/*

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-constrain', function(Y) {

    /**

     * The Drag & Drop Utility allows you to create a draggable interface efficiently, buffering you from browser-level abnormalities and enabling you to focus on the interesting logic surrounding your particular implementation. This component enables you to create a variety of standard draggable objects with just a few lines of code and then, using its extensive API, add your own specific implementation logic.

     * @module dd

     * @submodule dd-constrain

     */

    /**

     * This is a plugin for the dd-drag module to add the constraining methods to it. It supports constraining to a renodenode or viewport. It anode* supports tick based moves and XY axis constraints.

     * @class DragConstrained

     * @extends Base

     * @constructor

     * @namespace Plugin     

     */

    var DRAG_NODE = 'dragNode',

        OFFSET_HEIGHT = 'offsetHeight',

        OFFSET_WIDTH = 'offsetWidth',

        HOST = 'host',

        CON_2_REGION = 'constrain2region',

        CON_2_NODE = 'constrain2node',

        TICK_X_ARRAY = 'tickXArray',

        TICK_Y_ARRAY = 'tickYArray',

        DDM = Y.DD.DDM,

        TOP = 'top',

        RIGHT = 'right',

        BOTTOM = 'bottom',

        LEFT = 'left',

        proto = null;

    var C = function(config) {

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

    };

    C.NAME = 'DragConstrained';

    /**

    * @property con

    * @description The Constrained instance will be placed on the Drag instance under the con namespace.

    * @type {String}

    */

    C.NS = 'con';

    C.ATTRS = {

        host: {

        },

        /**

        * @attribute stickX

        * @description Stick the drag movement to the X-Axis. Default: false

        * @type Boolean

        */        

        stickX: {

            value: false

        },

        /**

        * @attribute stickY

        * @description Stick the drag movement to the Y-Axis

        * @type Boolean

        */        

        stickY: {

            value: false

        },

        /**

        * @attribute tickX

        * @description The X tick offset the drag node should snap to on each drag move. False for no ticks. Default: false

        * @type Number/false

        */        

        tickX: {

            value: false

        },

        /**

        * @attribute tickY

        * @description The Y tick offset the drag node should snap to on each drag move. False for no ticks. Default: false

        * @type Number/false

        */        

        tickY: {

            value: false

        },

        /**

        * @attribute tickXArray

        * @description An array of page coordinates to use as X ticks for drag movement.

        * @type Array

        */

        tickXArray: {

            value: false

        },

        /**

        * @attribute tickYArray

        * @description An array of page coordinates to use as Y ticks for drag movement.

        * @type Array

        */

        tickYArray: {

            value: false

        },

        /**

        * @attribute constrain2region

        * @description An Object Literal containing a valid region (top, right, bottom, left) of page positions to constrain the drag node to.

        * @type Object

        */

        constrain2region: {

            value: false,

            getter: function(r) {

                if (Y.Lang.isObject(r)) {

                    var o = {};

                    Y.mix(o, r);

                    return o;

                } else {

                    return false;

                }

            },

            setter: function (r) {

                if (Y.Lang.isObject(r)) {

                    if (Y.Lang.isNumber(r[TOP]) && Y.Lang.isNumber(r[RIGHT]) && Y.Lang.isNumber(r[LEFT]) && Y.Lang.isNumber(r[BOTTOM])) {

                        var o = {};

                        Y.mix(o, r);

                        return o;

                    } else {

                        return false;

                    }

                } else if (r !== false) {

                    return false;

                }

                return r;

            }

        },

        /**

        * @attribute gutter

        * @description CSS style string for the gutter of a region (supports negative values): '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)        

        * @type String

        */

        gutter: {

            value: '0',

            setter: function(gutter) {

                return Y.DD.DDM.cssSizestoObject(gutter);

            }

        },

        /**

        * @attribute constrain2node

        * @description Will attempt to constrain the drag node to the bounderies of this node.

        * @type Object

        */

        constrain2node: {

            value: false,

            setter: function(n) {

                if (!this.get(CON_2_REGION)) {

                    var node = Y.Node.get(n);

                    if (node) {

                        return node;

                    }

                } else if (this.get(CON_2_REGION) !== false) {

                }

                return false;

            }

        },

        /**

        * @attribute constrain2view

        * @description Will attempt to constrain the drag node to the bounderies of the viewport region.

        * @type Object

        */

        constrain2view: {

            value: false

        }

    };

    proto = {

        initializer: function() {

            this.get(HOST).on('drag:start', Y.bind(this._handleStart, this));

            this.get(HOST).after('drag:align', Y.bind(this.align, this));

        },

        /**

        * @private

        * @method _handleStart

        * @description Fires on drag:start and clears the _regionCache

        */

        _handleStart: function() {

            this._regionCache = null;

        },

        /**

        * @private

        * @property _regionCache

        * @description Store a cache of the region that we are constraining to

        * @type Object

        */

        _regionCache: null,

        /**

        * @private

        * @method _cacheRegion

        * @description Get's the region and caches it, called from window.resize and when the cache is null

        */

        _cacheRegion: function() {

            this._regionCache = this.get(CON_2_NODE).get('region');

        },

        /**

        * @method getRegion

        * @description Get the active region: viewport, node, custom region

        * @param {Boolean} inc Include the node's height and width

        * @return {Object}

        */

        getRegion: function(inc) {

            var r = {}, oh = null, ow = null,

                g = this.get('gutter'),

                host = this.get(HOST);

            if (this.get(CON_2_NODE)) {

                if (!this._regionCache) {

                    Y.on('resize', Y.bind(this._cacheRegion, this), window);

                    this._cacheRegion();

                }

                r = Y.clone(this._regionCache);

