/*
 * #%L
 * Image processing operations for SciJava Ops.
 * %%
 * Copyright (C) 2014 - 2024 SciJava developers.
 * %%
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package org.scijava.ops.image.geom.geom2d;

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

import org.scijava.ops.image.geom.GeomUtils;
import net.imglib2.RealLocalizable;
import net.imglib2.roi.geom.real.Polygon2D;
import net.imglib2.type.numeric.real.DoubleType;

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

/**
 * Generic implementation of {@code geom.mainElongation} based on
 * http://www.math.uci.edu/icamp/summer/research_11/park/
 * shape_descriptors_survey.pdf.
 *
 * @author Tim-Oliver Buchholz, University of Konstanz
 * @implNote op names='geom.mainElongation', label='Geometric (2D): Elongation'
 */
public class DefaultElongation implements
	Computers.Arity1<Polygon2D, DoubleType>
{

	@OpDependency(name = "geom.smallestEnclosingBoundingBox")
	private Function<Polygon2D, Polygon2D> minimumBoundingBoxFunc;

	/**
	 * TODO
	 *
	 * @param input
	 * @param elongation
	 */
	@Override
	public void compute(final Polygon2D input, final DoubleType elongation) {
		final List<? extends RealLocalizable> minBB = GeomUtils.vertices(
			minimumBoundingBoxFunc.apply(input));

		final var p1 = minBB.get(0);
		final var p2 = minBB.get(1);
		final var p3 = minBB.get(2);

        var width = Math.sqrt(Math.pow(p1.getDoublePosition(0) - p2
			.getDoublePosition(0), 2) + Math.pow(p1.getDoublePosition(1) - p2
				.getDoublePosition(1), 2));
        var length = Math.sqrt(Math.pow(p2.getDoublePosition(0) - p3
			.getDoublePosition(0), 2) + Math.pow(p2.getDoublePosition(1) - p3
				.getDoublePosition(1), 2));

		if (width > length) {
			final var tmp = width;
			width = length;
			length = tmp;
		}
		elongation.set(1d - (width / length));
	}

}
