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;
    }
    
    public int getDetailRow()
    {
        return mIndex;
    }
    
    public RowType getDetailItem()
    {
        return mItem;
    }
    
    public DetailRowAlignment getAlign()
    {
        return mAlign;
    }
    
    public boolean isDetailRow(int pIndex)
    {
        return mIndex == pIndex;
    }
    
    public boolean isDetailRow(RowType pItem)
    {
        return mItem == pItem;
    }
    
    private boolean canShowDetailFor(int index, RowType pItem)
    {
        if (mCallback != null)
        {
            return mCallback.canShowDetailFor(index, pItem);
        }
        return true;
    }
    
    /**
     * @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;
        }
    }
}