// This Source Code is in the Public Domain per: http://unlicense.org
package org.litesoft.GWT.client.widgets.nonpublic;

import org.litesoft.GWT.client.widgets.nonpublic.external.*;

public abstract class AbstractSplitterDragger extends AbstractDragger {
    private AbstractSizeableOneDimensionalPanel mSplitPanel;
    protected final int mIndex;

    public AbstractSplitterDragger( AbstractSizeableOneDimensionalPanel pSplitPanel, int pIndex ) {
        mSplitPanel = pSplitPanel;
        mIndex = pIndex;
    }

    @Override
    public void start( MouseEvent e ) {
        if ( mSplitPanel.getWidgetCount() > (mIndex + 1) ) {
            super.start( e );
        }
    }

    protected ISizeableWidget getSizeableAt( int pIndex ) {
        return (ISizeableWidget) mSplitPanel.getWidget( pIndex );
    }

    /**
     * @return false to prevent additional dragging
     */
    protected boolean adjustSizesBy( ISizeableDimensionHelper pPrevHelper, ISizeableDimensionHelper pNextHelper, int pDelta ) {
        return (pDelta == 0) || ((pDelta < 0) ? //
                                 shrinkExpandSizesBy( pPrevHelper, pNextHelper, -pDelta ) : //
                                 shrinkExpandSizesBy( pNextHelper, pPrevHelper, pDelta ));
    }

    private boolean shrinkExpandSizesBy( ISizeableDimensionHelper pShrinkingHelper, ISizeableDimensionHelper pExpandingHelper, int pDelta ) {
        int maxShrinkability = pShrinkingHelper.getDimensionMaxShrinkability();
        if ( maxShrinkability <= 1 ) {
            return false;
        }
        if ( pDelta >= maxShrinkability ) {
            pDelta = maxShrinkability - 1;
        }

        int shrinkingCurSize = pShrinkingHelper.getDimension();
        int expandingCurSize = pExpandingHelper.getDimension();
        //System.out.println( "Split Pair Panel:shrink (" + shrinkingCurSize + ") Expand (" +
        //                    expandingCurSize + ") SizesBy: " + pDelta );
        int shrinkingNewSize = shrinkingCurSize - pDelta;
        pShrinkingHelper.setDimension( shrinkingNewSize );
        if ( pShrinkingHelper.getDimension() != shrinkingNewSize ) {
            return false;
        }
        int expandingNewSize = expandingCurSize + pDelta;
        pExpandingHelper.setDimension( expandingNewSize );
        return true;
    }
}