[Xamarin.Android.Build.Tasks] Add AndroidPackagingOptionsExclude (#7356)

Fixes: #6920

Certainly NuGet packages pull in Kotlin-related artifacts which
aren't required at runtime.  These artifacts contribute to `.apk`
package size.

The [recommendation for native Android developers][0] is to
explicitly exclude these artifacts by using `packagingOptions`:

	packagingOptions {
	  exclude 'DebugProbesKt.bin'
	}

Xamarin.Android and .NET SDK for Android developers don't use Gradle,
so the above snippet is not useful.

Add support for a new `@(AndroidPackagingOptionsExclude)` item group.
This contains a "search pattern" a'la the `searchPattern` parameter
of [`Directory.EnumerateFiles(path, searchPattern)`][1], in which:

  * `*` matches 0 or more characters
  * `?` matches 1 character.

The default items within `@(AndroidPackagingOptionsExclude)` are:

  * `DebugProbesKt.bin`
  * `*.kotlin_*`

Files which match the search patterns within
`@(AndroidPackagingOptionsExclude)` are *excluded* from `.aab` and
`.apk` files, reducing app size.

[0]: Kotlin/kotlinx.coroutines#2274
[1]: https://docs.microsoft.com/en-us/dotnet/api/system.io.directory.enumeratefiles?view=net-6.0#system-io-directory-enumeratefiles(system-string-system-string)

