Add Linux sdk items and fix toolchain downloader to really respect HostOS.

- fix Android SDK Tools location.
- add SDK/NDK items for Linux.
- xbuild condition did not work and downloaded all the items. It was because
  condition by metadata didn't work with the complicated expression.
  So, split filtering and transformation into different tasks.
- xbuild aborts when the specified metadata %(HostOS) does not exist, so
  specify dummy HostOS metadata (which is ugly but not too annoying).

(Linux build verification is still ongoing, not assuring that this fixes
all the possible existing issues.)

Author: atsushieno

Makefile

@@ -1,5 +1,5 @@
 CONFIGURATION = Debug
-MSBUILD       = xbuild /p:Configuration=$(CONFIGURATION)
+MSBUILD       = xbuild /p:Configuration=$(CONFIGURATION) $(MSBUILD_ARGS)
 
 all:
 	$(MSBUILD)

build-tools/android-toolchain/android-toolchain.projitems

@@ -4,6 +4,20 @@
     <AndroidUri Condition=" '$(AndroidUri)' == '' ">https://dl-ssl.google.com/android/repository</AndroidUri>
   </PropertyGroup>
   <ItemGroup>
+    <AndroidNdkItem Include="android-ndk-r11c-linux-x86_64.zip">
+      <HostOS>Linux</HostOS>
+    </AndroidNdkItem>
+    <AndroidSdkItem Include="build-tools_r23-linux.zip">
+      <HostOS>Linux</HostOS>
+      <DestDir>build-tools\23.0.0</DestDir>
+    </AndroidSdkItem>
+    <AndroidSdkItem Include="platform-tools_r23-linux.zip">
+      <HostOS>Linux</HostOS>
+      <DestDir>platform-tools</DestDir>
+    </AndroidSdkItem>
+    <AndroidSdkItem Include="tools_r24.4.1-linux.zip">
+      <HostOS>Linux</HostOS>
+    </AndroidSdkItem>
     <AndroidNdkItem Include="android-ndk-r11c-darwin-x86_64.zip">
       <HostOS>Darwin</HostOS>
     </AndroidNdkItem>
@@ -15,13 +29,15 @@
       <HostOS>Darwin</HostOS>
       <DestDir>platform-tools</DestDir>
     </AndroidSdkItem>
-    <AndroidSdkItem Include="android-sdk_r24.4.1-macosx.zip">
+    <AndroidSdkItem Include="tools_r24.4.1-macosx.zip">
       <HostOS>Darwin</HostOS>
     </AndroidSdkItem>
     <AndroidSdkItem Include="platform-N_r01.zip">
+      <HostOS></HostOS>
       <DestDir>platforms\android-N</DestDir>
     </AndroidSdkItem>
     <AndroidSdkItem Include="android-23_r01.zip">
+      <HostOS></HostOS>
       <DestDir>platforms\android-23</DestDir>
     </AndroidSdkItem>
   </ItemGroup>

build-tools/android-toolchain/android-toolchain.targets

@@ -11,24 +11,37 @@
   <UsingTask AssemblyFile="$(OutputPath)\Xamarin.Android.Tools.BootstrapTasks.dll" TaskName="Xamarin.Android.Tools.BootstrapTasks.CreateTemporaryDirectory" />
   <UsingTask AssemblyFile="$(OutputPath)\Xamarin.Android.Tools.BootstrapTasks.dll" TaskName="Xamarin.Android.Tools.BootstrapTasks.DownloadUri" />
   <UsingTask AssemblyFile="$(OutputPath)\Xamarin.Android.Tools.BootstrapTasks.dll" TaskName="Xamarin.Android.Tools.BootstrapTasks.UnzipDirectoryChildren" />
+  <Target Name="_DetermineItems">
+    <CreateItem
+        Include="@(AndroidSdkItem)"
+        Condition=" '%(HostOS)' == '$(HostOS)' Or '%(HostOS)' == '' ">
+			<Output TaskParameter="Include" ItemName="_PlatformAndroidSdkItem"/>
+    </CreateItem>
+    <CreateItem
+        Include="@(AndroidNdkItem)"
+        Condition=" '%(HostOS)' == '$(HostOS)' Or '%(HostOS)' == '' ">
+			<Output TaskParameter="Include" ItemName="_PlatformAndroidNdkItem"/>
+    </CreateItem>
+  </Target>
   <Target Name="_DownloadItems"
-      Outputs="@(AndroidSdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)');@(AndroidNdkItems->'$(AndroidToolchainCacheDirectory)\%(Identity)')">
+      DependsOnTargets="_DetermineItems"
+      Outputs="@(_PlatformAndroidSdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)');@(_PlatformAndroidNdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)')">
     <DownloadUri
-        SourceUris="@(AndroidSdkItem->'$(AndroidUri)/%(Identity)');@(AndroidNdkItem->'$(AndroidUri)/%(Identity)')"
-        DestinationFiles="@(AndroidSdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)');@(AndroidNdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)')"
+        SourceUris="@(_PlatformAndroidSdkItem->'$(AndroidUri)/%(Identity)');@(_PlatformAndroidNdkItem->'$(AndroidUri)/%(Identity)')"
+        DestinationFiles="@(_PlatformAndroidSdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)');@(_PlatformAndroidNdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)')"
     />
   </Target>
   <Target Name="_UnzipFiles"
-      Inputs="@(AndroidSdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)')"
+      DependsOnTargets="_DetermineItems"
+      Inputs="@(_PlatformAndroidSdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)')"
       Outputs="$(AndroidToolchainDirectory)\.stamp-sdk">
     <CreateItem
-        Include="@(AndroidSdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)"
-        Condition=" '%(AndroidSdkItem.HostOS)' == '$(HostOS)' Or '%(AndroidSdkItem.HostOS)' == '' ">
-			<Output TaskParameter="Include" ItemName="_AndroidSdkItems"/>
+        Include="@(_PlatformAndroidSdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)">
+      <Output TaskParameter="Include" ItemName="_AndroidSdkItems"/>
     </CreateItem>
     <CreateItem
-        Include="@(AndroidNdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)"
-        Condition=" '%(AndroidSdkItem.HostOS)' == '$(HostOS)' Or '%(AndroidSdkItem.HostOS)' == '' ">
+        Include="@(_PlatformAndroidNdkItem->'$(AndroidToolchainCacheDirectory)\%(Identity)"
+        Condition=" '%(HostOS)' == '$(HostOS)' Or '%(HostOS)' == '' ">
       <Output TaskParameter="Include" ItemName="_AndroidNdkItems"/>
     </CreateItem>
 

src/Xamarin.Android.Tools.BootstrapTasks/Xamarin.Android.Tools.BootstrapTasks/DownloadUri.cs

@@ -57,6 +57,7 @@ async TTask DownloadFile (HttpClient client, string uri, string destinationFile)
 				Log.LogMessage (MessageImportance.Normal, $"Skipping uri '{uri}' as destination file already exists '{destinationFile}'.");
 				return;
 			}
+			Log.LogMessage (MessageImportance.Low, $"Downloading '{uri}'.");
 			using (var r = await client.GetAsync (uri))
 			using (var o = File.OpenWrite (destinationFile)) {
 				await r.Content.CopyToAsync (o);