package org.apache.lucene.analysis.de;

/**
 * Copyright 2004 The Apache Software Foundation
 *
 * 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.
 */

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.LineNumberReader;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;

/**
 * Loader for text files that represent a list of stopwords.
 *
 * @author Gerhard Schwarz
 * @version $Id: WordlistLoader.java,v 1.10 2004/03/30 15:54:48 otis Exp $
 *
 * @todo this is not specific to German, it should be moved up
 */
public class WordlistLoader {

  /**
   * Loads a text file and adds every line as an entry to a HashSet (omitting
   * leading and trailing whitespace). Every line of the file should contain only 
   * one word. The words need to be in lowercase if you make use of an
   * Analyzer which uses LowerCaseFilter (like GermanAnalyzer).
   * 
   * @param wordfile File containing the wordlist
   * @return A HashSet with the file's words
   */
  public static HashSet getWordSet(File wordfile) throws IOException {
    HashSet result = new HashSet();
    FileReader freader = null;
    LineNumberReader lnr = null;
    try {
      freader = new FileReader(wordfile);
      lnr = new LineNumberReader(freader);
      String word = null;
      while ((word = lnr.readLine()) != null) {
        result.add(word.trim());
      }
    }
    finally {
      if (lnr != null)
        lnr.close();
      if (freader != null)
        freader.close();
    }
    return result;
  }

  /**
   * @param path      Path to the wordlist
   * @param wordfile  Name of the wordlist
   * 
   * @deprecated Use {@link #getWordSet(File)} getWordSet(File)} instead
   */
  public static Hashtable getWordtable(String path, String wordfile) throws IOException {
    return getWordtable(new File(path, wordfile));
  }

  /**
   * @param wordfile  Complete path to the wordlist
   * 
   * @deprecated Use {@link #getWordSet(File)} getWordSet(File)} instead
   */
  public static Hashtable getWordtable(String wordfile) throws IOException {
    return getWordtable(new File(wordfile));
  }

  /**
   * @param wordfile  File object that points to the wordlist
   *
   * @deprecated Use {@link #getWordSet(File)} getWordSet(File)} instead
   */
  public static Hashtable getWordtable(File wordfile) throws IOException {
    HashSet wordSet = (HashSet)getWordSet(wordfile);
    Hashtable result = makeWordTable(wordSet);
    return result;
  }

  /**
   * Builds a wordlist table, using words as both keys and values
   * for backward compatibility.
   *
   * @param wordSet   stopword set
   */
  private static Hashtable makeWordTable(HashSet wordSet) {
    Hashtable table = new Hashtable();
    for (Iterator iter = wordSet.iterator(); iter.hasNext();) {
      String word = (String)iter.next();
      table.put(word, word);
    }
    return table;
  }
}