/*
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;
        },
        /**
        * @for DDM
        * @namespace DD
        * @private
        * @method _calcTickArray
        * @description This method is used with the tickXArray and tickYArray config options
        * @param {Number} pos The current X or Y position
        * @param {Number} ticks The array containing our custom tick positions.
        * @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 The tick position
        */
        _calcTickArray: function(pos, ticks, off1, off2) {
            var i = 0, len = ticks.length, next = 0,
                diff1, diff2, ret;

            if (!ticks || (ticks.length === 0)) {
                return pos;
            } else if (ticks[0] >= pos) {
                return ticks[0];
            } else {
                for (i = 0; i < len; i++) {
                    next = (i + 1);
                    if (ticks[next] && ticks[next] >= pos) {
                        diff1 = pos - ticks[i];
                        diff2 = ticks[next] - pos;
                        ret = (diff2 > diff1) ? ticks[i] : ticks[next];
                        if (off1 && off2) {
                            if (ret > off2) {
                                if (ticks[i]) {
                                    ret = ticks[i];
                                } else {
                                    ret = ticks[len - 1];
                                }
                            }
                        }
                        return ret;
                    }
                    
                }
                return ticks[ticks.length - 1];
            }
        }
    });




}, '3.0.0b1' ,{requires:['dd-drag'], skinnable:false});
