var STREAM = {};

function getID(obj) {
  return document.getElementById(obj);	
}

STREAM.counter = 0;

function showP() {
  STREAM.desc = getID("snippetDescription");
  
  STREAM.desc.para = STREAM.desc.getElementsByTagName("p");
  
  for ( var i = 0; i < STREAM.desc.para.length; i++) {
	with (STREAM) {
	  desc.para[i].id = i;  
	  
	  if (i === counter) {
	    desc.para[i].style.display = "block";
	  }
	  else {
	    desc.para[i].style.display = "none";
	  }
	}
  }
  
  // show/hide snippet description
  if (STREAM.counter === 0) {
	getID("snipPrev").style.visibility = "hidden";  
  }
  else {
    getID("snipPrev").style.visibility = "visible";  
  }
  
  if (STREAM.counter === STREAM.desc.para.length - 1) {
	getID("snipNext").style.visibility = "hidden"; 
  }
  else {
	getID("snipNext").style.visibility = "visible";  
  }
}

window.onload = function() {
  showP();
  
  getID("snipNext").onclick = function() {
    ++STREAM.counter;
	showP();
  }
  
  getID("snipPrev").onclick = function() {
 	--STREAM.counter;
	showP();
  }
}