/**
 * This is the layout style of choice for creating structural layouts in a multi-column format where the width of each
 * column can be specified as a percentage or fixed width, but the height is allowed to vary based on the content. This
 * class is intended to be extended or created via the layout:'column' {@link Ext.container.Container#layout} config,
 * and should generally not need to be created directly via the new keyword.
 *
 * ColumnLayout does not have any direct config options (other than inherited ones), but it does support a specific
 * config property of `columnWidth` that can be included in the config of any panel added to it. The layout will use
 * the columnWidth (if present) or width of each panel during layout to determine how to size each panel. If width or
 * columnWidth is not specified for a given panel, its width will default to the panel's width (or auto).
 *
 * The width property is always evaluated as pixels, and must be a number greater than or equal to 1. The columnWidth
 * property is always evaluated as a percentage, and must be a decimal value greater than 0 and less than 1 (e.g., .25).
 *
 * The basic rules for specifying column widths are pretty simple. The logic makes two passes through the set of
 * contained panels. During the first layout pass, all panels that either have a fixed width or none specified (auto)
 * are skipped, but their widths are subtracted from the overall container width.
 *
 * During the second pass, all panels with columnWidths are assigned pixel widths in proportion to their percentages
 * based on the total **remaining** container width. In other words, percentage width panels are designed to fill
 * the space left over by all the fixed-width and/or auto-width panels. Because of this, while you can specify any
 * number of columns with different percentages, the columnWidths must always add up to 1 (or 100%) when added
 * together, otherwise your layout may not render as expected.
 *
 *     @example
 *     // All columns are percentages -- they must add up to 1
 *     Ext.create('Ext.panel.Panel', {
 *         title: 'Column Layout - Percentage Only',
 *         width: 350,
 *         height: 250,
 *         layout:'column',
 *         items: [{
 *             title: 'Column 1',
 *             columnWidth: .25
 *         },{
 *             title: 'Column 2',
 *             columnWidth: .55
 *         },{
 *             title: 'Column 3',
 *             columnWidth: .20
 *         }],
 *         renderTo: Ext.getBody()
 *     });
 *
 *     // Mix of width and columnWidth -- all columnWidth values must add up
 *     // to 1. The first column will take up exactly 120px, and the last two
 *     // columns will fill the remaining container width.
 *
 *     Ext.create('Ext.Panel', {
 *         title: 'Column Layout - Mixed',
 *         width: 350,
 *         height: 250,
 *         layout:'column',
 *         items: [{
 *             title: 'Column 1',
 *             width: 120
 *         },{
 *             title: 'Column 2',
 *             columnWidth: .7
 *         },{
 *             title: 'Column 3',
 *             columnWidth: .3
 *         }],
 *         renderTo: Ext.getBody()
 *     });
 */
Ext.define('Ext.layout.container.Column', {

    extend: 'Ext.layout.container.Auto',
    alias: ['layout.column'],
    alternateClassName: 'Ext.layout.ColumnLayout',

    type: 'column',

    itemCls: Ext.baseCSSPrefix + 'column',

    targetCls: Ext.baseCSSPrefix + 'column-layout-ct',

    scrollOffset: 0,

    bindToOwnerCtComponent: false,

    getRenderTarget : function() {
        if (!this.innerCt) {

            // the innerCt prevents wrapping and shuffling while
            // the container is resizing
            this.innerCt = this.getTarget().createChild({
                cls: Ext.baseCSSPrefix + 'column-inner'
            });

            // Column 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"
            this.clearEl = this.innerCt.createChild({
                cls: Ext.baseCSSPrefix + 'clear',
                role: 'presentation'
            });
        }
        return this.innerCt;
    },

    // private
    onLayout : function() {
        var me = this,
            target = me.getTarget(),
            items = me.getLayoutItems(),
            len = items.length,
            item,
            i,
            parallelMargins = [],
            itemParallelMargins,
            size,
            availableWidth,
            columnWidth;

        size = me.getLayoutTargetSize();
        if (size.width < len * 10) { // Don't lay out in impossibly small target (probably display:none, or initial, unsized Container)
            return;
        }

        // On the first pass, for all except IE6-7, we lay out the items with no scrollbars visible using style overflow: hidden.
        // If, after the layout, it is detected that there is vertical overflow,
        // we will recurse back through here. Do not adjust overflow style at that time.
        if (me.adjustmentPass) {
            if (Ext.isIE6 || Ext.isIE7 || Ext.isIEQuirks) {
                size.width = me.adjustedWidth;
            }
        } else {
            i = target.getStyle('overflow');
            if (i && i != 'hidden') {
                me.autoScroll = true;
                if (!(Ext.isIE6 || Ext.isIE7 || Ext.isIEQuirks)) {
                    target.setStyle('overflow', 'hidden');
                    size = me.getLayoutTargetSize();
                }
            }
        }

        availableWidth = size.width - me.scrollOffset;
        me.innerCt.setWidth(availableWidth);

        // some columns can be percentages while others are fixed
        // so we need to make 2 passes
        for (i = 0; i < len; i++) {
            item = items[i];
            itemParallelMargins = parallelMargins[i] = item.getEl().getMargin('lr');
            if (!item.columnWidth) {
                availableWidth -= (item.getWidth() + itemParallelMargins);
            }
        }

        availableWidth = availableWidth < 0 ? 0 : availableWidth;
        for (i = 0; i < len; i++) {
            item = items[i];
            if (item.columnWidth) {
                columnWidth = Math.floor(item.columnWidth * availableWidth) - parallelMargins[i];
                me.setItemSize(item, columnWidth, item.height);
            } else {
                me.layoutItem(item);
            }
        }

        // After the first pass on an autoScroll layout, restore the overflow settings if it had been changed (only changed for non-IE6)
        if (!me.adjustmentPass && me.autoScroll) {

            // If there's a vertical overflow, relay with scrollbars
            target.setStyle('overflow', 'auto');
            me.adjustmentPass = (target.dom.scrollHeight > size.height);
            if (Ext.isIE6 || Ext.isIE7 || Ext.isIEQuirks) {
                me.adjustedWidth = size.width - Ext.getScrollBarWidth();
            } else {
                target.setStyle('overflow', 'auto');
            }

            // If the layout caused height overflow, recurse back and recalculate (with overflow setting restored on non-IE6)
            if (me.adjustmentPass) {
                me.onLayout();
            }
        }
        delete me.adjustmentPass;
    },

    configureItem: function(item) {
        this.callParent(arguments);

        if (item.columnWidth) {
            item.layoutManagedWidth = 1;
        }
    }
});