Merge .targets files in build script

We can only have one .targets file in a nupkg that gets auto-imported into the project (it must be named nuget-package-id.targets), and since some of our packages already were using this file, we need to merge the generated targets for Xamarin.Build.Download with these files.  This means the custom build tasks must be built before the nuget-setup task runs.  This changes the build script to build the existing custom tasks, copy their .targets files, and then detect them when generated the .targets files for Xamarin.Build.Download, and merge them together.

Author: Redth

build.cake

@@ -324,7 +324,7 @@ Task ("component-setup").Does (() =>
 });
 
 
-Task ("nuget-setup").Does (() => {
+Task ("nuget-setup").IsDependentOn ("buildtasks").Does (() => {
 	var templateText = FileReadText ("./template.targets");
 
 	if (FileExists ("./generated.targets"))
@@ -365,9 +365,31 @@ Task ("nuget-setup").Does (() => {
 		foreach (var kvp in items)
 			targetsText = targetsText.Replace (kvp.Key, kvp.Value);
 
-		var targetsFile = string.Format ("{0}/nuget/{1}.targets", aar.Path, aar.NugetId);
+		var targetsFile = new FilePath(string.Format ("{0}/nuget/{1}.targets", aar.Path, aar.NugetId));
 		FileWriteText (targetsFile, targetsText);
 
+		// Check for an existing .targets file in this nuget package
+		// we need to merge the generated one with it if it exists
+		// nuget only allows one automatic .targets file in the build/ folder
+		// of the nuget package, which must be named {nuget-package-id}.targets
+		// so we need to merge them all into one
+		var mergeFile = new FilePath (aar.Path + "/nuget/merge.targets");
+
+		if (FileExists (mergeFile)) {
+			Information ("merge.targets found, merging into generated file...");
+
+			// Load the doc to append to, and the doc to append
+			var xOrig = System.Xml.Linq.XDocument.Load (MakeAbsolute(targetsFile).FullPath);
+			System.Xml.Linq.XNamespace nsOrig = xOrig.Root.Name.Namespace;
+			var xMerge = System.Xml.Linq.XDocument.Load (MakeAbsolute(mergeFile).FullPath);
+			System.Xml.Linq.XNamespace nsMerge = xMerge.Root.Name.Namespace;
+			// Add all the elements under <Project> into the existing file's <Project> node
+			foreach (var xItemToAdd in xMerge.Element (nsMerge + "Project").Elements ())
+				xOrig.Element (nsOrig + "Project").Add (xItemToAdd);
+
+			xOrig.Save (MakeAbsolute (targetsFile).FullPath);
+		}
+
 		// Merge each generated targets file into one main one
 		// this makes one file to import into our actual binding projects
 		// which is much easier/less maintenance
@@ -377,7 +399,7 @@ Task ("nuget-setup").Does (() => {
 		// Load the doc to append to, and the doc to append
 		var xFileRoot = System.Xml.Linq.XDocument.Load ("./generated.targets");
 		System.Xml.Linq.XNamespace nsRoot = xFileRoot.Root.Name.Namespace;
-		var xFileChild = System.Xml.Linq.XDocument.Load (targetsFile);
+		var xFileChild = System.Xml.Linq.XDocument.Load (MakeAbsolute(targetsFile).FullPath);
 		System.Xml.Linq.XNamespace nsChild = xFileRoot.Root.Name.Namespace;
 
 		// Add all the elements under <Project> into the existing file's <Project> node
@@ -480,7 +502,7 @@ Task ("component-docs").Does (() =>
 	}
 });
 
-Task ("libs").IsDependentOn ("genapi").IsDependentOn ("nuget-setup");
+Task ("libs").IsDependentOn ("nuget-setup").IsDependentOn ("genapi").IsDependentOn ("libs-base");
 
 Task ("genapi").IsDependentOn ("libs-base").IsDependentOn ("externals").Does (() => {
 
@@ -522,6 +544,15 @@ Task ("genapi").IsDependentOn ("libs-base").IsDependentOn ("externals").Does (()
 	CopyFile ("./v4/source/bin/Release/Xamarin.Android.Support.v4.dll", "./output/Xamarin.Android.Support.v4.dll");
 });
 
+Task ("buildtasks").Does (() => 
+{
+	NuGetRestore ("./vector-drawable/buildtask/Vector-Drawable-BuildTasks.csproj");
+
+	DotNetBuild ("./vector-drawable/buildtask/Vector-Drawable-BuildTasks.csproj", c => c.Configuration = "Release");
+
+	CopyFile ("./vector-drawable/buildtask/bin/Release/Xamarin.Android.Support.Tasks.VectorDrawable.targets", "./vector-drawable/nuget/merge.targets");
+});
+
 SetupXamarinBuildTasks (buildSpec, Tasks, Task);
 
 RunTarget (TARGET);

vector-drawable/nuget/Xamarin.Android.Support.Vector.Drawable.nuspec

@@ -19,10 +19,7 @@
     </dependencies>
   </metadata>
   <files>
-    <!-- Include .targets file to setup AndroidResGenExtraArgs property to add -no-version-vectors to the aapt.exe call -->
-    <file src="vector-drawable/buildtask/bin/Release/Xamarin.Android.Support.Tasks.VectorDrawable.targets" target="build" />
     <file src="vector-drawable/buildtask/bin/Release/Xamarin.Android.Support.Tasks.VectorDrawable.dll" target="build" />
-
     <file src="vector-drawable/nuget/Xamarin.Android.Support.Vector.Drawable.targets" target="build" />
 
     <file src="output/Xamarin.Android.Support.Vector.Drawable.dll" target="lib/MonoAndroid70" />