/*
 * 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.java.operators;

import org.apache.flink.annotation.Public;
import org.apache.flink.api.common.functions.FilterFunction;
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.common.operators.Operator;
import org.apache.flink.api.java.operators.translation.PlanFilterOperator;
import org.apache.flink.api.java.DataSet;

/**
 * This operator represents the application of a "filter" function on a data set, and the
 * result data set produced by the function.
 * 
 * @param <T> The type of the data set filtered by the operator.
 */
@Public
public class FilterOperator<T> extends SingleInputUdfOperator<T, T, FilterOperator<T>> {
	
	protected final FilterFunction<T> function;
	
	protected final String defaultName;

	public FilterOperator(DataSet<T> input, FilterFunction<T> function, String defaultName) {
		super(input, input.getType());
		
		this.function = function;
		this.defaultName = defaultName;

		UdfOperatorUtils.analyzeSingleInputUdf(this, FilterFunction.class, defaultName, function, null);
	}
	
	@Override
	protected FilterFunction<T> getFunction() {
		return function;
	}
	
	@Override
	protected org.apache.flink.api.common.operators.base.FilterOperatorBase<T, FlatMapFunction<T,T>> translateToDataFlow(Operator<T> input) {
		
		String name = getName() != null ? getName() : "Filter at "+defaultName;
		
		// create operator
		PlanFilterOperator<T> po = new PlanFilterOperator<T>(function, name, getInputType());
		po.setInput(input);
		
		// set parallelism
		if (getParallelism() > 0) {
			// use specified parallelism
			po.setParallelism(getParallelism());
		} else {
			// if no parallelism has been specified, use parallelism of input operator to enable chaining
			po.setParallelism(input.getParallelism());
		}
		
		return po;
	}
}