/*
 * #%L
 * Image processing operations for SciJava Ops.
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 *    this list of conditions and the following disclaimer.
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package org.scijava.ops.image.stats;

import java.util.List;
import java.util.function.Function;

import net.imglib2.RandomAccessibleInterval;
import net.imglib2.loops.LoopBuilder;
import net.imglib2.type.numeric.RealType;
import net.imglib2.util.Pair;
import net.imglib2.util.Util;
import net.imglib2.util.ValuePair;

import org.scijava.ops.spi.Op;

/**
 * Op to calculate the {@code stats.minMax}.
 *
 * @author Daniel Seebacher (University of Konstanz)
 * @author Christian Dietz (University of Konstanz)
 * @param <I> input type
 * @implNote op names='stats.minMax', priority='100.'
 */
public class DefaultMinMax<I extends RealType<I>> implements
	Function<RandomAccessibleInterval<I>, Pair<I, I>>
{

	/**
	 * TODO
	 *
	 * @param input the {@link RandomAccessibleInterval} to iterate over
	 * @return the minimum and the maximum of the input data
	 */
	@Override
	public Pair<I, I> apply(final RandomAccessibleInterval<I> input) {
		// set minVal to the largest possible value and maxVal to the smallest
		// possible.
		final var minVal = Util.getTypeFromInterval(input).createVariable();
		minVal.setReal(minVal.getMinValue());
		final var maxVal = minVal.createVariable();
		maxVal.setReal(maxVal.getMaxValue());

		List<Pair<I, I>> minMaxes = LoopBuilder.setImages(input).multiThreaded()
			.forEachChunk(chunk -> {
				final var min = maxVal.copy();
				final var max = minVal.copy();

				chunk.forEachPixel((in) -> {
					if (in.compareTo(min) < 0) min.set(in);
					if (in.compareTo(max) > 0) max.set(in);
				});

				return new ValuePair<>(min, max);
			});

		final var raiMin = minMaxes.parallelStream() //
			.map(pair -> pair.getA()) //
			.reduce(maxVal, (result, min) -> min.compareTo(result) < 0 ? min
				: result);
		final var raiMax = minMaxes.parallelStream() //
			.map(pair -> pair.getB()) //
			.reduce(minVal, (result, max) -> max.compareTo(result) > 0 ? max
				: result);
		return new ValuePair<>(raiMin, raiMax);
	}

}
