[Xamarin.Android.Build.Tasks] Emit an Error if a custom view cannot b…

…e fixed up. (dotnet#1720)

Context: dotnet#1711

When using a custom view within a layout file we replace the
`namespace.classname` with an `md5hash.classname`.  We do this by
using the `acwmap.txt` file to map known types onto the `md5` hashed
ones.  This is done in a case sensitive manner.  We also only support
identically-cased and lower-cased namespace/package names:

	ClassLibrary1.CustomView=md5d6f7135293df7527c983d45d07471c5e.CustomTextView
	classlibrary1.CustomView=md5d6f7135293df7527c983d45d07471c5e.CustomTextView

Given that a user is able to type these manually it is possible that
typo's will occur.  If for example a user types

	Classlibrary1.CustomView

this will NOT be fixed up, due to the lowercase `l` in `library`.
Instead the user will see the following error at runtime.

	FATAL UNHANDLED EXCEPTION: Android.Views.InflateException: Binary XML file line #1: Binary XML file line #1: Error inflating class Classlibrary1.CustomTextView
	---> Android.Views.InflateException: Binary XML file line #1: Error inflating class Classlibrary1.CustomTextView
	---> Java.Lang.ClassNotFoundException: Didn't find class "Classlibrary1.CustomTextView"

If the control is used in a number of places this runtime error does
nothing to help track down the problem.

Improve this scenario by detecting these issues and emitting an
XA1002 build error.  This will not only inform the user about the
problem but also provide a link to the file causing the problem.

Documentation/guides/messages/README.md

@@ -44,6 +44,8 @@
 ### XA1xxx Project Related
 
 + [XA1000](xa1000.md): There was an problem parsing {file}. This is likely due to incomplete or invalid xml.
++ [XA1001](xa1001.md): AndroidResgen: Warning while updating Resource XML '{filename}': {Message}
++ [XA1002](xa1002.md): We found a matching key '{Key}' for '{Item}'. But the casing was incorrect. Please correct the casing
 
 ### XA2xxx Linker
 

Documentation/guides/messages/xa1001.md

@@ -0,0 +1,7 @@
+# Compiler Warning XA1001
+
+AndroidResgen: Warning while updating Resource XML '{filename}': {Message}
+
+This warning is raised if we encounter an unknown issue when processing
+the layout and resources. It is a generic warning that does not describe 
+any specific problem. The details will be in the `{Message}`.

Documentation/guides/messages/xa1002.md

@@ -0,0 +1,13 @@
+# Compiler Error XA1002
+
+This error will be emitted when we are unable to find a matching custom new in the 
+ResourceCaseMap string. 
+
+As part of the build process `Namespace.CustomViewFoo` items in layout files are
+replaced with `{MD5Hash}.CustomViewFoo`. We attempt to replace a couple of variants
+of the `Namespace.CustomViewFoo`. One is the original casing found in the C# source
+files. The other is all lowercase. If we cannot find a match we will do a case 
+insensitive lookup to see if there are items which do match. If we find one this 
+error will be raised.
+
+We found a matching key 'Namespace.CustomViewFoo' for 'NameSpace.CustomViewFoo'. But the casing was incorrect. Please correct the casing

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

@@ -92,7 +92,7 @@ public class Aapt : AsyncTask
 
 		public string ResourceSymbolsTextFileDirectory { get; set; }
 
-		Dictionary<string,string> resource_name_case_map = new Dictionary<string,string> ();
+		Dictionary<string,string> resource_name_case_map;
 		AssemblyIdentityMap assemblyMap = new AssemblyIdentityMap ();
 		string resourceDirectory;
 
