(function($) {

	// static constructs
	$.tools = $.tools || {
		version: '@VERSION'
	};

	$.tools.overlay = {

		addEffect: function(name, loadFn, closeFn) {
			effects[name] = [loadFn, closeFn];
		},

		conf: {
			close: null,
			closeOnClick: true,
			closeOnEsc: true,
			closeSpeed: 'fast',
			effect: 'default',

			// since 1.2. fixed positioning not supported by IE6
			fixed: !$.browser.msie || $.browser.version > 6,

			left: 'center',
			load: false, // 1.2
			mask: null,
			oneInstance: true,
			speed: 'normal',
			target: null, // target element to be overlayed. by default taken from [rel]
			top: '10%'
		}
	};


	var instances = [], effects = {};

	// the default effect. nice and easy!
	$.tools.overlay.addEffect('default',

		/*
onLoad/onClose functions must be called otherwise none of the
user supplied callback methods won't be called
*/
		function(pos, onLoad) {

			var conf = this.getConf(),
			w = $(window);

			if (!conf.fixed) {
				pos.top += w.scrollTop();
				pos.left += w.scrollLeft();
			}

			pos.position = conf.fixed ? 'fixed' : 'absolute';
			this.getOverlay().css(pos).fadeIn(conf.speed, onLoad);

		}, function(onClose) {
			this.getOverlay().fadeOut(this.getConf().closeSpeed, onClose);
		}
		);


	function Overlay(trigger, conf) {

		// private variables
		var self = this,
		fire = trigger.add(self),
		w = $(window),
		closers,
		overlay,
		opened,
		maskConf = $.tools.expose && (conf.mask || conf.expose),
		uid = Math.random().toString().slice(10);


		// mask configuration
		if (maskConf) {
			if (typeof maskConf == 'string') {
				maskConf = {
					color: maskConf
				};			
		}
		maskConf.closeOnClick = maskConf.closeOnEsc = false;
	}

	// get overlay and triggerr
	var jq = conf.target || trigger.attr("rel");
	overlay = jq ? $(jq) : null || trigger;

	// overlay not found. cannot continue
	if (!overlay.length) {
		throw "Could not find Overlay: " + jq;
	}

	// trigger's click event
	if (trigger && trigger.index(overlay) == -1) {
		trigger.click(function(e) {
			self.load(e);
			return e.preventDefault();
		});
	}

	// API methods
	$.extend(self, {

		load: function(e) {

			// can be opened only once
			if (self.isOpened()) {
				return self;
			}

			// find the effect
			var eff = effects[conf.effect];
			if (!eff) {
				throw "Overlay: cannot find effect : \"" + conf.effect + "\"";
			}

			// close other instances?
			if (conf.oneInstance) {
				$.each(instances, function() {
					this.close(e);
				});
			}

			// onBeforeLoad
			e = e || $.Event();
			e.type = "onBeforeLoad";
			fire.trigger(e);
			if (e.isDefaultPrevented()) {
				return self;
			}

			// opened
			opened = true;

			// possible mask effect
			if (maskConf) {
				$(overlay).expose(maskConf);
			}

			// position & dimensions
			var top = conf.top,
			left = conf.left,
			oWidth = overlay.outerWidth({
				margin:true
			}),
			oHeight = overlay.outerHeight({
				margin:true
			});

			if (typeof top == 'string') {
				top = top == 'center' ? Math.max((w.height() - oHeight) / 2, 0) :
				parseInt(top, 10) / 100 * w.height();
			}

			if (left == 'center') {
				left = Math.max((w.width() - oWidth) / 2, 0);
			}


			// load effect
			eff[0].call(self, {
				top: top, 
				left: left
			}, function() {
				if (opened) {
					e.type = "onLoad";
					fire.trigger(e);
				}
			});

			// mask.click closes overlay
			if (maskConf && conf.closeOnClick) {
				$.mask.getMask().one("click", self.close);
			}

			// when window is clicked outside overlay, we close
			if (conf.closeOnClick) {
				$(document).bind("click." + uid, function(e) {
					if (!$(e.target).parents(overlay).length) {
						self.close(e);
					}
				});
			}

			// keyboard::escape
			if (conf.closeOnEsc) {

				// one callback is enough if multiple instances are loaded simultaneously
				$(document).bind("keydown." + uid, function(e) {
					if (e.keyCode == 27) {
						self.close(e);
					}
				});
			}


			return self;
		},

		close: function(e) {

			if (!self.isOpened()) {
				return self;
			}

			e = e || $.Event();
			e.type = "onBeforeClose";
			fire.trigger(e);
			if (e.isDefaultPrevented()) {
				return;
			}

			opened = false;

			// close effect
			effects[conf.effect][1].call(self, function() {
				e.type = "onClose";
				fire.trigger(e);
			});

			// unbind the keyboard / clicking actions
			$(document).unbind("click." + uid).unbind("keydown." + uid);

			if (maskConf) {
				$.mask.close();
			}

			return self;
		},

		getOverlay: function() {
			return overlay;
		},

		getTrigger: function() {
			return trigger;
		},

		getClosers: function() {
			return closers;
		},

		isOpened: function() {
			return opened;
		},

		// manipulate start, finish and speeds
		getConf: function() {
			return conf;
		}

	});

	// callbacks
	$.each("onBeforeLoad,onStart,onLoad,onBeforeClose,onClose".split(","), function(i, name) {

		// configuration
		if ($.isFunction(conf[name])) {
			$(self).bind(name, conf[name]);
		}

		// API
		self[name] = function(fn) {
			if (fn) {
				$(self).bind(name, fn);
			}
			return self;
		};
	});

	// close button
	closers = overlay.find(conf.close || ".close");

	if (!closers.length && !conf.close) {
		closers = $('<a class="close"></a>');
		overlay.prepend(closers);
	}

	closers.click(function(e) {
		self.close(e);
	});

	// autoload
	if (conf.load) {
		self.load();
	}

}

// jQuery plugin initialization
$.fn.overlay = function(conf) {

	// already constructed --> return API
	var el = this.data("overlay");
	if (el) {
		return el;
	}

	if ($.isFunction(conf)) {
		conf = {
			onBeforeLoad: conf
		};
	}

	conf = $.extend(true, {}, $.tools.overlay.conf, conf);

	this.each(function() {
		el = new Overlay($(this), conf);
		instances.push(el);
		$(this).data("overlay", el);
	});

	return conf.api ? el: this;
};

})(jQuery);