/*
 * SkewFunc.hh
 *
 *  Created on: Jun 23, 2018
 *      Author: benjamin
 */

#ifndef SKEWFUNC_HH_
#define SKEWFUNC_HH_

#include "AbstractFunc.hh"
#include "Toolbox.hh"

namespace AMDA {
namespace Parameters {
namespace StatisticFunctions {

template <typename InputElemType, typename OutputElemType>
OutputElemType computeSkew(std::list<std::pair<double,InputElemType>>& mem, OutputElemType& nanVal) {
	OutputElemType result = nanVal;
	if (mem.empty()) {
		return result;
	}

	result << ElemNull();
	OutputElemType mean = result;
	int n = 0;
	for (auto val : mem) {
		if (isNAN(val.second))
			continue;
		mean = mean+val.second;
		++n;
	}
	if (n == 0) {
		result << NotANumber();
		return result;
	}
	mean = 1./n*mean;

	OutputElemType m3 = result;
	OutputElemType m2 = result;
	for (auto val : mem) {
		m3 = m3 + StatisticFunctions::pow((val.second - mean),3);
		m2 = m2 + StatisticFunctions::square((val.second - mean));
	}
	m3 = 1./n*m3;
	m2 = 1./n*m2;

	result = StatisticFunctions::div(m3,StatisticFunctions::pow(m2,1.5));

	return result;
}

/**
 * @class SkewFunc
 * @brief 
 * @details This class implements AbstractFunc.
 */
template <typename InputElemType, typename OutputElemType> 
class SkewFunc : public ClassicAbstractFunc<InputElemType,OutputElemType> {
public:
	/**
	 * @brief Constructor.
	 */
	SkewFunc(Process& pProcess, TimeIntervalListSPtr pTimeIntervalList, ParamDataSpec<InputElemType>& paramInput, double windowtime)
	: ClassicAbstractFunc<InputElemType,OutputElemType>(pProcess, pTimeIntervalList, paramInput, windowtime) {
	}

	virtual ~SkewFunc() {
	}

	OutputElemType compute() {
		return computeSkew(ClassicAbstractFunc<InputElemType,OutputElemType>::_mem, ClassicAbstractFunc<InputElemType,OutputElemType>::_nanVal);
	}
};  

/**
 * @class SkewFuncSm
 * @brief
 * @details This class implements AbstractFunc.
 */
template <typename InputElemType, typename OutputElemType>
class SkewSmFunc : public SmAbstractFunc<InputElemType,OutputElemType> {
public:
	/**
	 * @brief Constructor.
	 */
	SkewSmFunc(Process& pProcess, TimeIntervalListSPtr pTimeIntervalList, ParamDataSpec<InputElemType>& paramInput, double windowtime)
	: SmAbstractFunc<InputElemType,OutputElemType>(pProcess, pTimeIntervalList, paramInput, windowtime) {
        }

	virtual ~SkewSmFunc() {
	}

	OutputElemType compute() {
		return computeSkew(SmAbstractFunc<InputElemType,OutputElemType>::_mem, SmAbstractFunc<InputElemType,OutputElemType>::_nanVal);
        }
};


} /* namespace StatisticFunctions */
} /* namespace Parameters */
} /* namespace AMDA */
#endif /* SKEWFUNC_HH_ */