/**
 * Kenny Dialoggins creates pretty dialogs using prototype and 
 * scriptaculous. These functions work with ActionView 
 * helpers to provide dialog components that can be programmed 
 * using the same syntax as rendering partials.
 *
 * 
 * Brought to you by the good folks at Coroutine.  Hire us!
 * http://coroutine.com
 */
var KennyDialoggins = {}


/**
 * This property governs whether or not KD bothers creating and
 * managing a blocking iframe to accommodate ie6.
 * 
 * Defaults to false, but override if you must.
 */
KennyDialoggins.SUPPORT_IE6_BULLSHIT = false;   



/**
 * This function puts you on the highway to the danger
 * zone by defining the KD dialog class.
 */
KennyDialoggins.Dialog = function(content, options) {
    options             = options || {};
    
    this._element       = null;
    this._frame         = null;
    this._hideListener  = this._generateHideListener();
    this._is_showing    = false;
    
    this._beforeShow    = options["beforeShow"] || Prototype.emptyFunction
    this._afterShow     = options["afterShow"]  || Prototype.emptyFunction
    this._beforeHide    = options["beforeHide"] || Prototype.emptyFunction
    this._afterHide     = options["afterHide"]  || Prototype.emptyFunction
    
    this._makeDialog();
    this.setContent(content);
    document.body.appendChild(this._element);
    
    if (KennyDialoggins.SUPPORT_IE6_BULLSHIT) {
        this._makeFrame();
        document.body.appendChild(this._frame);
    }
}



// ----------------------------------------------------------------------------
// Class methods
// ----------------------------------------------------------------------------

/**
 * This hash maps the dialog id to the dialog object itself. It allows the Rails 
 * code a way to specify the js object it wishes to invoke.
 */ 
KennyDialoggins.Dialog.instances = {};


/**
 * This hash is a convenience that allows us to write slightly denser code when 
 * calculating the dialog's position.
 */
KennyDialoggins.Dialog._POSITION_FN_MAP = $H({
    left:   "getWidth",
    top:    "getHeight"
});


/**
 * This method shows the dialog with the corresponding id.
 *
 * @param {String} id   The id value of the dialog element (also the key 
 *                      in the instances hash.)
 *
 * @return {Object} an instance of KennyDialoggins.Dialog
 *
 */
KennyDialoggins.Dialog.show = function(id) {
    var dialog = this.instances[id];
    if(dialog) {
        dialog.show();
    }
    return dialog;
}


/**
 * This method hides the dialog with the corresponding id.
 *
 * @param {String} id   The id value of the dialog element (also the key 
 *                      in the instances hash.)
 *
 * @return {Object} an instance of KennyDialoggins.Dialog
 *
 */
KennyDialoggins.Dialog.hide = function(id) {
    var dialog = this.instances[id];
    if(dialog) {
        dialog.hide();
    }
    return dialog;
}


/**
 * This method returns a boolean indiciating whether or not the 
 * dialog with the corresponding id is showing.
 *
 * @param {String} id   The id value of the dialog element (also the key 
 *                      in the instances hash.)
 *
 * @return {Boolean}    Whether or not the dialog with the corresponding 
 *                      id is showing.
 *
 */
KennyDialoggins.Dialog.is_showing = function(id) {
    var dialog = this.instances[id];
    if (!dialog) {
        throw "No dialog cound be found for the supplied id.";
    }
    return dialog.is_showing();
}



// ----------------------------------------------------------------------------
// Instance methods
// ----------------------------------------------------------------------------

Object.extend(KennyDialoggins.Dialog.prototype, {
    
    /**
     * This function constructs the dialog element and hides it by default.
     *
     * The class name is set outside the element constructor to accommodate
     * a discrepancy in how prototype handles this particular attribute. The
     * attribute is set as className in IE8--rather than class--which means the 
     * styles are not applied and the element's positioning gets royally
     * screwed up.
     */
    _makeDialog: function() {
        if (!this._element) {
            this._element = new Element("DIV");
            this._element.className = "kenny_dialoggins_dialog";
            this._element.hide();
        }
    },
    
    
    /**
     * This function constructs the iframe element and hides it by default.
     *
     * The class name is set outside the element constructor to accommodate
     * a discrepancy in how prototype handles this particular attribute. The
     * attribute is set as className in IE8--rather than class--which means the 
     * styles are not applied and the element's positioning gets royally
     * screwed up.
     */
    _makeFrame: function() {
        if (!this._frame) {
            this._frame = new Element("IFRAME");
            this._frame.className = "kenny_dialoggins_dialog_frame";
            this._frame.setAttribute("src", "about:blank");
            this._frame.hide();
        }
    },
    
    
    /**
     * This function creates the function that handles click events when the dialog is 
     * shown.  The handler ignores clicks targeted from within the dialog; any click 
     * targeted outside the dialog causes the dialog to hide itself and cancel the 
     * observer.
     */
    _generateHideListener: function() {
        return function(evt) {
            var origin = evt.findElement(".kenny_dialoggins_dialog");
            if (this._element !== origin) {
                this.hide();
            }
        }.bind(this);
    },
    
    
    /**
     * This function sets the content of the dialog element.
     *
     * @param {Object} content  The html content for the dialog.
     */
    setContent: function(content) {
        this._element.update(content);
    },
    
    
    /**
     * This function displays the dialog. It uses a scriptaculous effect to fade in,
     * centers the dialog in the viewport (and adjusts the blocking iframe, if in use), 
     * and connects a click observer to hide the dialog whenever mouse focus leaves 
     * the dialog.
     */
    show: function() {
        KennyDialoggins.Dialog._POSITION_FN_MAP.each(function(pair) {
            var method = pair.last();
            this._element.style[pair.first()] = 
                (document.viewport[method]() / 2 + document.viewport.getScrollOffsets()[pair.first()] - this._element[method]() / 2) + "px";
        }.bind(this));
        
        if (this._frame) {
            this._frame.style.top       = this._element.style.top;
            this._frame.style.left      = this._element.style.left;
            this._frame.style.width     = this._element.getWidth() + "px";
            this._frame.style.height    = this._element.getHeight() + "px";
            
            new Effect.Appear(this._frame, {
                duration: 0.2
            });
        }
        
        new Effect.Appear(this._element, { 
            duration:       0.2,
            beforeStart:    this._beforeShow,
            afterFinish:    function() {
                this._is_showing = true;
                this._afterShow();
                document.observe("click", this._hideListener);
            }.bind(this)
        });
    },
    
    
    /**
     * This function hides the dialog. It uses a scriptaculous effect to fade out 
     * and disconnects the click observer to prevent memory leaks.
     */
    hide: function() {
        new Effect.Fade(this._element, {
            duration: 0.2,
            beforeStart:    this._beforeHide,
            afterFinish:    function() {
                this._is_showing = false;
                this._afterHide();
                document.stopObserving("click", this._hideListener);
            }.bind(this)
        });
        
        if (this._frame) {
            new Effect.Fade(this._frame, {
                duration: 0.2
            });
        }
    },
    
    
    /**
     * This function indicates whether or not the dialog is currently 
     * being shown.
     *
     * @return {Boolean}    Whether or not the dialog is being shown.
     */
    is_showing: function() {
        return this._is_showing;
    }
});