using System.Net;

namespace VFXReviewWorker;

/// <summary>
/// StreamContent that reports bytes sent, so a long upload can show progress.
/// Length is computed from the stream, so the PUT still carries Content-Length
/// (presigned S3 uploads reject chunked bodies).
/// </summary>
internal sealed class ProgressStreamContent : HttpContent
{
    private readonly Stream _source;
    private readonly Action<long>? _onProgress;

    public ProgressStreamContent(Stream source, Action<long>? onProgress)
    {
        _source = source;
        _onProgress = onProgress;
    }

    protected override Task SerializeToStreamAsync(Stream stream, TransportContext? context) =>
        SerializeToStreamAsync(stream, context, CancellationToken.None);

    protected override async Task SerializeToStreamAsync(Stream stream, TransportContext? context, CancellationToken ct)
    {
        var buffer = new byte[81920];
        long sent = 0;
        int read;
        while ((read = await _source.ReadAsync(buffer, ct)) > 0)
        {
            await stream.WriteAsync(buffer.AsMemory(0, read), ct);
            sent += read;
            _onProgress?.Invoke(sent);
        }
    }

    protected override bool TryComputeLength(out long length)
    {
        length = _source.Length;
        return true;
    }
}