gistfile1.scala

package code.comet

import net.liftweb._
import http._
import actor._
import js._
import JsCmds._
import js.jquery.JqJsCmds.{AppendHtml, FadeOut, Hide, FadeIn}
import java.util.Date
import scala.xml._
import util.Helpers._

object ChatServer extends LiftActor with ListenerManager {

  private var message: ChatCmd = _

  def createUpdate = message

  override def lowPriority = {
    case s: String => message = AddMessage(nextFuncName, s, new Date) ; updateListeners()
    case d: RemoveMessage => message = d; updateListeners()
  }
}

sealed trait ChatCmd

final case class AddMessage(guid: String, msg: String, date: Date) extends ChatCmd
final case class RemoveMessage(guid: String) extends ChatCmd

class Chat extends CometActor with CometListener {

  def registerWith = ChatServer

  override def lowPriority = {
    case m: ChatCmd => {
      updateMsg(m)
    }
  }

  def updateMsg(msg: ChatCmd) {
    partialUpdate(msg match {
      case m: AddMessage =>
	Noop & AppendHtml("ul_dude", doLine(m)) &
      Hide(m.guid) & FadeIn(m.guid, TimeSpan(0),TimeSpan(500))
      case RemoveMessage(guid) =>
	Noop & FadeOut(guid,TimeSpan(0),TimeSpan(500)) &
      After(TimeSpan(500),Replace(guid, NodeSeq.Empty))
    })
  }

  def render =
    bind("chat", // the namespace for binding                                                                                                                                                                
         "line" -> Nil,
         "input" -> SHtml.text("", s => ChatServer ! s)) // the input                    

  private def doLine(m: AddMessage): NodeSeq = {
    val xml = <li><chat:msg/><chat:btn/></li>
    bind("chat", addId(xml, m.guid),
         "msg" -> m.msg,
         "btn" -> SHtml.ajaxButton("delete",
                                   () => {
                                     ChatServer !
                                     RemoveMessage(m.guid)
                                     Noop}))
  }

  private def addId(in: NodeSeq, id: String): NodeSeq = in map {
    case e: Elem => e % ("id" -> id)
    case x => x
  }
}