/**
 * @class Ext.layout.AnchorLayout
 * @extends Ext.layout.ContainerLayout
 * 
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 layout:'anchor' {@link Ext.Container#layout}
 * 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.  For example:
 * 

var viewport = new Ext.Viewport({
    layout:'anchor',
    anchorSize: {width:800, height:600},
    items:[{
        title:'Item 1',
        html:'Content 1',
        width:800,
        anchor:'right 20%'
    },{
        title:'Item 2',
        html:'Content 2',
        width:300,
        anchor:'50% 30%'
    },{
        title:'Item 3',
        html:'Content 3',
        width:600,
        anchor:'-100 50%'
    }]
});
 * 
 */
Ext.layout.AnchorLayout = Ext.extend(Ext.layout.ContainerLayout, {
    
/**
     * @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%'
     * 
     *
     *
     * 
     */

    // private
    monitorResize:true,
    type: 'anchor',

    getLayoutTargetSize : function() {
        var target = this.container.getLayoutTarget();
        if (!target) {
            return {};
        }
        // Style Sized (scrollbars not included)
        return target.getStyleSize();
    },

    // private
    onLayout : function(ct, target){
        Ext.layout.AnchorLayout.superclass.onLayout.call(this, ct, target);
        var size = this.getLayoutTargetSize();

        var w = size.width, h = size.height;

        if(w < 20 && h < 20){
            return;
        }

        // find the container anchoring size
        var aw, ah;
        if(ct.anchorSize){
            if(typeof ct.anchorSize == 'number'){
                aw = ct.anchorSize;
            }else{
                aw = ct.anchorSize.width;
                ah = ct.anchorSize.height;
            }
        }else{
            aw = ct.initialConfig.width;
            ah = ct.initialConfig.height;
        }

        var cs = this.getRenderedItems(ct), len = cs.length, i, c, a, cw, ch, el, vs;
        for(i = 0; i < len; i++){
            c = cs[i];
            el = c.getPositionEl();
            if(c.anchor){
                a = c.anchorSpec;
                if(!a){ // cache all anchor values
                    vs = c.anchor.split(' ');
                    c.anchorSpec = a = {
                        right: this.parseAnchor(vs[0], c.initialConfig.width, aw),
                        bottom: this.parseAnchor(vs[1], c.initialConfig.height, ah)
                    };
                }
                cw = a.right ? this.adjustWidthAnchor(a.right(w) - el.getMargins('lr'), c) : undefined;
                ch = a.bottom ? this.adjustHeightAnchor(a.bottom(h) - el.getMargins('tb'), c) : undefined;

                if(cw || ch){
                    c.setSize(cw || undefined, ch || undefined);
                }
            }
        }
    },

    // private
    parseAnchor : function(a, start, cstart){
        if(a && a != 'none'){
            var last;
            if(/^(r|right|b|bottom)$/i.test(a)){   // standard anchor
                var diff = cstart - start;
                return function(v){
                    if(v !== last){
                        last = v;
                        return v - diff;
                    }
                }
            }else if(a.indexOf('%') != -1){
                var ratio = parseFloat(a.replace('%', ''))*.01;   // percentage
                return function(v){
                    if(v !== last){
                        last = v;
                        return Math.floor(v*ratio);
                    }
                }
            }else{
                a = parseInt(a, 10);
                if(!isNaN(a)){                            // simple offset adjustment
                    return function(v){
                        if(v !== last){
                            last = v;
                            return v + a;
                        }
                    }
                }
            }
        }
        return false;
    },

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

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

    
/**
     * @property activeItem
     * @hide
     */
});
Ext.Container.LAYOUTS['anchor'] = Ext.layout.AnchorLayout;