// Accessibility script

 var ScreenCSS_1 = 'styles/clean_air.css';
 var ScreenCSS_2 = 'styles/clean_air_access.css';
 
 function addStyle(currentStyle) {
   var headID = document.getElementsByTagName("head")[0];         
   var cssNode = document.createElement('link');
   cssNode.type = 'text/css';
   cssNode.rel = 'stylesheet';
   cssNode.href = currentStyle;
   cssNode.media = 'screen';
   headID.appendChild(cssNode);
   
   // Write a cookie
   if (currentStyle == ScreenCSS_2)
    writeCookie('accesscookie','accessible',0);
   else 
    writeCookie('accesscookie','normal',0);
 }
 
 // Initial checkup for state of the accessbility mode
 
 function checkState() {
	 
	 var currMode = readCookie('accesscookie');
	 if (currMode == 'accessible')
	   addStyle(ScreenCSS_2);
	 else 
	   addStyle(ScreenCSS_1);
	 
 }
 
 // Additional functions
 
 function writeCookie(name,value,days) {
	if (days) {
		var date = new Date();
		date.setTime(date.getTime()+(days*24*60*60*1000));
		var expires = "; expires="+date.toGMTString();
	}
	else var 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;
}