/**
 * @class Ext.layout.container.Anchor
 * @extends Ext.layout.container.Container
 * 
 * This is a layout that enables anchoring of contained elements relative to the container's dimensions.
 * If the container is resized, all anchored items are automatically rerendered according to their
 * `{@link #anchor}` rules.
 *
 * This class is intended to be extended or created via the {@link Ext.container.AbstractContainer#layout layout}: 'anchor' 
 * config, and should generally not need to be created directly via the new keyword.
 * 
 * AnchorLayout does not have any direct config options (other than inherited ones). By default,
 * AnchorLayout will calculate anchor measurements based on the size of the container itself. However, the
 * container using the AnchorLayout can supply an anchoring-specific config property of `anchorSize`.
 *
 * If anchorSize is specifed, the layout will use it as a virtual container for the purposes of calculating
 * anchor measurements based on it instead, allowing the container to be sized independently of the anchoring
 * logic if necessary.  
 *
 *     @example
 *     Ext.create('Ext.Panel', {
 *         width: 500,
 *         height: 400,
 *         title: "AnchorLayout Panel",
 *         layout: 'anchor',
 *         renderTo: Ext.getBody(),
 *         items: [
 *             {
 *                 xtype: 'panel',
 *                 title: '75% Width and 20% Height',
 *                 anchor: '75% 20%'
 *             },
 *             {
 *                 xtype: 'panel',
 *                 title: 'Offset -300 Width & -200 Height',
 *                 anchor: '-300 -200'		
 *             },
 *             {
 *                 xtype: 'panel',
 *                 title: 'Mixed Offset and Percent',
 *                 anchor: '-250 20%'
 *             }
 *         ]
 *     });
 */
Ext.define('Ext.layout.container.Anchor', {

    /* Begin Definitions */

    alias: 'layout.anchor',
    extend: 'Ext.layout.container.Container',
    alternateClassName: 'Ext.layout.AnchorLayout',

    /* End Definitions */

    /**
     * @cfg {String} anchor
     *
     * This configuation option is to be applied to **child `items`** of a container managed by
     * this layout (ie. configured with `layout:'anchor'`).
     *
     * This value is what tells the layout how an item should be anchored to the container. `items`
     * added to an AnchorLayout accept an anchoring-specific config property of **anchor** which is a string
     * containing two values: the horizontal anchor value and the vertical anchor value (for example, '100% 50%').
     * The following types of anchor values are supported:
     *
     * - **Percentage** : Any value between 1 and 100, expressed as a percentage.
     *
     *   The first anchor is the percentage width that the item should take up within the container, and the
     *   second is the percentage height.  For example:
     *
     *       // two values specified
     *       anchor: '100% 50%' // render item complete width of the container and
     *                          // 1/2 height of the container
     *       // one value specified
     *       anchor: '100%'     // the width value; the height will default to auto
     *
     * - **Offsets** : Any positive or negative integer value.
     *
     *   This is a raw adjustment where the first anchor is the offset from the right edge of the container,
     *   and the second is the offset from the bottom edge. For example:
     *
     *       // two values specified
     *       anchor: '-50 -100' // render item the complete width of the container
     *                          // minus 50 pixels and
     *                          // the complete height minus 100 pixels.
     *       // one value specified
     *       anchor: '-50'      // anchor value is assumed to be the right offset value
     *                          // bottom offset will default to 0
     *
     * - **Sides** : Valid values are `right` (or `r`) and `bottom` (or `b`).
     *
     *   Either the container must have a fixed size or an anchorSize config value defined at render time in
     *   order for these to have any effect.
     *   
     * - **Mixed** :
     *
     *   Anchor values can also be mixed as needed.  For example, to render the width offset from the container
     *   right edge by 50 pixels and 75% of the container's height use:
     *   
     *       anchor:   '-50 75%'
     */
    type: 'anchor',

    /**
     * @cfg {String} defaultAnchor
     * Default anchor for all child <b>container</b> items applied if no anchor or specific width is set on the child item.  Defaults to '100%'.
     */
    defaultAnchor: '100%',

    parseAnchorRE: /^(r|right|b|bottom)$/i,

    // private
    onLayout: function() {
        this.callParent(arguments);

        var me = this,
            size = me.getLayoutTargetSize(),
            owner = me.owner,
            target = me.getTarget(),
            ownerWidth = size.width,
            ownerHeight = size.height,
            overflow = target.getStyle('overflow'),
            components = me.getVisibleItems(owner),
            len = components.length,
            boxes = [],
            box, newTargetSize, component, anchorSpec, calcWidth, calcHeight,
            i, el, cleaner;

        if (ownerWidth < 20 && ownerHeight < 20) {
            return;
        }

        // Anchor layout uses natural HTML flow to arrange the child items.
        // To ensure that all browsers (I'm looking at you IE!) add the bottom margin of the last child to the
        // containing element height, we create a zero-sized element with style clear:both to force a "new line"
        if (!me.clearEl) {
            me.clearEl = target.createChild({
                cls: Ext.baseCSSPrefix + 'clear',
                role: 'presentation'
            });
        }

