/*
 * 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.exoplatform.services.jcr.impl.core.query.lucene;

import org.exoplatform.services.jcr.impl.core.query.QueryHandler;
import org.exoplatform.services.jcr.impl.core.query.QueryRootNode;

import java.io.IOException;

import javax.jcr.RepositoryException;

/**
 * <code>SpellChecker</code> defines an interface to run a spellchecker over a
 * fulltext query statement.
 */
public interface SpellChecker
{

   /**
    * Initializes this spell checker.
    * 
    * @param handler
    *            the query handler that created this spell checker.
    * @param minDistance
    *            minimal distance between  word and proposed close word. Float value 0..1.
    * @param morePopular
    *            return only the suggest words that are as frequent or more frequent than the searched word 
    * @throws IOException
    *             if an error occurs while initializing the spell checker.
    */
   void init(QueryHandler handler, float minDistance, boolean morePopular) throws IOException;

   /**
    * Runs the spell checker over the first spellcheck relation query node in
    * the abstract query tree and returns a suggestion in case this
    * spellchecker thinks the words are misspelled. If the spellchecker
    * determines that the words are spelled correctly <code>null</code> is
    * returned.
    * 
    * @param aqt
    *            the abstract query tree, which may contain a relation query
    *            node with a spellcheck operation.
    * @return a suggestion or <code>null</code> if this spell checker
    *         determines that the fulltext query statement is spelled
    *         correctly.
    * @throws RepositoryException
    */
   String check(QueryRootNode aqt) throws IOException, RepositoryException;

   /**
    * Closes this spell checker and allows it to free resources.
    */
   void close();

}