#ifndef K_MATH_DISTRIBUTION_VONMISES_H
#define K_MATH_DISTRIBUTION_VONMISES_H

#include <cmath>
#include <random>

#include "../Math.h"
#include "Bessel.h"
#include "LUT.h"

namespace Distribution {

	/** von-mises distribution */
	template <typename T> class VonMises {

	private:

		/** center of the distribution */
		const T mu;

		/** like 1.0/variance of the distribution */
		const T kappa;

		/** pre-calcuated look-up-table */
		std::vector<T> lut;

		/** helper for modified bessel I_0(kappa) */
		Bessel<T> bessel;

	public:

		/** ctor */
		VonMises(const T mu, const T kappa) : mu(mu), kappa(kappa) {

		}

		LUT<T> getLUT() const {
			return LUT<T>(*this, -M_PI, +M_PI, 10000);
		}

		/** get probability for the given value */
		T getProbability(const T _val) const {

			const T val = Math::clamp((T)-M_PI, (T)+M_PI, _val);

			return
					std::exp(kappa * std::cos(val - mu)) /
					(2 * M_PI * bessel.getModified(0, kappa));

		}

	};

}

#endif // K_MATH_DISTRIBUTION_VONMISES_H