/*
Copyright (c) 2006, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
version: 0.12.1
*/

/**
 * The dom module provides helper methods for manipulating Dom elements.
 * @module dom
 *
 */

(function() {
    var Y = YAHOO.util,     // internal shorthand
        getStyle,           // for load time browser branching
        setStyle,           // ditto
        id_counter = 0,     // for use with generateId
        propertyCache = {}; // for faster hyphen converts

    // brower detection
    var ua = navigator.userAgent.toLowerCase(),
        isOpera = (ua.indexOf('opera') > -1),
        isSafari = (ua.indexOf('safari') > -1),
        isGecko = (!isOpera && !isSafari && ua.indexOf('gecko') > -1),
        isIE = (!isOpera && ua.indexOf('msie') > -1);

    // regex cache
    var patterns = {
        HYPHEN: /(-[a-z])/i
    };

    var logger = {};
    logger.log = function() { YAHOO.log.apply(window, arguments); };

    var toCamel = function(property) {
        if ( !patterns.HYPHEN.test(property) ) {
            return property; // no hyphens
        }

        if (propertyCache[property]) { // already converted
            return propertyCache[property];
        }

        while( patterns.HYPHEN.exec(property) ) {
            property = property.replace(RegExp.$1,
                    RegExp.$1.substr(1).toUpperCase());
        }

        propertyCache[property] = property;
        return property;
        //return property.replace(/-([a-z])/gi, function(m0, m1) {return m1.toUpperCase()}) // cant use function as 2nd arg yet due to safari bug
    };

    // branching at load instead of runtime
    if (document.defaultView && document.defaultView.getComputedStyle) { // W3C DOM method
        getStyle = function(el, property) {
            var value = null;

            var computed = document.defaultView.getComputedStyle(el, '');
            if (computed) { // test computed before touching for safari
                value = computed[toCamel(property)];
            }

            return el.style[property] || value;
        };
    } else if (document.documentElement.currentStyle && isIE) { // IE method
        getStyle = function(el, property) {
            switch( toCamel(property) ) {
                case 'opacity' :// IE opacity uses filter
                    var val = 100;
                    try { // will error if no DXImageTransform
                        val = el.filters['DXImageTransform.Microsoft.Alpha'].opacity;

                    } catch(e) {
                        try { // make sure its in the document
                            val = el.filters('alpha').opacity;
                        } catch(e) {
                            logger.log('getStyle: IE filter failed',
                                    'error', 'Dom');
                        }
                    }
                    return val / 100;
                    break;
                default:
                    // test currentStyle before touching
                    var value = el.currentStyle ? el.currentStyle[property] : null;
                    return ( el.style[property] || value );
            }
        };
    } else { // default to inline only
        getStyle = function(el, property) { return el.style[property]; };
    }

    if (isIE) {
        setStyle = function(el, property, val) {
            switch (property) {
                case 'opacity':
                    if ( typeof el.style.filter == 'string' ) { // in case not appended
                        el.style.filter = 'alpha(opacity=' + val * 100 + ')';

                        if (!el.currentStyle || !el.currentStyle.hasLayout) {
                            el.style.zoom = 1; // when no layout or cant tell
                        }
                    }
                    break;
                default:
                el.style[property] = val;
            }
        };
    } else {
        setStyle = function(el, property, val) {
            el.style[property] = val;
        };
    }

    /**
     * Provides helper methods for DOM elements.
     * @namespace YAHOO.util
     * @class Dom
     */
    YAHOO.util.Dom = {
        /**
         * Returns an HTMLElement reference.
         * @method get
         * @param {String | HTMLElement |Array} el Accepts a string to use as an ID for getting a DOM reference, an actual DOM reference, or an Array of IDs and/or HTMLElements.
         * @return {HTMLElement | Array} A DOM reference to an HTML element or an array of HTMLElements.
         */
        get: function(el) {
            if (!el) { return null; } // nothing to work with

