/**
 * This layout manager is used to center contents within a container. As a subclass of
 * {@link Ext.layout.container.Fit fit layout}, CenterLayout expects to have one child
 * item; multiple items will be placed overlapping. The layout does not require any config
 * options. Items in the container can use percentage width or height rather than be fit
 * to the full size of the container.
 *
 * Example usage:
 *
 *      // The content panel is centered in the container
 *
 *      var p = Ext.create('Ext.Panel', {
 *          title: 'Center Layout',
 *          layout: 'ux.center',
 *          items: [{
 *              title: 'Centered Content',
 *              width: '75%',  // assign 75% of the container width to the item
 *              html: 'Some content'
 *          }]
 *      });
 *
 * If you leave the title blank and specify no border you can create a non-visual, structural
 * container just for centering the contents.
 *
 *      var p = Ext.create('Ext.Container', {
 *          layout: 'ux.center',
 *          items: [{
 *              title: 'Centered Content',
 *              width: 300,
 *              height: '90%', // assign 90% of the container height to the item
 *              html: 'Some content'
 *          }]
 *      });
 */
Ext.define('Ext.ux.layout.Center', {
    extend: 'Ext.layout.container.Fit',
    alias: 'layout.ux.center',

    percentRe: /^\d+(?:\.\d+)?\%$/,

    itemCls: 'ux-layout-center-item',

    initLayout: function () {
        this.callParent(arguments);

        this.owner.addCls('ux-layout-center');
    },

    getItemSizePolicy: function (item) {
        var policy = this.callParent(arguments);
        if (typeof item.width == 'number') {
            policy = this.sizePolicies[policy.setsHeight ? 2 : 0];
        }
        return policy;
    },

    getPos: function (itemContext, info, dimension) {
        var size = itemContext.props[dimension] + info.margins[dimension],
            pos = Math.round((info.targetSize[dimension] - size) / 2);

        return Math.max(pos, 0);
    },

    getSize: function (item, info, dimension) {
        var ratio = item[dimension];

        if (typeof ratio == 'string' && this.percentRe.test(ratio)) {
            ratio = parseFloat(ratio) / 100;
        } else {
            ratio = item[dimension + 'Ratio']; // backwards compat
        }

        return info.targetSize[dimension] * (ratio || 1) - info.margins[dimension];
    },

    positionItemX: function (itemContext, info) {
        var left = this.getPos(itemContext, info, 'width');

        itemContext.setProp('x', left);
    },

    positionItemY: function (itemContext, info) {
        var top = this.getPos(itemContext, info, 'height');

        itemContext.setProp('y', top);
    },

    setItemHeight: function (itemContext, info) {
        var height = this.getSize(itemContext.target, info, 'height');

        itemContext.setHeight(height);
    },

    setItemWidth: function (itemContext, info) {
        var width = this.getSize(itemContext.target, info, 'width');

        itemContext.setWidth(width);
    }
});