dir.targets

<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  
  <!-- Inline task to bootstrap the build to enable downloading nuget.exe -->
  <UsingTask TaskName="DownloadFile" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v12.0.dll">
    <ParameterGroup>
      <Address ParameterType="System.String" Required="true"/>
      <FileName ParameterType="System.String" Required="true" />
    </ParameterGroup>
    <Task>
      <Reference Include="System" />
      <Code Type="Fragment" Language="cs">
        <![CDATA[
           var directory = System.IO.Path.GetDirectoryName(FileName);
           System.IO.Directory.CreateDirectory(directory);
           var client = new System.Net.WebClient();
           client.Proxy = System.Net.WebRequest.DefaultWebProxy;
           client.Proxy.Credentials = System.Net.CredentialCache.DefaultCredentials;
           client.DownloadFile(Address, FileName);
        ]]>
      </Code>
    </Task>
  </UsingTask>

  <Target Name="_RestoreBuildTools"
    BeforeTargets="Build"
    Inputs="$(BuildToolsCoreCLRTargetInputs)"
    Outputs="$(BuildToolsCoreCLRTargetOutputs)"
    >

    <!-- Download latest nuget.exe -->
    <DownloadFile
      Condition="!Exists($(NuGetToolPath))"
      Address="http://nuget.org/nuget.exe"
      FileName="$(NuGetToolPath)" />

    <!-- Restore build tools -->
    <Exec
      StandardOutputImportance="Low"
      Command="&quot;$(NuGetToolPath)&quot; install &quot; $(SourceDir).nuget\packages.config &quot;  -o &quot; $(ToolsDir) &quot; $(NuGetConfigCommandLine)" />

    <Touch Files="$(BuildToolsInstallSemaphore)" AlwaysCreate="true" />
  </Target>
</Project>