import jenkins.model.Jenkins
import org.codefirst.SimpleThemeDecorator

def instance = Jenkins.get()
def decorators = instance.getExtensionList(SimpleThemeDecorator.class)

if (decorators?.size() > 0) {
  def theme = decorators[0]
  theme.setCssUrl("https://jenkins-contrib-themes.github.io/jenkins-material-theme/dist/material-ocean.css")
  theme.setJsUrl("")
  theme.setTheme("")
  instance.save()
  println("Applied simple-theme-plugin dark theme")
} else {
  println("simple-theme-plugin not installed; skipping theme configuration")
}