var cookie = readCookie("bwEnabled");
var bwEnabled = cookie ? cookie : "false";

swapImages();

function switchBWEnabled() {
	bwEnabled = (bwEnabled == "true") ? "false" : "true";
	
	swapImages();
	
	createCookie("bwEnabled", bwEnabled, 365);
}

function swapImages() {
	var foundSwitchableImage = false;
	var imgs = document.getElementsByTagName("img");
	for (i = 0; i < imgs.length; i++) {
		var img = imgs[i];
		if (img.className == "bw_switchable") {
			foundSwitchableImage = true;
			
			if (bwEnabled == "true") {
				img.src = img.src.replace(".jpg", "_bw.jpg");
			} else {
				img.src = img.src.replace("_bw.jpg", ".jpg");	
			}		
		}
	}
	
	if (foundSwitchableImage) {
		var switchEl = document.getElementById("bw_switch");
		switchEl.style.display = "inline";
		
		if (bwEnabled == "true") {
			switchEl.innerHTML = "Switch to Color";
		} else {
			switchEl.innerHTML = "Switch to B&amp;W";
		}
	}
}

function createCookie(name,value,days) {
  if (days) {
    var date = new Date();
    date.setTime(date.getTime()+(days*24*60*60*1000));
    var expires = "; expires="+date.toGMTString();
  }
  else expires = "";
  document.cookie = name+"="+value+expires+"; path=/";
}

function readCookie(name) {
  var nameEQ = name + "=";
  var ca = document.cookie.split(';');
  for(var i=0;i < ca.length;i++) {
    var c = ca[i];
    while (c.charAt(0)==' ') c = c.substring(1,c.length);
    if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
  }
  return null;
}