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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Threading;
using System.Threading.Channels;
using System.Threading.Tasks;
using Microsoft.Shared.Diagnostics;
#pragma warning disable VSTHRD003 // Avoid awaiting foreign Tasks
namespace Microsoft.Extensions.AI;
/// <summary>Represents a delegating chat client that wraps an inner client with implementations provided by delegates.</summary>
internal sealed class AnonymousDelegatingChatClient : DelegatingChatClient
{
/// <summary>The delegate to use as the implementation of <see cref="GetResponseAsync"/>.</summary>
private readonly Func<IEnumerable<ChatMessage>, ChatOptions?, IChatClient, CancellationToken, Task<ChatResponse>>? _getResponseFunc;
/// <summary>The delegate to use as the implementation of <see cref="GetStreamingResponseAsync"/>.</summary>
/// <remarks>
/// When non-<see langword="null"/>, this delegate is used as the implementation of <see cref="GetStreamingResponseAsync"/> and
/// will be invoked with the same arguments as the method itself, along with a reference to the inner client.
/// When <see langword="null"/>, <see cref="GetStreamingResponseAsync"/> will delegate directly to the inner client.
/// </remarks>
private readonly Func<IEnumerable<ChatMessage>, ChatOptions?, IChatClient, CancellationToken, IAsyncEnumerable<ChatResponseUpdate>>? _getStreamingResponseFunc;
/// <summary>The delegate to use as the implementation of both <see cref="GetResponseAsync"/> and <see cref="GetStreamingResponseAsync"/>.</summary>
private readonly Func<IEnumerable<ChatMessage>, ChatOptions?, Func<IEnumerable<ChatMessage>, ChatOptions?, CancellationToken, Task>, CancellationToken, Task>? _sharedFunc;
/// <summary>
/// Initializes a new instance of the <see cref="AnonymousDelegatingChatClient"/> class.
/// </summary>
/// <param name="innerClient">The inner client.</param>
/// <param name="sharedFunc">
/// A delegate that provides the implementation for both <see cref="GetResponseAsync"/> and <see cref="GetStreamingResponseAsync"/>.
/// In addition to the arguments for the operation, it's provided with a delegate to the inner client that should be
/// used to perform the operation on the inner client. It will handle both the non-streaming and streaming cases.
/// </param>
/// <remarks>
/// This overload may be used when the anonymous implementation needs to provide pre-processing and/or post-processing, but doesn't
/// need to interact with the results of the operation, which will come from the inner client.
/// </remarks>
/// <exception cref="ArgumentNullException"><paramref name="innerClient"/> is <see langword="null"/>.</exception>
/// <exception cref="ArgumentNullException"><paramref name="sharedFunc"/> is <see langword="null"/>.</exception>
public AnonymousDelegatingChatClient(
IChatClient innerClient,
Func<IEnumerable<ChatMessage>, ChatOptions?, Func<IEnumerable<ChatMessage>, ChatOptions?, CancellationToken, Task>, CancellationToken, Task> sharedFunc)
: base(innerClient)
{
_ = Throw.IfNull(sharedFunc);
_sharedFunc = sharedFunc;
}
/// <summary>
/// Initializes a new instance of the <see cref="AnonymousDelegatingChatClient"/> class.
/// </summary>
/// <param name="innerClient">The inner client.</param>
/// <param name="getResponseFunc">
/// A delegate that provides the implementation for <see cref="GetResponseAsync"/>. When <see langword="null"/>,
/// <paramref name="getStreamingResponseFunc"/> must be non-null, and the implementation of <see cref="GetResponseAsync"/>
/// will use <paramref name="getStreamingResponseFunc"/> for the implementation.
/// </param>
/// <param name="getStreamingResponseFunc">
/// A delegate that provides the implementation for <see cref="GetStreamingResponseAsync"/>. When <see langword="null"/>,
/// <paramref name="getResponseFunc"/> must be non-null, and the implementation of <see cref="GetStreamingResponseAsync"/>
/// will use <paramref name="getResponseFunc"/> for the implementation.
