/*
 * 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.flink.api.common.operators;

import java.io.Serializable;

import org.apache.flink.annotation.Internal;
import org.apache.flink.api.common.InvalidProgramException;
import org.apache.flink.api.common.operators.util.FieldSet;

/**
 * Container for the semantic properties associated to an operator.
 */
@Internal
public interface SemanticProperties extends Serializable {

	/**
	 * Returns the indexes of all target fields to which a source field has been
	 * unmodified copied by a function.
	 *
	 * @param input The input id for the requested source field (0 for first input, 1 for second input)
	 * @param sourceField The index of the field for which the target position index is requested.
	 * @return A set containing the indexes of all target fields to which the source field has been unmodified copied.
	 *
	 */
	public FieldSet getForwardingTargetFields(int input, int sourceField);

	/**
	 * Returns the index of the source field on the given input from which the target field
	 * has been unmodified copied by a function.
	 *
	 * @param input The input id for the requested source field (0 for first input, 1 for second input)
	 * @param targetField The index of the target field to which the source field has been copied.
	 * @return The index of the source field on the given index that was copied to the given target field.
	 * 			-1 if the target field was not copied from any source field of the given input.
	 */
	public int getForwardingSourceField(int input, int targetField);

	/**
	 * Returns the position indexes of all fields of an input that are accessed by a function.
	 *
	 * @param input The input id for which accessed fields are requested.
	 * @return A set of fields of the specified input which have been accessed by the function. Null if no information is available.
	 */
	public FieldSet getReadFields(int input);

	// ----------------------------------------------------------------------

	public static class InvalidSemanticAnnotationException extends InvalidProgramException {

		private static final long serialVersionUID = 1L;

		public InvalidSemanticAnnotationException(String s) {
			super(s);
		}

		public InvalidSemanticAnnotationException(String s, Throwable e) {
			super(s,e);
		}
	}

	public static class EmptySemanticProperties implements SemanticProperties {

		private static final long serialVersionUID = 1L;

		@Override
		public FieldSet getForwardingTargetFields(int input, int sourceField) {
			return FieldSet.EMPTY_SET;
		}

		@Override
		public int getForwardingSourceField(int input, int targetField) {
			return -1;
		}

		@Override
		public FieldSet getReadFields(int input) {
			return null;
		}

	}
}