// 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.Buffers;
using System.IO.Pipelines;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using BenchmarkDotNet.Attributes;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.Server.Kestrel.Core;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
using Microsoft.AspNetCore.InternalTesting;
 
namespace Microsoft.AspNetCore.Server.Kestrel.Microbenchmarks;
 
public class Http1WritingBenchmark
{
    // Standard completed task
    private static readonly Func<object, Task> _syncTaskFunc = (obj) => Task.CompletedTask;
    // Non-standard completed task
    private static readonly Task _pseudoAsyncTask = Task.FromResult(27);
    private static readonly Func<object, Task> _pseudoAsyncTaskFunc = (obj) => _pseudoAsyncTask;
 
    private TestHttp1Connection _http1Connection;
    private DuplexPipe.DuplexPipePair _pair;
    private MemoryPool<byte> _memoryPool;
    private Task _consumeResponseBodyTask;
 
    private readonly byte[] _writeData = Encoding.ASCII.GetBytes("Hello, World!");
 
    [GlobalSetup]
    public void GlobalSetup()
    {
        _memoryPool = PinnedBlockMemoryPoolFactory.Create();
        _http1Connection = MakeHttp1Connection();
        _consumeResponseBodyTask = ConsumeResponseBody();
    }
 
    [Params(true, false)]
    public bool WithHeaders { get; set; }
 
    [Params(true, false)]
    public bool Chunked { get; set; }
 
    [Params(Startup.None, Startup.Sync, Startup.Async)]
    public Startup OnStarting { get; set; }
 
    [IterationSetup]
    public void Setup()
    {
        _http1Connection.Reset();
        if (Chunked)
        {
            _http1Connection.RequestHeaders.Add("Transfer-Encoding", "chunked");
        }
        else
        {
            _http1Connection.RequestHeaders.ContentLength = _writeData.Length;
        }
 
        if (!WithHeaders)
        {
            _http1Connection.FlushAsync().GetAwaiter().GetResult();
        }
 
        ResetState();
    }
 
    private void ResetState()
    {
        if (WithHeaders)
        {
            _http1Connection.ResetState();
 
            switch (OnStarting)
            {
                case Startup.Sync:
                    _http1Connection.OnStarting(_syncTaskFunc, null);
                    break;
                case Startup.Async:
                    _http1Connection.OnStarting(_pseudoAsyncTaskFunc, null);
                    break;
            }
        }
    }
 
    [Benchmark]
    public Task WriteAsync()
    {
        ResetState();
 
        return _http1Connection.ResponseBody.WriteAsync(_writeData, 0, _writeData.Length, default(CancellationToken));
    }
 
    private TestHttp1Connection MakeHttp1Connection()
    {
        var options = new PipeOptions(_memoryPool, readerScheduler: PipeScheduler.Inline, writerScheduler: PipeScheduler.Inline, useSynchronizationContext: false);
        var pair = DuplexPipe.CreateConnectionPair(options, options);
        _pair = pair;
 
        var serviceContext = TestContextFactory.CreateServiceContext(
            serverOptions: new KestrelServerOptions(),
            httpParser: new HttpParser<Http1ParsingHandler>(),
            dateHeaderValueManager: new DateHeaderValueManager(TimeProvider.System));
 
        var connectionContext = TestContextFactory.CreateHttpConnectionContext(
            serviceContext: serviceContext,
            connectionContext: null,
            transport: pair.Transport,
            timeoutControl: new TimeoutControl(timeoutHandler: null, TimeProvider.System),
            memoryPool: _memoryPool,
            connectionFeatures: new FeatureCollection());
 
        var http1Connection = new TestHttp1Connection(connectionContext);
 
        http1Connection.Reset();
        http1Connection.InitializeBodyControl(MessageBody.ZeroContentLengthKeepAlive);
        serviceContext.DateHeaderValueManager.OnHeartbeat();
 
        return http1Connection;
    }
 
    private async Task ConsumeResponseBody()
    {
        var reader = _pair.Application.Input;
        var readResult = await reader.ReadAsync();
 
        while (!readResult.IsCompleted)
        {
            reader.AdvanceTo(readResult.Buffer.End);
            readResult = await reader.ReadAsync();
        }
 
        reader.Complete();
    }
 
    public enum Startup
    {
        None,
        Sync,
        Async
    }
 
    [GlobalCleanup]
    public void Dispose()
    {
        _pair.Transport.Output.Complete();
        _consumeResponseBodyTask.GetAwaiter().GetResult();
        _memoryPool?.Dispose();
    }
}