/*
 * 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.wayang.spark.operators;

import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.function.Function;
import org.apache.wayang.basic.operators.FilterOperator;
import org.apache.wayang.core.api.Configuration;
import org.apache.wayang.core.function.PredicateDescriptor;
import org.apache.wayang.core.optimizer.OptimizationContext;
import org.apache.wayang.core.optimizer.costs.LoadProfileEstimator;
import org.apache.wayang.core.optimizer.costs.LoadProfileEstimators;
import org.apache.wayang.core.plan.wayangplan.ExecutionOperator;
import org.apache.wayang.core.platform.ChannelDescriptor;
import org.apache.wayang.core.platform.ChannelInstance;
import org.apache.wayang.core.platform.lineage.ExecutionLineageNode;
import org.apache.wayang.core.types.DataSetType;
import org.apache.wayang.core.util.Tuple;
import org.apache.wayang.spark.channels.BroadcastChannel;
import org.apache.wayang.spark.channels.RddChannel;
import org.apache.wayang.spark.execution.SparkExecutor;

import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import org.apache.wayang.spark.platform.SparkPlatform;

/**
 * Spark implementation of the {@link FilterOperator}.
 */
public class SparkFilterOperator<Type>
        extends FilterOperator<Type>
        implements SparkExecutionOperator {

    SparkPlatform platform;

    /**
     * Creates a new instance.
     *
     * @param type type of the dataset elements
     */
    public SparkFilterOperator(DataSetType<Type> type, PredicateDescriptor<Type> predicate) {
        super(predicate, type);
    }

    /**
     * Copies an instance (exclusive of broadcasts).
     *
     * @param that that should be copied
     */
    public SparkFilterOperator(FilterOperator<Type> that) {
        super(that);
    }

    @Override
    public Tuple<Collection<ExecutionLineageNode>, Collection<ChannelInstance>> evaluate(
            ChannelInstance[] inputs,
            ChannelInstance[] outputs,
            SparkExecutor sparkExecutor,
            OptimizationContext.OperatorContext operatorContext) {
        assert inputs.length == this.getNumInputs();
        assert outputs.length == this.getNumOutputs();

        final Function<Type, Boolean> filterFunction = sparkExecutor.getCompiler().compile(
                this.predicateDescriptor, this, operatorContext, inputs
        );

        final JavaRDD<Type> inputRdd = ((RddChannel.Instance) inputs[0]).provideRdd();
        final JavaRDD<Type> outputRdd = inputRdd.filter(filterFunction);
        this.name(outputRdd);
        ((RddChannel.Instance) outputs[0]).accept(outputRdd, sparkExecutor);

        return ExecutionOperator.modelLazyExecution(inputs, outputs, operatorContext);
    }

    @Override
    public String getLoadProfileEstimatorConfigurationKey() {
        return "wayang.spark.filter.load";
    }

    @Override
    public Optional<LoadProfileEstimator> createLoadProfileEstimator(Configuration configuration) {
        final Optional<LoadProfileEstimator> optEstimator =
                SparkExecutionOperator.super.createLoadProfileEstimator(configuration);
        LoadProfileEstimators.nestUdfEstimator(optEstimator, this.predicateDescriptor, configuration);
        return optEstimator;
    }

    @Override
    public List<ChannelDescriptor> getSupportedInputChannels(int index) {
        if (index == 0) {
            return Arrays.asList(RddChannel.UNCACHED_DESCRIPTOR, RddChannel.CACHED_DESCRIPTOR);
        } else {
            return Collections.singletonList(BroadcastChannel.DESCRIPTOR);
        }
    }

    @Override
    public List<ChannelDescriptor> getSupportedOutputChannels(int index) {
        return Collections.singletonList(RddChannel.UNCACHED_DESCRIPTOR);
    }

    @Override
    public boolean containsAction() {
        return false;
    }

    @Override
    public SparkPlatform getPlatform() {
        if(this.platform == null) {
            return SparkExecutionOperator.super.getPlatform();
        }
        return this.platform;
    }

    @Override
    public SparkFilterOperator<Type> setPlatform(SparkPlatform sparkPlatform) {
        this.platform = sparkPlatform;
        return this;
    }
}