            if (typeof el != 'string' && !(el instanceof Array) ) { // assuming HTMLElement or HTMLCollection, so pass back as is
                logger.log('get(' + el + ') returning ' + el, 'info', 'Dom');
                return el;
            }

            if (typeof el == 'string') { // ID
                logger.log('get("' + el + '") returning ' + document.getElementById(el), 'info', 'Dom');
                return document.getElementById(el);
            }
            else { // array of ID's and/or elements
                var collection = [];
                for (var i = 0, len = el.length; i < len; ++i) {
                    collection[collection.length] = Y.Dom.get(el[i]);
                }

                logger.log('get("' + el + '") returning ' + collection, 'info', 'Dom');
                return collection;
            }

            logger.log('element ' + el + ' not found', 'error', 'Dom');
            return null; // safety, should never happen
        },

        /**
         * Normalizes currentStyle and ComputedStyle.
         * @method getStyle
         * @param {String | HTMLElement |Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements.
         * @param {String} property The style property whose value is returned.
         * @return {String | Array} The current value of the style property for the element(s).
         */
        getStyle: function(el, property) {
            property = toCamel(property);

            var f = function(element) {
                return getStyle(element, property);
            };

            return Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Wrapper for setting style properties of HTMLElements.  Normalizes "opacity" across modern browsers.
         * @method setStyle
         * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements.
         * @param {String} property The style property to be set.
         * @param {String} val The value to apply to the given property.
         */
        setStyle: function(el, property, val) {
            property = toCamel(property);

            var f = function(element) {
                setStyle(element, property, val);
                logger.log('setStyle setting ' + property + ' to ' + val, 'info', 'Dom');

            };

            Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Gets the current position of an element based on page coordinates.  Element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @method getXY
         * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements
         * @return {Array} The XY position of the element(s)
         */
        getXY: function(el) {
            var f = function(el) {

            // has to be part of document to have pageXY
                if (el.parentNode === null || el.offsetParent === null ||
                        this.getStyle(el, 'display') == 'none') {
                    logger.log('getXY failed: element not available', 'error', 'Dom');
                    return false;
                }

                var parentNode = null;
                var pos = [];
                var box;

                if (el.getBoundingClientRect) { // IE
                    box = el.getBoundingClientRect();
                    var doc = document;
                    if ( !this.inDocument(el) && parent.document != document) {// might be in a frame, need to get its scroll
                        doc = parent.document;

                        if ( !this.isAncestor(doc.documentElement, el) ) {
                            logger.log('getXY failed: element not available', 'error', 'Dom');
                            return false;
                        }

                    }

                    var scrollTop = Math.max(doc.documentElement.scrollTop, doc.body.scrollTop);
                    var scrollLeft = Math.max(doc.documentElement.scrollLeft, doc.body.scrollLeft);

                    return [box.left + scrollLeft, box.top + scrollTop];
                }
                else { // safari, opera, & gecko
                    pos = [el.offsetLeft, el.offsetTop];
                    parentNode = el.offsetParent;
                    if (parentNode != el) {
                        while (parentNode) {
                            pos[0] += parentNode.offsetLeft;
                            pos[1] += parentNode.offsetTop;
                            parentNode = parentNode.offsetParent;
                        }
                    }
                    if (isSafari && this.getStyle(el, 'position') == 'absolute' ) { // safari doubles in some cases
                        pos[0] -= document.body.offsetLeft;
                        pos[1] -= document.body.offsetTop;
                    }
                }

                if (el.parentNode) { parentNode = el.parentNode; }
                else { parentNode = null; }

                while (parentNode && parentNode.tagName.toUpperCase() != 'BODY' && parentNode.tagName.toUpperCase() != 'HTML')
                { // account for any scrolled ancestors
                    if (Y.Dom.getStyle(parentNode, 'display') != 'inline') { // work around opera inline scrollLeft/Top bug
                        pos[0] -= parentNode.scrollLeft;
                        pos[1] -= parentNode.scrollTop;
                    }

