ChatGPT Api Implementation and Example (#28)

Added
- Chat Completion API implemented
- ChatGPT sample created
- Messaging app like UI created for samples
Changed
- The previous ChatGPT sample moved into Text Completion Sample

Author: srcnalt

Runtime/DataTypes.cs

@@ -77,6 +77,47 @@ public class OpenAIModelResponse : OpenAIModel, IResponse
     }
     #endregion
 
+    #region Chat API Data Types
+    public sealed class CreateChatCompletionRequest
+    {
+        public string Model { get; set; }
+        public List<ChatMessage> Messages { get; set; }
+        public float? Temperature { get; set; } = 1;
+        public int? N { get; set; } = 1;
+        public bool? Stream { get; set; } = false;
+        public string Stop { get; set; }
+        public int? MaxTokens { get; set; }
+        public float? PresencePenalty { get; set; } = 0;
+        public float? FrequencyPenalty { get; set; } = 0;
+        public Dictionary<string, string> LogitBias { get; set; }
+        public string User { get; set; }
+    }
+
+    public struct CreateChatCompletionResponse : IResponse
+    {
+        public ApiError Error { get; set; }
+        public string Model { get; set; }
+        public string Id { get; set; }
+        public string Object { get; set; }
+        public long Created { get; set; }
+        public List<ChatChoice> Choices { get; set; }
+        public Usage Usage { get; set; }
+    }
+    
+    public struct ChatChoice
+    {
+        public ChatMessage Message { get; set; }
+        public int? Index { get; set; }
+        public string FinishReason { get; set; }
+    }
+
+    public struct ChatMessage
+    {
+        public string Role { get; set; }
+        public string Content { get; set; }
+    }
+    #endregion
+
     #region Completions API Data Types
     public sealed class CreateCompletionRequest
     {

Runtime/OpenAIApi.cs

@@ -166,6 +166,13 @@ public async Task<CreateCompletionResponse> CreateCompletion(CreateCompletionReq
             return await DispatchRequest<CreateCompletionResponse>(path, UnityWebRequest.kHttpVerbPOST, payload);
         }
 
+        public async Task<CreateChatCompletionResponse> CreateChatCompletion(CreateChatCompletionRequest request)
+        {
+            var path = $"{BASE_PATH}/chat/completions";
+            var payload = CreatePayload(request);
+            return await DispatchRequest<CreateChatCompletionResponse>(path, UnityWebRequest.kHttpVerbPOST, payload);
+        }
+        
         /// <summary>
         ///     Creates a new edit for the provided input, instruction, and parameters.
         /// </summary>