openai/openai-dotnet

using NUnit.Framework;
using OpenAI.Responses;
using System;
using System.ClientModel;
using System.Collections.Generic;
using System.Linq;
using System.Text.Json;
using System.Threading.Tasks;

namespace OpenAI.Examples;

// This example uses experimental APIs which are subject to change. To use experimental APIs,
// please acknowledge their experimental status by suppressing the corresponding warning.
#pragma warning disable OPENAI001

public partial class ResponseExamples
{
    // See Example03_FunctionCalling.cs for the tool and function definitions.

    [Test]
    public async Task Example04_FunctionCallingStreamingAsync()
    {
        ResponsesClient client = new(apiKey: Environment.GetEnvironmentVariable("OPENAI_API_KEY"));

        CreateResponseOptions options = new("gpt-5", [ResponseItem.CreateUserMessageItem("What's the weather like today for my current location?")])
        {
            Tools = { getCurrentLocationTool, getCurrentWeatherTool },
            StreamingEnabled = true,
        };

        PrintMessageItems(options.InputItems.OfType<MessageResponseItem>());

        bool requiresAction;

        do
        {
            requiresAction = false;

            AsyncCollectionResult<StreamingResponseUpdate> responseUpdates = client.CreateResponseStreamingAsync(options);

            await foreach (StreamingResponseUpdate update in responseUpdates)
            {
                if (update is StreamingResponseOutputItemAddedUpdate outputItemAddedUpdated)
                {
                    if (outputItemAddedUpdated.Item is MessageResponseItem message && message.Role == MessageRole.Assistant)
                    {
                        Console.WriteLine($"[ASSISTANT]:");
                    }
                }

                if (update is StreamingResponseOutputTextDeltaUpdate outputTextUpdate)
                {
                    Console.Write(outputTextUpdate.Delta);
                }

                if (update is StreamingResponseOutputItemDoneUpdate outputItemDoneUpdate)
                {
                    options.InputItems.Add(outputItemDoneUpdate.Item);

                    if (outputItemDoneUpdate.Item is FunctionCallResponseItem functionCall)
                    {
                        switch (functionCall.FunctionName)
                        {
                            case nameof(GetCurrentLocation):
                                {
                                    string functionOutput = GetCurrentLocation();
                                    options.InputItems.Add(new FunctionCallOutputResponseItem(functionCall.CallId, functionOutput));
                                    break;
                                }

                            case nameof(GetCurrentWeather):
                                {
                                    // The arguments that the model wants to use to call the function are specified as a
                                    // stringified JSON object based on the schema defined in the tool definition. Note that
                                    // the model may hallucinate arguments too. Consequently, it is important to do the
                                    // appropriate parsing and validation before calling the function.
                                    using JsonDocument argumentsJson = JsonDocument.Parse(functionCall.FunctionArguments);
                                    bool hasLocation = argumentsJson.RootElement.TryGetProperty("location", out JsonElement location);
                                    bool hasUnit = argumentsJson.RootElement.TryGetProperty("unit", out JsonElement unit);

                                    if (!hasLocation)
                                    {
                                        throw new ArgumentNullException(nameof(location), "The location argument is required.");
                                    }

                                    string functionOutput = hasUnit
                                        ? GetCurrentWeather(location.GetString(), unit.GetString())
                                        : GetCurrentWeather(location.GetString());
                                    options.InputItems.Add(new FunctionCallOutputResponseItem(functionCall.CallId, functionOutput));
                                    break;
                                }

                            default:
                                {
                                    // Handle other unexpected calls.
                                    throw new NotImplementedException();
                                }
                        }

                        requiresAction = true;
                        break;
                    }
                }
            }
        } while (requiresAction);
    }
}

#pragma warning restore OPENAI001