/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You 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 org.apache.poi.poifs.storage;

import java.io.IOException;

import org.apache.poi.poifs.common.POIFSBigBlockSize;
import org.apache.poi.poifs.property.RootProperty;

/**
 * This class implements reading the small document block list from an
 * existing file
 *
 * @author Marc Johnson (mjohnson at apache dot org)
 */
public final class SmallBlockTableReader {

    /**
     * fetch the small document block list from an existing file
     *
     * @param blockList the raw data from which the small block table
     *                  will be extracted
     * @param root the root property (which contains the start block
     *             and small block table size)
     * @param sbatStart the start block of the SBAT
     *
     * @return the small document block list
     *
     * @exception IOException
     */
    public static BlockList getSmallDocumentBlocks(
            final POIFSBigBlockSize bigBlockSize,
            final RawDataBlockList blockList, final RootProperty root,
            final int sbatStart)
        throws IOException
    {
       // Fetch the blocks which hold the Small Blocks stream
       ListManagedBlock [] smallBlockBlocks = 
          blockList.fetchBlocks(root.getStartBlock(), -1);
        
       // Turn that into a list
       BlockList list =new SmallDocumentBlockList(
             SmallDocumentBlock.extract(bigBlockSize, smallBlockBlocks));

       // Process
        new BlockAllocationTableReader(bigBlockSize,
                                       blockList.fetchBlocks(sbatStart, -1),
                                       list);
        return list;
    }
}
