(function HintNavigation() {

	var hint_num_str = '';
	var hint_elems = [];
	var hint_tags = [];
	var hint_enabled = false;

	var registeredElements = [];

	var keyId = {
	"U+0008" : "Backspace",
    "U+0009" : "Tab",
    "U+0018" : "Cancel",
    "U+001B" : "Esc",
    "U+0020" : "Space",
    "U+0021" : "!",
    "U+0023" : "#",
    "U+0024" : "$",
    "U+0029" : ")",
    "U+002A" : "*",
    "U+002B" : "+",
    "U+002C" : ",",
    "U+002E" : ".",
    "U+002F" : "/",
    "U+00C0" : "0",
    "U+0026" : "1",
    "U+00C9" : "2",
    "U+0022" : "3",
    "U+0027" : "4",
    "U+0028" : "5",
    "U+002D" : "6",
    "U+00C8" : "7",
    "U+005F" : "8",
    "U+00C7" : "9",
    "U+003A" : ":",
    "U+003B" : ";",
    "U+003C" : "<",
    "U+003D" : "=",
    "U+003E" : ">",
    "U+003F" : "?",
    "U+0040" : "@",
    "U+0041" : "a",
    "U+0042" : "b",
    "U+0043" : "c",
    "U+0044" : "d",
    "U+0045" : "e",
    "U+0046" : "f",
    "U+0047" : "g",
    "U+0048" : "h",
    "U+0049" : "i",
    "U+004A" : "j",
    "U+004B" : "k",
    "U+004C" : "l",
    "U+004D" : "m",
    "U+004E" : "n",
    "U+004F" : "o",
    "U+0050" : "p",
    "U+0051" : "q",
    "U+0052" : "r",
    "U+0053" : "s",
    "U+0054" : "t",
    "U+0055" : "u",
    "U+0056" : "v",
    "U+0057" : "w",
    "U+0058" : "x",
    "U+0059" : "y",
    "U+005A" : "z",
    "U+00DB" : "[",
    "U+00DC" : "\\",
    "U+00DD" : "]",
    "U+005E" : "^",
    "U+0060" : "`",
    "U+007B" : "{",
    "U+007C" : "|",
    "U+007D" : "}",
    "U+007F" : "Delete",
    "U+00A1" : "¡",
    "U+0300" : "CombGrave",
    "U+0301" : "CombAcute",
    "U+0302" : "CombCircum",
    "U+0303" : "CombTilde",
    "U+0304" : "CombMacron",
    "U+0306" : "CombBreve",
    "U+0307" : "CombDot",
    "U+0308" : "CombDiaer",
    "U+030A" : "CombRing",
    "U+030B" : "CombDblAcute",
    "U+030C" : "CombCaron",
    "U+0327" : "CombCedilla",
    "U+0328" : "CombOgonek",
    "U+0345" : "CombYpogeg",
    "U+20AC" : "€",
    "U+3099" : "CombVoice",
    "U+309A" : "CombSVoice",
};

	function interceptListeners(element) {
		var addEvent = element.prototype.addEventListener;
		var removeEvent = element.prototype.removeEventListener;
		element.prototype.addEventListener = function () {
			if (arguments[0] === "click" || arguments[0] === "mouseover") {
				registeredElements.push(this);
			}
			addEvent.call(this, arguments[0], arguments[1], arguments[2]);
		};

		element.prototype.removeEventListener = function () {
			if ((arguments[0] === "click" || arguments[1] === "mouseover") && registeredElements.indexOf(this)>= 0 ) {
				registeredElements.splice(registeredElements.indexOf(this), 1);
			}
			removeEvent.call(this, arguments[0], arguments[1], arguments[2]);
		};
	}


	function start(){
		hint_enabled = true;
		setHints();
		document.removeEventListener('keydown', initKeyBind, false);
		document.addEventListener('keydown', hintHandler, false);
		document.addEventListener('scroll', windowChanged, false);
		document.addEventListener('resize', windowChanged, false);
		hint_num_str = '';
	}

	function hintHandler(e){
		e.preventDefault();  //Stop Default Event 

		var pressedKey = get_key(e);
		var hint_num;

		if (pressedKey !== 'U+0000') {
			if (pressedKey === 'Backspace') {
				if (hint_num_str.length > 0) {
					hint_num_str = hint_num_str.substr(0,hint_num_str.length - 1);
				}
			}
			else if (pressedKey === 'Enter') {
				if (hint_num_str === '') {
					hint_num_str = '1';
				}
				judgeHintNum(Number(hint_num_str));
				return;
			}
			else if (/[0-9]/.test(pressedKey) === false) {
				stop();
			}
			else if (Number(hint_num_str + pressedKey) <= hint_elems.length) {
				hint_num_str += pressedKey;
				hint_num = Number(hint_num_str);