/// </param>
/// <exception cref="ArgumentNullException"><paramref name="innerClient"/> is <see langword="null"/>.</exception>
/// <exception cref="ArgumentNullException">Both <paramref name="getResponseFunc"/> and <paramref name="getStreamingResponseFunc"/> are <see langword="null"/>.</exception>
public AnonymousDelegatingChatClient(
IChatClient innerClient,
Func<IEnumerable<ChatMessage>, ChatOptions?, IChatClient, CancellationToken, Task<ChatResponse>>? getResponseFunc,
Func<IEnumerable<ChatMessage>, ChatOptions?, IChatClient, CancellationToken, IAsyncEnumerable<ChatResponseUpdate>>? getStreamingResponseFunc)
: base(innerClient)
{
ThrowIfBothDelegatesNull(getResponseFunc, getStreamingResponseFunc);
_getResponseFunc = getResponseFunc;
_getStreamingResponseFunc = getStreamingResponseFunc;
}
/// <inheritdoc/>
public override Task<ChatResponse> GetResponseAsync(
IEnumerable<ChatMessage> messages, ChatOptions? options = null, CancellationToken cancellationToken = default)
{
_ = Throw.IfNull(messages);
if (_sharedFunc is not null)
{
return GetResponseViaSharedAsync(messages, options, cancellationToken);
async Task<ChatResponse> GetResponseViaSharedAsync(
IEnumerable<ChatMessage> messages, ChatOptions? options, CancellationToken cancellationToken)
{
ChatResponse? response = null;
await _sharedFunc(messages, options, async (messages, options, cancellationToken) =>
{
response = await InnerClient.GetResponseAsync(messages, options, cancellationToken).ConfigureAwait(false);
}, cancellationToken).ConfigureAwait(false);
if (response is null)
{
Throw.InvalidOperationException("The wrapper completed successfully without producing a ChatResponse.");
}
return response;
}
}
else if (_getResponseFunc is not null)
{
return _getResponseFunc(messages, options, InnerClient, cancellationToken);
}
else
{
Debug.Assert(_getStreamingResponseFunc is not null, "Expected non-null streaming delegate.");
return _getStreamingResponseFunc!(messages, options, InnerClient, cancellationToken)
.ToChatResponseAsync(cancellationToken);
}
}
/// <inheritdoc/>
public override IAsyncEnumerable<ChatResponseUpdate> GetStreamingResponseAsync(
IEnumerable<ChatMessage> messages, ChatOptions? options = null, CancellationToken cancellationToken = default)
{
_ = Throw.IfNull(messages);
if (_sharedFunc is not null)
{
var updates = Channel.CreateBounded<ChatResponseUpdate>(1);
#pragma warning disable CA2016 // explicitly not forwarding the cancellation token, as we need to ensure the channel is always completed
_ = Task.Run(async () =>
#pragma warning restore CA2016
{
Exception? error = null;
try
{
await _sharedFunc(messages, options, async (messages, options, cancellationToken) =>
{
await foreach (var update in InnerClient.GetStreamingResponseAsync(messages, options, cancellationToken).ConfigureAwait(false))
{
await updates.Writer.WriteAsync(update, cancellationToken).ConfigureAwait(false);
}
}, cancellationToken).ConfigureAwait(false);
}
catch (Exception ex)
{
error = ex;
throw;
}
finally
{
_ = updates.Writer.TryComplete(error);
}
});
return updates.Reader.ReadAllAsync(cancellationToken);
}
else if (_getStreamingResponseFunc is not null)
{
return _getStreamingResponseFunc(messages, options, InnerClient, cancellationToken);
}
else
{
Debug.Assert(_getResponseFunc is not null, "Expected non-null non-streaming delegate.");
return GetStreamingResponseAsyncViaGetResponseAsync(_getResponseFunc!(messages, options, InnerClient, cancellationToken));
static async IAsyncEnumerable<ChatResponseUpdate> GetStreamingResponseAsyncViaGetResponseAsync(Task<ChatResponse> task)
{
ChatResponse response = await task.ConfigureAwait(false);
foreach (var update in response.ToChatResponseUpdates())
{
yield return update;
}
}
}
}
/// <summary>Throws an exception if both of the specified delegates are null.</summary>
/// <exception cref="ArgumentNullException">Both <paramref name="getResponseFunc"/> and <paramref name="getStreamingResponseFunc"/> are <see langword="null"/>.</exception>
internal static void ThrowIfBothDelegatesNull(object? getResponseFunc, object? getStreamingResponseFunc)
{
if (getResponseFunc is null && getStreamingResponseFunc is null)
{
Throw.ArgumentNullException(nameof(getResponseFunc), $"At least one of the {nameof(getResponseFunc)} or {nameof(getStreamingResponseFunc)} delegates must be non-null.");
}
}
}
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