/*
 * Ext JS Library 2.0 Copyright(c) 2006-2007, Ext JS, LLC. licensing@extjs.com
 * 
 * http://extjs.com/license
 */

/**
 * @class Ext.KeyNav
 *        <p>
 *        Provides a convenient wrapper for normalized keyboard navigation.
 *        KeyNav allows you to bind navigation keys to function calls that will
 *        get called when the keys are pressed, providing an easy way to
 *        implement custom navigation schemes for any UI component.
 *        </p>
 *        <p>
 *        The following are all of the possible keys that can be implemented:
 *        enter, left, right, up, down, tab, esc, pageUp, pageDown, del, home,
 *        end. Usage:
 *        </p>
 * 
 * <pre><code>
 * var nav = new Ext.KeyNav(&quot;my-element&quot;, {
 * 			&quot;left&quot; : function(e) {
 * 				this.moveLeft(e.ctrlKey);
 * 			},
 * 			&quot;right&quot; : function(e) {
 * 				this.moveRight(e.ctrlKey);
 * 			},
 * 			&quot;enter&quot; : function(e) {
 * 				this.save();
 * 			},
 * 			scope : this
 * 		});
 * </code></pre>
 * 
 * @constructor
 * @param {Mixed}
 *            el The element to bind to
 * @param {Object}
 *            config The config
 */
Ext.KeyNav = function(el, config) {
	this.el = Ext.get(el);
	Ext.apply(this, config);
	if (!this.disabled) {
		this.disabled = true;
		this.enable();
	}
};

Ext.KeyNav.prototype = {
	/**
	 * @cfg {Boolean} disabled True to disable this KeyNav instance (defaults to
	 *      false)
	 */
	disabled : false,
	/**
	 * @cfg {String} defaultEventAction The method to call on the
	 *      {@link Ext.EventObject} after this KeyNav intercepts a key. Valid
	 *      values are {@link Ext.EventObject#stopEvent},
	 *      {@link Ext.EventObject#preventDefault} and
	 *      {@link Ext.EventObject#stopPropagation} (defaults to 'stopEvent')
	 */
	defaultEventAction : "stopEvent",
	/**
	 * @cfg {Boolean} forceKeyDown Handle the keydown event instead of keypress
	 *      (defaults to false). KeyNav automatically does this for IE since IE
	 *      does not propagate special keys on keypress, but setting this to
	 *      true will force other browsers to also handle keydown instead of
	 *      keypress.
	 */
	forceKeyDown : false,

	// private
	prepareEvent : function(e) {
		var k = e.getKey();
		var h = this.keyToHandler[k];
		// if(h && this[h]){
		// e.stopPropagation();
		// }
		if (Ext.isSafari && h && k >= 37 && k <= 40) {
			e.stopEvent();
		}
	},

	// private
	relay : function(e) {
		var k = e.getKey();
		var h = this.keyToHandler[k];
		if (h && this[h]) {
			if (this.doRelay(e, this[h], h) !== true) {
				e[this.defaultEventAction]();
			}
		}
	},

	// private
	doRelay : function(e, h, hname) {
		return h.call(this.scope || this, e);
	},

	// possible handlers
	enter : false,
	left : false,
	right : false,
	up : false,
	down : false,
	tab : false,
	esc : false,
	pageUp : false,
	pageDown : false,
	del : false,
	home : false,
	end : false,

	// quick lookup hash
	keyToHandler : {
		37 : "left",
		39 : "right",
		38 : "up",
		40 : "down",
		33 : "pageUp",
		34 : "pageDown",
		46 : "del",
		36 : "home",
		35 : "end",
		13 : "enter",
		27 : "esc",
		9 : "tab"
	},

	/**
	 * Enable this KeyNav
	 */
	enable : function() {
		if (this.disabled) {
			// ie won't do special keys on keypress, no one else will repeat
			// keys with keydown
			// the EventObject will normalize Safari automatically
			if (this.forceKeyDown || Ext.isIE || Ext.isAir) {
				this.el.on("keydown", this.relay, this);
			} else {
				this.el.on("keydown", this.prepareEvent, this);
				this.el.on("keypress", this.relay, this);
			}
			this.disabled = false;
		}
	},

	/**
	 * Disable this KeyNav
	 */
	disable : function() {
		if (!this.disabled) {
			if (this.forceKeyDown || Ext.isIE || Ext.isAir) {
				this.el.un("keydown", this.relay);
			} else {
				this.el.un("keydown", this.prepareEvent);
				this.el.un("keypress", this.relay);
			}
			this.disabled = true;
		}
	}
};