feat: Android SAF StorageFolder/File operations

src/Uno.UWP/Generated/3.0.0.0/Windows.Storage.Streams/IInputStreamReference.cs

@@ -2,12 +2,12 @@
 #pragma warning disable 114 // new keyword hiding
 namespace Windows.Storage.Streams
 {
-	#if __ANDROID__ || __IOS__ || NET461 || __WASM__ || __SKIA__ || __NETSTD_REFERENCE__ || __MACOS__
+	#if false
 	[global::Uno.NotImplemented]
 	#endif
 	public  partial interface IInputStreamReference 
 	{
-		#if __ANDROID__ || __IOS__ || NET461 || __WASM__ || __SKIA__ || __NETSTD_REFERENCE__ || __MACOS__
+		#if false
 		global::Windows.Foundation.IAsyncOperation<global::Windows.Storage.Streams.IInputStream> OpenSequentialReadAsync();
 		#endif
 	}

src/Uno.UWP/Storage/Internal/SafHelpers.Android.cs

@@ -0,0 +1,62 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Android.App;
+using Android.Provider;
+using Windows.Storage.FileProperties;
+
+namespace Uno.Storage.Internal
+{
+	/// <summary>
+	/// Shared functionality handling for Android's Storage
+	/// Access Framework-based StorageFiles and StorageFolders.
+	/// </summary>
+	internal static class SafHelpers
+    {
+		/// <summary>
+		/// Retrieves basic properties for a given SAF Uri.
+		/// </summary>
+		/// <param name="safUri">SAF Uri.</param>
+		/// <param name="includeSize">A value indicating whether the size should be included (not useful for folders).</param>
+		/// <param name="token">Cancellation token.</param>
+		/// <returns>Basic properties.</returns>
+		public static async Task<BasicProperties> GetBasicPropertiesAsync(Android.Net.Uri safUri, bool includeSize, CancellationToken token)
+		{
+			if (Application.Context.ContentResolver == null)
+			{
+				throw new InvalidOperationException("Content resolver for app is not available.");
+			}
+
+			return await Task.Run(() =>
+			{
+				var cursor = Application.Context.ContentResolver.Query(safUri, null, null, null, null, null);
+				if (cursor == null)
+				{
+					throw new UnauthorizedAccessException("Cannot access the folder.");
+				}
+
+				using (cursor)
+				{
+					if (cursor.MoveToFirst())
+					{
+						int size = 0;
+						var sizeColumnIndex = cursor.GetColumnIndex(DocumentsContract.Document.ColumnSize);
+						if (includeSize && sizeColumnIndex >= 0)
+						{
+							size = cursor.GetInt(sizeColumnIndex);
+						}
+						var lastModified = DateTimeOffset.MinValue;
+						var lastModifiedIndex = cursor.GetColumnIndex(DocumentsContract.Document.ColumnLastModified);
+						if (lastModifiedIndex >= 0)
+						{
+							var lastModifiedTimestamp = cursor.GetLong(lastModifiedIndex);
+							lastModified = DateTimeOffset.FromUnixTimeMilliseconds(lastModifiedTimestamp);
+						}
+						return new BasicProperties((ulong)size, lastModified);
+					}
+				}
+				return new BasicProperties(0, DateTimeOffset.MinValue);
+			}, token);
+		}
+    }
+}

src/Uno.UWP/Storage/StorageFile.Base.cs

@@ -30,7 +30,7 @@ public void InitOwner(StorageFile owner)
 
 			public virtual string Path { get; protected set; } = string.Empty;
 
-			public virtual string FileType => global::System.IO.Path.GetExtension(Path);
+			public virtual string FileType => global::System.IO.Path.GetExtension(Name);
 
 			public virtual string Name => global::System.IO.Path.GetFileName(Path);
 

src/Uno.UWP/Storage/StorageFile.saf.Android.cs

@@ -8,13 +8,14 @@
 using System.Threading.Tasks;
 using Android.App;
 using AndroidX.DocumentFile.Provider;
+using Uno.Storage.Internal;
 using Windows.Storage.FileProperties;
 using Windows.Storage.Streams;
 
 namespace Windows.Storage
 {
-    public partial class StorageFile
-    {
+	public partial class StorageFile
+	{
 		public static StorageFile GetFromSafDocument(DocumentFile document) =>
 			new StorageFile(new SafFile(document));
 
