/*
 * 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.samoa.flink.topology.impl;

import com.google.common.collect.Lists;
import org.apache.flink.api.common.functions.Function;
import org.apache.flink.api.java.tuple.Tuple3;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.operators.AbstractUdfStreamOperator;
import org.apache.flink.streaming.api.operators.OneInputStreamOperator;
import org.apache.flink.streaming.api.watermark.Watermark;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
import org.apache.samoa.core.ContentEvent;
import org.apache.samoa.core.Processor;
import org.apache.samoa.flink.helpers.Utils;
import org.apache.samoa.topology.ProcessingItem;
import org.apache.samoa.topology.Stream;
import org.apache.samoa.utils.PartitioningScheme;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;


public class FlinkProcessingItem extends AbstractUdfStreamOperator<SamoaType, FlinkProcessingItem.SamoaDelegateFunction> 
		implements OneInputStreamOperator<SamoaType, SamoaType>, ProcessingItem, FlinkComponent, Serializable {

	private static final Logger logger = LoggerFactory.getLogger(FlinkProcessingItem.class);
	public static final int MAX_WAIT_TIME_MILLIS = 10000;

	private final Processor processor;
	private final transient StreamExecutionEnvironment env;
	private final SamoaDelegateFunction fun;
	private transient DataStream<SamoaType> inStream;
	private transient DataStream<SamoaType> outStream;
	private transient List<FlinkStream> outputStreams = Lists.newArrayList();
	private transient List<Tuple3<FlinkStream, PartitioningScheme, Integer>> inputStreams = Lists.newArrayList();
	private int parallelism;
	private static int numberOfPIs = 0;
	private int piID;
	private List<Integer> cycleId; //check if we can refactor this
	private boolean onIteration;

	public FlinkProcessingItem(StreamExecutionEnvironment env, Processor proc) {
		this(env, proc, 1);
	}

	public FlinkProcessingItem(StreamExecutionEnvironment env, Processor proc, int parallelism) {
		this(env, new SamoaDelegateFunction(proc), proc, parallelism);
	}

	public FlinkProcessingItem(StreamExecutionEnvironment env, SamoaDelegateFunction fun, Processor proc, int parallelism) {
		super(fun);
		this.env = env;
		this.fun = fun;
		this.processor = proc;
		this.parallelism = parallelism;
		this.piID = numberOfPIs++;
		this.cycleId = new ArrayList<Integer>() {
		}; // if size equals 0, then it is part of no cycle
	}

	public Stream createStream() {
		FlinkStream generatedStream = new FlinkStream(this);
		outputStreams.add(generatedStream);
		return generatedStream;
	}

	public void putToStream(ContentEvent data, Stream targetStream) {
		output.collect(new StreamRecord<>(SamoaType.of(data, targetStream.getStreamId())));
	}
	
	@Override
	public void open() throws Exception {
		super.open();
		this.processor.onCreate(getComponentId());
	}

	@Override
	public void initialise() {
		for (Tuple3<FlinkStream, PartitioningScheme, Integer> inputStream : inputStreams) {
			if (inputStream.f0.isInitialised()) { //if input stream is initialised
				try {
					DataStream toBeMerged = Utils.subscribe(inputStream.f0.getOutStream(), inputStream.f1);
					if (inStream == null) {
						inStream = toBeMerged;
					} else {
						inStream = inStream.union(toBeMerged);
					}
				} catch (RuntimeException e) {
					e.printStackTrace();
					System.exit(1);
				}
			}
		}

		if (onIteration) {
			inStream = inStream.iterate(MAX_WAIT_TIME_MILLIS);
		}
		outStream = inStream.transform("samoaProcessor", Utils.tempTypeInfo, this).setParallelism(parallelism);
	}

	public void initialiseStreams() {
		for (FlinkStream stream : this.getOutputStreams()) {
			stream.initialise();
		}
	}

	@Override
	public boolean canBeInitialised() {
		for (Tuple3<FlinkStream, PartitioningScheme, Integer> inputStream : inputStreams) {
			if (!inputStream.f0.isInitialised()) return false;
		}
		return true;
	}

	@Override
	public boolean isInitialised() {
		return outStream != null;
	}

	@Override
	public Processor getProcessor() {
		return processor;
	}

	@Override
	public void processElement(StreamRecord<SamoaType> streamRecord) throws Exception {
		fun.processEvent(streamRecord.getValue().f1);
	}

	@Override
	public void processWatermark(Watermark watermark) throws Exception {

	}

	@Override
	public ProcessingItem connectInputShuffleStream(Stream inputStream) {
		inputStreams.add(new Tuple3<>((FlinkStream) inputStream, PartitioningScheme.SHUFFLE, ((FlinkStream) inputStream).getSourcePiId()));
		return this;
	}

	@Override
	public ProcessingItem connectInputKeyStream(Stream inputStream) {
		inputStreams.add(new Tuple3<>((FlinkStream) inputStream, PartitioningScheme.GROUP_BY_KEY, ((FlinkStream) inputStream).getSourcePiId()));
		return this;
	}

	@Override
	public ProcessingItem connectInputAllStream(Stream inputStream) {
		inputStreams.add(new Tuple3<>((FlinkStream) inputStream, PartitioningScheme.BROADCAST, ((FlinkStream) inputStream).getSourcePiId()));
		return this;
	}

	@Override
	public int getParallelism() {
		return parallelism;
	}

	public List<FlinkStream> getOutputStreams() {
		return outputStreams;
	}

	public DataStream<SamoaType> getOutStream() {
		return this.outStream;
	}

	@Override
	public int getComponentId() {
		return piID;
	}

	public boolean isPartOfCycle() {
		return this.cycleId.size() > 0;
	}

	public List<Integer> getCycleIds() {
		return cycleId;
	}

	public void addPItoCycle(int piId) {
		this.cycleId.add(piId);
	}

	public DataStream<SamoaType> getDataStream() {
		return inStream;
	}

	public List<Tuple3<FlinkStream, PartitioningScheme, Integer>> getInputStreams() {
		return inputStreams;
	}

	public void setOnIteration(boolean onIteration) {
		this.onIteration = onIteration;
	}
	

	static class SamoaDelegateFunction implements Function, Serializable {
		private final Processor proc;

		SamoaDelegateFunction(Processor proc) {
			this.proc = proc;
		}

		public void processEvent(ContentEvent event) {
			proc.process(event);
		}
	}

	public FlinkStream getInputStreamBySourceID(int sourceID) {
		for (Tuple3<FlinkStream, PartitioningScheme, Integer> fstreams : inputStreams) {
			if (fstreams.f2 == sourceID) {
				return fstreams.f0;
			}
		}
		return null;
	}

}