/*
 * 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.lucene.analysis.icu;

import com.ibm.icu.text.FilteredNormalizer2;
import com.ibm.icu.text.Normalizer2;
import com.ibm.icu.text.UnicodeSet;
import java.util.Arrays;
import java.util.Map;
import org.apache.lucene.analysis.TokenFilterFactory;
import org.apache.lucene.analysis.TokenStream;

/**
 * Factory for {@link ICUNormalizer2Filter}
 *
 * <p>Supports the following attributes:
 *
 * <ul>
 *   <li>form: A <a href="http://unicode.org/reports/tr15/">Unicode Normalization Form</a>, one of
 *       'nfc','nfkc', 'nfkc_cf', 'nfkc_scf'. Default is nfkc_cf.
 *   <li>mode: Either 'compose' or 'decompose'. Default is compose. Use "decompose" with nfc or
 *       nfkc, to get nfd or nfkd, respectively.
 *   <li>filter: A {@link UnicodeSet} pattern. Codepoints outside the set are always left unchanged.
 *       Default is [] (the null set, no filtering).
 * </ul>
 *
 * @see ICUNormalizer2Filter
 * @see Normalizer2
 * @see FilteredNormalizer2
 * @since 3.1.0
 * @lucene.spi {@value #NAME}
 */
public class ICUNormalizer2FilterFactory extends TokenFilterFactory {

  /** SPI name */
  public static final String NAME = "icuNormalizer2";

  private final Normalizer2 normalizer;

  /** Creates a new ICUNormalizer2FilterFactory */
  public ICUNormalizer2FilterFactory(Map<String, String> args) {
    super(args);
    String form = get(args, "form", "nfkc_cf");
    String mode = get(args, "mode", Arrays.asList("compose", "decompose"), "compose");
    Normalizer2 normalizer =
        Normalizer2.getInstance(
            null,
            form,
            "compose".equals(mode) ? Normalizer2.Mode.COMPOSE : Normalizer2.Mode.DECOMPOSE);

    String filter = get(args, "filter");
    if (filter != null) {
      UnicodeSet set = new UnicodeSet(filter);
      if (!set.isEmpty()) {
        set.freeze();
        normalizer = new FilteredNormalizer2(normalizer, set);
      }
    }
    if (!args.isEmpty()) {
      throw new IllegalArgumentException("Unknown parameters: " + args);
    }
    this.normalizer = normalizer;
  }

  /** Default ctor for compatibility with SPI */
  public ICUNormalizer2FilterFactory() {
    throw defaultCtorException();
  }

  // TODO: support custom normalization

  @Override
  public TokenStream create(TokenStream input) {
    return new ICUNormalizer2Filter(input, normalizer);
  }

  @Override
  public TokenStream normalize(TokenStream input) {
    return create(input);
  }
}
