/*

Copyright (c) 2009, Yahoo! Inc. All rights reserved.

Code licensed under the BSD License:

http://developer.yahoo.net/yui/license.txt

version: 3.0.0b1

build: 1163

*/

YUI.add('dd-ddm-base', function(Y) {

    /**

     * Provides the base Drag Drop Manger required for making a Node draggable.

     * @module dd

     * @submodule dd-ddm-base

     */     

     /**

     * Provides the base Drag Drop Manger required for making a Node draggable.

     * @class DDM

     * @extends Base

     * @constructor

     * @namespace DD

     */

    var DDMBase = function() {

        DDMBase.superclass.constructor.apply(this, arguments);

    };

    DDMBase.NAME = 'ddm';

    DDMBase.ATTRS = {

        /**

        * @attribute dragCursor

        * @description The cursor to apply when dragging, if shimmed the shim will get the cursor.

        * @type String

        */

        dragCursor: {

            value: 'move'

        },

        /**

        * @attribute clickPixelThresh

        * @description The number of pixels to move to start a drag operation, default is 3.

        * @type Number

        */

        clickPixelThresh: {

            value: 3

        },

        /**

        * @attribute clickTimeThresh

        * @description The number of milliseconds a mousedown has to pass to start a drag operation, default is 1000.

        * @type Number

        */        

        clickTimeThresh: {

            value: 1000

        },

        /**

        * @attribute dragMode

        * @description This attribute only works if the dd-drop module is active. It will set the dragMode (point, intersect, strict) of all future Drag instances. 

        * @type String

        */        

        dragMode: {

            value: 'point',

            setter: function(mode) {

                this._setDragMode(mode);

                return mode;

            }           

        }

    };

    Y.extend(DDMBase, Y.Base, {

        /**

        * @property _active

        * @description flag set when we activate our first drag, so DDM can start listening for events.

        * @type {Boolean}

        */

        _active: null,

        /**

        * @private

        * @method _setDragMode

        * @description Handler for dragMode attribute setter.

        * @param String/Number The Number value or the String for the DragMode to default all future drag instances to.

        * @return Number The Mode to be set

        */

        _setDragMode: function(mode) {

            if (mode === null) {

                mode = Y.DD.DDM.get('dragMode');

            }

            switch (mode) {

                case 1:

                case 'intersect':

                    return 1;

                case 2:

                case 'strict':

                    return 2;

                case 0:

                case 'point':

                    return 0;

            }

            return 0;       

        },

        /**

        * @property CSS_PREFIX

        * @description The PREFIX to attach to all DD CSS class names

        * @type {String}

        */

        CSS_PREFIX: 'yui-dd',

        _activateTargets: function() {},        

        /**

        * @private

        * @property _drags

        * @description Holder for all registered drag elements.

        * @type {Array}

        */

        _drags: [],

        /**

        * @property activeDrag

        * @description A reference to the currently active draggable object.

        * @type {Drag}

        */

        activeDrag: false,

        /**

        * @private

        * @method _regDrag

        * @description Adds a reference to the drag object to the DDM._drags array, called in the constructor of Drag.

        * @param {Drag} d The Drag object

        */

        _regDrag: function(d) {

            this._drags[this._drags.length] = d;

            if (!this._active) {

                this._setupListeners();

            }

        },

        /**

        * @private

        * @method _unregDrag

        * @description Remove this drag object from the DDM._drags array.

        * @param {Drag} d The drag object.

        */

        _unregDrag: function(d) {

            var tmp = [];

            Y.each(this._drags, function(n, i) {

                if (n !== d) {

                    tmp[tmp.length] = n;

                }

            });

            this._drags = tmp;

        },

        /**

        * @private

        * @method _setupListeners

        * @description Add the document listeners.

        */

        _setupListeners: function() {

            this._active = true;

            var doc = Y.get(document);

            doc.on('mousemove', Y.bind(this._move, this));

            //Y.Event.nativeAdd(document, 'mousemove', Y.bind(this._move, this));

            doc.on('mouseup', Y.bind(this._end, this));

        },

        /**

        * @private

        * @method _start

        * @description Internal method used by Drag to signal the start of a drag operation

        * @param {Number} x The x position of the drag element

        * @param {Number} y The y position of the drag element

        * @param {Number} w The width of the drag element

        * @param {Number} h The height of the drag element

        */

        _start: function(x, y, w, h) {

            this.fire('ddm:start');

            this._startDrag.apply(this, arguments);

        },

        /**

        * @private

        * @method _startDrag

        * @description Factory method to be overwritten by other DDM's

        * @param {Number} x The x position of the drag element

        * @param {Number} y The y position of the drag element

        * @param {Number} w The width of the drag element

        * @param {Number} h The height of the drag element

        */

        _startDrag: function() {},

        /**

        * @private

        * @method _endDrag

        * @description Factory method to be overwritten by other DDM's

        */

        _endDrag: function() {},

        _dropMove: function() {},

        /**

        * @private

        * @method _end

        * @description Internal method used by Drag to signal the end of a drag operation

        */

        _end: function() {

            //@TODO - Here we can get a (click - drag - click - release) interaction instead of a (mousedown - drag - mouseup - release) interaction

            //Add as a config option??

            if (this.activeDrag) {

                this._endDrag();

                this.fire('ddm:end');

                this.activeDrag.end.call(this.activeDrag);

                this.activeDrag = null;

            }

        },

        /**

        * @method stopDrag

        * @description Method will forcefully stop a drag operation. For example calling this from inside an ESC keypress handler will stop this drag.

        * @return {Self}

        * @chainable

        */       

        stopDrag: function() {

            if (this.activeDrag) {

                this._end();

            }

            return this;

        },

        /**

        * @private

        * @method _move

        * @description Internal listener for the mousemove DOM event to pass to the Drag's move method.

        * @param {Event.Facade} ev The Dom mousemove Event

        */

        _move: function(ev) {

            if (this.activeDrag) {

                this.activeDrag._move.call(this.activeDrag, ev);

                this._dropMove();

            }

        },

        /**

        * //TODO Private, rename??...

        * @private

        * @method cssSizestoObject

        * @description Helper method to use to set the gutter from the attribute setter.

        * @param {String} gutter CSS style string for gutter: '5 0' (sets top and bottom to 5px, left and right to 0px), '1 2 3 4' (top 1px, right 2px, bottom 3px, left 4px)

        * @return {Object} The gutter Object Literal.

        */

        cssSizestoObject: function(gutter) {

            var x = gutter.split(' ');

            switch (x.length) {

                case 1: x[1] = x[2] = x[3] = x[0]; break;

                case 2: x[2] = x[0]; x[3] = x[1]; break;

                case 3: x[3] = x[1]; break;

            }

            return {

                top   : parseInt(x[0],10),

                right : parseInt(x[1],10),

                bottom: parseInt(x[2],10),

                left  : parseInt(x[3],10)

            };

        },

        /**

        * @method getDrag

        * @description Get a valid Drag instance back from a Node or a selector string, false otherwise

        * @param {String/Object} node The Node instance or Selector string to check for a valid Drag Object

        * @return {Object}

        */

        getDrag: function(node) {

            var drag = false,

                n = Y.get(node);

            if (n instanceof Y.Node) {

                Y.each(this._drags, function(v, k) {

                    if (n.compareTo(v.get('node'))) {

                        drag = v;

                    }

                });

            }

            return drag;

        }

    });

    Y.namespace('DD');

    Y.DD.DDM = new DDMBase();

}, '3.0.0b1' ,{requires:['node', 'base'], skinnable:false});