				if (hint_num * 10 > hint_elems.length + 1) {
					judgeHintNum(hint_num);
					return;
				}
			}

			for (var i = 1 ; i <= hint_tags.length ; ++i ) {
				var iStr = i.toString();

				if (iStr === hint_num_str) {
					hint_tags[i - 1].style.display = 'inline';
					hint_tags[i - 1].style.border = 'solid 6px blue';
				}
				else if (iStr.length > hint_num_str.length && iStr.substr(0,hint_num_str.length) === hint_num_str) {
					hint_tags[i - 1].style.display = 'inline';
					hint_tags[i - 1].style.border = 'none';
				}
				else {
					hint_tags[i - 1].style.display = 'none';
					hint_tags[i - 1].style.border = 'none';
				}
			}
		}
	}

	function judgeHintNum(hint_num) {
		var hint_elem = hint_elems[hint_num - 1];
		if (hint_elem) {
			execSelect(hint_elem);
		} else {
			stop();
		}
	}
	
	function execSelect(elem) {
		var tag_name = elem.tagName.toLowerCase();
		var type = elem.type ? elem.type.toLowerCase() : '';

		elem.dispatchEvent(new Event('mouseover'));
		elem.dispatchEvent(new Event('click', {
			'bubbles': true,
			'cancelable': true}));

			if (tag_name === 'input' && (type === "radio" || type === "checkbox")) {
				elem.checked = !elem.checked;
			}
			else if (tag_name === 'input' || tag_name === 'textarea') {
				elem.focus();
				elem.setSelectionRange(0, elem.value.length);
			}

			stop();
	}

	function setHints() {
		var win_top = window.pageYOffset;
		var win_bottom = win_top + window.innerHeight;
		var win_left = window.pageXOffset;
		var elems = document.body.querySelectorAll('a, input:not([type=hidden]), textarea, select, button, [onclick], [onmouseover], [for]');

		var elements = [];

		for (var i = 0 ; i < elems.length ; ++i) {
			elements.push(elems[i]);
		}

		for (i = 0 ; i < registeredElements.length ; ++i) {
			elements.push(registeredElements[i]);
		}

		var div = document.createElement('div');
		div.setAttribute('highlight', 'hints');
		document.body.appendChild(div);

		for (i = 0; i < elements.length; i++) {
			var elem = elements[i];
			if (!isHintDisplay(elem)) {
				continue;
			}
			var pos = elem.getBoundingClientRect();
			var elem_top = win_top + pos.top;
			var elem_bottom = win_top + pos.bottom;
			var elem_left = win_left + pos.left;

			if ( elem_bottom >= win_top && elem_top <= win_bottom) {
				hint_elems.push(elem);
				var span = document.createElement('span');
				span.style.cssText = [ 
					'left: ', elem_left, 'px;',
					'top: ', elem_top, 'px;',
					'position: absolute;',
					'font-size: 13px;',
					'background-color: red;',
					'color: white;',
					'font-weight: bold;',
					'padding: 0px 1px;',
					'z-index: 10000;'
				].join('');
				span.innerHTML = hint_elems.length;
				div.appendChild(span);
				hint_tags.push(span);
			}
		}
	}

	function isHintDisplay(elem) {
		var pos = elem.getBoundingClientRect();
		return (pos.height !== 0 && pos.width !== 0);
	}

	function stop() {
		if (!hint_enabled){
			return;
		}

		hint_enabled = false;
		hint_elems = [];
		hint_tags = [];
		hint_num_str = '';
		var div = document.body.querySelector('div[highlight=hints]');
		if (div) {
			document.body.removeChild(div);
		}
		document.removeEventListener('keydown', hintHandler, false);
		document.removeEventListener('scroll', windowChanged, false);
		document.removeEventListener('resize', windowChanged, false);
		document.addEventListener('keydown', initKeyBind, false);
		if (refreshTimeout) {
			window.clearTimeout(refreshTimeout);
		}
	}

	function initKeyBind(e){
		if (e.target.nodeType === 1 && e.ctrlKey){
			if (get_key(e) === 'f') {
				e.preventDefault();
				start();
			}
			else if (get_key(e) === 'c') {
				e.preventDefault();
				stop();
			}
		}
	}

	var refreshTimeout;
	function windowChanged(){
		if (refreshTimeout) {
			window.clearTimeout(refreshTimeout);
		}

		refreshTimeout = window.setTimeout(refreshHints, 200);
	}

	function refreshHints() {
		stop();
		start();
		refreshTimeout = undefined;
	}

	function get_key(evt){
		return keyId[evt.keyIdentifier] || evt.keyIdentifier;
	}

	interceptListeners(HTMLElement);
	document.addEventListener( 'keydown', initKeyBind, false );
})();