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/*
 * 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 opennlp.tools.namefind;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import opennlp.tools.util.SequenceCodec;
import opennlp.tools.util.SequenceValidator;
import opennlp.tools.util.Span;

public class BilouCodec implements SequenceCodec {

  public static final String START = "start";
  public static final String CONTINUE = "cont";
  public static final String LAST = "last";
  public static final String UNIT = "unit";
  public static final String OTHER = "other";

  @Override
  public Span[] decode(List c) {
    int start = -1;
    int end = -1;
    List spans = new ArrayList<>(c.size());
    for (int li = 0; li < c.size(); li++) {
      String chunkTag = c.get(li);
      if (chunkTag.endsWith(BioCodec.START)) {
        start = li;
        end = li + 1;
      }
      else if (chunkTag.endsWith(BioCodec.CONTINUE)) {
        end = li + 1;
      }
      else if (chunkTag.endsWith(LAST)) {
        if (start != -1) {
          spans.add(new Span(start, end + 1, BioCodec.extractNameType(c.get(li - 1))));
          start = -1;
          end = -1;
        }
      }
      else if (chunkTag.endsWith(UNIT)) {
        spans.add(new Span(li, li + 1, BioCodec.extractNameType(c.get(li))));
      }
    }

    return spans.toArray(new Span[spans.size()]);
  }

  @Override
  public String[] encode(Span[] names, int length) {
    String[] outcomes = new String[length];
    Arrays.fill(outcomes, BioCodec.OTHER);

    for (Span name : names) {

      if (name.length() > 1) {
        if (name.getType() == null) {
          outcomes[name.getStart()] = "default" + "-" + BioCodec.START;
        }
        else {
          outcomes[name.getStart()] = name.getType() + "-" + BioCodec.START;
        }
        // now iterate from begin + 1 till end
        for (int i = name.getStart() + 1; i < name.getEnd() - 1; i++) {
          if (name.getType() == null) {
            outcomes[i] = "default" + "-" + BioCodec.CONTINUE;
          }
          else {
            outcomes[i] = name.getType() + "-" + BioCodec.CONTINUE;
          }
        }

        if (name.getType() == null) {
          outcomes[name.getEnd() - 1] = "default" + "-" + BilouCodec.LAST;
        }
        else {
          outcomes[name.getEnd() - 1] = name.getType() + "-" + BilouCodec.LAST;
        }
      }
      else {
        if (name.getType() == null) {
          outcomes[name.getEnd() - 1] = "default" + "-" + BilouCodec.UNIT;
        }
        else {
          outcomes[name.getEnd() - 1] = name.getType() + "-" + BilouCodec.UNIT;
        }
      }
    }

    return outcomes;
  }

  @Override
  public SequenceValidator createSequenceValidator() {
    return new BilouNameFinderSequenceValidator();
  }

  @Override
  public boolean areOutcomesCompatible(String[] outcomes) {
    return true;
  }
}