/*
 * 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.streaming.api.transformations;

import com.google.common.collect.Lists;
import java.util.Collection;
import java.util.List;
import org.apache.flink.annotation.Internal;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.java.functions.KeySelector;
import org.apache.flink.streaming.api.operators.ChainingStrategy;
import org.apache.flink.streaming.api.operators.OneInputStreamOperator;

/**
 * This Transformation represents the application of a
 * {@link org.apache.flink.streaming.api.operators.OneInputStreamOperator} to one input
 * {@link org.apache.flink.streaming.api.transformations.StreamTransformation}.
 *
 * @param <IN> The type of the elements in the nput {@code StreamTransformation}
 * @param <OUT> The type of the elements that result from this {@code OneInputTransformation}
 */
@Internal
public class OneInputTransformation<IN, OUT> extends StreamTransformation<OUT> {

	private final StreamTransformation<IN> input;

	private final OneInputStreamOperator<IN, OUT> operator;

	private KeySelector<IN, ?> stateKeySelector;

	private TypeInformation<?> stateKeyType;

	/**
	 * Creates a new {@code OneInputTransformation} from the given input and operator.
	 *
	 * @param input The input {@code StreamTransformation}
	 * @param name The name of the {@code StreamTransformation}, this will be shown in Visualizations and the Log
	 * @param operator The {@code TwoInputStreamOperator}
	 * @param outputType The type of the elements produced by this {@code OneInputTransformation}
	 * @param parallelism The parallelism of this {@code OneInputTransformation}
	 */
	public OneInputTransformation(
			StreamTransformation<IN> input,
			String name,
			OneInputStreamOperator<IN, OUT> operator,
			TypeInformation<OUT> outputType,
			int parallelism) {
		super(name, outputType, parallelism);
		this.input = input;
		this.operator = operator;
	}

	/**
	 * Returns the input {@code StreamTransformation} of this {@code OneInputTransformation}.
	 */
	public StreamTransformation<IN> getInput() {
		return input;
	}

	/**
	 * Returns the {@code TypeInformation} for the elements of the input.
	 */
	public TypeInformation<IN> getInputType() {
		return input.getOutputType();
	}

	/**
	 * Returns the {@code TwoInputStreamOperator} of this Transformation.
	 */
	public OneInputStreamOperator<IN, OUT> getOperator() {
		return operator;
	}

	/**
	 * Sets the {@link KeySelector} that must be used for partitioning keyed state of this operation.
	 *
	 * @param stateKeySelector The {@code KeySelector} to set
	 */
	public void setStateKeySelector(KeySelector<IN, ?> stateKeySelector) {
		this.stateKeySelector = stateKeySelector;
	}

	/**
	 * Returns the {@code KeySelector} that must be used for partitioning keyed state in this
	 * Operation.
	 *
	 * @see #setStateKeySelector
	 */
	public KeySelector<IN, ?> getStateKeySelector() {
		return stateKeySelector;
	}

	public void setStateKeyType(TypeInformation<?> stateKeyType) {
		this.stateKeyType = stateKeyType;
	}

	public TypeInformation<?> getStateKeyType() {
		return stateKeyType;
	}

	@Override
	public Collection<StreamTransformation<?>> getTransitivePredecessors() {
		List<StreamTransformation<?>> result = Lists.newArrayList();
		result.add(this);
		result.addAll(input.getTransitivePredecessors());
		return result;
	}

	@Override
	public final void setChainingStrategy(ChainingStrategy strategy) {
		operator.setChainingStrategy(strategy);
	}
}