import org.scalatra.ScalatraKernel
import org.thymeleaf.templateresolver._
import org.thymeleaf.TemplateEngine
import org.thymeleaf.context.WebContext

trait ThymeleafSupport {

  self: ScalatraKernel =>

  lazy val thymeleafResolver: TemplateResolver = {
    val resolver = new ServletContextTemplateResolver
    resolver.setTemplateMode("LEGACYHTML5")
    resolver.setPrefix("/WEB-INF/layouts/")
    resolver.setSuffix(".html")
    resolver.setCacheTTLMs(3600000L)
    resolver
  }

  lazy val thymeleafTemplateEngine: TemplateEngine = {
    val engine = new TemplateEngine
    engine.setTemplateResolver(thymeleafResolver)
    engine
  }

  def render(templateName: String, attributes: (String, Any)*): String = {
    contentType = "text/html; charset=utf-8"
    val context = new WebContext(request, servletContext)
    attributes.foreach {
      case (key, value: Map[_,_]) => context.setVariable(key, value.asJava)
      case (key, value: Iterable[_]) => context.setVariable(key, value.asJava)
      case (key, value) => context.setVariable(key, value)
    }
    thymeleafTemplateEngine.process(templateName, context)
  }

}