                    if (parentNode.parentNode) {
                        parentNode = parentNode.parentNode;
                    } else { parentNode = null; }
                }

                logger.log('getXY returning ' + pos, 'info', 'Dom');

                return pos;
            };

            return Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Gets the current X position of an element based on page coordinates.  The element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @method getX
         * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements
         * @return {String | Array} The X position of the element(s)
         */
        getX: function(el) {
            var f = function(el) {
                return Y.Dom.getXY(el)[0];
            };

            return Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Gets the current Y position of an element based on page coordinates.  Element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @method getY
         * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements
         * @return {String | Array} The Y position of the element(s)
         */
        getY: function(el) {
            var f = function(el) {
                return Y.Dom.getXY(el)[1];
            };

            return Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Set the position of an html element in page coordinates, regardless of how the element is positioned.
         * The element(s) must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @method setXY
         * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements
         * @param {Array} pos Contains X & Y values for new position (coordinates are page-based)
         * @param {Boolean} noRetry By default we try and set the position a second time if the first fails
         */
        setXY: function(el, pos, noRetry) {
            var f = function(el) {
                var style_pos = this.getStyle(el, 'position');
                if (style_pos == 'static') { // default to relative
                    this.setStyle(el, 'position', 'relative');
                    style_pos = 'relative';
                }

                var pageXY = this.getXY(el);
                if (pageXY === false) { // has to be part of doc to have pageXY
                    logger.log('setXY failed: element not available', 'error', 'Dom');
                    return false;
                }

                var delta = [ // assuming pixels; if not we will have to retry
                    parseInt( this.getStyle(el, 'left'), 10 ),
                    parseInt( this.getStyle(el, 'top'), 10 )
                ];

                if ( isNaN(delta[0]) ) {// in case of 'auto'
                    delta[0] = (style_pos == 'relative') ? 0 : el.offsetLeft;
                }
                if ( isNaN(delta[1]) ) { // in case of 'auto'
                    delta[1] = (style_pos == 'relative') ? 0 : el.offsetTop;
                }

                if (pos[0] !== null) { el.style.left = pos[0] - pageXY[0] + delta[0] + 'px'; }
                if (pos[1] !== null) { el.style.top = pos[1] - pageXY[1] + delta[1] + 'px'; }

                if (!noRetry) {
                    var newXY = this.getXY(el);

                    // if retry is true, try one more time if we miss
                   if ( (pos[0] !== null && newXY[0] != pos[0]) ||
                        (pos[1] !== null && newXY[1] != pos[1]) ) {
                       this.setXY(el, pos, true);
                   }
                }

                logger.log('setXY setting position to ' + pos, 'info', 'Dom');
            };

            Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Set the X position of an html element in page coordinates, regardless of how the element is positioned.
         * The element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @method setX
         * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements.
         * @param {Int} x The value to use as the X coordinate for the element(s).
         */
        setX: function(el, x) {
            Y.Dom.setXY(el, [x, null]);
        },

        /**
         * Set the Y position of an html element in page coordinates, regardless of how the element is positioned.
         * The element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @method setY
         * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements.
         * @param {Int} x To use as the Y coordinate for the element(s).
         */
        setY: function(el, y) {
            Y.Dom.setXY(el, [null, y]);
        },

        /**
         * Returns the region position of the given element.
         * The element must be part of the DOM tree to have a region (display:none or elements not appended return false).
         * @method getRegion
         * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements.
         * @return {Region | Array} A Region or array of Region instances containing "top, left, bottom, right" member data.
         */
        getRegion: function(el) {
            var f = function(el) {
                var region = new Y.Region.getRegion(el);
                logger.log('getRegion returning ' + region, 'info', 'Dom');
                return region;
            };

            return Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Returns the width of the client (viewport).
         * @method getClientWidth
         * @deprecated Now using getViewportWidth.  This interface left intact for back compat.
         * @return {Int} The width of the viewable area of the page.
         */
        getClientWidth: function() {
            return Y.Dom.getViewportWidth();
        },

