(function(Y) {

/**
 * Adds position and region management functionality to DOM.
 * @module dom
 * @submodule dom-screen
 * @for DOM
 */

var DOCUMENT_ELEMENT = 'documentElement',
    COMPAT_MODE = 'compatMode',
    POSITION = 'position',
    FIXED = 'fixed',
    RELATIVE = 'relative',
    LEFT = 'left',
    TOP = 'top',
    _BACK_COMPAT = 'BackCompat',
    MEDIUM = 'medium',
    BORDER_LEFT_WIDTH = 'borderLeftWidth',
    BORDER_TOP_WIDTH = 'borderTopWidth',
    GET_BOUNDING_CLIENT_RECT = 'getBoundingClientRect',
    GET_COMPUTED_STYLE = 'getComputedStyle',

    Y_DOM = Y.DOM,

    // TODO: how about thead/tbody/tfoot/tr?
    // TODO: does caption matter?
    RE_TABLE = /^t(?:able|d|h)$/i,

    SCROLL_NODE;

if (Y.UA.ie) {
    if (Y.config.doc[COMPAT_MODE] !== 'BackCompat') {
        SCROLL_NODE = DOCUMENT_ELEMENT;
    } else {
        SCROLL_NODE = 'body';
    }
}

Y.mix(Y_DOM, {
    /**
     * Returns the inner height of the viewport (exludes scrollbar).
     * @method winHeight
     * @return {Number} The current height of the viewport.
     */
    winHeight: function(node) {
        var h = Y_DOM._getWinSize(node).height;
        Y.log('winHeight returning ' + h, 'info', 'dom-screen');
        return h;
    },

    /**
     * Returns the inner width of the viewport (exludes scrollbar).
     * @method winWidth
     * @return {Number} The current width of the viewport.
     */
    winWidth: function(node) {
        var w = Y_DOM._getWinSize(node).width;
        Y.log('winWidth returning ' + w, 'info', 'dom-screen');
        return w;
    },

    /**
     * Document height
     * @method docHeight
     * @return {Number} The current height of the document.
     */
    docHeight:  function(node) {
        var h = Y_DOM._getDocSize(node).height;
        Y.log('docHeight returning ' + h, 'info', 'dom-screen');
        return Math.max(h, Y_DOM._getWinSize(node).height);
    },

    /**
     * Document width
     * @method docWidth
     * @return {Number} The current width of the document.
     */
    docWidth:  function(node) {
        var w = Y_DOM._getDocSize(node).width;
        Y.log('docWidth returning ' + w, 'info', 'dom-screen');
        return Math.max(w, Y_DOM._getWinSize(node).width);
    },

    /**
     * Amount page has been scroll horizontally
     * @method docScrollX
     * @return {Number} The current amount the screen is scrolled horizontally.
     */
    docScrollX: function(node, doc) {
        doc = doc || (node) ? Y_DOM._getDoc(node) : Y.config.doc; // perf optimization
        var dv = doc.defaultView,
            pageOffset = (dv) ? dv.pageXOffset : 0;
        return Math.max(doc[DOCUMENT_ELEMENT].scrollLeft, doc.body.scrollLeft, pageOffset);
    },

    /**
     * Amount page has been scroll vertically
     * @method docScrollY
     * @return {Number} The current amount the screen is scrolled vertically.
     */
    docScrollY:  function(node, doc) {
        doc = doc || (node) ? Y_DOM._getDoc(node) : Y.config.doc; // perf optimization
        var dv = doc.defaultView,
            pageOffset = (dv) ? dv.pageYOffset : 0;
        return Math.max(doc[DOCUMENT_ELEMENT].scrollTop, doc.body.scrollTop, pageOffset);
    },

    /**
     * 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 element The target element
     * @return {Array} The XY position of the element

     TODO: test inDocument/display?
     */
    getXY: function() {
        if (Y.config.doc[DOCUMENT_ELEMENT][GET_BOUNDING_CLIENT_RECT]) {
            return function(node) {
                var xy = null,
                    scrollLeft,
                    scrollTop,
                    mode,
                    box,
                    offX,
                    offY,
                    doc,
                    win,
                    inDoc,
                    rootNode;

                if (node && node.tagName) {
                    doc = node.ownerDocument;
                    mode = doc[COMPAT_MODE];

                    if (mode !== _BACK_COMPAT) {
                        rootNode = doc[DOCUMENT_ELEMENT];
                    } else {
                        rootNode = doc.body;
                    }

