/*
 * 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.queryparser.flexible.standard.processors;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.CachingTokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.queryparser.flexible.core.QueryNodeException;
import org.apache.lucene.queryparser.flexible.core.config.QueryConfigHandler;
import org.apache.lucene.queryparser.flexible.core.nodes.BooleanQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.FieldQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.FuzzyQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.GroupQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.ModifierQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.ModifierQueryNode.Modifier;
import org.apache.lucene.queryparser.flexible.core.nodes.NoTokenFoundQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.QueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.QuotedFieldQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.RangeQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.TokenizedPhraseQueryNode;
import org.apache.lucene.queryparser.flexible.core.processors.QueryNodeProcessorImpl;
import org.apache.lucene.queryparser.flexible.standard.config.StandardQueryConfigHandler.ConfigurationKeys;
import org.apache.lucene.queryparser.flexible.standard.config.StandardQueryConfigHandler.Operator;
import org.apache.lucene.queryparser.flexible.standard.nodes.MultiPhraseQueryNode;
import org.apache.lucene.queryparser.flexible.standard.nodes.SynonymQueryNode;
import org.apache.lucene.queryparser.flexible.standard.nodes.WildcardQueryNode;

/**
 * This processor verifies if {@link ConfigurationKeys#ANALYZER} is defined in the {@link
 * QueryConfigHandler}. If it is and the analyzer is not <code>null</code>, it looks for every
 * {@link FieldQueryNode} that is not {@link WildcardQueryNode}, {@link FuzzyQueryNode} or {@link
 * RangeQueryNode} contained in the query node tree, then it applies the analyzer to that {@link
 * FieldQueryNode} object. <br>
 * <br>
 * If the analyzer return only one term, the returned term is set to the {@link FieldQueryNode} and
 * it's returned. <br>
 * <br>
 * If the analyzer return more than one term, a {@link TokenizedPhraseQueryNode} or {@link
 * MultiPhraseQueryNode} is created, whether there is one or more terms at the same position, and
 * it's returned. <br>
 * <br>
 * If no term is returned by the analyzer a {@link NoTokenFoundQueryNode} object is returned.
 *
 * @see ConfigurationKeys#ANALYZER
 * @see Analyzer
 * @see TokenStream
 */
public class AnalyzerQueryNodeProcessor extends QueryNodeProcessorImpl {

  private Analyzer analyzer;

  private boolean positionIncrementsEnabled;

  private Operator defaultOperator;

  public AnalyzerQueryNodeProcessor() {
    // empty constructor
  }

  @Override
  public QueryNode process(QueryNode queryTree) throws QueryNodeException {
    Analyzer analyzer = getQueryConfigHandler().get(ConfigurationKeys.ANALYZER);

    if (analyzer != null) {
      this.analyzer = analyzer;
      this.positionIncrementsEnabled = false;
      Boolean positionIncrementsEnabled =
          getQueryConfigHandler().get(ConfigurationKeys.ENABLE_POSITION_INCREMENTS);
      Operator defaultOperator = getQueryConfigHandler().get(ConfigurationKeys.DEFAULT_OPERATOR);
      this.defaultOperator = defaultOperator != null ? defaultOperator : Operator.OR;

      if (positionIncrementsEnabled != null) {
        this.positionIncrementsEnabled = positionIncrementsEnabled;
      }

      if (this.analyzer != null) {
        return super.process(queryTree);
      }
    }

    return queryTree;
  }

  @Override
  protected QueryNode postProcessNode(QueryNode node) throws QueryNodeException {

    if (node instanceof FieldQueryNode
        && !(node instanceof WildcardQueryNode)
        && !(node instanceof FuzzyQueryNode)
        && !(node.getParent() instanceof RangeQueryNode)) {

      FieldQueryNode fieldNode = ((FieldQueryNode) node);
      String text = fieldNode.getTextAsString();
      String field = fieldNode.getFieldAsString();

      CachingTokenFilter buffer = null;
      PositionIncrementAttribute posIncrAtt = null;
      int numTokens = 0;
      int positionCount = 0;
      boolean severalTokensAtSamePosition = false;

      try {
        try (TokenStream source = this.analyzer.tokenStream(field, text)) {
          buffer = new CachingTokenFilter(source);
          buffer.reset();

          if (buffer.hasAttribute(PositionIncrementAttribute.class)) {
            posIncrAtt = buffer.getAttribute(PositionIncrementAttribute.class);
          }

          try {

            while (buffer.incrementToken()) {
              numTokens++;
              int positionIncrement = (posIncrAtt != null) ? posIncrAtt.getPositionIncrement() : 1;
              if (positionIncrement != 0) {
                positionCount += positionIncrement;

              } else {
                severalTokensAtSamePosition = true;
              }
            }

          } catch (
              @SuppressWarnings("unused")
              IOException e) {
            // ignore
          }

          // rewind the buffer stream
          buffer.reset(); // will never through on subsequent reset calls
        } catch (IOException e) {
          throw new RuntimeException(e);
        }

        if (!buffer.hasAttribute(CharTermAttribute.class)) {
          return new NoTokenFoundQueryNode();
        }

        CharTermAttribute termAtt = buffer.getAttribute(CharTermAttribute.class);

        if (numTokens == 0) {
          return new NoTokenFoundQueryNode();

        } else if (numTokens == 1) {
          String term = null;
          try {
            boolean hasNext;
            hasNext = buffer.incrementToken();
            assert hasNext == true;
            term = termAtt.toString();

