/*
    * ====================================================================
    * 
    * The Apache Software License, Version 1.1
    *
    * Copyright (c) 2003 Nick Lothian. All rights reserved.
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer. 
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowlegement:  
   *       "This product includes software developed by the 
   *        developers of Classifier4J (http://classifier4j.sf.net/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The name "Classifier4J" must not be used to endorse or promote 
   *    products derived from this software without prior written 
   *    permission. For written permission, please contact   
   *    http://sourceforge.net/users/nicklothian/.
   *
   * 5. Products derived from this software may not be called 
   *    "Classifier4J", nor may "Classifier4J" appear in their names 
   *    without prior written permission. For written permission, please 
   *    contact http://sourceforge.net/users/nicklothian/.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   */
  
  package net.sf.classifier4J.bayesian;
  
  import java.io.IOException;
  
  import jdbm.btree.BTree;
  import jdbm.helper.MRU;
  import jdbm.helper.ObjectCache;
  import jdbm.helper.StringComparator;
  import jdbm.recman.RecordManager;
  import net.sf.classifier4J.ICategorisedClassifier;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  public class JDBMWordsDataSource implements ICategorisedWordsDataSource {
  	Log log = LogFactory.getLog(this.getClass());
  
  	RecordManager recordManager = null;
  	BTree tree = null;
  
  	String dir = ".";
  	static String databaseName = "wordprobs";
  	static String tableName = "wordprobabilities";
  
  	public JDBMWordsDataSource() {
  	}
  
  	public JDBMWordsDataSource(String directory) {
  		this.dir = directory;
  	}
  
  	public void close() {
  		if (recordManager != null) {
  			try {
  				recordManager.commit();
  			} catch (IOException e) {
  				// do nothing				
  			}
  			try {
  				recordManager.close();
  			} catch (IOException e1) {
  				// do nothing				
  			}
  		}
  	}
  
  	public void open() throws IOException {
  		recordManager = new RecordManager(dir + "/" + databaseName);
 		ObjectCache cache = new ObjectCache(recordManager, new MRU(100));
 
 		long recid = recordManager.getNamedObject(tableName);
 		if (recid != 0) {
 			// already exists
 			tree = BTree.load(recordManager, cache, recid);
 		} else {
 			// does not exist
 			tree = new BTree(recordManager, cache, new StringComparator());
 			recordManager.setNamedObject(tableName, tree.getRecid());
 		}
 	}
 
 	/***
 	 * @see net.sf.classifier4J.bayesian.IWordsDataSource#addMatch(java.lang.String)
 	 */
 	public void addMatch(String word) {
 		addMatch(ICategorisedClassifier.DEFAULT_CATEGORY, word);
 	}
 
 	/***
 	 * @see net.sf.classifier4J.bayesian.IWordsDataSource#addNonMatch(java.lang.String)
 	 */
 	public void addNonMatch(String word) {
 		addNonMatch(ICategorisedClassifier.DEFAULT_CATEGORY, word);
 	}
 
 	/***
 	 * @see net.sf.classifier4J.bayesian.ICategorisedWordsDataSource#addMatch(java.lang.String, java.lang.String)
 	 */
 	public void addMatch(String category, String word) {
 		try {
 			WordProbability wp = getWordProbability(category, word);
 			if (wp == null) {
 				wp = new WordProbability(word, 1, 0);
 			} else {
 				wp.setMatchingCount(wp.getMatchingCount() + 1);
 			}
 			tree.insert(getKey(category, word), wp, true);
 		} catch (IOException e) {
 			log.error("Error with JDBM datasource", e);
 			throw new RuntimeException("Error with JDBM datasource");
 		}
 
 	}
 
 	/***
 	 * @see net.sf.classifier4J.bayesian.ICategorisedWordsDataSource#addNonMatch(java.lang.String, java.lang.String)
 	 */
 	public void addNonMatch(String category, String word) {
 		try {
 			WordProbability wp = getWordProbability(category, word);
 			if (wp == null) {
 				wp = new WordProbability(word, 0, 1);
 			} else {
 				wp.setNonMatchingCount(wp.getNonMatchingCount() + 1);
 			}
 			tree.insert(getKey(category, word), wp, true);
 		} catch (IOException e) {
 			log.error("Error with JDBM datasource", e);
 			throw new RuntimeException("Error with JDBM datasource");
 		}
 	}
 
 	/***
 	 * @see net.sf.classifier4J.bayesian.IWordsDataSource#getWordProbability(java.lang.String)
 	 */
 	public WordProbability getWordProbability(String word) {
 		return getWordProbability(ICategorisedClassifier.DEFAULT_CATEGORY, word);
 	}
 
 	/***
 	 * @see net.sf.classifier4J.bayesian.ICategorisedWordsDataSource#getWordProbability(java.lang.String, java.lang.String)
 	 */
 	public WordProbability getWordProbability(String category, String word) {
 		try {
 			return (WordProbability) tree.find(getKey(category,word));
 		} catch (IOException e) {
 			log.error("Error in JDBM datasource", e);
 			throw new RuntimeException("Error in JDBM datasource");
 		}
 	}
 
 	/***
 	 * 
 	 * @param category The category, or null for the default
 	 * @param word The word, cannot be null
 	 * @return the key for the category and word. By default this is "category : word"
 	 * @throws IllegalArgumentException if word is null
 	 */
 	protected String getKey(String category, String word) throws IllegalArgumentException {
 		if (word == null) {
 			throw new IllegalArgumentException("Word cannot be null");
 		}
 		StringBuffer result = new StringBuffer("");
 		if (category == null) {
 			result.append(ICategorisedClassifier.DEFAULT_CATEGORY);
 		} else {
 			result.append(category);
 		}
 		result.append(" : "); // space:space
 		result.append(word);
 
 		return result.toString();
 	}
 
     protected void finalize() throws Throwable {
         close();
     }
 
 
 }