SPT-AKI-Installer/SPTInstaller/Helpers/HttpClientProgressExtensions.cs

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

namespace SPTInstaller.Helpers;

public static class HttpClientProgressExtensions
{
    public static async Task DownloadDataAsync(this HttpClient client, string requestUrl, Stream destination, IProgress<double> progress = null, CancellationToken cancellationToken = default(CancellationToken))
    {
        using (var response = await client.GetAsync(requestUrl, HttpCompletionOption.ResponseHeadersRead))
        {
            var contentLength = response.Content.Headers.ContentLength;
            using (var download = await response.Content.ReadAsStreamAsync())
            {
                // no progress... no contentLength... very sad
                if (progress is null || !contentLength.HasValue)
                {
                    await download.CopyToAsync(destination);
                    return;
                }
                // Such progress and contentLength much reporting Wow!
                var progressWrapper = new Progress<long>(totalBytes => progress.Report(GetProgressPercentage(totalBytes, contentLength.Value)));
                await download.CopyToAsync(destination, 81920, progressWrapper, cancellationToken);
            }
        }

        float GetProgressPercentage(float totalBytes, float currentBytes) => (totalBytes / currentBytes) * 100f;
    }

    static async Task CopyToAsync(this Stream source, Stream destination, int bufferSize, IProgress<long> progress = null, CancellationToken cancellationToken = default(CancellationToken))
    {
        if (bufferSize < 0)
            throw new ArgumentOutOfRangeException(nameof(bufferSize));
        if (source is null)
            throw new ArgumentNullException(nameof(source));
        if (!source.CanRead)
            throw new InvalidOperationException($"'{nameof(source)}' is not readable.");
        if (destination == null)
            throw new ArgumentNullException(nameof(destination));
        if (!destination.CanWrite)
            throw new InvalidOperationException($"'{nameof(destination)}' is not writable.");

        var buffer = new byte[bufferSize];
        long totalBytesRead = 0;
        int bytesRead;
        while ((bytesRead = await source.ReadAsync(buffer, 0, buffer.Length, cancellationToken).ConfigureAwait(false)) != 0)
        {
            await destination.WriteAsync(buffer, 0, bytesRead, cancellationToken).ConfigureAwait(false);
            totalBytesRead += bytesRead;
            progress?.Report(totalBytesRead);
        }
    }
}