var lastAnswer = null; // Last shown answer div

/* Add trim function to strings */
String.prototype.trim = function() {
	return this.replace(/^\s+|\s+$/g,"");
}

$(document).ready(function() {
	
	var style = readCookie('style');
	if (style) {
		switchStyle(style);
	}
	
});


function showAnswer(id) {
	var div = document.getElementById(id);
	
	if (!lastAnswer)
		lastAnswer = document.getElementById("startans");
	
	if (lastAnswer)
		lastAnswer.style.display = "none";
		
	div.style.display = "block";
	
	lastAnswer = div;
}

// Change stylesheet
function switchStyle(newStyle) {
	$("link[@rel*=style][@title]").each(function() {
		this.disabled = true;
		if (this.getAttribute('title') == newStyle) 
			this.disabled = false;
	});
	
	createCookie('style', newStyle, 365);
}

// Create cookie
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 
		var expires = "";
	
	document.cookie = name+"="+value+expires+"; path=/";
}

// Read cookie
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;
}

// Delete cookie
function eraseCookie(name) {
	createCookie(name,"",-1);
}