/*
 * 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.flink.operators;

import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import org.apache.commons.lang3.Validate;
import org.apache.flink.api.java.DataSet;
import org.apache.wayang.core.api.Configuration;
import org.apache.wayang.core.optimizer.OptimizationContext;
import org.apache.wayang.core.optimizer.cardinality.CardinalityEstimator;
import org.apache.wayang.core.optimizer.cardinality.DefaultCardinalityEstimator;
import org.apache.wayang.core.plan.wayangplan.ExecutionOperator;
import org.apache.wayang.core.plan.wayangplan.UnaryToUnaryOperator;
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.flink.channels.DataSetChannel;
import org.apache.wayang.flink.execution.FlinkExecutor;
import org.apache.wayang.java.channels.CollectionChannel;


/**
 * Converts {@link DataSetChannel} into a {@link CollectionChannel}
 */
public class FlinkCollectionSink<Type> extends UnaryToUnaryOperator<Type, Type>
        implements FlinkExecutionOperator  {
    public FlinkCollectionSink(DataSetType<Type> type) {
        super(type, type, false);
    }

    @Override
    public Tuple<Collection<ExecutionLineageNode>, Collection<ChannelInstance>> evaluate(ChannelInstance[] inputs, ChannelInstance[] outputs, FlinkExecutor flinkExecutor, OptimizationContext.OperatorContext operatorContext) throws Exception {

        assert inputs.length == this.getNumInputs();
        assert outputs.length == this.getNumOutputs();

        final DataSetChannel.Instance input  = (DataSetChannel.Instance) inputs[0];
        final CollectionChannel.Instance output = (CollectionChannel.Instance) outputs[0];

        final DataSet<Type> dataSetInput = input.provideDataSet();

        output.accept(dataSetInput.filter(a -> true).setParallelism(1).collect());

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

    }

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

    @Override
    public List<ChannelDescriptor> getSupportedInputChannels(int index) {
        return Collections.singletonList(DataSetChannel.DESCRIPTOR);
    }

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

    @Override
    public Optional<CardinalityEstimator> createCardinalityEstimator(
            final int outputIndex,
            final Configuration configuration) {
        Validate.inclusiveBetween(0, 0, outputIndex);
        return Optional.of(new DefaultCardinalityEstimator(1d, 1, this.isSupportingBroadcastInputs(),
                inputCards -> inputCards[0]));
    }

    @Override
    public String getLoadProfileEstimatorConfigurationKey() {
        return "wayang.flink.collect.load";
    }
}