Add base Android tool runner infrastructure

src/Xamarin.Android.Tools.AndroidSdk/Runners/AndroidEnvironmentHelper.cs

@@ -0,0 +1,38 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace Xamarin.Android.Tools
+{
+/// <summary>
+/// Helper for setting up environment variables for Android SDK tools.
+/// </summary>
+public static class AndroidEnvironmentHelper
+{
+/// <summary>
+/// Creates environment variables for running Android SDK tools.
+/// </summary>
+public static Dictionary<string, string>? GetToolEnvironment (string? sdkPath, string? jdkPath)
+{
+if (string.IsNullOrEmpty (sdkPath) && string.IsNullOrEmpty (jdkPath))
+return null;
+
+var env = new Dictionary<string, string> (StringComparer.OrdinalIgnoreCase);
+
+if (!string.IsNullOrEmpty (sdkPath))
+env ["ANDROID_HOME"] = sdkPath;
+
+if (!string.IsNullOrEmpty (jdkPath)) {
+env ["JAVA_HOME"] = jdkPath;
+var jdkBin = Path.Combine (jdkPath, "bin");
+var currentPath = Environment.GetEnvironmentVariable ("PATH") ?? "";
+env ["PATH"] = string.IsNullOrEmpty (currentPath) ? jdkBin : jdkBin + Path.PathSeparator + currentPath;
+}
+
+return env;
+}
+}
+}