theme.gradle

apply plugin: ThemePlugin

class ThemePlugin implements Plugin<Project> {

    @Override
    void apply(Project project) {
        def themes = project.container(Theme)
        project.extensions.themes = themes

        themes.all { theme ->
            theme.cssFiles = project.sourceSets.main.resources.matching {
                include "com/gluonhq/otn/${theme.name}*.css"
            }
            def copyTask = project.task("theme${theme.name.capitalize()}", type: Copy) {
                from theme.cssFiles
                into project.sourceSets.main.output.resourcesDir
                rename { String fileName ->
                    fileName.replace("${theme.name}", "javaone")
                }
            }
            copyTask.dependsOn project.tasks.classes
            def task = project.task("theme${theme.name.capitalize()}Run")
            task.dependsOn copyTask, project.tasks.run
            project.tasks.run.mustRunAfter copyTask
        }
    }
}

class Theme {
    final String name
    FileCollection cssFiles

    Theme(String name) {
        this.name = name
    }
}