Improved handling and falback for retrieving Downloads folder path on Windows

* Catch exceptions from 'SHGetKnownFolderPath'

* Catch exceptions from 'Registry.GetValue'

* Add COM object integration for Known Folder retrieval

Author: tobibodamer

DownloadAssistant/Utilities/IOManager.cs

@@ -124,20 +124,50 @@ public static bool TryGetFullPath(string path, out string result)
         /// <returns>The path to the downloads folder, or <c>null</c> if the path cannot be determined.</returns>
         /// <exception cref="ArgumentNullException">Thrown when the home path is null or an empty string on Unix platforms.</exception>
         /// <exception cref="ArgumentException">Thrown when the path to the downloads folder is not of the correct format.</exception>
-        /// <exception cref="IOException">Thrown when an I/O error occurs.</exception>
         /// <exception cref="SecurityException">Thrown when the caller does not have the required permission to perform this operation.</exception>
         public static string? GetDownloadFolderPath()
         {
             if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
             {
-                string path = SHGetKnownFolderPath(new("374DE290-123F-4565-9164-39C4925E467B"), 0);
-                if (string.IsNullOrEmpty(path))
-                    return Convert.ToString(
-                    Registry.GetValue(
-                         @"HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders"
-                        , "{374DE290-123F-4565-9164-39C4925E467B}"
-                        , string.Empty));
-                else return path;
+                string? path = null;
+
+                try
+                {
+                    path = SHGetKnownFolderPath(new("374DE290-123F-4565-9164-39C4925E467B"), 0);
+                    if (!string.IsNullOrEmpty(path))
+                        return path;
+                }
+                catch (Exception) { }
+
+                try
+                {
+                    path = Convert.ToString(
+                     Registry.GetValue(
+                          @"HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders"
+                         , "{374DE290-123F-4565-9164-39C4925E467B}"
+                         , string.Empty));
+                }
+                catch (Exception) { }
+
+                IKnownFolderManager? knownFolderManager = null;
+                IKnownFolder? knownFolder = null;
+                try
+                {
+                    if (Type.GetTypeFromCLSID(new Guid("4DF0C730-DF9D-4AE3-9153-AA6B82E9795A")) is Type comClass && Activator.CreateInstance(comClass) is IKnownFolderManager manager)
+                        knownFolderManager = manager;
+                    knownFolderManager?.GetFolderByName("Downloads", out knownFolder);
+                    knownFolder?.GetPath(0, out path);
+                    if (!string.IsNullOrEmpty(path))
+                        return path;
+                }
+                catch (Exception) { }
+                finally
+                {
+                    if (knownFolder != null) Marshal.ReleaseComObject(knownFolder);
+                    if (knownFolderManager != null) Marshal.ReleaseComObject(knownFolderManager);
+                }
+
+                return string.IsNullOrEmpty(path) ? null : path;
             }
             else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) || RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
             {
@@ -155,6 +185,15 @@ private static extern string SHGetKnownFolderPath(
         [MarshalAs(UnmanagedType.LPStruct)] Guid rfid, uint dwFlags,
         nint hToken = 0);
 
+        [ComImport]
+        [Guid("8BE2D872-86AA-4D47-B776-32CCA40C7018")]
+        [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+        private interface IKnownFolderManager { void GetFolderByName(string canonicalName, out IKnownFolder knownFolder); }
+
+        [ComImport]
+        [Guid("3AA7AF7E-9B36-420C-A8E3-F77D4674A488")]
+        [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+        private interface IKnownFolder { void GetPath(int flags, [MarshalAs(UnmanagedType.LPWStr)] out string path); }
 
         /// <summary>
         /// Moves a file to a new location, overwriting the existing file if it exists.