/*
  ==============================================================================

    Layer.hpp
    Created: 21 Sep 2014 1:55:15pm
    Author:  jens

  ==============================================================================
*/

#ifndef LAYER_HPP
#define LAYER_HPP
#include <cstdint>
#include "noise.h"
#include "Weights.hpp"

class Layer
{
public:
	Layer(uint32_t numUnits = 0, const double *pStatesInit = nullptr)
	: m_numUnits(numUnits)
	, m_pProbs(nullptr)
	, m_pStates(nullptr)
	, m_pStatesInit(pStatesInit)
	{
		setNumUnits(numUnits);
		Noise_Init(&m_noise, 0x12345677);
	}

	virtual ~Layer()
	{
		setNumUnits(0);
		Noise_Free(&m_noise);
	}

	void setNumUnits(uint32_t numUnits)
	{
		if (m_numUnits)
		{
			delete [] m_pProbs;
			delete [] m_pStates;
		}
		m_numUnits = numUnits;
		if (m_numUnits)
		{
			uint32_t i;

			m_pProbs = new double[m_numUnits];
			m_pStates = new double[m_numUnits];

			for (i=0; i < m_numUnits; i++)
			{
				m_pProbs[i] = 0.0;
			}

			for (i=0; i < m_numUnits; i++)
			{
				m_pStates[i] = 0.0;
			}
			if (m_pStatesInit)
			{
				memcpy(m_pStates, m_pStatesInit, m_numUnits*sizeof(double));
			}
		}
	}

	Layer& operator= (const Layer &rhs)
	{
		memcpy(m_pProbs, rhs.m_pProbs, m_numUnits*sizeof(double));
		memcpy(m_pStates, rhs.m_pStates, m_numUnits*sizeof(double));

		return *this;
	}

	void probsUpdate(const Layer &layer, const Weights &weights) const
	{
		uint32_t i;

		for (i=0; i < m_numUnits; i++)
		{
			m_pProbs[i] = logSigmoid(accum(layer, weights, i));
		}
	}

	void statesAssignfromProbs()
	{
		memcpy(m_pStates, m_pProbs, m_numUnits*sizeof(double));
	}

	void statesUpdateStochastic()
	{
		uint32_t i;
		double sample;

		for (i=0; i < m_numUnits; i++)
		{
			sample = Noise_Uniform(&m_noise, 0.5);
			m_pStates[i] = (double)(sample <= m_pProbs[i]);
		}
	}

	const double *getProbs() const
	{
		return m_pProbs;
	}

	const double *getStates() const
	{
		return m_pStates;
	}

	uint32_t getNumUnits() const
	{
		return m_numUnits;
	}

	virtual double getEnergy(const Weights &weights) = 0;

private:
	uint32_t m_numUnits;
	noise_gen_t m_noise;

	inline double logSigmoid(double x) const
	{
		return 1./(1 + exp(-x));
	}

protected:
	double *m_pProbs;
	double *m_pStates;
	const double *m_pStatesInit;

	virtual double accum(const Layer &layer, const Weights &weights, uint32_t index) const = 0;


};

#endif  // LAYER_HPP