#ifndef NETWORK_HPP
#define NETWORK_HPP

#include <iostream>
#include <vector>
#include <random>
#include <algorithm>
#include "dataset.hpp"
#include "vector.hpp"
#include "matrix.hpp"

using namespace std;

class Trainer;

double sigmoid(double x);
double sigmoid_prime(double x);
double cost_derivative(double a,double y);

class Network{
  friend class Trainer;
protected:
  size_t depth;
  vector<size_t> sizes;
  Matrix* weights;
  Vector *biais;
  Vector *a;
  Vector *z;
  Vector *nabla_b;
  Matrix *nabla_w;
  Vector *delta;
  void shuffle(size_t* tab,size_t size);
  void compute_z(size_t l);
  void compute_a(size_t l);
  void compute_last_delta(const Vector& y);
  void compute_delta(size_t l);
  void init_nabla_b(size_t l);
  void init_nabla_w(size_t l);
  void update_nabla_b(size_t l);
  void update_nabla_w(size_t l);
  void update_b(size_t l,double eta_batch);
  void update_w(size_t l,double eta_batch);
public:
  template<typename ... Sizes> Network(Sizes ... _sizes);
  void init_normal_distribution(double m,double d);
  void init_standard();
  double* new_output_vector() const;
  const Vector& feed_forward(const Vector& x);
  double eval(Dataset* dataset);
  void train(Dataset* dataset,size_t nb_epochs,size_t batch_size,double eta);
  void update_batch(Dataset* dataset,size_t* indices,size_t begin,size_t end,double eta);
  void back_propagation(const Vector& x,const Vector& y,double eta);
  Vector hack(const Vector& x,const Vector& y,double eta,size_t nb_steps,void (*)(const Vector&));
};


inline double
sigmoid(double x){
  return 1.0/(1.0+exp(-x));
};

inline double
sigmoid_prime(double x){
  double t=sigmoid(x);
  return t*(1.0-t);
};

template<typename ... Sizes> inline
Network::Network(Sizes ... _sizes):sizes({(size_t)_sizes ...}){
  depth=sizes.size();

  // Biais vectors
  biais=new Vector[depth];
  for(size_t l=0;l<depth;++l){
    biais[l].resize(sizes[l]);
  }

  // Weights vectors
  weights=new Matrix[depth];
  for(size_t l=1;l<depth;++l){
    weights[l].resize(sizes[l],sizes[l-1]);
  }

  // Activation vectors
  a=new Vector[depth];
  for(size_t l=0;l<depth;++l){
    a[l].resize(sizes[l]);
  }

  // Activation vectors
  z=new Vector[depth];
  for(size_t l=0;l<depth;++l){
    z[l].resize(sizes[l]);
  }

  nabla_b=new Vector[depth];
  for(size_t l=0;l<depth;++l){
    nabla_b[l].resize(sizes[l]);
  }

  nabla_w=new Matrix[depth];
  for(size_t l=1;l<depth;++l){
    nabla_w[l].resize(sizes[l],sizes[l-1]);
  }

  delta=new Vector[depth];
  for(size_t l=0;l<depth;++l){
    delta[l].resize(sizes[l]);
  }
}

inline double
cost_derivative(double a,double y){
  return a-y;
}

#endif