pusher.scala

// Implementing the publishing Pusher REST API
// @see http://pusher.com/docs/rest_api
// with Play (scala) Framework 
// @see http://scala.playframework.org/

class Pusher {
  val appId = Play.configuration.getProperty("pusher.appId")
  val key = Play.configuration.getProperty("pusher.key")
  val secret = Play.configuration.getProperty("pusher.secret")
  
  import java.security.MessageDigest
  import java.math.BigInteger
  import javax.crypto.Mac
  import javax.crypto.spec.SecretKeySpec
  
  def trigger(channel:String, event:String, message:String):HttpResponse = {
    val domain = "api.pusherapp.com"
    val url = "/apps/"+appId+"/channels/"+channel+"/events";
    val body = message
    
    val params = List( 
      ("auth_key", key),
      ("auth_timestamp", (new Date().getTime()/1000) toInt ),
      ("auth_version", "1.0"),
      ("name", event),
      ("body_md5", md5(body))
    ).sort( (a,b) => a._1 < b._1 ).map( o => o._1+"="+WS.encode(o._2.toString) ).mkString("&");
    
    val signature = sha256( List("POST", url, params).mkString("\n"), secret ); 
     
    WS.url("http://"+domain+url+"?"+params+"&auth_signature="+WS.encode(signature)).body(body).post()
  }
  
  def byteArrayToString(data: Array[Byte]) = {
     val hash = new BigInteger(1, data).toString(16);
     "0"*(32-hash.length) + hash
  }
  def md5(s: String):String = byteArrayToString(MessageDigest.getInstance("MD5").digest(s.getBytes("US-ASCII")));
  
  def sha256(s: String, secret: String):String = {
    val mac = Mac.getInstance("HmacSHA256");
    mac.init(new SecretKeySpec( secret.getBytes(), "HmacSHA256"));
    val digest = mac.doFinal(s.getBytes());
    String.format("%0" + (digest.length << 1) + "x", new BigInteger(1, digest));
  }
}

/*
Usage example :

object WebSockets extends Pusher {
  val channel = Play.configuration.getProperty("websockets.channel")
  def trigger(event:String, message:String):HttpResponse = trigger(channel, event, message)
}

object Test {
  def test = WebSockets.trigger("hello", "{ \"message\": \"test\" }")
}
*/