ChatGPT 聊天程式練習 - 使用 .NET + Azure OpenAI API

using Azure;
using Azure.AI.OpenAI;

public class ChatRecord
{
    public DateTime Time { get; set; }
    public string Role { get; set; } // U-User, A-Assistant
    public string Message { get; set;}
    public ChatRecord(string msg, string role = "U") {
        this.Message = msg;
        this.Role = role;
    }
}

public class ChatGptService
{
    private readonly string apiUrl;
    private readonly string apiKey;
    private readonly string deployName;
    OpenAIClient client;
    public float Temperature = (float)0.7;
    public int MaxTokens = 800;
    public float NucleusSamplingFactor = (float)0.95;
    public int FrequencyPenalty = 0;
    public int PresencePenalty = 0;
    public string SystemPrompt = "你是一名 AI 助理，使用繁體中文提供解答";

    public ChatGptService(string apiUrl, string apiKey, string deployName)
    {
        this.apiUrl = apiUrl;
        this.apiKey = apiKey;
        this.deployName = deployName;
        client = new OpenAIClient(
            new Uri(apiUrl),
            new AzureKeyCredential(apiKey));

    }

    public async Task<string> Generate(IEnumerable<ChatRecord> contextMessags)
    {
        var chatMessages = new List<ChatMessage>() {
                new ChatMessage(ChatRole.System, SystemPrompt)
        };
        chatMessages.AddRange(contextMessags.Select(m => new ChatMessage(
            m.Role == "A" ? ChatRole.Assistant : ChatRole.User,
            m.Message
        )));

        Response<ChatCompletions> response = await client.GetChatCompletionsAsync(
        deploymentOrModelName: deployName,
        new ChatCompletionsOptions(chatMessages)
        {
            Temperature = Temperature,
            MaxTokens = MaxTokens,
            NucleusSamplingFactor = NucleusSamplingFactor,
            FrequencyPenalty = FrequencyPenalty,
            PresencePenalty = PresencePenalty
        });

        ChatCompletions completions = response.Value;
        return completions.Choices.First().Message.Content;
    }
}

using System.Diagnostics;
using System.Text;
using System.Security.Cryptography;
using System.Text.RegularExpressions;
Func<string, string> GetOrSetEnvVar = (varName) =>
{
    var val = Environment.GetEnvironmentVariable(varName, EnvironmentVariableTarget.User);
    if (!string.IsNullOrEmpty(val))
    {
        try
        {
            val = Encoding.UTF8.GetString(
                ProtectedData.Unprotect(Convert.FromBase64String(val), null, DataProtectionScope.CurrentUser));
            return val;
        }
        catch
        {
            Console.WriteLine("非有效加密格式，請重新輸入");
        }
    }
    Console.Write($"請設定[{varName}]：");
    val = Console.ReadLine() ?? string.Empty;
    //加密後存入環境變數
    var enc =
        Convert.ToBase64String(
            ProtectedData.Protect(Encoding.UTF8.GetBytes(val), null, DataProtectionScope.CurrentUser));
    Environment.SetEnvironmentVariable(varName, enc, EnvironmentVariableTarget.User);
    return val;
};

var apiUrl = GetOrSetEnvVar("OpenAI_Url");
var apiKey = GetOrSetEnvVar("OpenAI_Key");
var deployName = "GPT35-16K";
var chatSvc = new ChatGptService(apiUrl, apiKey, deployName);
var context = new Queue<ChatRecord>();
var sb = new StringBuilder();
Console.WriteLine("ChatGPT API 練習");
Console.WriteLine("/new 開始新對話、/quit 結束程式");
Action showPrompt = () =>
{
    Console.ForegroundColor = ConsoleColor.Yellow;
    Console.Write(">");
};
showPrompt();
while (true)
{
    var line = Console.ReadLine();
    if (line == "/quit")
    {
        Print("再見，下次再聊", ConsoleColor.Green);
        Console.ResetColor();
        break;
    }
    else if (line == "/new")
    {
        Print("清空對話，重新開始", ConsoleColor.Magenta);
        context.Clear();
    }
    else if (string.IsNullOrEmpty(line) && Regex.IsMatch(sb.ToString(), "\\S"))
    {
        // 送出內容
        context.Enqueue(new ChatRecord(sb.ToString()));
        Console.ForegroundColor = ConsoleColor.Cyan;
        Console.Write("傳送中，請稍侯");

        var cts = new CancellationTokenSource();
        var cancelToken = cts.Token;
        var progress = Task.Run(async () =>
        {
            while (!cancelToken.IsCancellationRequested)
            {
                await Task.Delay(500, cancelToken);
                Console.Write(".");
            }
        }, cancelToken);
        
        var ts = new Stopwatch();
        ts.Start();
        var res = await chatSvc.Generate(context);
        ts.Stop();

        // 將回答也納入上下文
        context.Enqueue(new ChatRecord(res, "A"));
        // 上下文內容有 Token 數上限，不能無限累加，取最新十次對話
        // TODO: 更精巧做法是將先前對話摘要成精簡版
        while (context.Count > 10) context.Dequeue();

        // 印出回答
        cts.Cancel();
        Console.WriteLine($" {ts.ElapsedMilliseconds:n0}ms");
        Print(res, ConsoleColor.White);
    }
    else
    {
        sb.AppendLine(line);
    }
}

void Print(string msg, ConsoleColor color = ConsoleColor.White)
{
    Console.ForegroundColor = color;
    Console.WriteLine(msg);
    showPrompt();
}

    public async IAsyncEnumerable<String> StreamingGenerate(IEnumerable<ChatRecord> contextMessags)
    {
        var chatMessages = new List<ChatMessage>() {
                new ChatMessage(ChatRole.System, SystemPrompt)
        };
        chatMessages.AddRange(contextMessags.Select(m => new ChatMessage(
            m.Role == "A" ? ChatRole.Assistant : ChatRole.User,
            m.Message
        )));
        Response<StreamingChatCompletions> response = await client.GetChatCompletionsStreamingAsync(
        deploymentOrModelName: deployName,
        new ChatCompletionsOptions(chatMessages)
        {
            Temperature = Temperature,
            MaxTokens = MaxTokens,
            NucleusSamplingFactor = NucleusSamplingFactor,
            FrequencyPenalty = FrequencyPenalty,
            PresencePenalty = PresencePenalty
        });
        // https://blog.darkthread.net/blog/iasyncenumerable-in-mvc/
        await foreach (var choice in  response.Value.GetChoicesStreaming()) {
            await foreach (var msg in choice.GetMessageStreaming()) {
                yield return msg.Content;
            }
        }
    }

    else if (string.IsNullOrEmpty(line) && Regex.IsMatch(sb.ToString(), "\\S")) {
        // 送出內容
        context.Enqueue(new ChatRecord(sb.ToString()));
        sb.Clear();
        Console.ForegroundColor = ConsoleColor.Cyan;
        Console.WriteLine("傳送中，請稍侯...");
        Console.ForegroundColor = ConsoleColor.White;
        await foreach (var msg in chatSvc.StreamingGenerate(context)) {
            sb.Append(msg);
            Console.Write(msg);
        }
        // 將回答也納入上下文
        context.Enqueue(new ChatRecord(sb.ToString(), "A"));
        // 上下文內容有 Token 數上限，不能無限累加，取最新十次對話
        // TODO: 更精巧做法是將先前對話摘要成精簡版
        while (context.Count > 10) context.Dequeue();

        Print("");
    }