Improved download system

PluginManager/Online/Helpers/OnlineFunctions.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Net.Http;
+using System.Threading.Tasks;
+using System.IO;
+using System.Threading;
+using PluginManager.Others;
+
+namespace PluginManager.Online.Helpers
+{
+    internal static class OnlineFunctions
+    {
+        internal static async Task DownloadFileAsync(this HttpClient client, string url, Stream destination, IProgress<float> progress = null, CancellationToken cancellation = default)
+        {
+            using (var response = await client.GetAsync(url, HttpCompletionOption.ResponseHeadersRead))
+            {
+                var contentLength = response.Content.Headers.ContentLength;
+
+                using (var download = await response.Content.ReadAsStreamAsync())
+                {
+
+                    // Ignore progress reporting when no progress reporter was 
+                    // passed or when the content length is unknown
+                    if (progress == null || !contentLength.HasValue)
+                    {
+                        await download.CopyToAsync(destination);
+                        return;
+                    }
+
+                    // Convert absolute progress (bytes downloaded) into relative progress (0% - 100%)
+                    var relativeProgress = new Progress<long>(totalBytes => progress.Report((float)totalBytes / contentLength.Value * 100));
+                    // Use extension method to report progress while downloading
+                    await download.CopyToOtherStreamAsync(destination, 81920, relativeProgress, cancellation);
+                    progress.Report(1);
+                }
+            }
+        }
+
+        internal static async Task<string> DownloadStringAsync(string url, CancellationToken cancellation = default)
+        {
+            using (var client = new HttpClient())
+            {
+                return await client.GetStringAsync(url);
+            }
+        }
+    }
+}