/*
 * #%L
 * Image processing operations for SciJava Ops.
 * %%
 * Copyright (C) 2014 - 2024 SciJava developers.
 * %%
 * Redistribution and use in source and binary forms, with or without
 * 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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 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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package org.scijava.ops.image.stats;

import net.imglib2.RandomAccessibleInterval;
import net.imglib2.type.numeric.RealType;

import org.scijava.function.Computers;
import org.scijava.ops.spi.Op;
import org.scijava.ops.spi.OpDependency;

/**
 * Op to calculate the {@code stats.kurtosis} using {@code stats.stdDev} and
 * {@code stats.moment4AboutMean}.
 *
 * @author Daniel Seebacher (University of Konstanz)
 * @author Christian Dietz (University of Konstanz)
 * @param <I> input type
 * @param <O> output type
 * @implNote op names='stats.kurtosis'
 */
public class DefaultKurtosis<I extends RealType<I>, O extends RealType<O>>
	implements Computers.Arity1<RandomAccessibleInterval<I>, O>
{

	@OpDependency(name = "stats.stdDev")
	private Computers.Arity1<RandomAccessibleInterval<I>, O> stdDevComputer;

	@OpDependency(name = "stats.moment4AboutMean")
	private Computers.Arity1<RandomAccessibleInterval<I>, O> moment4AboutMeanComputer;

	/**
	 * TODO
	 *
	 * @param input
	 * @param kurtosis
	 */
	@Override
	public void compute(final RandomAccessibleInterval<I> input,
		final O kurtosis)
	{
		kurtosis.setReal(Double.NaN);

		final var std = kurtosis.createVariable();
		stdDevComputer.compute(input, std);
		final var moment4 = kurtosis.createVariable();
		moment4AboutMeanComputer.compute(input, moment4);

		if (std.getRealDouble() != 0) {
			kurtosis.setReal(moment4.getRealDouble() / Math.pow(std.getRealDouble(),
				4));
		}
	}
}