@@ -251,9 +251,7 @@ public override bool Execute ()
 
 		void DoExecute ()
 		{
-			if (ResourceNameCaseMap != null)
-				foreach (var arr in ResourceNameCaseMap.Split (';').Select (l => l.Split ('|')).Where (a => a.Length == 2))
-					resource_name_case_map [arr [1]] = arr [0]; // lowercase -> original
+			resource_name_case_map = MonoAndroidHelper.LoadResourceCaseMap (ResourceNameCaseMap);
 
 			assemblyMap.Load (Path.Combine (WorkingDirectory, AssemblyIdentityMapFile));
 

src/Xamarin.Android.Build.Tasks/Tasks/Aapt2.cs

@@ -18,7 +18,7 @@ namespace Xamarin.Android.Tasks {
 
 	public class Aapt2 : AsyncTask {
 
-		protected Dictionary<string, string> resource_name_case_map = new Dictionary<string, string> ();
+		protected Dictionary<string, string> resource_name_case_map;
 
 		public ITaskItem [] ResourceDirectories { get; set; }
 
@@ -174,9 +174,7 @@ protected bool LogAapt2EventsFromOutput (string singleLine, MessageImportance me
 
 		protected void LoadResourceCaseMap ()
 		{
-			if (ResourceNameCaseMap != null)
-				foreach (var arr in ResourceNameCaseMap.Split (';').Select (l => l.Split ('|')).Where (a => a.Length == 2))
-					resource_name_case_map [arr [1]] = arr [0]; // lowercase -> original
+			resource_name_case_map = MonoAndroidHelper.LoadResourceCaseMap (ResourceNameCaseMap);
 		}
 	}
 }

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

@@ -1,6 +1,7 @@
 // Copyright (C) 2011 Xamarin, Inc. All rights reserved.
 
 using System;
+using System.Diagnostics;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -20,13 +21,19 @@ public class ConvertResourcesCases : Task
 
 		public string AndroidConversionFlagFile { get; set; }
 
+		public string ResourceNameCaseMap { get; set; }
+
+		Dictionary<string,string> resource_name_case_map;
+
 		public override bool Execute ()
 		{
 			Log.LogDebugMessage ("ConvertResourcesCases Task");
 			Log.LogDebugMessage ("  ResourceDirectories: {0}", ResourceDirectories);
 			Log.LogDebugMessage ("  AcwMapFile: {0}", AcwMapFile);
 			Log.LogDebugMessage ("  AndroidConversionFlagFile: {0}", AndroidConversionFlagFile);
+			Log.LogDebugMessage ("  ResourceNameCaseMap: {0}", ResourceNameCaseMap);
 
+			resource_name_case_map = MonoAndroidHelper.LoadResourceCaseMap (ResourceNameCaseMap);
 			var acw_map = MonoAndroidHelper.LoadAcwMapFile (AcwMapFile);
 
 			// Look in the resource xml's for capitalized stuff and fix them
@@ -71,7 +78,26 @@ void FixupResources (ITaskItem item, Dictionary<string, string> acwMap)
 				MonoAndroidHelper.SetWriteable (tmpdest);
 				try {
 					AndroidResource.UpdateXmlResource (resdir, tmpdest, acwMap,
-						ResourceDirectories.Where (s => s != item).Select(s => s.ItemSpec));
+						ResourceDirectories.Where (s => s != item).Select(s => s.ItemSpec), (t, m) => {
+							string targetfile = file;
+							if (targetfile.StartsWith (resdir, StringComparison.InvariantCultureIgnoreCase)) {
+								targetfile = file.Substring (resdir.Length).TrimStart (Path.DirectorySeparatorChar);
+								if (resource_name_case_map.TryGetValue (targetfile, out string temp))
+									targetfile = temp;
+								targetfile = Path.Combine ("Resources", targetfile);
+							}
+							switch (t) {
+								case TraceLevel.Error:
+									Log.LogCodedError ("XA1002", file: targetfile, lineNumber: 0, message: m);
+									break;
+								case TraceLevel.Warning:
+									Log.LogCodedWarning ("XA1001", file: targetfile, lineNumber: 0, message: m);
+									break;
+								default:
+									Log.LogDebugMessage (m);
+									break;
+							}
+						});
 
 					// We strip away an eventual UTF-8 BOM from the XML file.
 					// This is a requirement for the Android designer because the desktop Java renderer

