/*
 * Copyright 2008 Fedora Commons, 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 org.mulgara.store.stringpool.xa11;

import java.io.IOException;

import org.apache.log4j.Logger;
import org.mulgara.util.IntFile;
import org.mulgara.util.LongMapper;

/**
 * Manages node-to-node mapping, including our blank nodes that need to be mapped to other nodes.
 *
 * @created Sep 26, 2008
 * @author Paula Gearon
 * @copyright © 2008 <a href="http://www.fedora-commons.org/">Fedora Commons</a>
 */
public class BlankNodeMapper implements LongMapper {

  private static final Logger logger = Logger.getLogger(BlankNodeMapper.class);
  
  /** Maps normal node values to other node values. */
  private IntFile nodeMap;

  /** Maps blank node values to other node values. */
  private IntFile blankNodeMap;

  public BlankNodeMapper(String baseName) throws IOException {
    nodeMap = IntFile.newTempIntFile(baseName);
    blankNodeMap = IntFile.newTempIntFile(baseName + "_b");
  }

  /**
   * @see org.mulgara.util.LongMapper#delete()
   */
  public void delete() throws IOException {
    boolean success = false;
    try {
      nodeMap.delete();
      success = true;
    } finally {
      try {
        blankNodeMap.delete();
      } catch (IOException e) {
        if (success) { // nodeMap was successfully deleted, this is a new exception so re-throw it.
          throw e;
        } else { // nodeMap failed also, so suppress this exception and allow the original one to be thrown.
          logger.info("I/O exception on failed delete", e);
        }
      }
    }
  }

  /**
   * @see org.mulgara.util.LongMapper#getLong(long)
   */
  public long getLong(long key) throws Exception {
    if (BlankNodeAllocator.isBlank(key)) {
      return blankNodeMap.getLong(BlankNodeAllocator.nodeToCounter(key));
    } else {
      return nodeMap.getLong(key);
    }
  }

  /**
   * @see org.mulgara.util.LongMapper#putLong(long, long)
   */
  public void putLong(long key, long value) throws Exception {
    if (BlankNodeAllocator.isBlank(key)) {
      blankNodeMap.putLong(BlankNodeAllocator.nodeToCounter(key), value);
    } else {
      nodeMap.putLong(key, value);
    }
  }

}