Author: dellis1972

Documentation/guides/building-apps/build-items.md

@@ -204,6 +204,26 @@ used to specify the ABI that the library targets. Thus, if you add
 </ItemGroup>
 ```
 
+## AndroidPackagingOptionsExclude
+
+A set of file glob compatible items which will allow for items to be
+excluded from the final package. The default values are as follows
+
+```
+<ItemGroup>
+	<AndroidPackagingOptionsExclude Include="DebugProbesKt.bin" />
+	<AndroidPackagingOptionsExclude Include="$([MSBuild]::Escape('*.kotlin_*')" />
+</ItemGroup>
+```
+Items can use file blob characters for wildcards such as `*` and `?`.
+However these Items MUST use URL encoding or '$([MSBuild]::Escape(''))'.
+This is so MSBuild does not try to interpret them as actual file wildcards.
+
+NOTE: `*`, `?` and `.` will be replaced in the `BuildApk` task with the
+appropriate RegEx expressions.
+
+Added in Xamarin.Android 13.1 and .NET 7.
+
 ## AndroidResource
 
 All files with an *AndroidResource* build action are compiled into

src/Xamarin.Android.Build.Tasks/Tasks/BuildApk.cs

@@ -74,6 +74,8 @@ public class BuildApk : AndroidTask
 
 		public string[] DoNotPackageJavaLibraries { get; set; }
 
+		public string [] ExcludeFiles { get; set; }
+
 		public string Debug { get; set; }
 
 		public string AndroidSequencePointsMode { get; set; }
@@ -122,6 +124,8 @@ protected virtual void FixupArchive (ZipArchiveEx zip) { }
 
 		List<string> existingEntries = new List<string> ();
 
+		List<Regex> excludePatterns = new List<Regex> ();
+
 		void ExecuteWithAbi (string [] supportedAbis, string apkInputPath, string apkOutputPath, bool debug, bool compress, IDictionary<string, CompressedAssemblyInfo> compressedAssembliesInfo, string assemblyStoreApkName)
 		{
 			ArchiveFileList files = new ArchiveFileList ();
@@ -248,6 +252,13 @@ void ExecuteWithAbi (string [] supportedAbis, string apkInputPath, string apkOut
 								Log.LogDebugMessage ($"Skipping {path} as the archive file is up to date.");
 								continue;
 							}
+							// check for ignored items
+							foreach (var pattern in excludePatterns) {
+								if(pattern.IsMatch (path)) {
+									Log.LogDebugMessage ($"Ignoring jar entry '{name}' from '{Path.GetFileName (jarFile)}'. Filename matched the exclude pattern '{pattern}'.");
+									continue;
+								}
+							}
 							if (string.Compare (Path.GetFileName (name), "AndroidManifest.xml", StringComparison.OrdinalIgnoreCase) == 0) {
 								Log.LogDebugMessage ("Ignoring jar entry {0} from {1}: the same file already exists in the apk", name, Path.GetFileName (jarFile));
 								continue;
@@ -293,6 +304,10 @@ public override bool RunTask ()
 
 			existingEntries.Clear ();
 
+			foreach (var pattern in ExcludeFiles ?? Array.Empty<string> ()) {
+				excludePatterns.Add (FileGlobToRegEx (pattern, RegexOptions.IgnoreCase | RegexOptions.Compiled));
+			}
+
 			bool debug = _Debug;
 			bool compress = !debug && EnableCompression;
 			IDictionary<string, CompressedAssemblyInfo> compressedAssembliesInfo = null;
@@ -326,6 +341,24 @@ public override bool RunTask ()
 			return !Log.HasLoggedErrors;
 		}
 
+		static Regex FileGlobToRegEx (string fileGlob, RegexOptions options)
+		{
+			StringBuilder sb = new StringBuilder ();
+			foreach (char c in fileGlob) {
+				switch (c) {
+					case '*': sb.Append (".*");
+						break;
+					case '?': sb.Append (".");
+						break;
+					case '.': sb.Append (@"\.");
+						break;
+					default: sb.Append (c);
+						break;
+				}
+			}
+			return new Regex (sb.ToString (), options);
+		}
+
 		void AddAssemblies (ZipArchiveEx apk, bool debug, bool compress, IDictionary<string, CompressedAssemblyInfo> compressedAssembliesInfo, string assemblyStoreApkName)
 		{
 			string sourcePath;

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/PackagingTest.cs

@@ -916,6 +916,26 @@ public class Test
 			}
 		}
 
+		[Test]
+		public void CheckExcludedFilesAreMissing ()
+		{
+
+			var proj = new XamarinAndroidApplicationProject () {
+				IsRelease = true,
+			};
+			proj.PackageReferences.Add (KnownPackages.Xamarin_Kotlin_StdLib_Common);
+			using (var b = CreateApkBuilder ()) {
+				Assert.IsTrue (b.Build (proj), "Build should have succeeded.");
+				var apk = Path.Combine (Root, b.ProjectDirectory,
+					proj.OutputPath, $"{proj.PackageName}-Signed.apk");
+				string expected = $"Ignoring jar entry 'kotlin/Error.kotlin_metadata'";
+				Assert.IsTrue (b.LastBuildOutput.ContainsText (expected), $"Error.kotlin_metadata should have been ignored.");
+				using (var zip = ZipHelper.OpenZip (apk)) {
+					Assert.IsFalse (zip.ContainsEntry ("Error.kotlin_metadata"), "Error.kotlin_metadata should have been ignored.");
+				}
+			}
+		}
+
 		[Test]
 		public void ExtractNativeLibsTrue ()
 		{

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Android/KnownPackages.cs

@@ -499,6 +499,10 @@ public static class KnownPackages
 			Id = "Xamarin.GooglePlayServices.Maps",
 			Version = "117.0.1.2",
 		};
+		public static Package Xamarin_Kotlin_StdLib_Common = new Package {
+			Id = "Xamarin.Kotlin.Stdlib.Common",
+			Version = "1.6.20.1"
+		};
 		public static Package Acr_UserDialogs = new Package {
 			Id = "Acr.UserDialogs",
 			Version = "6.5.1",

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets

@@ -351,6 +351,11 @@ Copyright (C) 2011-2012 Xamarin. All rights reserved.
 	</AllowedReferenceRelatedFileExtensions>
 </PropertyGroup>
 
+<ItemGroup>
+	<AndroidPackagingOptionsExclude Include="DebugProbesKt.bin" />
+	<AndroidPackagingOptionsExclude Include="$([MSBuild]::Escape('*.kotlin_*'))" />
+</ItemGroup>
+
 <!--
 *******************************************
           Imports
@@ -2037,6 +2042,11 @@ because xbuild doesn't support framework reference assemblies.
   Outputs="$(_BuildApkEmbedOutputs)"
   Condition="'$(EmbedAssembliesIntoApk)' == 'True'">
   <!-- Put the assemblies and native libraries in the apk -->
+  <!--
+    NOTE: Adding Arguments to BuildApk or BuildBaseAppBundle
+    also need to have the args added to Xamarin.Android.Common.Debugging.targets
+    in monodroid.
+  -->
   <BuildApk
     Condition=" '$(AndroidPackageFormat)' != 'aab' "
     AndroidNdkDirectory="$(_AndroidNdkDirectory)"
@@ -2067,6 +2077,7 @@ because xbuild doesn't support framework reference assemblies.
     IncludeWrapSh="$(AndroidIncludeWrapSh)"
     CheckedBuild="$(_AndroidCheckedBuild)"
     RuntimeConfigBinFilePath="$(_BinaryRuntimeConfigPath)"
+    ExcludeFiles="@(AndroidPackagingOptionsExclude)"
     UseAssemblyStore="$(AndroidUseAssemblyStore)">
     <Output TaskParameter="OutputFiles" ItemName="ApkFiles" />
   </BuildApk>
@@ -2100,6 +2111,7 @@ because xbuild doesn't support framework reference assemblies.
       IncludeWrapSh="$(AndroidIncludeWrapSh)"
       CheckedBuild="$(_AndroidCheckedBuild)"
       RuntimeConfigBinFilePath="$(_BinaryRuntimeConfigPath)"
+      ExcludeFiles="@(AndroidPackagingOptionsExclude)"
       UseAssemblyStore="$(AndroidUseAssemblyStore)">
     <Output TaskParameter="OutputFiles" ItemName="BaseZipFile" />
   </BuildBaseAppBundle>