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

@@ -0,0 +1,87 @@
+using System;
+using System.Collections.Generic;
+using NUnit.Framework;
+using Xamarin.ProjectTools;
+using System.IO;
+using System.Linq;
+using Microsoft.Build.Framework;
+using System.Text;
+using Xamarin.Android.Tasks;
+using Microsoft.Build.Utilities;
+
+namespace Xamarin.Android.Build.Tests {
+
+	[TestFixture]
+	[Parallelizable (ParallelScope.Self)]
+	public class ConvertResourcesCasesTests  : BaseTest {
+		[Test]
+		public void CheckClassIsReplacedWithMd5 ()
+		{
+			var path = Path.Combine (Root, "temp", "CheckClassIsReplacedWithMd5");
+			Directory.CreateDirectory (path);
+			var resPath = Path.Combine (path, "res");
+			Directory.CreateDirectory (Path.Combine (resPath, "layout"));
+			File.WriteAllText (Path.Combine (resPath, "layout", "main.xml"), @"<?xml version='1.0' ?>
+<LinearLayout xmlns:android='http://schemas.android.com/apk/res/android'>
+<ClassLibrary1.CustomView xmlns:android='http://schemas.android.com/apk/res/android' />
+<classlibrary1.CustomView xmlns:android='http://schemas.android.com/apk/res/android' />
+</LinearLayout>
+");
+			var errors = new List<BuildErrorEventArgs> ();
+			IBuildEngine engine = new MockBuildEngine (TestContext.Out, errors);
+			var task = new ConvertResourcesCases {
+				BuildEngine = engine
+			};
+			task.ResourceDirectories = new ITaskItem [] {
+				new TaskItem (resPath),
+			};
+			task.AcwMapFile = Path.Combine (path, "acwmap.txt");
+			File.WriteAllLines (task.AcwMapFile, new string [] {
+				"ClassLibrary1.CustomView;md5d6f7135293df7527c983d45d07471c5e.CustomTextView",
+				"classlibrary1.CustomView;md5d6f7135293df7527c983d45d07471c5e.CustomTextView",
+			});
+			Assert.IsTrue (task.Execute (), "Task should have executed successfully");
+			var output = File.ReadAllText (Path.Combine (resPath, "layout", "main.xml"));
+			StringAssert.Contains ("md5d6f7135293df7527c983d45d07471c5e.CustomTextView", output, "md5d6f7135293df7527c983d45d07471c5e.CustomTextView should exist in the main.xml");
+			StringAssert.DoesNotContain ("ClassLibrary1.CustomView", output, "ClassLibrary1.CustomView should have been replaced.");
+			StringAssert.DoesNotContain ("classlibrary1.CustomView", output, "classlibrary1.CustomView should have been replaced.");
+			Directory.Delete (path, recursive: true);
+		}
+
+		[Test]
+		public void CheckClassIsNotReplacedWithMd5 ()
+		{
+			var path = Path.Combine (Root, "temp", "CheckClassIsNotReplacedWithMd5");
+			Directory.CreateDirectory (path);
+			var resPath = Path.Combine (path, "res");
+			Directory.CreateDirectory (Path.Combine (resPath, "layout"));
+			File.WriteAllText (Path.Combine (resPath, "layout", "main.xml"), @"<?xml version='1.0' ?>
+<LinearLayout xmlns:android='http://schemas.android.com/apk/res/android'>
+<ClassLibrary1.CustomView xmlns:android='http://schemas.android.com/apk/res/android' />
+<classLibrary1.CustomView xmlns:android='http://schemas.android.com/apk/res/android' />
+</LinearLayout>
+");
+			var errors = new List<BuildErrorEventArgs> ();
+			IBuildEngine engine = new MockBuildEngine (TestContext.Out, errors);
+			var task = new ConvertResourcesCases {
+				BuildEngine = engine
+			};
+			task.ResourceDirectories = new ITaskItem [] {
+				new TaskItem (resPath),
+			};
+			task.AcwMapFile = Path.Combine (path, "acwmap.txt");
+			File.WriteAllLines (task.AcwMapFile, new string [] {
+				"ClassLibrary1.CustomView;md5d6f7135293df7527c983d45d07471c5e.CustomTextView",
+				"classlibrary1.CustomView;md5d6f7135293df7527c983d45d07471c5e.CustomTextView",
+			});
+			Assert.IsTrue (task.Execute (), "Task should have executed successfully");
+			var output = File.ReadAllText (Path.Combine (resPath, "layout", "main.xml"));
+			StringAssert.Contains ("md5d6f7135293df7527c983d45d07471c5e.CustomTextView", output, "md5d6f7135293df7527c983d45d07471c5e.CustomTextView should exist in the main.xml");
+			StringAssert.DoesNotContain ("ClassLibrary1.CustomView", output, "ClassLibrary1.CustomView should have been replaced.");
+			StringAssert.Contains ("classLibrary1.CustomView", output, "classLibrary1.CustomView should have been replaced.");
+			Assert.AreEqual (1, errors.Count, "One Error should have been raised.");
+			Assert.AreEqual ("XA1002", errors [0].Code, "XA1002 should have been raised.");
+			Directory.Delete (path, recursive: true);
+		}
+	}
+}