        /**
         * Returns the height of the client (viewport).
         * @method getClientHeight
         * @deprecated Now using getViewportHeight.  This interface left intact for back compat.
         * @return {Int} The height of the viewable area of the page.
         */
        getClientHeight: function() {
            return Y.Dom.getViewportHeight();
        },

        /**
         * Returns a array of HTMLElements with the given class.
         * For optimized performance, include a tag and/or root node when possible.
         * @method getElementsByClassName
         * @param {String} className The class name to match against
         * @param {String} tag (optional) The tag name of the elements being collected
         * @param {String | HTMLElement} root (optional) The HTMLElement or an ID to use as the starting point
         * @return {Array} An array of elements that have the given class name
         */
        getElementsByClassName: function(className, tag, root) {
            var method = function(el) { return Y.Dom.hasClass(el, className); };
            return Y.Dom.getElementsBy(method, tag, root);
        },

        /**
         * Determines whether an HTMLElement has the given className.
         * @method hasClass
         * @param {String | HTMLElement | Array} el The element or collection to test
         * @param {String} className the class name to search for
         * @return {Boolean | Array} A boolean value or array of boolean values
         */
        hasClass: function(el, className) {
            var re = new RegExp('(?:^|\\s+)' + className + '(?:\\s+|$)');

            var f = function(el) {
                logger.log('hasClass returning ' + re.test(el['className']), 'info', 'Dom');
                return re.test(el['className']);
            };

            return Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Adds a class name to a given element or collection of elements.
         * @method addClass
         * @param {String | HTMLElement | Array} el The element or collection to add the class to
         * @param {String} className the class name to add to the class attribute
         */
        addClass: function(el, className) {
            var f = function(el) {
                if (this.hasClass(el, className)) { return; } // already present

                logger.log('addClass adding ' + className, 'info', 'Dom');

                el['className'] = [el['className'], className].join(' ');
            };

            Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Removes a class name from a given element or collection of elements.
         * @method removeClass
         * @param {String | HTMLElement | Array} el The element or collection to remove the class from
         * @param {String} className the class name to remove from the class attribute
         */
        removeClass: function(el, className) {
            var re = new RegExp('(?:^|\\s+)' + className + '(?:\\s+|$)', 'g');

            var f = function(el) {
                if (!this.hasClass(el, className)) { return; } // not present

                logger.log('removeClass removing ' + className, 'info', 'Dom');

                var c = el['className'];
                el['className'] = c.replace(re, ' ');
                if ( this.hasClass(el, className) ) { // in case of multiple adjacent
                    this.removeClass(el, className);
                }

            };

            Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Replace a class with another class for a given element or collection of elements.
         * If no oldClassName is present, the newClassName is simply added.
         * @method replaceClass
         * @param {String | HTMLElement | Array} el The element or collection to remove the class from
         * @param {String} oldClassName the class name to be replaced
         * @param {String} newClassName the class name that will be replacing the old class name
         */
        replaceClass: function(el, oldClassName, newClassName) {
            if (oldClassName === newClassName) { // avoid infinite loop
                return false;
            }

            var re = new RegExp('(?:^|\\s+)' + oldClassName + '(?:\\s+|$)', 'g');

            var f = function(el) {
                logger.log('replaceClass replacing ' + oldClassName + ' with ' + newClassName, 'info', 'Dom');

                if ( !this.hasClass(el, oldClassName) ) {
                    this.addClass(el, newClassName); // just add it if nothing to replace
                    return; // note return
                }

                el['className'] = el['className'].replace(re, ' ' + newClassName + ' ');

                if ( this.hasClass(el, oldClassName) ) { // in case of multiple adjacent
                    this.replaceClass(el, oldClassName, newClassName);
                }
            };

            Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Generates a unique ID
         * @method generateId
         * @param {String | HTMLElement | Array} el (optional) An optional element array of elements to add an ID to (no ID is added if one is already present).
         * @param {String} prefix (optional) an optional prefix to use (defaults to "yui-gen").
         * @return {String | Array} The generated ID, or array of generated IDs (or original ID if already present on an element)
         */
        generateId: function(el, prefix) {
            prefix = prefix || 'yui-gen';
            el = el || {};

            var f = function(el) {
                if (el) {
                    el = Y.Dom.get(el);
                } else {
                    el = {}; // just generating ID in this case
                }

                if (!el.id) {
                    el.id = prefix + id_counter++;
                    logger.log('generateId generating ' + el.id, 'info', 'Dom');
                } // dont override existing

                logger.log('generateId returning ' + el.id, 'info', 'Dom');

                return el.id;
            };

            return Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Determines whether an HTMLElement is an ancestor of another HTML element in the DOM hierarchy.
         * @method isAncestor
         * @param {String | HTMLElement} haystack The possible ancestor
         * @param {String | HTMLElement} needle The possible descendent
         * @return {Boolean} Whether or not the haystack is an ancestor of needle
         */
        isAncestor: function(haystack, needle) {
            haystack = Y.Dom.get(haystack);
            if (!haystack || !needle) { return false; }

            var f = function(needle) {
                if (haystack.contains && !isSafari) { // safari "contains" is broken
                    logger.log('isAncestor returning ' + haystack.contains(needle), 'info', 'Dom');
                    return haystack.contains(needle);
                }
                else if ( haystack.compareDocumentPosition ) {
                    logger.log('isAncestor returning ' + !!(haystack.compareDocumentPosition(needle) & 16), 'info', 'Dom');
                    return !!(haystack.compareDocumentPosition(needle) & 16);
                }
                else { // loop up and test each parent
                    var parent = needle.parentNode;

                    while (parent) {
                        if (parent == haystack) {
                            logger.log('isAncestor returning true', 'info', 'Dom');
                            return true;
                        }
                        else if (!parent.tagName || parent.tagName.toUpperCase() == 'HTML') {
                            logger.log('isAncestor returning false', 'info', 'Dom');
                            return false;
                        }

                        parent = parent.parentNode;
                    }
                    logger.log('isAncestor returning false', 'info', 'Dom');
                    return false;
                }
            };

            return Y.Dom.batch(needle, f, Y.Dom, true);
        },

        /**
         * Determines whether an HTMLElement is present in the current document.
         * @method inDocument
         * @param {String | HTMLElement} el The element to search for
         * @return {Boolean} Whether or not the element is present in the current document
         */
        inDocument: function(el) {
            var f = function(el) {
                return this.isAncestor(document.documentElement, el);
            };

            return Y.Dom.batch(el, f, Y.Dom, true);
        },

        /**
         * Returns a array of HTMLElements that pass the test applied by supplied boolean method.
         * For optimized performance, include a tag and/or root node when possible.
         * @method getElementsBy
         * @param {Function} method - A boolean method for testing elements which receives the element as its only argument.

         * @param {String} tag (optional) The tag name of the elements being collected
         * @param {String | HTMLElement} root (optional) The HTMLElement or an ID to use as the starting point
         */
        getElementsBy: function(method, tag, root) {
            tag = tag || '*';

            var nodes = [];

            if (root) {
                root = Y.Dom.get(root);
                if (!root) { // if no root node, then no children
                    return nodes;
                }
            } else {
                root = document;
            }

            var elements = root.getElementsByTagName(tag);

            if ( !elements.length && (tag == '*' && root.all) ) {
                elements = root.all; // IE < 6
            }

            for (var i = 0, len = elements.length; i < len; ++i) {
                if ( method(elements[i]) ) { nodes[nodes.length] = elements[i]; }
            }

            logger.log('getElementsBy returning ' + nodes, 'info', 'Dom');

