namespace Sunfish.Http;

/// <summary>
/// Envuelve el flujo de la conexion y cancela cada lectura o escritura que tarde demasiado
/// (conexiones abandonadas o lentas a proposito). El plazo es por operacion, no total: una
/// descarga larga por un modem lento no se corta mientras avance.
/// </summary>
internal sealed class TimeoutStream(Stream inner, CancellationToken shutdown) : Stream
{
    public TimeSpan ReadLimit { get; set; } = TimeSpan.FromSeconds(30);
    public TimeSpan WriteLimit { get; set; } = TimeSpan.FromSeconds(120);

    public override async ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken ct = default)
    {
        using var cts = CancellationTokenSource.CreateLinkedTokenSource(ct, shutdown);
        cts.CancelAfter(ReadLimit);
        return await inner.ReadAsync(buffer, cts.Token);
    }

    public override async ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, CancellationToken ct = default)
    {
        using var cts = CancellationTokenSource.CreateLinkedTokenSource(ct, shutdown);
        cts.CancelAfter(WriteLimit);
        await inner.WriteAsync(buffer, cts.Token);
    }

    public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken ct) =>
        ReadAsync(buffer.AsMemory(offset, count), ct).AsTask();

    public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken ct) =>
        WriteAsync(buffer.AsMemory(offset, count), ct).AsTask();

    public override int Read(byte[] buffer, int offset, int count) =>
        ReadAsync(buffer.AsMemory(offset, count)).AsTask().GetAwaiter().GetResult();

    public override void Write(byte[] buffer, int offset, int count) =>
        WriteAsync(buffer.AsMemory(offset, count)).AsTask().GetAwaiter().GetResult();

    public override Task FlushAsync(CancellationToken ct) => inner.FlushAsync(ct);
    public override void Flush() => inner.Flush();
    public override bool CanRead => true;
    public override bool CanSeek => false;
    public override bool CanWrite => true;
    public override long Length => throw new NotSupportedException();
    public override long Position { get => throw new NotSupportedException(); set => throw new NotSupportedException(); }
    public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();
    public override void SetLength(long value) => throw new NotSupportedException();

    protected override void Dispose(bool disposing)
    {
        if (disposing)
            inner.Dispose();
        base.Dispose(disposing);
    }
}