/**
 * Copyright 2014 National University of Ireland, Galway.
 *
 * This file is part of the SIREn project. Project and contact information:
 *
 *  https://github.com/rdelbru/SIREn
 *
 * 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.sindice.siren.analysis;

import java.io.Reader;
import java.util.Map.Entry;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.util.CharArrayMap;
import org.apache.lucene.util.Version;
import org.sindice.siren.analysis.filter.DatatypeAnalyzerFilter;
import org.sindice.siren.analysis.filter.PositionAttributeFilter;
import org.sindice.siren.analysis.filter.SirenPayloadFilter;
import org.sindice.siren.util.JSONDatatype;
import org.sindice.siren.util.XSDDatatype;

/**
 * The JsonAnalyzer is especially designed to process JSON data.
 */
public class JsonAnalyzer extends Analyzer {

  private Analyzer                     valueAnalyzer;
  private Analyzer                     fieldAnalyzer;

  private final Version                matchVersion;

  private final CharArrayMap<Analyzer> regAnalyzers;

  /**
   * Create a {@link JsonAnalyzer} with the specified {@link Analyzer}s for
   * field names and values.
   * <p>
   * The default analyzer for field names will be associated with the datatype
   * {@link JSONDatatype#JSON_FIELD}. The default analyzer for values will be
   * associated with the datatype {@link XSDDatatype#XSD_STRING}.
   *
   * @param fieldAnalyzer Default {@link Analyzer} for the field names
   * @param valueAnalyzer Default {@link Analyzer} for the values
   */
  public JsonAnalyzer(final Version version, final Analyzer fieldAnalyzer,
                      final Analyzer valueAnalyzer) {
    matchVersion = version;
    this.valueAnalyzer = valueAnalyzer;
    this.fieldAnalyzer = fieldAnalyzer;
    regAnalyzers = new CharArrayMap<Analyzer>(version, 64, false);

  }

  public void setValueAnalyzer(final Analyzer analyzer) {
    valueAnalyzer = analyzer;
  }

  public void setFieldAnalyzer(final Analyzer analyzer) {
    fieldAnalyzer = analyzer;
  }

  /**
   * Assign an {@link Analyzer} to be used with that key. That analyzer is used
   * to process tokens generated by the {@link JsonTokenizer}.
   *
   * @param datatype The datatype key
   * @param a the associated {@link Analyzer}
   */
  public void registerDatatype(final char[] datatype, final Analyzer a) {
    if (!regAnalyzers.containsKey(datatype)) {
      regAnalyzers.put(datatype, a);
    }
  }

  /**
   * Remove all registered Datatype {@link Analyzer}s.
   */
  public void clearDatatypes() {
    regAnalyzers.clear();
  }

  @Override
  protected TokenStreamComponents createComponents(final String fieldName, final Reader reader) {
    final JsonTokenizer source = new JsonTokenizer(reader);

    final DatatypeAnalyzerFilter tt = new DatatypeAnalyzerFilter(matchVersion, source, fieldAnalyzer, valueAnalyzer);
    for (final Entry<Object, Analyzer> e : regAnalyzers.entrySet()) {
      tt.register((char[]) e.getKey(), e.getValue());
    }
    TokenStream sink = new PositionAttributeFilter(tt);
    sink = new SirenPayloadFilter(sink);
    return new TokenStreamComponents(source, sink);
  }

}