// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.IO.Pipelines;
 
namespace Microsoft.AspNetCore.ResponseCaching;
 
internal sealed class CachedResponseBody
{
    public CachedResponseBody(List<byte[]> segments, long length)
    {
        Segments = segments;
        Length = length;
    }
 
    public List<byte[]> Segments { get; }
 
    public long Length { get; }
 
    public async Task CopyToAsync(PipeWriter destination, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(destination);
 
        foreach (var segment in Segments)
        {
            cancellationToken.ThrowIfCancellationRequested();
 
            Copy(segment, destination);
 
            await destination.FlushAsync(cancellationToken);
        }
    }
 
    private static void Copy(byte[] segment, PipeWriter destination)
    {
        var span = destination.GetSpan(segment.Length);
 
        segment.CopyTo(span);
        destination.Advance(segment.Length);
    }
}