/*
 * 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.iteration.operator.allround;

import org.apache.flink.iteration.IterationRecord;
import org.apache.flink.streaming.api.operators.BoundedMultiInput;
import org.apache.flink.streaming.api.operators.Input;
import org.apache.flink.streaming.api.operators.MultipleInputStreamOperator;
import org.apache.flink.streaming.api.operators.StreamOperatorFactory;
import org.apache.flink.streaming.api.operators.StreamOperatorParameters;
import org.apache.flink.streaming.api.watermark.Watermark;
import org.apache.flink.streaming.runtime.streamrecord.LatencyMarker;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
import org.apache.flink.streaming.runtime.watermarkstatus.WatermarkStatus;
import org.apache.flink.util.FlinkRuntimeException;

import java.util.ArrayList;
import java.util.List;

/** All-round wrapper for the multiple-inputs operator. */
public class MultipleInputAllRoundWrapperOperator<OUT>
        extends AbstractAllRoundWrapperOperator<OUT, MultipleInputStreamOperator<OUT>>
        implements MultipleInputStreamOperator<IterationRecord<OUT>>, BoundedMultiInput {

    public MultipleInputAllRoundWrapperOperator(
            StreamOperatorParameters<IterationRecord<OUT>> parameters,
            StreamOperatorFactory<OUT> operatorFactory) {
        super(parameters, operatorFactory);
    }

    private <IN> void processElement(
            int inputIndex,
            Input<IN> input,
            StreamRecord<IN> reusedInput,
            StreamRecord<IterationRecord<IN>> element)
            throws Exception {
        switch (element.getValue().getType()) {
            case RECORD:
                reusedInput.replace(element.getValue().getValue(), element.getTimestamp());
                setIterationContextRound(element.getValue().getEpoch());
                input.processElement(reusedInput);
                clearIterationContextRound();
                break;
            case EPOCH_WATERMARK:
                onEpochWatermarkEvent(inputIndex, element.getValue());
                break;
            default:
                throw new FlinkRuntimeException("Not supported iteration record type: " + element);
        }
    }

    @Override
    @SuppressWarnings({"unchecked", "rawtypes"})
    public List<Input> getInputs() {
        List<Input> proxyInputs = new ArrayList<>();
        for (int i = 0; i < wrappedOperator.getInputs().size(); ++i) {
            // TODO: Note that here we relies on the assumption that the
            // stream graph generator labels the input from 1 to n for
            // the input array, which we map them from 0 to n - 1.
            proxyInputs.add(new ProxyInput(i));
        }
        return proxyInputs;
    }

    @Override
    public void endInput(int i) throws Exception {
        super.endInput(i);

        if (wrappedOperator instanceof BoundedMultiInput) {
            setIterationContextRound(IterationRecord.END_EPOCH_WATERMARK);
            ((BoundedMultiInput) wrappedOperator).endInput(i);
            clearIterationContextRound();
        }
    }

    private class ProxyInput<IN> implements Input<IterationRecord<IN>> {

        private final int inputIndex;

        private final StreamRecord<IN> reusedInput;

        private final Input<IN> input;

        public ProxyInput(int inputIndex) {
            this.inputIndex = inputIndex;
            this.reusedInput = new StreamRecord<>(null, 0);
            this.input = wrappedOperator.getInputs().get(inputIndex);
        }

        @Override
        public void processElement(StreamRecord<IterationRecord<IN>> element) throws Exception {
            MultipleInputAllRoundWrapperOperator.this.processElement(
                    inputIndex, input, reusedInput, element);
        }

        @Override
        public void processWatermark(Watermark mark) throws Exception {
            input.processWatermark(mark);
        }

        @Override
        public void processWatermarkStatus(WatermarkStatus watermarkStatus) throws Exception {
            input.processWatermarkStatus(watermarkStatus);
        }

        @Override
        public void processLatencyMarker(LatencyMarker latencyMarker) throws Exception {
            input.processLatencyMarker(latencyMarker);
        }

        @Override
        public void setKeyContextElement(StreamRecord<IterationRecord<IN>> record)
                throws Exception {
            reusedInput.replace(record.getValue(), record.getTimestamp());
            input.setKeyContextElement(reusedInput);
        }
    }
}