          } catch (
              @SuppressWarnings("unused")
              IOException e) {
            // safe to ignore, because we know the number of tokens
          }

          fieldNode.setText(term);

          return fieldNode;

        } else if (severalTokensAtSamePosition || !(node instanceof QuotedFieldQueryNode)) {
          if (positionCount == 1 || !(node instanceof QuotedFieldQueryNode)) {
            // no phrase query:

            if (positionCount == 1) {
              // simple case: only one position, with synonyms
              LinkedList<QueryNode> children = new LinkedList<>();

              for (int i = 0; i < numTokens; i++) {
                String term = null;
                try {
                  boolean hasNext = buffer.incrementToken();
                  assert hasNext == true;
                  term = termAtt.toString();

                } catch (
                    @SuppressWarnings("unused")
                    IOException e) {
                  // safe to ignore, because we know the number of tokens
                }

                children.add(new FieldQueryNode(field, term, -1, -1));
              }
              return new GroupQueryNode(new SynonymQueryNode(children));
            } else {
              // multiple positions
              QueryNode q = new BooleanQueryNode(Collections.<QueryNode>emptyList());
              QueryNode currentQuery = null;
              for (int i = 0; i < numTokens; i++) {
                String term = null;
                try {
                  boolean hasNext = buffer.incrementToken();
                  assert hasNext == true;
                  term = termAtt.toString();
                } catch (
                    @SuppressWarnings("unused")
                    IOException e) {
                  // safe to ignore, because we know the number of tokens
                }
                if (posIncrAtt != null && posIncrAtt.getPositionIncrement() == 0) {
                  if (!(currentQuery instanceof BooleanQueryNode)) {
                    QueryNode t = currentQuery;
                    currentQuery = new SynonymQueryNode(Collections.<QueryNode>emptyList());
                    ((BooleanQueryNode) currentQuery).add(t);
                  }
                  ((BooleanQueryNode) currentQuery).add(new FieldQueryNode(field, term, -1, -1));
                } else {
                  if (currentQuery != null) {
                    if (this.defaultOperator == Operator.OR) {
                      q.add(currentQuery);
                    } else {
                      q.add(new ModifierQueryNode(currentQuery, Modifier.MOD_REQ));
                    }
                  }
                  currentQuery = new FieldQueryNode(field, term, -1, -1);
                }
              }
              if (this.defaultOperator == Operator.OR) {
                q.add(currentQuery);
              } else {
                q.add(new ModifierQueryNode(currentQuery, Modifier.MOD_REQ));
              }

              if (q instanceof BooleanQueryNode) {
                q = new GroupQueryNode(q);
              }
              return q;
            }
          } else {
            // phrase query:
            MultiPhraseQueryNode mpq = new MultiPhraseQueryNode();

            List<FieldQueryNode> multiTerms = new ArrayList<>();
            int position = -1;
            int i = 0;
            int termGroupCount = 0;
            for (; i < numTokens; i++) {
              String term = null;
              int positionIncrement = 1;
              try {
                boolean hasNext = buffer.incrementToken();
                assert hasNext == true;
                term = termAtt.toString();
                if (posIncrAtt != null) {
                  positionIncrement = posIncrAtt.getPositionIncrement();
                }

              } catch (
                  @SuppressWarnings("unused")
                  IOException e) {
                // safe to ignore, because we know the number of tokens
              }

              if (positionIncrement > 0 && multiTerms.size() > 0) {

                for (FieldQueryNode termNode : multiTerms) {

                  if (this.positionIncrementsEnabled) {
                    termNode.setPositionIncrement(position);
                  } else {
                    termNode.setPositionIncrement(termGroupCount);
                  }

                  mpq.add(termNode);
                }

                // Only increment once for each "group" of
                // terms that were in the same position:
                termGroupCount++;

                multiTerms.clear();
              }

              position += positionIncrement;
              multiTerms.add(new FieldQueryNode(field, term, -1, -1));
            }

            for (FieldQueryNode termNode : multiTerms) {

              if (this.positionIncrementsEnabled) {
                termNode.setPositionIncrement(position);

              } else {
                termNode.setPositionIncrement(termGroupCount);
              }

              mpq.add(termNode);
            }

            return mpq;
          }

        } else {

          TokenizedPhraseQueryNode pq = new TokenizedPhraseQueryNode();

          int position = -1;

          for (int i = 0; i < numTokens; i++) {
            String term = null;
            int positionIncrement = 1;

            try {
              boolean hasNext = buffer.incrementToken();
              assert hasNext == true;
              term = termAtt.toString();

              if (posIncrAtt != null) {
                positionIncrement = posIncrAtt.getPositionIncrement();
              }

            } catch (
                @SuppressWarnings("unused")
                IOException e) {
              // safe to ignore, because we know the number of tokens
            }

            FieldQueryNode newFieldNode = new FieldQueryNode(field, term, -1, -1);

            if (this.positionIncrementsEnabled) {
              position += positionIncrement;
              newFieldNode.setPositionIncrement(position);

            } else {
              newFieldNode.setPositionIncrement(i);
            }

            pq.add(newFieldNode);
          }

          return pq;
        }
      } finally {
        if (buffer != null) {
          try {
            buffer.close();
          } catch (
              @SuppressWarnings("unused")
              IOException e) {
            // safe to ignore
          }
        }
      }
    }

    return node;
  }

  @Override
  protected QueryNode preProcessNode(QueryNode node) throws QueryNodeException {

    return node;
  }

  @Override
  protected List<QueryNode> setChildrenOrder(List<QueryNode> children) throws QueryNodeException {

    return children;
  }
}
