Add parameter to mantain conversation setup (#51)

README.md

@@ -39,6 +39,8 @@ ChatGPT is aimed to support conversational scenarios: user can talk to ChatGPT w
 * *MessageLimit*: specifies how many messages for each conversation must be saved. When this limit is reached, oldest messages are automatically removed.
 * *MessageExpiration*: specifies the time interval used to maintain messages in cache, regardless their count.
 
+We can also set ChatGPT parameters for chat completion at startup. Check the [official documentation](https://platform.openai.com/docs/api-reference/chat/create) for the list of available parameters and their meaning.
+
 The configuration can be automatically read from [IConfiguration](https://learn.microsoft.com/en-us/dotnet/api/microsoft.extensions.configuration.iconfiguration), using for example a _ChatGPT_ section in the _appsettings.json_ file:
 
  "ChatGPT": {
@@ -141,7 +143,7 @@ Response streaming works by returning an [IAsyncEnumerable](https://learn.micros
 
 **Changing the assistant's behavior**
 
-ChatGPT supports messages with the *system* role to influence how the assistant should behave. For example, we can tell to ChatGPT something like that:
+ChatGPT supports messages with the _system_ role to influence how the assistant should behave. For example, we can tell to ChatGPT something like that:
 
 - You are an helpful assistant
 - Answer like Shakespeare
@@ -161,7 +163,9 @@ The *system* message does not count for messages limit number.
 
 Conversation history is automatically deleted when expiration time (specified by *MessageExpiration* property) is reached. However, if necessary it is possible to immediately clear the history:
 
- await chatGptClient.DeleteConversationAsync(conversationId);
+ await chatGptClient.DeleteConversationAsync(conversationId, preserveSetup: false);
+
+The _preserveSetup_ argument allows to decide whether mantain also the _system_ message that has been set with the **SetupAsync** method (default: _false_).
 
 **Contribute**
 

src/ChatGptNet/ChatGptClient.cs

@@ -180,9 +180,20 @@ public Task<IEnumerable<ChatGptMessage>> GetConversationAsync(Guid conversationI
  return Task.FromResult(messages);
  }
 
- public Task DeleteConversationAsync(Guid conversationId)
+ public Task DeleteConversationAsync(Guid conversationId, bool preserveSetup = false)
  {
- cache.Remove(conversationId);
+ if (!preserveSetup)
+ {
+ // We don't want to preserve setup message, so just deletes all the cache history.
+ cache.Remove(conversationId);
+ }
+ else if (cache.TryGetValue<List<ChatGptMessage>>(conversationId, out var messages))
+ {
+ // Removes all the messages, except system ones.
+ messages!.RemoveAll(m => m.Role != ChatGptRoles.System);
+ cache.Set(conversationId, messages, options.MessageExpiration);
+ }
+
  return Task.CompletedTask;
  }
 

src/ChatGptNet/IChatGptClient.cs

@@ -110,6 +110,7 @@ Task<Guid> SetupAsync(string message)
  /// Deletes a chat conversation, clearing all the history.
  /// </summary>
  /// <param name="conversationId">The unique identifier of the conversation.</param>
+ /// <param name="preserveSetup"><see langword="true"/> to maintain the system message that has been specified with the <see cref="SetupAsync(Guid, string)"/> method.</param>
  /// <returns>The <see cref="Task"/> corresponding to the asynchronous operation.</returns>
- Task DeleteConversationAsync(Guid conversationId);
+ Task DeleteConversationAsync(Guid conversationId, bool preserveSetup = false);
 }