/*
 * 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.util.HashMap;
import java.util.Map;

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

/**
 * Container for the semantic properties associated to a single input operator.
 */
@Internal
public class SingleInputSemanticProperties implements SemanticProperties {
	private static final long serialVersionUID = 1L;

	/**
	 * Mapping from fields in the source record(s) to fields in the destination
	 * record(s).
	 */
	private Map<Integer,FieldSet> fieldMapping;

	/**
	 * Set of fields that are read in the source record(s).
	 */
	private FieldSet readFields;

	public SingleInputSemanticProperties() {
		this.fieldMapping = new HashMap<Integer, FieldSet>();
		this.readFields = null;
	}

	@Override
	public FieldSet getForwardingTargetFields(int input, int sourceField) {
		if (input != 0) {
			throw new IndexOutOfBoundsException();
		}

		return this.fieldMapping.containsKey(sourceField) ? this.fieldMapping.get(sourceField) : FieldSet.EMPTY_SET;
	}

	@Override
	public int getForwardingSourceField(int input, int targetField) {
		if (input != 0) {
			throw new IndexOutOfBoundsException();
		}

		for (Map.Entry<Integer, FieldSet> e : fieldMapping.entrySet()) {
			if (e.getValue().contains(targetField)) {
				return e.getKey();
			}
		}
		return -1;
	}

	@Override
	public FieldSet getReadFields(int input) {
		if (input != 0) {
			throw new IndexOutOfBoundsException();
		}

		return this.readFields;
	}

	/**
	 * Adds, to the existing information, a field that is forwarded directly
	 * from the source record(s) to the destination record(s).
	 *
	 * @param sourceField the position in the source record(s)
	 * @param targetField the position in the destination record(s)
	 */
	public void addForwardedField(int sourceField, int targetField) {
		if(isTargetFieldPresent(targetField)) {
			throw new InvalidSemanticAnnotationException("Target field "+targetField+" was added twice.");
		}

		FieldSet targetFields = fieldMapping.get(sourceField);
		if (targetFields != null) {
			fieldMapping.put(sourceField, targetFields.addField(targetField));
		} else {
			fieldMapping.put(sourceField, new FieldSet(targetField));
		}
	}

	private boolean isTargetFieldPresent(int targetField) {
		for(FieldSet targetFields : fieldMapping.values()) {
			if(targetFields.contains(targetField)) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Adds, to the existing information, field(s) that are read in
	 * the source record(s).
	 *
	 * @param readFields the position(s) in the source record(s)
	 */
	public void addReadFields(FieldSet readFields) {
		if (this.readFields == null) {
			this.readFields = readFields;
		} else {
			this.readFields = this.readFields.addFields(readFields);
		}
	}

	@Override
	public String toString() {
		return "SISP(" + this.fieldMapping + ")";
	}


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

	public static class AllFieldsForwardedProperties extends SingleInputSemanticProperties {

		private static final long serialVersionUID = 1L;

		@Override
		public FieldSet getForwardingTargetFields(int input, int sourceField) {
			if(input != 0) {
				throw new IndexOutOfBoundsException();
			}
			return new FieldSet(sourceField);
		}

		@Override
		public int getForwardingSourceField(int input, int targetField) {
			if(input != 0) {
				throw new IndexOutOfBoundsException();
			}
			return targetField;
		}

		@Override
		public void addForwardedField(int sourceField, int targetField) {
			throw new UnsupportedOperationException("Cannot modify forwarded fields");
		}

	}
}