dart

@@ -1,3 +1,4 @@
+import 'package:scribe/scribe/ai/data/model/ai_message.dart';
 import 'package:scribe/scribe/ai/presentation/model/ai_action.dart';
 import 'package:scribe/scribe/ai/presentation/model/ai_scribe_menu_action.dart';
 
@@ -8,8 +9,8 @@ class AIPrompts {
   static const _doNotAddInfoPrompt =
       "Do not add any extra information or interpret anything beyond the explicit task.";
 
-  static String buildPrompt(AIAction action, String? text) {
-    return switch (action) {
+  static List<AIMessage> buildPrompt(AIAction action, String? text) {
+    final prompt =  switch (action) {
       PredefinedAction(action: final menuAction) =>
       text?.trim().isNotEmpty == true
           ? buildPredefinedPrompt(menuAction, text!)
@@ -17,6 +18,10 @@ class AIPrompts {
       CustomPromptAction(prompt: final customPrompt) =>
         buildCustomPrompt(customPrompt, text),
     };
+
+    final message = [AIMessage.ofUser(prompt)];
+
+    return message;
   }
 
   static String buildPredefinedPrompt(AIScribeMenuAction action, String text) {

scribe/lib/scribe/ai/domain/repository/ai_scribe_repository.dart

@@ -1,5 +1,6 @@
+import 'package:scribe/scribe/ai/data/model/ai_message.dart';
 import 'package:scribe/scribe/ai/domain/model/ai_response.dart';
 
 abstract class AIScribeRepository {
-  Future<AIResponse> generateMessage(String prompt);
+  Future<AIResponse> generateMessage(List<AIMessage> messages);
 }