SeemGen/Services/DeepSeekApiService.cs

using BLAIzor.Models;
using Newtonsoft.Json;
using System.Net.Http;
using System.Text.Json;
using System.Text;

namespace BLAIzor.Services
{
    public class DeepSeekApiService
    {
        private readonly IConfiguration _configuration;
        private readonly HttpClient _httpClient;

        public DeepSeekApiService(IConfiguration configuration, HttpClient httpClient)
        {
            _configuration = configuration;
            _httpClient = httpClient;
        }

        private const string DeepSeekEndpoint = "https://api.deepseek.com/chat/completions";
        public string _apiKey;
        private Action<string> _callback;
        public string GetApiKey()
        {
            if (_configuration == null)
            {
                return string.Empty;
            }
            if (_configuration.GetSection("DeepSeek") == null)
            {
                return string.Empty;
            }

            return _configuration.GetSection("DeepSeek").GetValue<string>("ApiKey")!;

        }

        public void RegisterCallback(Action<string> callback)
        {
            _callback = callback;
        }

        public async Task<string> GetSimpleChatGPTResponse(string systemMessage, string userMessage, string? assistantMessage = null)
        {
            _apiKey = GetApiKey();

            var requestBody = new ChatGPTRequest();

            if (assistantMessage == null)
            {
                requestBody = new ChatGPTRequest
                {
                    Model = "deepseek-chat",
                    Temperature = 0.2,
                    Messages = new[]
                    {
                        new Message { Role = "system", Content = systemMessage },
                        new Message { Role = "user", Content = userMessage }
                    },
                    Stream = false
                };
            }
            else
            {
                requestBody = new ChatGPTRequest
                {
                    Model = "deepseek-chat",
                    Temperature = 0.2,
                    Messages = new[]
                    {
                        new Message { Role = "system", Content = systemMessage },
                        new Message {Role = "assistant", Content = assistantMessage },
                        new Message { Role = "user", Content = userMessage }
                    },
                    Stream = false
                };
            }
            string requestJson = System.Text.Json.JsonSerializer.Serialize(requestBody, new JsonSerializerOptions
            {
                PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
                WriteIndented = false
            }
            );

            var requestContent = new StringContent(requestJson, Encoding.UTF8, "application/json");

            _httpClient.DefaultRequestHeaders.Clear();
            _httpClient.DefaultRequestHeaders.Add("Authorization", $"Bearer {_apiKey}");

            var response = await _httpClient.PostAsync(DeepSeekEndpoint, requestContent);
            response.EnsureSuccessStatusCode();
            Console.Write(response.Content.ReadAsStringAsync());
            var responseBody = await response.Content.ReadFromJsonAsync<JsonElement>();
            Console.Write(responseBody.GetRawText());

            var result = responseBody.GetProperty("choices")[0].GetProperty("message").GetProperty("content").GetString() ?? "No response";
            Console.Write("Answer: " + result);
            return result;
        }

        public async Task<string> GetChatGPTStreamedResponse(string sessionId, string systemMessage, string userMessage, string? assistanMessage = null)
        {
            _apiKey = GetApiKey();

            ChatGPTRequest finalRequestBody;

            if (assistanMessage == null)
            {
                finalRequestBody = new ChatGPTRequest
                {
                    Model = "deepseek-chat",
                    Temperature = 0.2,
                    Messages = new[]
                    {
                        new Message { Role = "system", Content = systemMessage },
                        new Message { Role = "user", Content = userMessage }
                    },
                    Stream = true
                };
            }
            else
            {
                finalRequestBody = new ChatGPTRequest
                {
                    Model = "deepseek-chat",
                    Temperature = 0.2,
                    Messages = new[]
                    {
                        new Message { Role = "system", Content = systemMessage },
                        new Message {Role = "assistant", Content= assistanMessage},
                        new Message { Role = "user", Content = userMessage }
                    },
                    Stream = true
                };

            }
            string requestJson = System.Text.Json.JsonSerializer.Serialize(finalRequestBody, new JsonSerializerOptions
            {
                PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
                WriteIndented = true
            }
            );
            var finalRequestContent = new StringContent(requestJson, Encoding.UTF8, "application/json");

            Console.Write(finalRequestContent);

            var httpRequest = new HttpRequestMessage(HttpMethod.Post, DeepSeekEndpoint)
            {
                Content = finalRequestContent
            };

            _httpClient.DefaultRequestHeaders.Clear();
            _httpClient.DefaultRequestHeaders.Add("Authorization", $"Bearer {_apiKey}");

            // Use SendAsync with streamed response
            var sResponse = await _httpClient.SendAsync(httpRequest, HttpCompletionOption.ResponseHeadersRead);
            sResponse.EnsureSuccessStatusCode();

            using var responseStream = await sResponse.Content.ReadAsStreamAsync();
            using var reader = new StreamReader(responseStream);

            //Console.Write("Streamed response:");
            string streamedHtmlContent = string.Empty;

            while (!reader.EndOfStream)
            {
                var line = await reader.ReadLineAsync();
                //Console.WriteLine($"Raw Stream Line: {line}"); // Log each line
                if (!string.IsNullOrWhiteSpace(line) && line.StartsWith("data: "))
                {
                    var jsonResponse = line.Substring(6); // Remove "data: " prefix
                    if (jsonResponse == "[DONE]")
                    {
                        Console.WriteLine("Stream ended.");
                        break; // End of stream
                    }

                    try
                    {
                        //Console.WriteLine($"JSON Response: {jsonResponse}"); // Debug JSON response
                        //TODO: do we really have to += the content, or should we just invoke with the delta?
                        var chunk = JsonConvert.DeserializeObject<StreamedResponse>(jsonResponse);
                        if (chunk?.Choices != null && chunk.Choices.Count > 0 && chunk.Choices[0].Delta?.Content != null)
                        {
                            streamedHtmlContent += chunk.Choices[0].Delta.Content; // Append the streamed content
                            if (!string.IsNullOrEmpty(streamedHtmlContent) && _callback != null)
                            {
                                _callback?.Invoke(streamedHtmlContent); 
                            }
                            //Console.WriteLine($"Appended Text: {chunk.Choices[0].Delta.Content}"); // Debug appended text

                        }
                        else
                        {
                            Console.WriteLine("No content in this chunk.");
                        }
                    }
                    catch (JsonSerializationException ex)
                    {
                        Console.WriteLine($"Deserialization error: {ex.Message}");
                    }
                }
            }

            Console.WriteLine("Final streamed content:");
            Console.WriteLine(streamedHtmlContent);



            return streamedHtmlContent;
        }
    }
}