content: /**
   * 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.solr.spelling.suggest;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.UnsupportedEncodingException;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  
  import org.apache.lucene.analysis.Token;
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.search.spell.Dictionary;
  import org.apache.lucene.search.spell.HighFrequencyDictionary;
  import org.apache.lucene.search.suggest.FileDictionary;
  import org.apache.lucene.search.suggest.Lookup;
  import org.apache.lucene.search.suggest.Lookup.LookupResult;
  
  import org.apache.solr.common.util.NamedList;
  import org.apache.solr.core.SolrCore;
  import org.apache.solr.search.SolrIndexSearcher;
  import org.apache.solr.spelling.SolrSpellChecker;
  import org.apache.solr.spelling.SpellingOptions;
  import org.apache.solr.spelling.SpellingResult;
  import org.apache.solr.spelling.suggest.fst.FSTLookupFactory;
  import org.apache.solr.spelling.suggest.jaspell.JaspellLookupFactory;
  import org.apache.solr.spelling.suggest.tst.TSTLookupFactory;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class Suggester extends SolrSpellChecker {
    private static final Logger LOG = LoggerFactory.getLogger(Suggester.class);
    
    /** Location of the source data - either a path to a file, or null for the
     * current IndexReader.
     */
    public static final String LOCATION = "sourceLocation";
    /** Fully-qualified class of the {@link Lookup} implementation. */
    public static final String LOOKUP_IMPL = "lookupImpl";
    /**
     * Minimum frequency of terms to consider when building the dictionary.
     */
    public static final String THRESHOLD_TOKEN_FREQUENCY = "threshold";
    /**
     * Name of the location where to persist the dictionary. If this location
     * is relative then the data will be stored under the core's dataDir. If this
     * is null the storing will be disabled.
     */
    public static final String STORE_DIR = "storeDir";
    
    protected String sourceLocation;
    protected File storeDir;
    protected float threshold;
    protected Dictionary dictionary;
    protected IndexReader reader;
    protected Lookup lookup;
    protected String lookupImpl;
    protected SolrCore core;
    
    @Override
    public String init(NamedList config, SolrCore core) {
      LOG.info("init: " + config);
      String name = super.init(config, core);
      threshold = config.get(THRESHOLD_TOKEN_FREQUENCY) == null ? 0.0f
              : (Float)config.get(THRESHOLD_TOKEN_FREQUENCY);
      sourceLocation = (String) config.get(LOCATION);
      lookupImpl = (String)config.get(LOOKUP_IMPL);
  
      // support the old classnames without -Factory for config file backwards compatibility.
      if (lookupImpl == null || "org.apache.solr.spelling.suggest.jaspell.JaspellLookup".equals(lookupImpl)) {
        lookupImpl = JaspellLookupFactory.class.getName();
      } else if ("org.apache.solr.spelling.suggest.tst.TSTLookup".equals(lookupImpl)) {
        lookupImpl = TSTLookupFactory.class.getName();
      } else if ("org.apache.solr.spelling.suggest.fst.FSTLookup".equals(lookupImpl)) {
        lookupImpl = FSTLookupFactory.class.getName();
      }
  
      LookupFactory factory = (LookupFactory) core.getResourceLoader().newInstance(lookupImpl);
      lookup = factory.create(config, core);
      String store = (String)config.get(STORE_DIR);
      if (store != null) {
        storeDir = new File(store);
        if (!storeDir.isAbsolute()) {
          storeDir = new File(core.getDataDir() + File.separator + storeDir);
        }
        if (!storeDir.exists()) {
          storeDir.mkdirs();
        } else {
          // attempt reload of the stored lookup
          try {
            lookup.load(storeDir);
          } catch (IOException e) {
            LOG.warn("Loading stored lookup data failed", e);
          }
        }
      }
      return name;
    }
    
    @Override
    public void build(SolrCore core, SolrIndexSearcher searcher) {
      LOG.info("build()");
      if (sourceLocation == null) {
        reader = searcher.getIndexReader();
        dictionary = new HighFrequencyDictionary(reader, field, threshold);
      } else {
        try {
          dictionary = new FileDictionary(new InputStreamReader(
                  core.getResourceLoader().openResource(sourceLocation), "UTF-8"));
        } catch (UnsupportedEncodingException e) {
          // should not happen
          LOG.error("should not happen", e);
        }
      }
      try {
        lookup.build(dictionary);
        if (storeDir != null) {
          lookup.store(storeDir);
        }
      } catch (Exception e) {
        LOG.error("Error while building or storing Suggester data", e);
      }
    }
  
    @Override
    public void reload(SolrCore core, SolrIndexSearcher searcher) throws IOException {
      LOG.info("reload()");
      if (dictionary == null && storeDir != null) {
        // this may be a firstSearcher event, try loading it
        if (lookup.load(storeDir)) {
          return;  // loaded ok
        }
        LOG.debug("load failed, need to build Lookup again");
      }
      // loading was unsuccessful - build it again
      build(core, searcher);
    }
  
    public void add(String query, int numHits) {
      LOG.info("add " + query + ", " + numHits);
      lookup.add(query, new Integer(numHits));
    }
    
    static SpellingResult EMPTY_RESULT = new SpellingResult();
  
    @Override
    public SpellingResult getSuggestions(Collection<Token> tokens, IndexReader reader, int count, boolean onlyMorePopular, boolean extendedResults) throws IOException {
      return getSuggestions(new SpellingOptions(tokens, reader, count, onlyMorePopular, extendedResults, Float.MIN_VALUE, null));
    }
  
    @Override
    public SpellingResult getSuggestions(SpellingOptions options) throws IOException {
      LOG.debug("getSuggestions: " + options.tokens);
      if (lookup == null) {
        LOG.info("Lookup is null - invoke spellchecker.build first");
        return EMPTY_RESULT;
      }
      SpellingResult res = new SpellingResult();
      for (Token t : options.tokens) {
        String term = new String(t.buffer(), 0, t.length());
        List<LookupResult> suggestions = lookup.lookup(term,
            options.onlyMorePopular, options.count);
        if (suggestions == null) {
          continue;
        }
        if (!options.onlyMorePopular) {
          Collections.sort(suggestions);
        }
        for (LookupResult lr : suggestions) {
          res.add(t, lr.key, ((Number)lr.value).intValue());
        }
      }
      return res;
    }
  }
  