/*
 * 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.precedence.processors;

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

import org.apache.lucene.queryparser.flexible.precedence.PrecedenceQueryParser;
import org.apache.lucene.queryparser.flexible.standard.config.StandardQueryConfigHandler;
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.core.QueryNodeException;
import org.apache.lucene.queryparser.flexible.core.nodes.*;
import org.apache.lucene.queryparser.flexible.core.processors.QueryNodeProcessorImpl;
import org.apache.lucene.queryparser.flexible.core.nodes.ModifierQueryNode.Modifier;

 This processor is used to apply the correct ModifierQueryNode to BooleanQueryNodes children. 
 It walks through the query node tree looking for BooleanQueryNodes. If an AndQueryNode is found, every child, which is not a ModifierQueryNode or the ModifierQueryNode is Modifier.MOD_NONE, becomes a Modifier.MOD_REQ. For any other BooleanQueryNode which is not an OrQueryNode, it checks the default operator is Operator.AND, if it is, the same operation when an AndQueryNode is found is applied to it. 
See Also:
ConfigurationKeys.DEFAULT_OPERATOR
StandardQueryParser.setDefaultOperator/**
 * <p>
 * This processor is used to apply the correct {@link ModifierQueryNode} to {@link BooleanQueryNode}s children.
 * </p>
 * <p>
 * It walks through the query node tree looking for {@link BooleanQueryNode}s. If an {@link AndQueryNode} is found,
 * every child, which is not a {@link ModifierQueryNode} or the {@link ModifierQueryNode} 
 * is {@link Modifier#MOD_NONE}, becomes a {@link Modifier#MOD_REQ}. For any other
 * {@link BooleanQueryNode} which is not an {@link OrQueryNode}, it checks the default operator is {@link Operator#AND},
 * if it is, the same operation when an {@link AndQueryNode} is found is applied to it.
 * </p>
 * 
 * @see ConfigurationKeys#DEFAULT_OPERATOR
 * @see PrecedenceQueryParser#setDefaultOperator
 */
public class BooleanModifiersQueryNodeProcessor extends QueryNodeProcessorImpl {

  private ArrayList<QueryNode> childrenBuffer = new ArrayList<>();

  private Boolean usingAnd = false;

  public BooleanModifiersQueryNodeProcessor() {
    // empty constructor
  }

  @Override
  public QueryNode process(QueryNode queryTree) throws QueryNodeException {
    Operator op = getQueryConfigHandler().get(ConfigurationKeys.DEFAULT_OPERATOR);
    
    if (op == null) {
      throw new IllegalArgumentException(
          "StandardQueryConfigHandler.ConfigurationKeys.DEFAULT_OPERATOR should be set on the QueryConfigHandler");
    }

    this.usingAnd = StandardQueryConfigHandler.Operator.AND == op;

    return super.process(queryTree);

  }

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

    if (node instanceof AndQueryNode) {
      this.childrenBuffer.clear();
      List<QueryNode> children = node.getChildren();

      for (QueryNode child : children) {
        this.childrenBuffer.add(applyModifier(child, ModifierQueryNode.Modifier.MOD_REQ));
      }

      node.set(this.childrenBuffer);

    } else if (this.usingAnd && node instanceof BooleanQueryNode
        && !(node instanceof OrQueryNode)) {

      this.childrenBuffer.clear();
      List<QueryNode> children = node.getChildren();

      for (QueryNode child : children) {
        this.childrenBuffer.add(applyModifier(child, ModifierQueryNode.Modifier.MOD_REQ));
      }

      node.set(this.childrenBuffer);

    }

    return node;

  }

  private QueryNode applyModifier(QueryNode node, ModifierQueryNode.Modifier mod) {

    // check if modifier is not already defined and is default
    if (!(node instanceof ModifierQueryNode)) {
      return new ModifierQueryNode(node, mod);

    } else {
      ModifierQueryNode modNode = (ModifierQueryNode) node;

      if (modNode.getModifier() == ModifierQueryNode.Modifier.MOD_NONE) {
        return new ModifierQueryNode(modNode.getChild(), mod);
      }

    }

    return node;

  }

  @Override
  protected QueryNode preProcessNode(QueryNode node) throws QueryNodeException {
    return node;
  }

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

    return children;

  }

}