// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Composition;
using System.Threading;
using Microsoft.CodeAnalysis.ExternalAccess.Copilot.Completion;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Threading;

namespace Microsoft.CodeAnalysis.ExternalAccess.Copilot.Internal.Completion;

[Export(typeof(ICSharpCopilotContextProviderService)), Shared]
[method: ImportingConstructor]
[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
internal sealed class CSharpContextProviderService([ImportMany] IEnumerable<IContextProvider> providers)
    : ICSharpCopilotContextProviderService
{
    private readonly ImmutableArray<IContextProvider> _providers = [.. providers];

    public IAsyncEnumerable<IContextItem> GetContextItemsAsync(Document document, int position, IReadOnlyDictionary<string, object> activeExperiments, CancellationToken cancellationToken)
        => ProducerConsumer<IContextItem>.RunParallelStreamAsync(
            _providers,
            static async (provider, callback, args, cancellationToken) =>
                await provider.ProvideContextItemsAsync(
                    args.document, args.position, args.activeExperiments,
                    (items, cancellationToken) =>
                    {
                        foreach (var item in items)
                            callback(item);

                        return default;
                    }, cancellationToken).ConfigureAwait(false),
            args: (document, position, activeExperiments),
            cancellationToken);
}