                    // inline inDoc check for perf
                    if (rootNode.contains) {
                        inDoc = rootNode.contains(node);
                    } else {
                        inDoc = Y.DOM.contains(rootNode, node);
                    }

                    if (inDoc) {
                        win = doc.defaultView;

                        // inline scroll calc for perf
                        if (win && 'pageXOffset' in win) {
                            scrollLeft = win.pageXOffset;
                            scrollTop = win.pageYOffset;
                        } else {
                            scrollLeft = (SCROLL_NODE) ? doc[SCROLL_NODE].scrollLeft : Y_DOM.docScrollX(node, doc);
                            scrollTop = (SCROLL_NODE) ? doc[SCROLL_NODE].scrollTop : Y_DOM.docScrollY(node, doc);
                        }

                        if (Y.UA.ie) { // IE < 8, quirks, or compatMode
                            if (!doc.documentMode || doc.documentMode < 8 || mode === _BACK_COMPAT) {
                                offX = rootNode.clientLeft;
                                offY = rootNode.clientTop;
                            }
                        }
                        box = node[GET_BOUNDING_CLIENT_RECT]();
                        xy = [box.left, box.top];

                        if (offX || offY) {
                                xy[0] -= offX;
                                xy[1] -= offY;

                        }
                        if ((scrollTop || scrollLeft)) {
                            if (!Y.UA.ios || (Y.UA.ios >= 4.2)) {
                                xy[0] += scrollLeft;
                                xy[1] += scrollTop;
                            }

                        }
                    } else {
                        xy = Y_DOM._getOffset(node);
                    }
                }
                return xy;
            };
        } else {
            return function(node) { // manually calculate by crawling up offsetParents
                //Calculate the Top and Left border sizes (assumes pixels)
                var xy = null,
                    doc,
                    parentNode,
                    bCheck,
                    scrollTop,
                    scrollLeft;

                if (node) {
                    if (Y_DOM.inDoc(node)) {
                        xy = [node.offsetLeft, node.offsetTop];
                        doc = node.ownerDocument;
                        parentNode = node;
                        // TODO: refactor with !! or just falsey
                        bCheck = ((Y.UA.gecko || Y.UA.webkit > 519) ? true : false);

                        // TODO: worth refactoring for TOP/LEFT only?
                        while ((parentNode = parentNode.offsetParent)) {
                            xy[0] += parentNode.offsetLeft;
                            xy[1] += parentNode.offsetTop;
                            if (bCheck) {
                                xy = Y_DOM._calcBorders(parentNode, xy);
                            }
                        }

                        // account for any scrolled ancestors
                        if (Y_DOM.getStyle(node, POSITION) != FIXED) {
                            parentNode = node;

                            while ((parentNode = parentNode.parentNode)) {
                                scrollTop = parentNode.scrollTop;
                                scrollLeft = parentNode.scrollLeft;

                                //Firefox does something funky with borders when overflow is not visible.
                                if (Y.UA.gecko && (Y_DOM.getStyle(parentNode, 'overflow') !== 'visible')) {
                                        xy = Y_DOM._calcBorders(parentNode, xy);
                                }


                                if (scrollTop || scrollLeft) {
                                    xy[0] -= scrollLeft;
                                    xy[1] -= scrollTop;
                                }
                            }
                            xy[0] += Y_DOM.docScrollX(node, doc);
                            xy[1] += Y_DOM.docScrollY(node, doc);

                        } else {
                            //Fix FIXED position -- add scrollbars
                            xy[0] += Y_DOM.docScrollX(node, doc);
                            xy[1] += Y_DOM.docScrollY(node, doc);
                        }
                    } else {
                        xy = Y_DOM._getOffset(node);
                    }
                }

                return xy;
            };
        }
    }(),// NOTE: Executing for loadtime branching

    /**
    Gets the width of vertical scrollbars on overflowed containers in the body
    content.