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Xamarin.Android.Build.Tests.csproj

@@ -84,6 +84,7 @@
     <Compile Include="Aapt2Tests.cs" />
     <Compile Include="Tasks\ValidateJavaVersionTests.cs" />
     <Compile Include="ZipArchiveExTests.cs" />
+    <Compile Include="ConvertResourcesCasesTests.cs" />
   </ItemGroup>
   <ItemGroup>
     <Content Include="Expected\GenerateDesignerFileExpected.cs">

src/Xamarin.Android.Build.Tasks/Utilities/AndroidResource.cs

@@ -1,22 +1,24 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
+using System.Text;
 using System.Text.RegularExpressions;
 using System.Xml.Linq;
 using System.Xml.XPath;
 
 namespace Monodroid {
 	static class AndroidResource {
 
-		public static void UpdateXmlResource (string res, string filename, Dictionary<string, string> acwMap, IEnumerable<string> additionalDirectories = null)
+		public static void UpdateXmlResource (string res, string filename, Dictionary<string, string> acwMap, IEnumerable<string> additionalDirectories = null, Action<TraceLevel, string> logMessage = null)
 		{
 			// use a temporary file so we only update the real file if things actually changed
 			string tmpfile = filename + ".bk";
 			try {
 				XDocument doc = XDocument.Load (filename, LoadOptions.SetLineInfo);
 
-				UpdateXmlResource (res, doc.Root, acwMap, additionalDirectories);
+				UpdateXmlResource (res, doc.Root, acwMap, additionalDirectories, logMessage);
 				using (var stream = File.OpenWrite (tmpfile))
 					using (var xw = new LinePreservedXmlWriter (new StreamWriter (stream)))
 						xw.WriteNode (doc.CreateNavigator (), false);
@@ -27,7 +29,8 @@ public static void UpdateXmlResource (string res, string filename, Dictionary<st
 				if (File.Exists (tmpfile)) {
 					File.Delete (tmpfile);
 				}
-				Console.Error.WriteLine ("AndroidResgen: Warning while updating Resource XML '{0}': {1}", filename, e.Message);
+				if (logMessage != null)
+					logMessage (TraceLevel.Warning, $"AndroidResgen: Warning while updating Resource XML '{filename}': {e.Message}");
 				return;
 			}
 		}
@@ -59,10 +62,10 @@ static IEnumerable<T> Prepend<T> (this IEnumerable<T> l, T another) where T : XN
 				yield return e;
 		}
 
-		static void UpdateXmlResource (string resourcesBasePath, XElement e, Dictionary<string, string> acwMap, IEnumerable<string> additionalDirectories = null)
+		static void UpdateXmlResource (string resourcesBasePath, XElement e, Dictionary<string, string> acwMap, IEnumerable<string> additionalDirectories = null, Action<TraceLevel, string> logMessage = null)
 		{
 			foreach (var elem in GetElements (e).Prepend (e)) {
-				TryFixCustomView (elem, acwMap);
+				TryFixCustomView (elem, acwMap, logMessage);
 			}
 
