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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
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package org.apache.cayenne.query;

import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.map.DataMap;
import org.apache.cayenne.map.EntityResolver;

/**
 * A base superclass for queries that resolve into some other queries during the
 * routing phase. Provides caching of a replacement query.
 * 
 * @since 1.2
 */
public abstract class IndirectQuery implements Query {

	private static final long serialVersionUID = 974666786498898209L;

	protected String name;

	/**
	 * @since 3.1
	 */
	protected DataMap dataMap;

	protected transient Query replacementQuery;
	protected transient EntityResolver lastResolver;

	/**
	 * @since 3.1
	 */
	@Override
	@Deprecated
	public DataMap getDataMap() {
		return dataMap;
	}

	/**
	 * @since 3.1
	 */
	@Deprecated
	public void setDataMap(DataMap dataMap) {
		this.dataMap = dataMap;
	}

	/**
	 * Returns the metadata obtained from the replacement query.
	 */
	@Override
	public QueryMetadata getMetaData(EntityResolver resolver) {
		return getReplacementQuery(resolver).getMetaData(resolver);
	}

	@Override
	@Deprecated
	public String getName() {
		return name;
	}

	@Deprecated
	public void setName(String name) {
		this.name = name;
	}

	/**
	 * Delegates routing to a replacement query.
	 */
	@Override
	public void route(QueryRouter router, EntityResolver resolver, Query substitutedQuery) {
		getReplacementQuery(resolver).route(router, resolver, substitutedQuery != null ? substitutedQuery : this);
	}

	/**
	 * Creates a substitute query. An implementor is free to provide an
	 * arbitrary replacement query.
	 */
	protected abstract Query createReplacementQuery(EntityResolver resolver);

	/**
	 * Returns a replacement query, creating it on demand and caching it for
	 * reuse.
	 */
	protected Query getReplacementQuery(EntityResolver resolver) {
		if (replacementQuery == null || lastResolver != resolver) {
			this.replacementQuery = createReplacementQuery(resolver);
			this.lastResolver = resolver;
		}

		return replacementQuery;
	}

	/**
	 * Throws an exception as indirect query should not be executed directly.
	 */
	@Override
	public SQLAction createSQLAction(SQLActionVisitor visitor) {
		throw new CayenneRuntimeException("%s is an indirect query and doesn't support its own sql actions. "
				+ "It should've been delegated to another query during resolution or routing phase.", getClass().getName());
	}
}