/*
 * 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 java.io.IOException;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Sort;
import org.exoplatform.services.jcr.dataflow.ItemDataConsumer;
import org.exoplatform.services.jcr.datamodel.InternalQName;
import org.exoplatform.services.jcr.impl.core.SessionImpl;
import org.exoplatform.services.jcr.impl.core.query.lucene.constraint.EvaluationContext;

/**
 * <code>JackrabbitIndexSearcher</code> implements an index searcher with
 * jackrabbit specific optimizations.
 */
public class JcrIndexSearcher
        extends IndexSearcher
        implements EvaluationContext {

    /**
     * The session that executes the query.
     */
    private final SessionImpl session;

    /**
     * The underlying index reader.
     */
    private final IndexReader reader;

    /**
     * The item state manager of the workspace.
     */
    private final ItemDataConsumer ism;

    /**
     * Creates a new jackrabbit index searcher.
     *
     * @param s the session that executes the query.
     * @param r the index reader.
     * @param ism the shared item state manager.
     */
    public JcrIndexSearcher(SessionImpl s,
                                   IndexReader r,
                                   ItemDataConsumer ism) {
        super(r);
        this.session = s;
        this.reader = r;
        this.ism = ism;
    }

    /**
     * Executes the query and returns the hits that match the query.
     *
     * @param query           the query to execute.
     * @param sort            the sort criteria.
     * @param resultFetchHint a hint on how many results should be fetched.
     * @param selectorName    the single selector name for the query hits.
     * @return the query hits.
     * @throws IOException if an error occurs while executing the query.
     */
    public MultiColumnQueryHits execute(Query query,
                                        Sort sort,
                                        long resultFetchHint,
                                        InternalQName selectorName)
            throws IOException {
        return new QueryHitsAdapter(
                evaluate(query, sort, resultFetchHint), selectorName);
    }

    /**
     * Evaluates the query and returns the hits that match the query.
     *
     * @param query           the query to execute.
     * @param sort            the sort criteria.
     * @param resultFetchHint a hint on how many results should be fetched.
     * @return the query hits.
     * @throws IOException if an error occurs while executing the query.
     */
    public QueryHits evaluate(Query query, Sort sort, long resultFetchHint)
            throws IOException {
        query = query.rewrite(reader);
        QueryHits hits = null;
        if (query instanceof JcrQuery) {
            hits = ((JcrQuery) query).execute(this, session, sort);
        }
        if (hits == null) {
            if (sort == null) {
                hits = new LuceneQueryHits(reader, this, query);
            } else {
                hits = new SortedLuceneQueryHits(
                        reader, this, query, sort, resultFetchHint);
            }
        }
        return hits;
    }

    //------------------------< EvaluationContext >-----------------------------

    /**
     * Evaluates the query and returns the hits that match the query.
     *
     * @param query           the query to execute.
     * @return the query hits.
     * @throws IOException if an error occurs while executing the query.
     */
    public QueryHits evaluate(Query query) throws IOException {
        return evaluate(query, new Sort(), Integer.MAX_VALUE);
    }

    /**
     * @return session that executes the query.
     */
    public SessionImpl getSession() {
        return session;
    }

    /**
     * @return the item state manager of the workspace.
     */
    public ItemDataConsumer getItemStateManager() {
        return ism;
    }
}
