feat: add kotlin support

.gitignore

@@ -54,3 +54,4 @@ package-lock.json
 # Eclipse Buildship files
 .project
 .settings
+.classpath

bin/templates/cordova/lib/prepare.js

@@ -46,11 +46,16 @@ module.exports.prepare = function (cordovaProject, options) {
     const maxSdkVersion = this._config.getPreference('android-maxSdkVersion', 'android');
     const targetSdkVersion = this._config.getPreference('android-targetSdkVersion', 'android');
     const androidXEnabled = this._config.getPreference('AndroidXEnabled', 'android');
+    const isGradlePluginKotlinEnabled = this._config.getPreference('GradlePluginKotlinEnabled', 'android');
+    const gradlePluginKotlinCodeStyle = this._config.getPreference('GradlePluginKotlinCodeStyle', 'android');
 
     let gradlePropertiesUserConfig = {};
     if (minSdkVersion) gradlePropertiesUserConfig.cdvMinSdkVersion = minSdkVersion;
     if (maxSdkVersion) gradlePropertiesUserConfig.cdvMaxSdkVersion = maxSdkVersion;
     if (targetSdkVersion) gradlePropertiesUserConfig.cdvTargetSdkVersion = targetSdkVersion;
+    if (isGradlePluginKotlinEnabled) {
+        gradlePropertiesUserConfig['kotlin.code.style'] = gradlePluginKotlinCodeStyle || 'official';
+    }
 
     // Both 'useAndroidX' and 'enableJetifier' are linked together.
     if (androidXEnabled) {

bin/templates/project/app/build.gradle

@@ -19,7 +19,31 @@
 
 apply plugin: 'com.android.application'
 
+if (cdvHelpers.getConfigPreference('GradlePluginKotlinEnabled', 'false').toBoolean()) {
+    apply plugin: 'kotlin-android'
+    apply plugin: 'kotlin-android-extensions'
+}
+
 buildscript {
+    apply from: '../CordovaLib/cordova.gradle'
+
+    if(cdvHelpers.getConfigPreference('GradlePluginKotlinEnabled', 'false').toBoolean()) {
+        String defaultGradlePluginKotlinVersion = kotlin_version
+
+        /**
+         * Fetches the user's defined Kotlin Version from config.xml.
+         * If the version is not set or invalid, it will default to the ${defaultGradlePluginKotlinVersion}
+         */
+        String gradlePluginKotlinVersion = cdvHelpers.getConfigPreference('GradlePluginKotlinVersion', defaultGradlePluginKotlinVersion)
+        if(!cdvHelpers.isVersionValid(gradlePluginKotlinVersion)) {
+            println("The defined Kotlin version (${gradlePluginKotlinVersion}) does not appear to be a valid version. Falling back to version: ${defaultGradlePluginKotlinVersion}.")
+            gradlePluginKotlinVersion = defaultGradlePluginKotlinVersion
+        }
+
+        // Change the version to be used.
+        ext.kotlin_version = gradlePluginKotlinVersion
+    }
+
     repositories {
         mavenCentral()
         google()
@@ -31,6 +55,10 @@ buildscript {
 
         classpath 'com.android.tools.build:gradle:3.5.3'
 
+        if (cdvHelpers.getConfigPreference('GradlePluginKotlinEnabled', 'false').toBoolean()) {
+            classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+        }
+
         if(cdvHelpers.getConfigPreference('GradlePluginGoogleServicesEnabled', 'false').toBoolean()) {
             String defaultGradlePluginGoogleServicesVersion = '4.2.0'
 
@@ -301,6 +329,10 @@ android {
     if (cdvDebugSigningPropertiesFile) {
         addSigningProps(cdvDebugSigningPropertiesFile, signingConfigs.debug)
     }
+
+    sourceSets {
+        main.java.srcDirs += 'src/main/kotlin'
+    }
 }
 
 /*
@@ -312,6 +344,11 @@ android {
 
 dependencies {
     implementation fileTree(dir: 'libs', include: '*.jar')
+
+    if (cdvHelpers.getConfigPreference('GradlePluginKotlinEnabled', 'false').toBoolean()) {
+        implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    }
+
     // SUB-PROJECT DEPENDENCIES START
     debugCompile(project(path: ":CordovaLib", configuration: "debug"))
     releaseCompile(project(path: ":CordovaLib", configuration: "release"))

bin/templates/project/build.gradle

@@ -19,16 +19,16 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
+    ext.kotlin_version = '1.3.50'
     repositories {
         google()
         jcenter()
     }
-
     dependencies {
+        classpath 'com.android.tools.build:gradle:3.5.3'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
-
-        classpath 'com.android.tools.build:gradle:3.5.3'
     }
 }
 

test/android/app/build.gradle

@@ -17,6 +17,8 @@
 */
 
 apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
 
 android {
     compileSdkVersion 29
@@ -51,4 +53,9 @@ dependencies {
     implementation 'com.android.support:appcompat-v7:26.1.0'
     testImplementation 'junit:junit:4.12'
     testImplementation 'org.json:json:20140107'
+
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+}
+repositories {
+    jcenter()
 }

test/android/build.gradle

@@ -19,6 +19,8 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
+    ext.kotlin_version = '1.3.50'
+
     repositories {
         google()
         jcenter()
@@ -29,6 +31,7 @@ buildscript {
         // in the individual module build.gradle files
 
         classpath 'com.android.tools.build:gradle:3.5.3'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }