Yi.Admin/Yi.Abp.Net8/module/ai-hub/Yi.Framework.AiHub.Application/Services/OpenApiService.cs

using System.Collections.Concurrent;
using System.Text;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using OpenAI.Chat;
using Volo.Abp.Application.Services;
using Yi.Framework.AiHub.Application.Contracts.Dtos;
using Yi.Framework.AiHub.Application.Contracts.Dtos.OpenAiDto;
using Yi.Framework.AiHub.Domain.Managers;
using Yi.Framework.AiHub.Domain.Shared.Dtos;

namespace Yi.Framework.AiHub.Application.Services;

public class OpenApiService : ApplicationService
{
    private readonly IHttpContextAccessor _httpContextAccessor;
    private readonly ILogger<OpenApiService> _logger;

    public OpenApiService(IHttpContextAccessor httpContextAccessor, ILogger<OpenApiService> logger)
    {
        _httpContextAccessor = httpContextAccessor;
        _logger = logger;
    }

    [HttpPost("/v1/chat/completions")]
    public async Task ChatCompletionsAsync(ChatCompletionsInput input, CancellationToken cancellationToken)
    {
        //前面都是校验，后面才是真正的调用
        var httpContext = this._httpContextAccessor.HttpContext;
        var response = httpContext.Response;
        // 设置响应头，声明是 SSE 流
        response.ContentType = "text/event-stream";
        response.Headers.Append("Cache-Control", "no-cache");
        response.Headers.Append("Connection", "keep-alive");


        var history = new List<ChatMessage>();
        foreach (var aiChatContextDto in input.Messages)
        {
            if (aiChatContextDto.Role == "assistant")
            {
                history.Add(ChatMessage.CreateAssistantMessage(aiChatContextDto.Content));
            }
            else if (aiChatContextDto.Role == "user")
            {
                history.Add(ChatMessage.CreateUserMessage(aiChatContextDto.Content));
            }
        }

        var gateWay = LazyServiceProvider.GetRequiredService<AiGateWayManager>();
        var completeChatResponse = gateWay.CompleteChatAsync(input.Model, history, cancellationToken);
        var tokenUsage = new TokenUsage();
        await using var writer = new StreamWriter(response.Body, Encoding.UTF8, leaveOpen: true);


        //缓存队列算法
        // 创建一个队列来缓存消息
        var messageQueue = new ConcurrentQueue<string>();

        StringBuilder backupSystemContent = new StringBuilder();
        // 设置输出速率（例如每50毫秒输出一次）
        var outputInterval = TimeSpan.FromMilliseconds(100);
        // 标记是否完成接收
        var isComplete = false;
        // 启动一个后台任务来消费队列
        var outputTask = Task.Run(async () =>
        {
            while (!(isComplete && messageQueue.IsEmpty))
            {
                if (messageQueue.TryDequeue(out var message))
                {
                    await writer.WriteLineAsync(message);
                    await writer.FlushAsync(cancellationToken);
                }

                if (!isComplete)
                {
                    // 如果没有完成，才等待，已完成，全部输出
                    await Task.Delay(outputInterval, cancellationToken);
                }
            }
        }, cancellationToken);


        //IAsyncEnumerable 只能在最外层捕获异常（如果你有其他办法的话...）
        try
        {
            await foreach (var data in completeChatResponse)
            {
                if (data.IsFinish)
                {
                    tokenUsage = data.TokenUsage;
                }

                var model = MapToMessage(input.Model, data.Content);
                var message = JsonConvert.SerializeObject(model, new JsonSerializerSettings
                {
                    ContractResolver = new CamelCasePropertyNamesContractResolver()
                });
                backupSystemContent.Append(data.Content);
                // 将消息加入队列而不是直接写入
                messageQueue.Enqueue($"data: {message}\n");
            }
        }
        catch (Exception e)
        {
            _logger.LogError(e, $"Ai对话异常");
            var errorContent = $"Ai对话异常，异常信息：\n{e.Message}";
            var model = MapToMessage(input.Model, errorContent);
            var message = JsonConvert.SerializeObject(model, new JsonSerializerSettings
            {
                ContractResolver = new CamelCasePropertyNamesContractResolver()
            });
            backupSystemContent.Append(errorContent);
            messageQueue.Enqueue($"data: {message}\n");
        }

        //断开连接
        messageQueue.Enqueue("data: [DONE]\n");
        // 标记完成并发送结束标记
        isComplete = true;

        await outputTask;
    }

    private SendMessageOutputDto MapToMessage(string modelId, string content)
    {
        var output = new SendMessageOutputDto
        {
            Id = "chatcmpl-BotYP3BlN5T4g9YPnW0fBSBvKzXdd",
            Object = "chat.completion.chunk",
            Created = 1750336171,
            Model = modelId,
            Choices = new()
            {
                new Choice
                {
                    Index = 0,
                    Delta = new Delta
                    {
                        Content = content,
                        Role = "assistant"
                    },
                    FinishReason = null,
                    ContentFilterResults = new()
                    {
                        Hate = new()
                        {
                            Filtered = false,
                            Detected = null
                        },
                        SelfHarm = new()
                        {
                            Filtered = false,
                            Detected = null
                        },
                        Sexual = new()
                        {
                            Filtered = false,
                            Detected = null
                        },
                        Violence = new()
                        {
                            Filtered = false,
                            Detected = null
                        },
                        Jailbreak = new()
                        {
                            Filtered = false,
                            Detected = false
                        },
                        Profanity = new()
                        {
                            Filtered = false,
                            Detected = false
                        },
                    }
                }
            },
            SystemFingerprint = "",
            Usage = new Usage
            {
                PromptTokens = 0,
                CompletionTokens = 0,
                TotalTokens = 0,
                PromptTokensDetails = new()
                {
                    AudioTokens = 0,
                    CachedTokens = 0
                },
                CompletionTokensDetails = new()
                {
                    AudioTokens = 0,
                    ReasoningTokens = 0,
                    AcceptedPredictionTokens = 0,
                    RejectedPredictionTokens = 0
                }
            }
        };

        return output;
    }
}