L.Control.Layers = L.Control.extend({
	options: {
		collapsed: true,
		position: 'topright',
		autoZIndex: true
	},

	initialize: function (baseLayers, overlays, options) {
		L.Util.setOptions(this, options);

		this._layers = {};
		this._lastZIndex = 0;

		for (var i in baseLayers) {
			if (baseLayers.hasOwnProperty(i)) {
				this._addLayer(baseLayers[i], i);
			}
		}

		for (i in overlays) {
			if (overlays.hasOwnProperty(i)) {
				this._addLayer(overlays[i], i, true);
			}
		}
	},

	onAdd: function (map) {
		this._initLayout();
		this._update();

		return this._container;
	},

	addBaseLayer: function (layer, name) {
		this._addLayer(layer, name);
		this._update();
		return this;
	},

	addOverlay: function (layer, name) {
		this._addLayer(layer, name, true);
		this._update();
		return this;
	},

	removeLayer: function (layer) {
		var id = L.Util.stamp(layer);
		delete this._layers[id];
		this._update();
		return this;
	},

	_initLayout: function () {
		var className = 'leaflet-control-layers',
		    container = this._container = L.DomUtil.create('div', className);

		if (!L.Browser.touch) {
			L.DomEvent.disableClickPropagation(container);
		} else {
			L.DomEvent.on(container, 'click', L.DomEvent.stopPropagation);
		}

		var form = this._form = L.DomUtil.create('form', className + '-list');

		if (this.options.collapsed) {
			L.DomEvent
				.on(container, 'mouseover', this._expand, this)
				.on(container, 'mouseout', this._collapse, this);

			var link = this._layersLink = L.DomUtil.create('a', className + '-toggle', container);
			link.href = '#';
			link.title = 'Layers';

			if (L.Browser.touch) {
				L.DomEvent
					.on(link, 'click', L.DomEvent.stopPropagation)
					.on(link, 'click', L.DomEvent.preventDefault)
					.on(link, 'click', this._expand, this);
			}
			else {
				L.DomEvent.on(link, 'focus', this._expand, this);
			}

			this._map.on('movestart', this._collapse, this);
			// TODO keyboard accessibility
		} else {
			this._expand();
		}

		this._baseLayersList = L.DomUtil.create('div', className + '-base', form);
		this._separator = L.DomUtil.create('div', className + '-separator', form);
		this._overlaysList = L.DomUtil.create('div', className + '-overlays', form);

		container.appendChild(form);
	},

	_addLayer: function (layer, name, overlay) {
		var id = L.Util.stamp(layer);

		this._layers[id] = {
			layer: layer,
			name: name,
			overlay: overlay
		};

		if (this.options.autoZIndex && layer.setZIndex) {
			this._lastZIndex++;
			layer.setZIndex(this._lastZIndex);
		}
	},

	_update: function () {
		if (!this._container) {
			return;
		}

		this._baseLayersList.innerHTML = '';
		this._overlaysList.innerHTML = '';

		var baseLayersPresent = false,
			overlaysPresent = false;

		for (var i in this._layers) {
			if (this._layers.hasOwnProperty(i)) {
				var obj = this._layers[i];
				this._addItem(obj);
				overlaysPresent = overlaysPresent || obj.overlay;
				baseLayersPresent = baseLayersPresent || !obj.overlay;
			}
		}

		this._separator.style.display = (overlaysPresent && baseLayersPresent ? '' : 'none');
	},

	// IE7 bugs out if you create a radio dynamically, so you have to do it this hacky way (see http://bit.ly/PqYLBe)
	_createRadioElement: function (name, checked) {

		var radioHtml = '<input type="radio" name="' + name + '"';
		if (checked) {
			radioHtml += ' checked="checked"';
		}
		radioHtml += '/>';

		var radioFragment = document.createElement('div');
		radioFragment.innerHTML = radioHtml;

		return radioFragment.firstChild;
	},

	_addItem: function (obj) {
		var label = document.createElement('label'),
		    input,
		    checked = this._map.hasLayer(obj.layer);

		if (obj.overlay) {
			input = document.createElement('input');
			input.type = 'checkbox';
			input.defaultChecked = checked;
		} else {
			input = this._createRadioElement('leaflet-base-layers', checked);
		}

		input.layerId = L.Util.stamp(obj.layer);

		L.DomEvent.on(input, 'click', this._onInputClick, this);

		var name = document.createTextNode(' ' + obj.name);

		label.appendChild(input);
		label.appendChild(name);

		var container = obj.overlay ? this._overlaysList : this._baseLayersList;
		container.appendChild(label);
	},

	_onInputClick: function () {
		var i, input, obj,
			inputs = this._form.getElementsByTagName('input'),
			inputsLen = inputs.length;

		for (i = 0; i < inputsLen; i++) {
			input = inputs[i];
			obj = this._layers[input.layerId];

			if (input.checked) {
				this._map.addLayer(obj.layer, !obj.overlay);
			} else {
				this._map.removeLayer(obj.layer);
			}
		}
	},

	_expand: function () {
		L.DomUtil.addClass(this._container, 'leaflet-control-layers-expanded');
	},

	_collapse: function () {
		this._container.className = this._container.className.replace(' leaflet-control-layers-expanded', '');
	}
});

L.control.layers = function (baseLayers, overlays, options) {
	return new L.Control.Layers(baseLayers, overlays, options);
};