using System.Net.Http;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;

namespace Млаумчерб.Клиент;

public record struct NetworkTransferResult(long BytesTotal, long BytesTransferred, long BytesPerSecond)
{
    public override string ToString()
    {
        return $"transferred {BytesTransferred}/{BytesTotal} bytes ({BytesPerSecond}) bps";
    }
}

public class NetworkTransferTask
{
    public Task Task { get; private set; }
    public Progress<NetworkTransferResult> Progress { get; private set; }

    private Stream _src;
    private Stream _dst;
    private CancellationTokenSource _cts;
    private DTLib.Timer _timer;
    
    public NetworkTransferTask(Stream src, Stream dst)
    {
        _src = src;
        _dst = dst;
        _cts = new CancellationTokenSource();
        Progress = new Progress<NetworkTransferResult>();
        _timer = new(true, 1000, ReportProgress);
        Task = Task.CompletedTask;
    }

    public void Start()
    {
        _timer.Start();
        Task = _src.CopyToAsync(_dst);
        _timer.Stop();
    }

    public void Stop()
    {
        _cts.Cancel();
        _timer.Stop();
    }

    private long previousBytesTransferred;
    private void ReportProgress()
    {
        long bytesTotal = _src.Length, bytesTransferred = _src.Position;
        long bytesPerSecond = bytesTransferred - previousBytesTransferred;
        previousBytesTransferred = bytesTransferred;
        ((IProgress<NetworkTransferResult>)Progress).Report(new NetworkTransferResult(bytesTotal, bytesTransferred, bytesPerSecond));
    }
    
    public TaskAwaiter GetAwaiter() => Task.GetAwaiter();
}

public static class NetworkHelper
{
    private static HttpClient http = new();

    public static NetworkTransferTask DownloadHTTPFileAsync(string url, Stream destinationStream)
    {
        var sourceStream = http.GetStreamAsync(url).GetAwaiter().GetResult();
        NetworkTransferTask task = new(sourceStream, destinationStream);
        task.Start();
        return task;
    }
}