/*
 * Copyright 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.gen2.table.client;

import java.util.*;

import com.google.gwt.gen2.table.client.TableModelHelper.*;

/**
 * A {@link ClientTableModel} that uses a 2D {@link List} of Objects as its
 * source of data.
 */
public class ListTableModel extends MutableTableModel<List<Object>>
{
    /**
     * An {@link Iterator} over the requested rows.
     */
    private class RowIterator implements Iterator<List<Object>>
    {
        private int curRow;
        private int lastRow;

        public RowIterator( Request request )
        {
            curRow = request.getStartRow() - 1;
            lastRow = Math.min( rowValues.size() - 1, curRow + request.getNumRows() );
        }

        public boolean hasNext()
        {
            return curRow < lastRow;
        }

        public List<Object> next()
        {
            if ( !hasNext() )
            {
                throw new NoSuchElementException();
            }

            curRow++;
            return rowValues.get( new Integer( curRow ) );
        }

        public void remove()
        {
            throw new UnsupportedOperationException();
        }
    }

    /**
     * The values associated with each cell.
     */
    private List<List<Object>> rowValues;

    /**
     * Construct a new {@link ListTableModel}.
     *
     * @param rows the data that this model feeds from
     */
    public ListTableModel( List<List<Object>> rows )
    {
        this.rowValues = rows;
        setRowCount( rows.size() );
    }

    @Override
    public void requestRows( Request request, Callback<List<Object>> callback )
    {
        final RowIterator it = new RowIterator( request );
        Response<List<Object>> response = new Response<List<Object>>()
        {
            @Override
            public Iterator<List<Object>> getRowValues()
            {
                return it;
            }
        };
        callback.onRowsReady( request, response );
    }

    @Override
    protected boolean onRowInserted( int beforeRow )
    {
        if ( beforeRow < rowValues.size() )
        {
            rowValues.add( beforeRow, null );
        }
        return true;
    }

    @Override
    protected boolean onRowRemoved( int row )
    {
        if ( row < rowValues.size() )
        {
            rowValues.remove( row );
        }
        return true;
    }

    @Override
    protected boolean onSetRowValue( int row, List<Object> rowValue )
    {
        // Expand to fit row
        for ( int i = rowValues.size(); i <= row; i++ )
        {
            rowValues.add( null );
        }

        // Set the new row value
        rowValues.set( row, rowValue );
        return true;
    }

    /**
     * Get the value at a given cell. This is used for testing.
     *
     * @param rowIndex  the index of the row
     * @param cellIndex the index of the cell
     *
     * @return the cell value, or null if it does not exist
     */
    Object getCellValue( int rowIndex, int cellIndex )
    {
        // Row does not exist
        if ( rowIndex >= rowValues.size() )
        {
            return null;
        }

        // Get the cell value from the row
        List<Object> rowList = rowValues.get( rowIndex );
        if ( rowList != null && rowList.size() > cellIndex )
        {
            return rowList.get( cellIndex );
        }
        return null;
    }
}