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

import java.util.*;

class DetailRowModelImpl<RowType> implements DetailRowModel<RowType>
{
    private DetailRowAlignment mAlign = DetailRowAlignment.Top;
    private int mIndex = -1;
    private RowType mItem = null;
    private DetailRowCallback<RowType> mCallback = null;

    public DetailRowCallback<RowType> getCallback()
    {
        return mCallback;
    }

    public void setCallback( DetailRowCallback<RowType> pCallback )
    {
        mCallback = pCallback;
    }

    @Override
    public int getDetailRow()
    {
        return mIndex;
    }

    public RowType getDetailItem()
    {
        return mItem;
    }

    @Override
    public DetailRowAlignment getAlign()
    {
        return mAlign;
    }

    @Override
    public boolean isDetailRow( int pIndex )
    {
        return mIndex == pIndex;
    }

    public boolean isDetailRow( RowType pItem )
    {
        return mItem == pItem;
    }

    private boolean canShowDetailFor( int index, RowType pItem )
    {
        return (mCallback == null) || mCallback.canShowDetailFor( index, pItem );
    }

    /**
     * @return true if changed
     */
    public boolean maybeSetDetailRow( int pIndex, RowType pItem )
    {
        if ( mIndex != pIndex && canShowDetailFor( pIndex, pItem ) )
        {
            setDetailRow( pIndex, pItem );
            return true;
        }
        return false;
    }

    private void setDetailRow( int pIndex, RowType pItem )
    {
        assert pIndex >= 0;
        assert pItem != null;
        if ( mIndex != pIndex && canShowDetailFor( pIndex, pItem ) )
        {
            int oldIndex = mIndex;
            mIndex = pIndex;
            mItem = pItem;
            mAlign = (oldIndex == -1 || pIndex < oldIndex) ? DetailRowAlignment.Top : DetailRowAlignment.Bottom;
        }
    }

    private void clearDetailRow()
    {
        mIndex = -1;
        mItem = null;
    }

    /**
     * @return true if changed
     */
    public boolean update( List<RowType> pRowValues, int pOffset, int pCount )
    {
        assert pOffset + pCount <= pRowValues.size() : "size=" + pRowValues.size() + ",offset=" + pOffset + ",count=" + pCount;

        if ( mIndex >= 0 && mIndex < pCount && canShowDetailFor( mIndex, mItem ) )
        {
            return false;
        }

        int candidateIndex = mIndex;
        if ( candidateIndex > pCount )
        {
            candidateIndex = pCount;
        }
        for ( int i = candidateIndex + 1; i < pCount; i++ )
        {
            RowType candidate = pRowValues.get( i + pOffset );
            if ( canShowDetailFor( i, candidate ) )
            {
                setDetailRow( i, candidate );
                return true;
            }
        }
        for ( int i = candidateIndex - 1; i >= 0; i-- )
        {
            RowType candidate = pRowValues.get( i + pOffset );
            if ( canShowDetailFor( i, candidate ) )
            {
                setDetailRow( i, candidate );
                return true;
            }
        }
        if ( mIndex != -1 )
        {
            clearDetailRow();
            return true;
        }
        else
        {
            return false;
        }
    }
}