// JavaScript Document

function setTypeSize(type_size) {
	//Set the cookie for future pages
	setCookie('css_size', type_size);
	
	// Update CSS in current page
	setStyleSheet('type_base_' + type_size, 'type_size')
}


function setStyleSheet (css_filename, css_id) {
	css_url = 'http://www.herib.co.uk/css/' + css_filename + '.css';
	document.getElementById (css_id).href = css_url;
	return null;
}

function swapCSS(css_style) {
	
	var new_value;
	
	switch (css_style) {
		case 'layout' :
			target_cookie = 'css_layout';
			default_value = 'img';
			alt_value = 'txt';
			break;
			
		case 'colour' :
			target_cookie = 'css_colour';
			default_value = 'hivis';
			alt_value = 'stdrd';
			break;
	}
	
	if (getCookie(target_cookie) == default_value) {
		new_value = alt_value;
	} else {
		new_value = default_value;
	}
		
	//Set the cookie for future pages
	setCookie(target_cookie, new_value);
	
	// Update CSS in current page
	setStyleSheet(css_style + '_' + new_value, css_style + '_css');
	
	// Deal with anomalies
	if (new_value == 'txt') {
		// We are changing to text only layout so deal with colour issue
		setCookie('css_colour', 'txt');
		setStyleSheet('colour_txt', 'colour_css');
	} else if (new_value == 'hivis') {
		// We are changing to high contrast so revert to default layout
		setCookie('css_layout', 'img');
		setStyleSheet('layout_img', 'layout_css');
	} else if (css_style == 'layout') {
		// Revert to default colour scheme
		setCookie('css_colour', 'stdrd');
		setStyleSheet('colour_stdrd', 'colour_css');
	}
}

function setCookie(cookie_name, cookie_value) {
	
	// Define the expiry date for 28 days time
	var ms = 28 * 24 * 60 * 60 * 1000;
	var cookie_date = new Date();
    cookie_date.setTime(cookie_date.getTime() + ms);
	
	// Set the cookie
	document.cookie = cookie_name + '=' + cookie_value + '; expires=' + cookie_date.toGMTString() +'; path=/';
}

function getCookie (needle) {
	// Split cookie string value into an array
	var pair_array = document.cookie.split(/[; ]+/);
	
	// Iterate across array and turn each element into a key=value
	var cookie_array = new Array();
	
    for (var i = 0 ; i < pair_array.length; i++) {
		var cookie_pair = pair_array[i].split('=');
		//cookie_array[cookie_pair[0]] = cookie_pair[1];
		if (cookie_pair[0] == needle) {
			return cookie_pair[1];
		}
    } 
	
}