/*
This file is part of Ext JS 4.2

Copyright (c) 2011-2013 Sencha Inc

Contact:  http://www.sencha.com/contact

GNU General Public License Usage
This file may be used under the terms of the GNU General Public License version 3.0 as
published by the Free Software Foundation and appearing in the file LICENSE included in the
packaging of this file.

Please review the following information to ensure the GNU General Public License version 3.0
requirements will be met: http://www.gnu.org/copyleft/gpl.html.

If you are unsure which license is appropriate for your use, please contact the sales department
at http://www.sencha.com/contact.

Build date: 2013-05-16 14:36:50 (f9be68accb407158ba2b1be2c226a6ce1f649314)
*/
/*
 * This is a derivative of the similarly named class in the YUI Library.
 * The original license:
 * Copyright (c) 2006, Yahoo! Inc. All rights reserved.
 * Code licensed under the BSD License:
 * http://developer.yahoo.net/yui/license.txt
 */

/**
 * A DragDrop implementation that inserts an empty, bordered div into
 * the document that follows the cursor during drag operations.  At the time of
 * the click, the frame div is resized to the dimensions of the linked html
 * element, and moved to the exact location of the linked element.
 *
 * References to the "frame" element refer to the single proxy element that
 * was created to be dragged in place of all DDProxy elements on the
 * page.
 */
Ext.define('Ext.dd.DDProxy', {
    extend: 'Ext.dd.DD',

    statics: {
        /**
         * The default drag frame div id
         * @static
         */
        dragElId: "ygddfdiv"
    },

    /**
     * Creates new DDProxy.
     * @param {String} id the id of the linked html element
     * @param {String} sGroup the group of related DragDrop objects
     * @param {Object} config an object containing configurable attributes.
     * Valid properties for DDProxy in addition to those in DragDrop:
     * 
     * - resizeFrame
     * - centerFrame
     * - dragElId
     */
    constructor: function(id, sGroup, config) {
        if (id) {
            this.init(id, sGroup, config);
            this.initFrame();
        }
    },

    /**
     * @property {Boolean} resizeFrame
     * By default we resize the drag frame to be the same size as the element
     * we want to drag (this is to get the frame effect).  We can turn it off
     * if we want a different behavior.
     */
    resizeFrame: true,

    /**
     * @property {Boolean} centerFrame
     * By default the frame is positioned exactly where the drag element is, so
     * we use the cursor offset provided by Ext.dd.DD.  Another option that works only if
     * you do not have constraints on the obj is to have the drag frame centered
     * around the cursor.  Set centerFrame to true for this effect.
     */
    centerFrame: false,

    /**
     * Creates the proxy element if it does not yet exist
     */
    createFrame: function() {
        var self = this,
            body = document.body,
            div,
            s;

        if (!body || !body.firstChild) {
            setTimeout( function() { self.createFrame(); }, 50 );
            return;
        }

        div = this.getDragEl();

        if (!div) {
            div    = document.createElement("div");
            div.id = this.dragElId;
            s  = div.style;

            s.position   = "absolute";
            s.visibility = "hidden";
            s.cursor     = "move";
            s.border     = "2px solid #aaa";
            s.zIndex     = 999;

            // appendChild can blow up IE if invoked prior to the window load event
            // while rendering a table.  It is possible there are other scenarios
            // that would cause this to happen as well.
            body.insertBefore(div, body.firstChild);
        }
    },

    /**
     * Initialization for the drag frame element.  Must be called in the
     * constructor of all subclasses
     */
    initFrame: function() {
        this.createFrame();
    },

    applyConfig: function() {
        this.callParent();

        this.resizeFrame = (this.config.resizeFrame !== false);
        this.centerFrame = (this.config.centerFrame);
        this.setDragElId(this.config.dragElId || Ext.dd.DDProxy.dragElId);
    },

    /**
     * Resizes the drag frame to the dimensions of the clicked object, positions
     * it over the object, and finally displays it
     * @param {Number} iPageX X click position
     * @param {Number} iPageY Y click position
     * @private
     */
    showFrame: function(iPageX, iPageY) {
        var el = this.getEl(),
            dragEl = this.getDragEl(),
            s = dragEl.style;

        this._resizeProxy();

        if (this.centerFrame) {
            this.setDelta( Math.round(parseInt(s.width,  10)/2),
                           Math.round(parseInt(s.height, 10)/2) );
        }

        this.setDragElPos(iPageX, iPageY);

        Ext.fly(dragEl).show();
    },

    /**
     * The proxy is automatically resized to the dimensions of the linked
     * element when a drag is initiated, unless resizeFrame is set to false
     * @private
     */
    _resizeProxy: function() {
        if (this.resizeFrame) {
            var el = this.getEl();
            Ext.fly(this.getDragEl()).setSize(el.offsetWidth, el.offsetHeight);
        }
    },

    // overrides Ext.dd.DragDrop
    b4MouseDown: function(e) {
        var x = e.getPageX(),
            y = e.getPageY();
        this.autoOffset(x, y);
        this.setDragElPos(x, y);
    },

    // overrides Ext.dd.DragDrop
    b4StartDrag: function(x, y) {
        // show the drag frame
        this.showFrame(x, y);
    },

    // overrides Ext.dd.DragDrop
    b4EndDrag: function(e) {
        Ext.fly(this.getDragEl()).hide();
    },

    // overrides Ext.dd.DragDrop
    // By default we try to move the element to the last location of the frame.
    // This is so that the default behavior mirrors that of Ext.dd.DD.
    endDrag: function(e) {

        var lel = this.getEl(),
            del = this.getDragEl();

        // Show the drag frame briefly so we can get its position
        del.style.visibility = "";

        this.beforeMove();
        // Hide the linked element before the move to get around a Safari
        // rendering bug.
        lel.style.visibility = "hidden";
        Ext.dd.DDM.moveToEl(lel, del);
        del.style.visibility = "hidden";
        lel.style.visibility = "";

        this.afterDrag();
    },

    beforeMove : function(){

    },

    afterDrag : function(){

    },

    toString: function() {
        return ("DDProxy " + this.id);
    }

});