            return nodes;
        },

        /**
         * Returns an array of elements that have had the supplied method applied.
         * The method is called with the element(s) as the first arg, and the optional param as the second ( method(el, o) ).
         * @method batch
         * @param {String | HTMLElement | Array} el (optional) An element or array of elements to apply the method to
         * @param {Function} method The method to apply to the element(s)
         * @param {Any} o (optional) An optional arg that is passed to the supplied method
         * @param {Boolean} override (optional) Whether or not to override the scope of "method" with "o"
         * @return {HTMLElement | Array} The element(s) with the method applied
         */
        batch: function(el, method, o, override) {
            var id = el;
            el = Y.Dom.get(el);

            var scope = (override) ? o : window;

            if (!el || el.tagName || !el.length) { // is null or not a collection (tagName for SELECT and others that can be both an element and a collection)
                if (!el) {
                    logger.log(id + ' not available', 'error', 'Dom');
                    return false;
                }
                return method.call(scope, el, o);
            }

            var collection = [];

            for (var i = 0, len = el.length; i < len; ++i) {
                if (!el[i]) {
                    id = el[i];
                    logger.log(id + ' not available', 'error', 'Dom');
                }
                collection[collection.length] = method.call(scope, el[i], o);
            }

            return collection;
        },

        /**
         * Returns the height of the document.
         * @method getDocumentHeight
         * @return {Int} The height of the actual document (which includes the body and its margin).
         */
        getDocumentHeight: function() {
            var scrollHeight = (document.compatMode != 'CSS1Compat') ? document.body.scrollHeight : document.documentElement.scrollHeight;

            var h = Math.max(scrollHeight, Y.Dom.getViewportHeight());
            logger.log('getDocumentHeight returning ' + h, 'info', 'Dom');
            return h;
        },

        /**
         * Returns the width of the document.
         * @method getDocumentWidth
         * @return {Int} The width of the actual document (which includes the body and its margin).
         */
        getDocumentWidth: function() {
            var scrollWidth = (document.compatMode != 'CSS1Compat') ? document.body.scrollWidth : document.documentElement.scrollWidth;
            var w = Math.max(scrollWidth, Y.Dom.getViewportWidth());
            logger.log('getDocumentWidth returning ' + w, 'info', 'Dom');
            return w;
        },

        /**
         * Returns the current height of the viewport.
         * @method getViewportHeight
         * @return {Int} The height of the viewable area of the page (excludes scrollbars).
         */
        getViewportHeight: function() {
            var height = self.innerHeight; // Safari, Opera
            var mode = document.compatMode;

            if ( (mode || isIE) && !isOpera ) { // IE, Gecko
                height = (mode == 'CSS1Compat') ?
                        document.documentElement.clientHeight : // Standards
                        document.body.clientHeight; // Quirks
            }

            logger.log('getViewportHeight returning ' + height, 'info', 'Dom');
            return height;
        },

        /**
         * Returns the current width of the viewport.
         * @method getViewportWidth
         * @return {Int} The width of the viewable area of the page (excludes scrollbars).
         */

        getViewportWidth: function() {
            var width = self.innerWidth;  // Safari
            var mode = document.compatMode;

            if (mode || isIE) { // IE, Gecko, Opera
                width = (mode == 'CSS1Compat') ?
                        document.documentElement.clientWidth : // Standards
                        document.body.clientWidth; // Quirks
            }
            logger.log('getViewportWidth returning ' + width, 'info', 'Dom');
            return width;
        }
    };
})();
/**
 * A region is a representation of an object on a grid.  It is defined
 * by the top, right, bottom, left extents, so is rectangular by default.  If
 * other shapes are required, this class could be extended to support it.
 * @namespace YAHOO.util
 * @class Region
 * @param {Int} t the top extent
 * @param {Int} r the right extent
 * @param {Int} b the bottom extent
 * @param {Int} l the left extent
 * @constructor
 */
YAHOO.util.Region = function(t, r, b, l) {

    /**
     * The region's top extent
     * @property top
     * @type Int
     */
    this.top = t;

    /**
     * The region's top extent as index, for symmetry with set/getXY
     * @property 1
     * @type Int
     */
    this[1] = t;

    /**
     * The region's right extent
     * @property right
     * @type int
     */
    this.right = r;

