// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Threading;
using System.Threading.Tasks;
using System.Threading.Tasks.Sources;

namespace System.IO.Pipelines
{
    /// <summary>The default <see cref="System.IO.Pipelines.PipeWriter" /> and <see cref="System.IO.Pipelines.PipeReader" /> implementation.</summary>
    public sealed partial class Pipe
    {
        private sealed class DefaultPipeWriter : PipeWriter, IValueTaskSource<FlushResult>
        {
            private readonly Pipe _pipe;

            public DefaultPipeWriter(Pipe pipe)
            {
                _pipe = pipe;
            }

            public override void Complete(Exception? exception = null) => _pipe.CompleteWriter(exception);

            public override void CancelPendingFlush() => _pipe.CancelPendingFlush();

            public override bool CanGetUnflushedBytes => true;

#pragma warning disable CS0672 // Member overrides obsolete member
            public override void OnReaderCompleted(Action<Exception?, object?> callback, object? state) => _pipe.OnReaderCompleted(callback, state);
#pragma warning restore CS0672 // Member overrides obsolete member

            public override ValueTask<FlushResult> FlushAsync(CancellationToken cancellationToken = default) => _pipe.FlushAsync(cancellationToken);

            public override void Advance(int bytes) => _pipe.Advance(bytes);

            public override Memory<byte> GetMemory(int sizeHint = 0) => _pipe.GetMemory(sizeHint);

            public override Span<byte> GetSpan(int sizeHint = 0) => _pipe.GetSpan(sizeHint);

            public ValueTaskSourceStatus GetStatus(short token) => _pipe.GetFlushAsyncStatus();

            public FlushResult GetResult(short token) => _pipe.GetFlushAsyncResult();

            public void OnCompleted(Action<object?> continuation, object? state, short token, ValueTaskSourceOnCompletedFlags flags) => _pipe.OnFlushAsyncCompleted(continuation, state, flags);

            public override long UnflushedBytes => _pipe.GetUnflushedBytes();

            public override ValueTask<FlushResult> WriteAsync(ReadOnlyMemory<byte> source, CancellationToken cancellationToken = default)
            {
                return _pipe.WriteAsync(source, cancellationToken);
            }
        }
    }
}