var Events = new EventManager();

function EventManager()
{
    var reg = null;
}





/**
 * Attach an event listener to an object
 *
 * @param object    The object you want to attach to
 * @param string    The event type
 * @param function  The listener function
 */
EventManager.prototype.add = function(obj, evType, fn)
{
    evType = this.checkType(evType);
    this.initElm(obj, evType);
    obj[evType] = this.genListener(obj.id, evType, fn);
}





/**
 * Remove an event listener from an object
 *
 * @param object    The object to remove from
 * @param string    The event type the listener is attached to
 * @param function  The function to remove
 */
EventManager.prototype.remove = function(obj, evType, fn)
{
    evType = this.checkType(evType);
    this.initElm(obj, evType);

    del = this.reg.inArray(fn);

    if(del == -1)
        return;

    this.reg.splice(del, 1);

    obj[evType] = this.genListener(obj.id, evType);
}





/**
 * Generate the anonymous listener function
 *
 * To create a "virtual" event manager, we must create custom anonymous
 * functions to call the other listener functions attached to an object. This
 * method goes through the attached listeners and automatically generates
 * the new anonymous function.
 *
 * @param string    The ID of the object you are generating for
 * @param string    The event type you are generating for
 * @param function  <i>(Opt)</i> The function you want to add
 */
EventManager.prototype.genListener = function(id, evType, fn)
{
    if(typeof fn == 'function')
        this.reg[id][evType].push(fn);

    if(this.reg[id][evType].length == 1)
        new_func = this.reg[id][evType][0];
    else
    {
        var eval_str = 'var func; ';

        for(var i = 0; i < this.reg[id][evType].length; i++)
        {
            eval_str += 'func = Events.reg[\'' + id + '\'][\'' + evType + '\'][' + i + ']; func.call(getElm(\'' + id + '\'), e); ';
        }

        eval('var new_func = function(e) { ' + eval_str + '};');
    }

    return new_func;
}





/**
 * Initiate an element with the registry
 *
 * - Creates a random, unique ID for this element if it does not have one
 * - Creates a place in the registry if it does not exist
 * - Creates a new event array in the registry if it does not exist
 *
 * @param object    The object to use
 * @param string    The event to use
 */
EventManager.prototype.initElm = function(obj, evType)
{
    if(!obj.id)
        obj.id = this.genUniqueId();

    if(!this.reg)
        this.reg = new Array();

    if(!this.reg[obj.id])
        this.reg[obj.id] = new Array();

    if(!this.reg[obj.id][evType])
    {
        this.reg[obj.id][evType] = new Array();

        if(obj[evType])
            this.reg[obj.id][evType].push(obj[evType]);
    }
}





/**
 * Check to make sure the event type has the 'on' prefix
 *
 * @param string The event string to check
 */
EventManager.prototype.checkType = function(evType)
{
    if(evType.substring(0, 2) != 'on')
        return 'on' + evType;
    else
        return evType;
}




/**
 * Generate a unique ID to use
 */
EventManager.prototype.genUniqueId = function()
{
    var date = new Date();
    var id;

    do {
        id = 'ID_' + (date.valueOf() + (Math.floor(100 * Math.random())) + (Math.floor(100 * Math.random())) );
    } while(getElm(id));

    return id;
}