    @method getScrollbarWidth
    @return {Number} Pixel width of a scrollbar in the current browser
    **/
    getScrollbarWidth: Y.cached(function () {
        var doc      = Y.config.doc,
            testNode = doc.createElement('div'),
            body     = doc.getElementsByTagName('body')[0],
            // 0.1 because cached doesn't support falsy refetch values
            width    = 0.1;

        if (body) {
            testNode.style.cssText = "position:absolute;visibility:hidden;overflow:scroll;width:20px;";
            testNode.appendChild(doc.createElement('p')).style.height = '1px';
            body.insertBefore(testNode, body.firstChild);
            width = testNode.offsetWidth - testNode.clientWidth;

            body.removeChild(testNode);
        }

        return width;
    }, null, 0.1),

    /**
     * Gets the current X 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 getX
     * @param element The target element
     * @return {Number} The X position of the element
     */

    getX: function(node) {
        return Y_DOM.getXY(node)[0];
    },

    /**
     * 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 element The target element
     * @return {Number} The Y position of the element
     */

    getY: function(node) {
        return Y_DOM.getXY(node)[1];
    },

    /**
     * Set the position of an html element in page coordinates.
     * The element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
     * @method setXY
     * @param element The target element
     * @param {Array} xy 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(node, xy, noRetry) {
        var setStyle = Y_DOM.setStyle,
            pos,
            delta,
            newXY,
            currentXY;

        if (node && xy) {
            pos = Y_DOM.getStyle(node, POSITION);

            delta = Y_DOM._getOffset(node);
            if (pos == 'static') { // default to relative
                pos = RELATIVE;
                setStyle(node, POSITION, pos);
            }
            currentXY = Y_DOM.getXY(node);

            if (xy[0] !== null) {
                setStyle(node, LEFT, xy[0] - currentXY[0] + delta[0] + 'px');
            }

            if (xy[1] !== null) {
                setStyle(node, TOP, xy[1] - currentXY[1] + delta[1] + 'px');
            }

            if (!noRetry) {
                newXY = Y_DOM.getXY(node);
                if (newXY[0] !== xy[0] || newXY[1] !== xy[1]) {
                    Y_DOM.setXY(node, xy, true);
                }
            }

            Y.log('setXY setting position to ' + xy, 'info', 'dom-screen');
        } else {
            Y.log('setXY failed to set ' + node + ' to ' + xy, 'info', 'dom-screen');
        }
    },

    /**
     * Set the X 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 setX
     * @param element The target element
     * @param {Number} x The X values for new position (coordinates are page-based)
     */
    setX: function(node, x) {
        return Y_DOM.setXY(node, [x, null]);
    },

    /**
     * Set the Y 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 setY
     * @param element The target element
     * @param {Number} y The Y values for new position (coordinates are page-based)
     */
    setY: function(node, y) {
        return Y_DOM.setXY(node, [null, y]);
    },

    /**
     * @method swapXY
     * @description Swap the xy position with another node
     * @param {Node} node The node to swap with
     * @param {Node} otherNode The other node to swap with
     * @return {Node}
     */
    swapXY: function(node, otherNode) {
        var xy = Y_DOM.getXY(node);
        Y_DOM.setXY(node, Y_DOM.getXY(otherNode));
        Y_DOM.setXY(otherNode, xy);
    },

    _calcBorders: function(node, xy2) {
        var t = parseInt(Y_DOM[GET_COMPUTED_STYLE](node, BORDER_TOP_WIDTH), 10) || 0,
            l = parseInt(Y_DOM[GET_COMPUTED_STYLE](node, BORDER_LEFT_WIDTH), 10) || 0;
        if (Y.UA.gecko) {
            if (RE_TABLE.test(node.tagName)) {
                t = 0;
                l = 0;
            }
        }
        xy2[0] += l;
        xy2[1] += t;
        return xy2;
    },

    _getWinSize: function(node, doc) {
        doc  = doc || (node) ? Y_DOM._getDoc(node) : Y.config.doc;
        var win = doc.defaultView || doc.parentWindow,
            mode = doc[COMPAT_MODE],
            h = win.innerHeight,
            w = win.innerWidth,
            root = doc[DOCUMENT_ELEMENT];

        if ( mode && !Y.UA.opera ) { // IE, Gecko
            if (mode != 'CSS1Compat') { // Quirks
                root = doc.body;
            }
            h = root.clientHeight;
            w = root.clientWidth;
        }
        return { height: h, width: w };
    },

    _getDocSize: function(node) {
        var doc = (node) ? Y_DOM._getDoc(node) : Y.config.doc,
            root = doc[DOCUMENT_ELEMENT];

        if (doc[COMPAT_MODE] != 'CSS1Compat') {
            root = doc.body;
        }

        return { height: root.scrollHeight, width: root.scrollWidth };
    }
});

})(Y);