 			foreach (var path in fixResourcesAliasPaths) {
@@ -184,17 +187,17 @@ private static bool TryFixFragment (XAttribute attr, Dictionary<string, string>
 				return false;
 
 			if (attr.Name == "class" || attr.Name == android + "name") {
-				if (acwMap.ContainsKey (attr.Value)) {
-					attr.Value = acwMap[attr.Value];
+				if (acwMap.TryGetValue (attr.Value, out string mappedValue)) {
+					attr.Value = mappedValue;
 
 					return true;
 				}
 				else if (attr.Value?.Contains (',') ?? false) {
 					// attr.Value could be an assembly-qualified name that isn't in acw-map.txt;
 					// see e5b1c92c, https://github.com/xamarin/xamarin-android/issues/1296#issuecomment-365091948
 					var n = attr.Value.Substring (0, attr.Value.IndexOf (','));
-					if (acwMap.ContainsKey (n)) {
-						attr.Value = acwMap [n];
+					if (acwMap.TryGetValue (n, out mappedValue)) {
+						attr.Value = mappedValue;
 						return true;
 					}
 				}
@@ -217,15 +220,23 @@ private static bool TryFixResAuto (XAttribute attr, Dictionary<string, string> a
 			return false;
 		}
 
-		private static bool TryFixCustomView (XElement elem, Dictionary<string, string> acwMap)
+		private static bool TryFixCustomView (XElement elem, Dictionary<string, string> acwMap, Action<TraceLevel, string> logMessage = null)
 		{
 			// Looks for any <My.DotNet.Class ...
 			// and tries to change it to the ACW name
-			if (acwMap.ContainsKey (elem.Name.ToString ())) {
-				elem.Name = acwMap[elem.Name.ToString ()];
+			string name = elem.Name.ToString ();
+			if (acwMap.TryGetValue (name, out string mappedValue)) {
+				elem.Name = mappedValue;
 				return true;
 			}
-
+			if (logMessage == null)
+				return false;
+			var matchingKey = acwMap.FirstOrDefault(x => String.Equals(x.Key, name, StringComparison.OrdinalIgnoreCase));
+			if (matchingKey.Key != null) {
+				// we have elements with slightly different casing.
+				// lets issue a error.
+				logMessage (TraceLevel.Error, $"We found a matching key '{matchingKey.Key}' for '{name}'. But the casing was incorrect. Please correct the casing");
+			}
 			return false;
 		}
 
@@ -238,8 +249,7 @@ private static bool TryFixCustomClassAttribute (XAttribute attr, Dictionary<stri
 			    && (attr.Parent.Name != "transition" || attr.Name.LocalName != "class")) // For custom transitions
 				return false;
 
-			string mappedValue;
-			if (!acwMap.TryGetValue (attr.Value, out mappedValue))
+			if (!acwMap.TryGetValue (attr.Value, out string mappedValue))
 				return false;
 
 			attr.Value = mappedValue;

src/Xamarin.Android.Build.Tasks/Utilities/MonoAndroidHelper.cs

@@ -553,5 +553,15 @@ public static string TryGetAndroidJarPath (TaskLoggingHelper log, string platfor
 			}
 			return Path.Combine (platformPath, "android.jar");
 		}
+
+		public static Dictionary<string, string> LoadResourceCaseMap (string resourceCaseMap)
+		{
+			var result = new Dictionary<string, string> ();
+			if (resourceCaseMap != null) {
+				foreach (var arr in resourceCaseMap.Split (';').Select (l => l.Split ('|')).Where (a => a.Length == 2))
+					result [arr [1]] = arr [0]; // lowercase -> original
+			}
+			return result;
+		}
 	}
 }

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

@@ -2219,6 +2219,7 @@ because xbuild doesn't support framework reference assemblies.
   </GenerateJavaStubs>
   <ConvertResourcesCases 
 	ResourceDirectories="$(MonoAndroidResDirIntermediate);@(LibraryResourceDirectories)"
+	ResourceNameCaseMap="$(_AndroidResourceNameCaseMap)"
 	AcwMapFile="$(_AcwMapFile)" />
 </Target>