    /**
     * The region's bottom extent
     * @property bottom
     * @type Int
     */
    this.bottom = b;

    /**
     * The region's left extent
     * @property left
     * @type Int
     */
    this.left = l;

    /**
     * The region's left extent as index, for symmetry with set/getXY
     * @property 0
     * @type Int
     */
    this[0] = l;
};

/**
 * Returns true if this region contains the region passed in
 * @method contains
 * @param  {Region}  region The region to evaluate
 * @return {Boolean}        True if the region is contained with this region,
 *                          else false
 */
YAHOO.util.Region.prototype.contains = function(region) {
    return ( region.left   >= this.left   &&
             region.right  <= this.right  &&
             region.top    >= this.top    &&
             region.bottom <= this.bottom    );

    // this.logger.debug("does " + this + " contain " + region + " ... " + ret);
};

/**
 * Returns the area of the region
 * @method getArea
 * @return {Int} the region's area
 */
YAHOO.util.Region.prototype.getArea = function() {
    return ( (this.bottom - this.top) * (this.right - this.left) );
};

/**
 * Returns the region where the passed in region overlaps with this one
 * @method intersect
 * @param  {Region} region The region that intersects
 * @return {Region}        The overlap region, or null if there is no overlap
 */
YAHOO.util.Region.prototype.intersect = function(region) {
    var t = Math.max( this.top,    region.top    );
    var r = Math.min( this.right,  region.right  );
    var b = Math.min( this.bottom, region.bottom );
    var l = Math.max( this.left,   region.left   );

    if (b >= t && r >= l) {
        return new YAHOO.util.Region(t, r, b, l);
    } else {
        return null;
    }
};

/**
 * Returns the region representing the smallest region that can contain both
 * the passed in region and this region.
 * @method union
 * @param  {Region} region The region that to create the union with
 * @return {Region}        The union region
 */
YAHOO.util.Region.prototype.union = function(region) {
    var t = Math.min( this.top,    region.top    );
    var r = Math.max( this.right,  region.right  );
    var b = Math.max( this.bottom, region.bottom );
    var l = Math.min( this.left,   region.left   );

    return new YAHOO.util.Region(t, r, b, l);
};

/**
 * toString
 * @method toString
 * @return string the region properties
 */
YAHOO.util.Region.prototype.toString = function() {
    return ( "Region {"    +
             "top: "       + this.top    +
             ", right: "   + this.right  +
             ", bottom: "  + this.bottom +
             ", left: "    + this.left   +
             "}" );
};

/**
 * Returns a region that is occupied by the DOM element
 * @method getRegion
 * @param  {HTMLElement} el The element
 * @return {Region}         The region that the element occupies
 * @static
 */
YAHOO.util.Region.getRegion = function(el) {
    var p = YAHOO.util.Dom.getXY(el);

    var t = p[1];
    var r = p[0] + el.offsetWidth;
    var b = p[1] + el.offsetHeight;
    var l = p[0];

    return new YAHOO.util.Region(t, r, b, l);
};

/////////////////////////////////////////////////////////////////////////////


/**
 * A point is a region that is special in that it represents a single point on
 * the grid.
 * @namespace YAHOO.util
 * @class Point
 * @param {Int} x The X position of the point
 * @param {Int} y The Y position of the point
 * @constructor
 * @extends YAHOO.util.Region
 */
YAHOO.util.Point = function(x, y) {
   if (x instanceof Array) { // accept output from Dom.getXY
      y = x[1];
      x = x[0];
   }

    /**
     * The X position of the point, which is also the right, left and index zero (for Dom.getXY symmetry)
     * @property x
     * @type Int
     */

    this.x = this.right = this.left = this[0] = x;

    /**
     * The Y position of the point, which is also the top, bottom and index one (for Dom.getXY symmetry)
     * @property y
     * @type Int
     */
    this.y = this.top = this.bottom = this[1] = y;
};

YAHOO.util.Point.prototype = new YAHOO.util.Region();

