/*
 * #%L
 * Image processing operations for SciJava Ops.
 * %%
 * Copyright (C) 2014 - 2024 SciJava developers.
 * %%
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 * modification, are permitted provided that the following conditions are met:
 * 
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 *    this list of conditions and the following disclaimer.
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 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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package org.scijava.ops.image.thread.chunker;

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

import org.scijava.concurrent.Parallelization;
import org.scijava.function.Inplaces;

/**
 * Implementation of a {@code thread.chunker} Op that interleaves the chunks. In
 * a element enumeration from 1..n with <b>k</b> {@link Chunk}s the first one
 * will process the elements 1, k+1, 2k+1, ... the second chunk executable 2,
 * k+2, 2k+2 and so on.
 *
 * @author Michael Zinsmaier (University of Konstanz)
 * @implNote op names='thread.chunker', priority='-10000.'
 */
public class ChunkerInterleaved implements Inplaces.Arity2_1<Chunk, Long> {

	private String cancellationMsg;

	/**
	 * TODO
	 *
	 * @param chunk
	 * @param numberOfElements
	 */
	@Override
	public void mutate(final Chunk chunk, final Long numberOfElements) {

		final var numThreads = Runtime.getRuntime().availableProcessors();
		final var numStepsFloor = (int) (numberOfElements / numThreads);
		final var remainder = numberOfElements.intValue() - (numStepsFloor *
			numThreads);

		final List<Runnable> list = new ArrayList<>(numThreads);

		for (var i = 0; i < numThreads; i++) {
			final var j = i;

			list.add(() -> {

				if (j < remainder) {
					chunk.execute(j, numThreads, (numStepsFloor + 1));
				}
				else {
					chunk.execute(j, numThreads, numStepsFloor);
				}
			});
		}

		Parallelization.getTaskExecutor().runAll(list);
	}

}
