Add Kotlin support

model/src/main/java/com/microsoft/java/bs/gradle/model/KotlinExtension.java

@@ -0,0 +1,20 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+package com.microsoft.java.bs.gradle.model;
+
+import java.util.List;
+
+/**
+ * The extension model for Kotlin language.
+ */
+public interface KotlinExtension extends LanguageExtension {
+
+  String getKotlinLanguageVersion();
+
+  String getKotlinApiVersion();
+
+  List<String> getKotlincOptions();
+
+  List<String> getKotlinAssociates();
+}

model/src/main/java/com/microsoft/java/bs/gradle/model/LanguageExtension.java

@@ -57,6 +57,13 @@ public interface LanguageExtension extends Serializable {
    */
   boolean isScalaExtension();
 
+  /**
+   * Checks if the implementing class is a {@link ScalaExtension}.
+   *
+   * @return true if the extension is for Scala, false otherwise.
+   */
+  boolean isKotlinExtension();
+
   /**
    * Attempts to cast the current object to a {@link JavaExtension} instance.
    * <p>
@@ -80,4 +87,17 @@ public interface LanguageExtension extends Serializable {
    *        or null if the cast fails.
    */
   ScalaExtension getAsScalaExtension();
+
+  /**
+   * Attempts to cast the current object to a {@link KotlinExtension} instance.
+   * <p>
+   * This method should ideally be used only when the implementing class
+   * is known to be a {@link KotlinExtension}.
+   * </p>
+   *
+   * @return the current object cast to a {@link KotlinExtension} instance,
+   *        or null if the cast fails.
+   */
+  KotlinExtension getAsKotlinExtension();
+
 }

model/src/main/java/com/microsoft/java/bs/gradle/model/SupportedLanguages.java

@@ -4,6 +4,7 @@
 package com.microsoft.java.bs.gradle.model;
 
 import com.microsoft.java.bs.gradle.model.impl.DefaultJavaLanguage;
+import com.microsoft.java.bs.gradle.model.impl.DefaultKotlinLanguage;
 import com.microsoft.java.bs.gradle.model.impl.DefaultScalaLanguage;
 
 import java.util.LinkedList;
@@ -16,6 +17,7 @@
 public class SupportedLanguages {
   public static final DefaultJavaLanguage JAVA = new DefaultJavaLanguage();
   public static final DefaultScalaLanguage SCALA = new DefaultScalaLanguage();
+  public static final DefaultKotlinLanguage KOTLIN = new DefaultKotlinLanguage();
 
   public static final List<SupportedLanguage<?>> all;
   public static final List<String> allBspNames;
@@ -24,6 +26,7 @@ public class SupportedLanguages {
     all = new LinkedList<>();
     all.add(JAVA);
     all.add(SCALA);
+    all.add(KOTLIN);
     allBspNames = all.stream().map(SupportedLanguage::getBspName).collect(Collectors.toList());
   }
 }

model/src/main/java/com/microsoft/java/bs/gradle/model/impl/DefaultGradleSourceSet.java

@@ -107,6 +107,10 @@ private LanguageExtension convertLanguageExtension(LanguageExtension object) {
       return object.getAsScalaExtension();
     }
 
+    if (object.isKotlinExtension()) {
+      return object.getAsKotlinExtension();
+    }
+
     throw new IllegalArgumentException("No conversion methods defined for object: " + object);
   }
 

model/src/main/java/com/microsoft/java/bs/gradle/model/impl/DefaultJavaExtension.java

@@ -4,6 +4,7 @@
 package com.microsoft.java.bs.gradle.model.impl;
 
 import com.microsoft.java.bs.gradle.model.JavaExtension;
+import com.microsoft.java.bs.gradle.model.KotlinExtension;
 import com.microsoft.java.bs.gradle.model.ScalaExtension;
 
 import java.io.File;
@@ -155,6 +156,11 @@ public boolean isScalaExtension() {
     return false;
   }
 
+  @Override
+  public boolean isKotlinExtension() {
+    return false;
+  }
+
   @Override
   public JavaExtension getAsJavaExtension() {
     return this;
@@ -164,4 +170,9 @@ public JavaExtension getAsJavaExtension() {
   public ScalaExtension getAsScalaExtension() {
     return null;
   }
+
+  @Override
+  public KotlinExtension getAsKotlinExtension() {
+    return null;
+  }
 }

model/src/main/java/com/microsoft/java/bs/gradle/model/impl/DefaultKotlinExtension.java

