Fix IOException spam in TryDownloadToCompleteness

1. Use HashSet on both url and fileInfo input to detect and skip duplicate requests
2. Move to use FileStream for any file operation

Finally?? pls no jinx

Author: bagusnl

CollapseLauncher/Classes/Helper/Image/ImageLoaderHelper.cs

@@ -479,14 +479,25 @@ private static bool TryGetMd5HashFromFilename([NotNull] string fileName, out byt
         }
 #nullable restore
 
+        private static HashSet<FileInfo> _processingFiles = new();
+        private static HashSet<string> _processingUrls = new();
+    
         public static async void TryDownloadToCompletenessAsync(string url, FileInfo fileInfo, CancellationToken token)
             => await TryDownloadToCompleteness(url, fileInfo, token);
 
         public static async ValueTask TryDownloadToCompleteness(string url, FileInfo fileInfo, CancellationToken token)
         {
+            if (_processingFiles.Contains(fileInfo) || _processingUrls.Contains(url))
+            {
+                Logger.LogWriteLine("Found duplicate download request, skipping...\r\n\t" +
+                                    $"URL : {url}", LogType.Warning, true);
+                return;
+            }
             byte[] buffer = ArrayPool<byte>.Shared.Rent(4 << 10);
             try
             {
+                _processingFiles.Add(fileInfo);
+                _processingUrls.Add(url);
                 // Initialize file temporary name
                 FileInfo fileInfoTemp = new FileInfo(fileInfo.FullName + "_temp");
                 long fileLength = 0;
@@ -499,23 +510,27 @@ public static async ValueTask TryDownloadToCompleteness(string url, FileInfo fil
                 // Try to get the remote stream and download the file
                 await using (Stream netStream = await FallbackCDNUtil.GetHttpStreamFromResponse(url, token))
                 {
-                    await using (Stream outStream = fileInfoTemp.Create())
+                    await using (FileStream outStream = new FileStream(fileInfoTemp.FullName, FileMode.Create, 
+                                                                       FileAccess.ReadWrite, FileShare.ReadWrite))
                     {
                         // Get the file length
                         fileLength = netStream.Length;
 
                         // Create the prop file for download completeness checking
                         string outputParentPath = Path.GetDirectoryName(fileInfoTemp.FullName);
-                        string outputFilename = Path.GetFileName(fileInfoTemp.FullName);
+                        string outputFilename   = Path.GetFileName(fileInfoTemp.FullName);
                         if (outputParentPath != null)
                         {
                             string propFilePath = Path.Combine(outputParentPath, $"{outputFilename}#{netStream.Length}");
-                            await File.Create(propFilePath).DisposeAsync();
+                            await using (FileStream _ = new FileStream(propFilePath, FileMode.Create, FileAccess.ReadWrite, FileShare.Delete))
+                            {
+                                // Just create the file
+                            }
                         }
 
                         // Copy (and download) the remote streams to local
                         int read;
-                        while ((read = await netStream.ReadAsync(buffer, token)) > 0)
+                        while ((read = await netStream.ReadAsync(buffer, 0, buffer.Length, token)) > 0)
                             await outStream.WriteAsync(buffer, 0, read, token);
                     }
                 }
@@ -539,6 +554,8 @@ public static async ValueTask TryDownloadToCompleteness(string url, FileInfo fil
             finally
             {
                 ArrayPool<byte>.Shared.Return(buffer);
+                _processingFiles.Remove(fileInfo);
+                _processingUrls.Remove(url);
             }
         }