@@ -25,19 +26,19 @@ internal class SafFile : ImplementationBase
 		{
 			private static readonly StorageProvider _provider = new StorageProvider("Android.StorageAccessFramework", "Android Storage Access Framework");
 
-			private readonly Android.Net.Uri _folderUri;
+			private readonly Android.Net.Uri _fileUri;
 			private readonly DocumentFile _directoryDocument;
 
 			internal SafFile(Android.Net.Uri uri)
 			{
-				_folderUri = uri ?? throw new ArgumentNullException(nameof(uri));
-				_directoryDocument = DocumentFile.FromTreeUri(Application.Context, uri);
+				_fileUri = uri ?? throw new ArgumentNullException(nameof(uri));
+				_directoryDocument = DocumentFile.FromSingleUri(Application.Context, uri);
 			}
 
 			internal SafFile(DocumentFile directoryDocument)
 			{
 				_directoryDocument = directoryDocument ?? throw new ArgumentNullException(nameof(directoryDocument));
-				_folderUri = _directoryDocument.Uri;
+				_fileUri = _directoryDocument.Uri;
 			}
 
 			public override StorageProvider Provider => _provider;
@@ -47,12 +48,44 @@ internal SafFile(DocumentFile directoryDocument)
 
 			public override DateTimeOffset DateCreated => throw new NotImplementedException();
 
-			public override Task DeleteAsync(CancellationToken ct, StorageDeleteOption options) => throw new NotImplementedException();
-			public override Task<BasicProperties> GetBasicPropertiesAsync(CancellationToken ct) => throw new NotImplementedException();
-			public override Task<StorageFolder?> GetParentAsync(CancellationToken ct) => throw new NotImplementedException();
-			public override Task<IRandomAccessStreamWithContentType> OpenAsync(CancellationToken ct, FileAccessMode accessMode, StorageOpenOptions options) => throw new NotImplementedException();
+			public override async Task DeleteAsync(CancellationToken ct, StorageDeleteOption options)
+			{
+				await Task.Run(() =>
+				{
+					_directoryDocument.Delete();
+				}, ct);
+			}
+
+			public override Task<BasicProperties> GetBasicPropertiesAsync(CancellationToken ct) =>
+				SafHelpers.GetBasicPropertiesAsync(_fileUri, true, ct);
+
+			public override Task<StorageFolder?> GetParentAsync(CancellationToken ct)
+			{
+				if (_directoryDocument.ParentFile == null)
+				{
+					return Task.FromResult<StorageFolder?>(null);
+				}
+
+				var parentFolder = StorageFolder.GetFromSafDocument(_directoryDocument.ParentFile);
+				return Task.FromResult<StorageFolder?>(parentFolder);
+			}
+
+			public override Task<IRandomAccessStreamWithContentType> OpenAsync(CancellationToken ct, FileAccessMode accessMode, StorageOpenOptions options) =>
+				Task.FromResult<IRandomAccessStreamWithContentType>(new RandomAccessStreamWithContentType(FileRandomAccessStream.CreateFromSafUri(_fileUri, accessMode), ContentType));
+
 			public override Task<StorageStreamTransaction> OpenTransactedWriteAsync(CancellationToken ct, StorageOpenOptions option) => throw new NotImplementedException();
-			protected override bool IsEqual(ImplementationBase implementation) => throw new NotImplementedException();
+
+			protected override bool IsEqual(ImplementationBase implementation)
+			{
+				if (implementation is SafFile otherFile)
+				{
+					var path = _directoryDocument.Uri?.ToString() ?? string.Empty;
+					var otherPath = otherFile._directoryDocument.Uri?.ToString() ?? string.Empty;
+					return path.Equals(otherPath, StringComparison.InvariantCulture);
+				}
+
+				return false;
+			}
 		}
 	}
 }