@@ -0,0 +1,166 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+package com.microsoft.java.bs.gradle.model.impl;
+
+import com.microsoft.java.bs.gradle.model.JavaExtension;
+import com.microsoft.java.bs.gradle.model.KotlinExtension;
+import com.microsoft.java.bs.gradle.model.ScalaExtension;
+
+import java.io.File;
+import java.util.List;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * Default implementation of {@link KotlinExtension}.
+ */
+public class DefaultKotlinExtension implements KotlinExtension {
+  private static final long serialVersionUID = 1L;
+
+  private Set<File> sourceDirs;
+
+  private Set<File> generatedSourceDirs;
+
+  private String compileTaskName;
+
+  private File classesDir;
+
+  private String kotlinLanguageVersion;
+
+  private String kotlinApiVersion;
+
+  private List<String> kotlincOptions;
+
+  private List<String> kotlinAssociates;
+
+  @Override
+  public Set<File> getSourceDirs() {
+    return sourceDirs;
+  }
+
+  public void setSourceDirs(Set<File> sourceDirs) {
+    this.sourceDirs = sourceDirs;
+  }
+
+  @Override
+  public Set<File> getGeneratedSourceDirs() {
+    return generatedSourceDirs;
+  }
+
+  public void setGeneratedSourceDirs(Set<File> generatedSourceDirs) {
+    this.generatedSourceDirs = generatedSourceDirs;
+  }
+
+  @Override
+  public String getCompileTaskName() {
+    return compileTaskName;
+  }
+
+  public void setCompileTaskName(String compileTaskName) {
+    this.compileTaskName = compileTaskName;
+  }
+
+  @Override
+  public File getClassesDir() {
+    return classesDir;
+  }
+
+  public void setClassesDir(File classesDir) {
+    this.classesDir = classesDir;
+  }
+
+  @Override
+  public String getKotlinLanguageVersion() {
+    return kotlinLanguageVersion;
+  }
+
+  public void setKotlinLanguageVersion(String kotlinLanguageVersion) {
+    this.kotlinLanguageVersion = kotlinLanguageVersion;
+  }
+
+  @Override
+  public String getKotlinApiVersion() {
+    return kotlinApiVersion;
+  }
+
+  public void setKotlinApiVersion(String kotlinApiVersion) {
+    this.kotlinApiVersion = kotlinApiVersion;
+  }
+
+  @Override
+  public List<String> getKotlincOptions() {
+    return kotlincOptions;
+  }
+
+  public void setKotlincOptions(List<String> kotlincOptions) {
+    this.kotlincOptions = kotlincOptions;
+  }
+
+  @Override
+  public List<String> getKotlinAssociates() {
+    return kotlinAssociates;
+  }
+
+  public void setKotlinAssociates(List<String> kotlinAssociates) {
+    this.kotlinAssociates = kotlinAssociates;
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(sourceDirs, generatedSourceDirs, compileTaskName, classesDir,
+              kotlinLanguageVersion, kotlinApiVersion, kotlincOptions, kotlinAssociates);
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (obj == null) {
+      return false;
+    }
+    if (getClass() != obj.getClass()) {
+      return false;
+    }
+    DefaultKotlinExtension other = (DefaultKotlinExtension) obj;
+    return Objects.equals(sourceDirs, other.sourceDirs)
+            && Objects.equals(generatedSourceDirs, other.generatedSourceDirs)
+            && Objects.equals(compileTaskName, other.compileTaskName)
+            && Objects.equals(classesDir, other.classesDir)
+            && Objects.equals(kotlinLanguageVersion, other.kotlinLanguageVersion)
+            && Objects.equals(kotlinApiVersion, other.kotlinApiVersion)
+            && Objects.equals(kotlincOptions, other.kotlincOptions)
+            && Objects.equals(kotlinAssociates, other.kotlinAssociates);
+  }
+
+  @Override
+  public boolean isJavaExtension() {
+    return false;
+  }
+
+  @Override
+  public boolean isScalaExtension() {
+    return false;
+  }
+
+  @Override
+  public boolean isKotlinExtension() {
+    return true;
+  }
+
+  @Override
+  public JavaExtension getAsJavaExtension() {
+    return null;
+  }
+
+  @Override
+  public ScalaExtension getAsScalaExtension() {
+    return null;
+  }
+
+  @Override
+  public KotlinExtension getAsKotlinExtension() {
+    return this;
+  }
+}

model/src/main/java/com/microsoft/java/bs/gradle/model/impl/DefaultKotlinLanguage.java

@@ -0,0 +1,40 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+package com.microsoft.java.bs.gradle.model.impl;
+
+import com.microsoft.java.bs.gradle.model.KotlinExtension;
+import com.microsoft.java.bs.gradle.model.LanguageExtension;
+import com.microsoft.java.bs.gradle.model.SupportedLanguage;
+
+import java.util.Map;
+
+/**
+ * Default Kotlin implementation of {@link SupportedLanguage}.
+ */
+public class DefaultKotlinLanguage implements SupportedLanguage<KotlinExtension> {
+
+  @Override
+  public String getBspName() {
+    return "kotlin";
+  }
+
+  @Override
+  public String getGradleName() {
+    return "kotlin";
+  }
+
+  @Override
+  public KotlinExtension getExtension(Map<String, LanguageExtension> extensions) {
+    LanguageExtension extension = extensions.get(getBspName());
+    if (extension == null) {
+      return null;
+    }
+    if (extension.isKotlinExtension()) {
+      return extension.getAsKotlinExtension();
+    }
+    throw new IllegalArgumentException(
+        "LanguageExtension: " + extension + " is not a KotlinExtension."
+    );
+  }
+}

model/src/main/java/com/microsoft/java/bs/gradle/model/impl/DefaultScalaExtension.java

@@ -4,6 +4,7 @@
 package com.microsoft.java.bs.gradle.model.impl;
 
 import com.microsoft.java.bs.gradle.model.JavaExtension;
+import com.microsoft.java.bs.gradle.model.KotlinExtension;
 import com.microsoft.java.bs.gradle.model.ScalaExtension;
 
 import java.io.File;
@@ -155,6 +156,11 @@ public boolean isScalaExtension() {
     return true;
   }
 
+  @Override
+  public boolean isKotlinExtension() {
+    return false;
+  }
+
   @Override
   public JavaExtension getAsJavaExtension() {
     return null;
@@ -164,4 +170,9 @@ public JavaExtension getAsJavaExtension() {
   public ScalaExtension getAsScalaExtension() {
     return this;
   }
+
+  @Override
+  public KotlinExtension getAsKotlinExtension() {
+    return null;
+  }
 }