            } else if (this.get(CON_2_REGION)) {

                r = this.get(CON_2_REGION);

            } else if (this.get('constrain2view')) {

                r = host.get(DRAG_NODE).get('viewportRegion');

            } else {

                return false;

            }

            Y.each(g, function(i, n) {

                if ((n == RIGHT) || (n == BOTTOM)) {

                    r[n] -= i;

                } else {

                    r[n] += i;

                }

            });

            if (inc) {

                oh = host.get(DRAG_NODE).get(OFFSET_HEIGHT);

                ow = host.get(DRAG_NODE).get(OFFSET_WIDTH);

                r[RIGHT] = r[RIGHT] - ow;

                r[BOTTOM] = r[BOTTOM] - oh;

            }

            return r;

        },

        /**

        * @private

        * @method _checkRegion

        * @description Check if xy is inside a given region, if not change to it be inside.

        * @param {Array} _xy The XY to check if it's in the current region, if it isn't inside the region, it will reset the xy array to be inside the region.

        * @return {Array} The new XY that is inside the region

        */

        _checkRegion: function(_xy) {

            var oxy = _xy,

                r = this.getRegion(),

                host = this.get(HOST),

                oh = host.get(DRAG_NODE).get(OFFSET_HEIGHT),

                ow = host.get(DRAG_NODE).get(OFFSET_WIDTH);

                if (oxy[1] > (r[BOTTOM] - oh)) {

                    _xy[1] = (r[BOTTOM] - oh);

                }

                if (r[TOP] > oxy[1]) {

                    _xy[1] = r[TOP];

                }

                if (oxy[0] > (r[RIGHT] - ow)) {

                    _xy[0] = (r[RIGHT] - ow);

                }

                if (r[LEFT] > oxy[0]) {

                    _xy[0] = r[LEFT];

                }

            return _xy;

        },

        /**

        * @method inRegion

        * @description Checks if the XY passed or the dragNode is inside the active region.

        * @param {Array} xy Optional XY to check, if not supplied this.get('dragNode').getXY() is used.

        * @return {Boolean} True if the XY is inside the region, false otherwise.

        */

        inRegion: function(xy) {

            xy = xy || this.get(HOST).get(DRAG_NODE).getXY();

            var _xy = this._checkRegion([xy[0], xy[1]]),

                inside = false;

                if ((xy[0] === _xy[0]) && (xy[1] === _xy[1])) {

                    inside = true;

                }

            return inside;

        },

        /**

        * @method align

        * @description Modifies the Drag.actXY method from the after drag:align event. This is where the constraining happens.

        */

        align: function() {

            var host = this.get(HOST),

                _xy = host.actXY,

                r = this.getRegion(true);

            if (this.get('stickX')) {

                _xy[1] = (host.startXY[1] - host.deltaXY[1]);

            }

            if (this.get('stickY')) {

                _xy[0] = (host.startXY[0] - host.deltaXY[0]);

            }

            if (r) {

                _xy = this._checkRegion(_xy);

            }

            _xy = this._checkTicks(_xy, r);

            host.actXY = _xy;

        },

        /**

        * @private

        * @method _checkTicks

        * @description This method delegates the proper helper method for tick calculations

        * @param {Array} xy The XY coords for the Drag

        * @param {Object} r The optional region that we are bound to.

        * @return {Array} The calced XY coords

        */

        _checkTicks: function(xy, r) {

            var host = this.get(HOST),

                lx = (host.startXY[0] - host.deltaXY[0]),

                ly = (host.startXY[1] - host.deltaXY[1]),

                xt = this.get('tickX'),

                yt = this.get('tickY');

                if (xt && !this.get(TICK_X_ARRAY)) {

                    xy[0] = DDM._calcTicks(xy[0], lx, xt, r[LEFT], r[RIGHT]);

                }

                if (yt && !this.get(TICK_Y_ARRAY)) {

                    xy[1] = DDM._calcTicks(xy[1], ly, yt, r[TOP], r[BOTTOM]);

                }

                if (this.get(TICK_X_ARRAY)) {

                    xy[0] = DDM._calcTickArray(xy[0], this.get(TICK_X_ARRAY), r[LEFT], r[RIGHT]);

                }

                if (this.get(TICK_Y_ARRAY)) {

                    xy[1] = DDM._calcTickArray(xy[1], this.get(TICK_Y_ARRAY), r[TOP], r[BOTTOM]);

                }

            return xy;

        }

    };

    Y.namespace('Plugin');

    Y.extend(C, Y.Base, proto);

    Y.Plugin.DDConstrained = C;

    Y.mix(DDM, {

        /**

        * @for DDM

        * @namespace DD

        * @private

        * @method _calcTicks

        * @description Helper method to calculate the tick offsets for a given position

        * @param {Number} pos The current X or Y position

        * @param {Number} start The start X or Y position

        * @param {Number} tick The X or Y tick increment

        * @param {Number} off1 The min offset that we can't pass (region)

        * @param {Number} off2 The max offset that we can't pass (region)

        * @return {Number} The new position based on the tick calculation

        */

        _calcTicks: function(pos, start, tick, off1, off2) {

            var ix = ((pos - start) / tick),

                min = Math.floor(ix),

                max = Math.ceil(ix);

                if ((min !== 0) || (max !== 0)) {

                    if ((ix >= min) && (ix <= max)) {

                        pos = (start + (tick * min));

                        if (off1 && off2) {

                            if (pos < off1) {

                                pos = (start + (tick * (min + 1)));

                            }

                            if (pos > off2) {

                                pos = (start + (tick * (min - 1)));

                            }

                        }

                    }

                }

                return pos;

        },