        // Work around WebKit RightMargin bug. We're going to inline-block all the children only ONCE and remove it when we're done
        if (!Ext.supports.RightMargin) {
            cleaner = Ext.Element.getRightMarginFixCleaner(target);
            target.addCls(Ext.baseCSSPrefix + 'inline-children');
        }

        for (i = 0; i < len; i++) {
            component = components[i];
            el = component.el;

            anchorSpec = component.anchorSpec;
            if (anchorSpec) {
                if (anchorSpec.right) {
                    calcWidth = me.adjustWidthAnchor(anchorSpec.right(ownerWidth) - el.getMargin('lr'), component);
                } else {
                    calcWidth = undefined;
                }
                if (anchorSpec.bottom) {
                    calcHeight = me.adjustHeightAnchor(anchorSpec.bottom(ownerHeight) - el.getMargin('tb'), component);
                } else {
                    calcHeight = undefined;
                }

                boxes.push({
                    component: component,
                    anchor: true,
                    width: calcWidth || undefined,
                    height: calcHeight || undefined
                });
            } else {
                boxes.push({
                    component: component,
                    anchor: false
                });
            }
        }

        // Work around WebKit RightMargin bug. We're going to inline-block all the children only ONCE and remove it when we're done
        if (!Ext.supports.RightMargin) {
            target.removeCls(Ext.baseCSSPrefix + 'inline-children');
            cleaner();
        }

        for (i = 0; i < len; i++) {
            box = boxes[i];
            me.setItemSize(box.component, box.width, box.height);
        }

        if (overflow && overflow != 'hidden' && !me.adjustmentPass) {
            newTargetSize = me.getLayoutTargetSize();
            if (newTargetSize.width != size.width || newTargetSize.height != size.height) {
                me.adjustmentPass = true;
                me.onLayout();
            }
        }

        delete me.adjustmentPass;
    },

    // private
    parseAnchor: function(a, start, cstart) {
        if (a && a != 'none') {
            var ratio;
            // standard anchor
            if (this.parseAnchorRE.test(a)) {
                var diff = cstart - start;
                return function(v) {
                    return v - diff;
                };
            }    
            // percentage
            else if (a.indexOf('%') != -1) {
                ratio = parseFloat(a.replace('%', '')) * 0.01;
                return function(v) {
                    return Math.floor(v * ratio);
                };
            }    
            // simple offset adjustment
            else {
                a = parseInt(a, 10);
                if (!isNaN(a)) {
                    return function(v) {
                        return v + a;
                    };
                }
            }
        }
        return null;
    },

    // private
    adjustWidthAnchor: function(value, comp) {
        return value;
    },

    // private
    adjustHeightAnchor: function(value, comp) {
        return value;
    },

    configureItem: function(item) {
        var me = this,
            owner = me.owner,
            anchor= item.anchor,
            anchorsArray,
            anchorSpec,
            anchorWidth,
            anchorHeight;

        if (!item.anchor && item.items && !Ext.isNumber(item.width) && !(Ext.isIE6 && Ext.isStrict)) {
            item.anchor = anchor = me.defaultAnchor;
        }

        // find the container anchoring size
        if (owner.anchorSize) {
            if (typeof owner.anchorSize == 'number') {
                anchorWidth = owner.anchorSize;
            }
            else {
                anchorWidth = owner.anchorSize.width;
                anchorHeight = owner.anchorSize.height;
            }
        }
        else {
            anchorWidth = owner.initialConfig.width;
            anchorHeight = owner.initialConfig.height;
        }

        if (anchor) {
            // cache all anchor values
            anchorsArray = anchor.split(' ');
            item.anchorSpec = anchorSpec = {
                right: me.parseAnchor(anchorsArray[0], item.initialConfig.width, anchorWidth),
                bottom: me.parseAnchor(anchorsArray[1], item.initialConfig.height, anchorHeight)
            };

            if (anchorSpec.right) {
                item.layoutManagedWidth = 1;
            } else {
                item.layoutManagedWidth = 2;
            }

            if (anchorSpec.bottom) {
                item.layoutManagedHeight = 1;
            } else {
                item.layoutManagedHeight = 2;
            }
        } else {
            item.layoutManagedWidth = 2;
            item.layoutManagedHeight = 2;
        }
        this.callParent(arguments);
    }

});