/*****************************************************************
 *   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.cayenne.reflect;

import org.apache.cayenne.map.ObjAttribute;
import org.apache.cayenne.map.ObjEntity;
import org.apache.cayenne.query.EntityResultSegment;

import java.util.HashMap;
import java.util.Map;

/**
 * @since 3.0
 */
class PersistentDescriptorResultMetadata implements EntityResultSegment {

	ClassDescriptor classDescriptor;
	Map<String, String> fields;
	Map<String, String> reverseFields;

	PersistentDescriptorResultMetadata(ClassDescriptor classDescriptor) {
		this.classDescriptor = classDescriptor;
		this.fields = new HashMap<>();
		this.reverseFields = new HashMap<>();
	}

	public ClassDescriptor getClassDescriptor() {
		return classDescriptor;
	}

	public Map<String, String> getFields() {
		return fields;
	}

	public String getColumnPath(String resultSetLabel) {
		return reverseFields.get(resultSetLabel);
	}

	void addObjectField(String attributeName, String column) {
		ObjEntity entity = classDescriptor.getEntity();

		ObjAttribute attribute = entity.getAttribute(attributeName);
		fields.put(attribute.getDbAttributePath(), column);
		reverseFields.put(column, attribute.getDbAttributePath());
	}

	/**
	 * Adds a result set column mapping for a single object property of a
	 * specified entity that may differ from the root entity if inheritance is
	 * involved.
	 */
	void addObjectField(String entityName, String attributeName, String column) {
		ObjEntity entity = classDescriptor.getEntity().getDataMap().getObjEntity(entityName);

		ObjAttribute attribute = entity.getAttribute(attributeName);
		fields.put(attribute.getDbAttributePath(), column);
		reverseFields.put(column, attribute.getDbAttributePath());
	}

	/**
	 * Adds a result set column mapping for a single DbAttribute.
	 */
	void addDbField(String dbAttributeName, String column) {
		fields.put(dbAttributeName, column);
		reverseFields.put(column, dbAttributeName);
	}

	public int getColumnOffset() {
		throw new UnsupportedOperationException("Column offset only makes sense in the context of a query");
	}
}