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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 org.apache.solr.handler.component;

import java.io.IOException;
import java.lang.reflect.Array;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.apache.lucene.search.Query;
import org.apache.solr.common.SolrException;
import org.apache.solr.common.params.HighlightParams;
import org.apache.solr.common.params.SolrParams;
import org.apache.solr.common.util.NamedList;
import org.apache.solr.common.util.SimpleOrderedMap;
import org.apache.solr.core.PluginInfo;
import org.apache.solr.core.SolrCore;
import org.apache.solr.highlight.DefaultSolrHighlighter;
import org.apache.solr.highlight.SolrHighlighter;
import org.apache.solr.highlight.UnifiedSolrHighlighter;
import org.apache.solr.request.SolrQueryRequest;
import org.apache.solr.search.QParser;
import org.apache.solr.search.QParserPlugin;
import org.apache.solr.search.QueryLimits;
import org.apache.solr.search.QueryParsing;
import org.apache.solr.search.SyntaxError;
import org.apache.solr.util.SolrPluginUtils;
import org.apache.solr.util.SolrResponseUtil;
import org.apache.solr.util.plugin.PluginInfoInitialized;
import org.apache.solr.util.plugin.SolrCoreAware;

/**
 * Highlights query words in the search results. See the ref guide.
 *
 * @since solr 1.3
 */
public class HighlightComponent extends SearchComponent
    implements PluginInfoInitialized, SolrCoreAware {
  public enum HighlightMethod {
    UNIFIED("unified"),
    FAST_VECTOR("fastVector"),
    ORIGINAL("original");

    private static final Map METHODS =
        Stream.of(values())
            .collect(
                Collectors.toUnmodifiableMap(HighlightMethod::getMethodName, Function.identity()));

    private final String methodName;

    HighlightMethod(String method) {
      this.methodName = method;
    }

    public String getMethodName() {
      return methodName;
    }

    public static HighlightMethod parse(String method) {
      return METHODS.get(method);
    }
  }

  public static final String COMPONENT_NAME = "highlight";

  protected PluginInfo info = PluginInfo.EMPTY_INFO;

  // TODO lets restructure the abstractions/relationships
  protected SolrHighlighter solrConfigHighlighter;

  @Override
  public void init(PluginInfo info) {
    this.info = info;
  }

  @Override
  public void prepare(ResponseBuilder rb) throws IOException {
    SolrParams params = rb.req.getParams();
    rb.doHighlights = solrConfigHighlighter.isHighlightingEnabled(params);
    if (rb.doHighlights) {
      rb.setNeedDocList(true);
      String hlq = params.get(HighlightParams.Q);
      String hlparser =
          Objects.requireNonNullElse(
              params.get(HighlightParams.QPARSER),
              params.get(QueryParsing.DEFTYPE, QParserPlugin.DEFAULT_QTYPE));
      if (hlq != null) {
        try {
          QParser parser = QParser.getParser(hlq, hlparser, rb.req);
          rb.setHighlightQuery(parser.getHighlightQuery());
        } catch (SyntaxError e) {
          throw new SolrException(SolrException.ErrorCode.BAD_REQUEST, e);
        }
      }
    }
  }

  @Override
  public void inform(SolrCore core) {
    List children = info.getChildren("highlighting");
    if (children.isEmpty()) {
      DefaultSolrHighlighter defHighlighter = new DefaultSolrHighlighter(core);
      defHighlighter.init(PluginInfo.EMPTY_INFO);
      solrConfigHighlighter = defHighlighter;
    } else {
      solrConfigHighlighter =
          core.createInitInstance(
              children.get(0), SolrHighlighter.class, null, DefaultSolrHighlighter.class.getName());
    }
  }

  @Override
  public void process(ResponseBuilder rb) throws IOException {

    if (rb.doHighlights) {
      SolrQueryRequest req = rb.req;
      SolrParams params = req.getParams();

      SolrHighlighter highlighter = getHighlighter(params);

      // TODO: get from builder by default?
      String[] defaultHighlightFields =
          rb.getQparser() != null ? rb.getQparser().getDefaultHighlightFields() : null;

      Query highlightQuery = rb.getHighlightQuery();
      if (highlightQuery == null) {
        if (rb.getQparser() != null) {
          try {
            highlightQuery = rb.getQparser().getHighlightQuery();
            rb.setHighlightQuery(highlightQuery);
          } catch (Exception e) {
            throw new SolrException(SolrException.ErrorCode.BAD_REQUEST, e);
          }
        } else {
          highlightQuery = rb.getQuery();
          rb.setHighlightQuery(highlightQuery);
        }
      }

      // No highlighting if there is no query -- consider q.alt=*:*
      if (highlightQuery != null) {
        NamedList