/**
* hashgrid (jQuery version)
* http://github.com/dotjay/hashgrid
* Version 4, 29 Mar 2010
* By Jon Gibbins, accessibility.co.uk
*
* // Using a basic #grid setup
* var grid = new hashgrid();
*
* // Using #grid with a custom id (e.g. #mygrid)
* var grid = new hashgrid("mygrid");
*
* // Using #grid with additional options
* var grid = new hashgrid({
* id: 'mygrid', // id for the grid container
* modifierKey: 'alt', // optional 'ctrl', 'alt' or 'shift'
* showGridKey: 's', // key to show the grid
* holdGridKey: 'enter', // key to hold the grid in place
* foregroundKey: 'f', // key to toggle foreground/background
* jumpGridsKey: 'd', // key to cycle through the grid classes
* numberOfGrids: 2, // number of grid classes used
* classPrefix: 'class', // prefix for the grid classes
* cookiePrefix: 'mygrid' // prefix for the cookie name
* });
*/


/**
* You can call hashgrid from your own code, but it's loaded here by
* default for convenience.
*/
$(document).ready(function() {

var grid = new hashgrid({
numberOfGrids: 2
});

});


/**
* hashgrid overlay
*/
var hashgrid = function(set) {

var options = {
id: 'grid', // id for the grid container
modifierKey: null, // optional 'ctrl', 'alt' or 'shift'
showGridKey: 'g', // key to show the grid
holdGridKey: 'h', // key to hold the grid in place
foregroundKey: 'f', // key to toggle foreground/background
jumpGridsKey: 'j', // key to cycle through the grid classes
numberOfGrids: 1, // number of grid classes used
classPrefix: 'grid-', // prefix for the grid classes
cookiePrefix: 'hashgrid'// prefix for the cookie name
};
var overlayOn = false,
sticky = false,
overlayZState = 'B',
overlayZBackground = -1,
overlayZForeground = 9999,
classNumber = 1;

// Apply options
if (typeof set == 'object') {
var k;
for (k in set) options[k] = set[k];
}
else if (typeof set == 'string') {
options.id = set;
}

// Remove any conflicting overlay
if ($('#' + options.id).length > 0) {
$('#' + options.id).remove();
}

// Create overlay, hidden before adding to DOM
var overlayEl = $('<div></div>');
overlayEl
.attr('id', options.id)
.css('display', 'none');
$("body").prepend(overlayEl);
var overlay = $('#' + options.id);

// Unless a custom z-index is set, ensure the overlay will be behind everything
if (overlay.css('z-index') == 'auto') overlay.css('z-index', overlayZBackground);

// Override the default overlay height with the actual page height
var pageHeight = parseFloat($(document).height());
overlay.height(pageHeight);

// Add the first grid line so that we can measure it
overlay.append('<div class="horiz first-line">');

// Calculate the number of grid lines needed
var overlayGridLines = overlay.children('.horiz'),
overlayGridLineHeight = parseFloat(overlayGridLines.css('height')) + parseFloat(overlayGridLines.css('border-bottom-width'));

// Break on zero line height
if (overlayGridLineHeight <= 0) return true;

// Add the remaining grid lines
var i, numGridLines = Math.floor(pageHeight / overlayGridLineHeight);
for (i = numGridLines - 1; i >= 1; i--) {
overlay.append('<div class="horiz"></div>');
}

// Check for saved state
var overlayCookie = readCookie(options.cookiePrefix + options.id);
if (typeof overlayCookie == 'string') {
var state = overlayCookie.split(',');
state[2] = Number(state[2]);
if ((typeof state[2] == 'number') && !isNaN(state[2])) {
classNumber = state[2].toFixed(0);
overlay.addClass(options.classPrefix + classNumber);
}
if (state[1] == 'F') {
overlayZState = 'F';
overlay.css('z-index', overlayZForeground);
}
if (state[0] == '1') {
overlayOn = true;
sticky = true;
overlay.show();
}
}
else {
overlay.addClass(options.classPrefix + classNumber)
}

// Keyboard controls
$(document).bind('keydown', keydownHandler);
$(document).bind('keyup', keyupHandler);

/**
* Helpers
*/

function getModifier(e) {
if (options.modifierKey == null) return true; // Bypass by default
var m = true;
switch(options.modifierKey) {
case 'ctrl':
m = (e.ctrlKey ? e.ctrlKey : false);
break;

case 'alt':
m = (e.altKey ? e.altKey : false);
break;

case 'shift':
m = (e.shiftKey ? e.shiftKey : false);
break;
}
return m;
}

function getKey(e) {
var k = false, c = (e.keyCode ? e.keyCode : e.which);
// Handle keywords
if (c == 13) k = 'enter';
// Handle letters
else k = String.fromCharCode(c).toLowerCase();
return k;
}

function saveState() {
createCookie(options.cookiePrefix + options.id, (sticky ? '1' : '0') + ',' + overlayZState + ',' + classNumber, 1);
}

/**
* Event handlers
*/

function keydownHandler(e) {
var source = e.target.tagName.toLowerCase();
if ((source == 'input') || (source == 'textarea') || (source == 'select')) return true;
var m = getModifier(e);
if (!m) return true;
var k = getKey(e);
if (!k) return true;
switch(k) {
case options.showGridKey:
if (!overlayOn) {
overlay.show();
overlayOn = true;
}
else if (sticky) {
overlay.hide();
overlayOn = false;
sticky = false;
saveState();
}
break;
case options.holdGridKey:
if (overlayOn && !sticky) {
// Turn sticky overlay on
sticky = true;
saveState();
}
break;
case options.foregroundKey:
if (overlayOn) {
// Toggle sticky overlay z-index
if (overlay.css('z-index') == overlayZForeground) {
overlay.css('z-index', overlayZBackground);
overlayZState = 'B';
}
else {
overlay.css('z-index', overlayZForeground);
overlayZState = 'F';
}
saveState();
}
break;
case options.jumpGridsKey:
if (overlayOn && (options.numberOfGrids > 1)) {
// Cycle through the available grids
overlay.removeClass(options.classPrefix + classNumber);
classNumber++;
if (classNumber > options.numberOfGrids) classNumber = 1;
overlay.addClass(options.classPrefix + classNumber);
if (/webkit/.test( navigator.userAgent.toLowerCase() )) {
forceRepaint();
}
saveState();
}
break;
}
}

function keyupHandler(e) {
var m = getModifier(e);
if (!m) return true;
var k = getKey(e);
if (!k) return true;
if ((k == options.showGridKey) && !sticky) {
overlay.hide();
overlayOn = false;
}
}

}


/**
* Cookie functions
*
* By Peter-Paul Koch:
* http://www.quirksmode.org/js/cookies.html
*/
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=/";
}

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;
}

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


/**
* Forces a repaint (because WebKit has issues)
* http://www.sitepoint.com/forums/showthread.php?p=4538763
* http://www.phpied.com/the-new-game-show-will-it-reflow/
*/
function forceRepaint() {
var ss = document.styleSheets[0];
try {
ss.addRule('.xxxxxx', 'position: relative');
ss.removeRule(ss.rules.length - 1);
} catch(e){}
}