//===-- rosa/support/math.hpp -----------------------------------*- C++ -*-===//
//
//                                 The RoSA Framework
//
//===----------------------------------------------------------------------===//
///
/// \file rosa/support/math.hpp
///
/// \author David Juhasz (david.juhasz@tuwien.ac.at)
///
/// \date 2017
///
/// \brief Math helpers.
///
//===----------------------------------------------------------------------===//

// !!!!!! Please check lines 60 - 180 forward !!!!!!!!!!!!!!

#ifndef ROSA_SUPPORT_MATH_HPP
#define ROSA_SUPPORT_MATH_HPP

#include "debug.hpp"
#include <algorithm>
#include <array>
#include <cmath>
#include <cstdarg>
#include <cstdlib>
#include <limits>
#include <type_traits>

namespace rosa {

/// Computes log base 2 of a number.
///
/// \param N the number to compute log base 2 for
///
/// \return log base 2 of \p N
constexpr size_t log2(const size_t N) {
  return ((N < 2) ? 1 : 1 + log2(N / 2));
}

/// Tells the next representable floating point value.
///
/// \tparam T type to operate on
///
/// \note The second type argument enforces \p T being a floating point type,
/// always use the default value!
///
/// \param V value to which find the next representable one
///
/// \return the next representable value of type \p T after value \p V
///
/// \pre Type \p T must be a floating point type, which is enforced by
/// `std::enable_if` in the second type argument.
template <typename T,
          typename = std::enable_if_t<std::is_floating_point<T>::value>>
T nextRepresentableFloatingPoint(const T V) {
  return std::nextafter(V, std::numeric_limits<T>::infinity());
}


/// Conjuncts two or more values with each other.
///
/// \param Data an array of the data
///
/// \return the conjunction of the values given as parameter.
template <typename CONFDATATYPE, std::size_t size>
CONFDATATYPE fuzzyAND(const std::array<CONFDATATYPE, size> & Data) noexcept {
  STATIC_ASSERT(std::is_arithmetic<CONFDATATYPE>::value,
                "Type of FuzzyAnd is not arithmetic");
  STATIC_ASSERT(size > 1, "Number of Arguments is to little");
  for (auto tmp : Data)
    ASSERT(tmp <= 1 && tmp >= 0);
  return *std::min_element(Data.begin(), Data.end());
}

/// Conjuncts two or more values with each other. It's a wrapper for \c fuzzyAND() [array]
///
/// \param Data first data to get the type explicitly
///
/// \param Datan a package of data 
/// 
/// \note the types of Datan must be the same type as Data
///
/// \return the conjunction of the values given as parameter.
template <typename CONFDATATYPE, typename... _CONFDATATYPE>
std::enable_if_t<
    std::conjunction_v<std::is_same<CONFDATATYPE, _CONFDATATYPE>...>,
    CONFDATATYPE>
fuzzyAND(const CONFDATATYPE Data, const _CONFDATATYPE... Datan) noexcept {
  return fuzzyAND(
      std::array<CONFDATATYPE, sizeof...(Datan) + 1>{Data, Datan...});
}




/// Disjuncts two or more values with each other.
/// 
/// \param Data an array with the data.
/// 
/// \return the disjunction of the values given as parameter.
template <typename CONFDATATYPE, std::size_t size>
CONFDATATYPE fuzzyOR(const std::array<CONFDATATYPE, size> & Data) noexcept {
  STATIC_ASSERT(std::is_arithmetic<CONFDATATYPE>::value,
                "Type of FuzzyAnd is not arithmetic");
  STATIC_ASSERT(size > 1, "Number of Arguments is to little");
  ASSERT(std::all_of(Data.begin(), Data.end(),
                     [](const auto &v) { return v <= 1 && v >= 0; }));
  return *std::max_element(Data.begin(), Data.end());
}

/// Disjuncts two or more values with each other. It's a wrapper for \c fuzzyOR() [array]
///
/// \param Data first data to get the type explicitly
///
/// \param Datan a package of data
///
/// \note the types of Datan must be the same type as Data
///
/// \return the disjunction of the values given as parameter.
template <typename CONFDATATYPE, typename... _CONFDATATYPE>
std::enable_if_t<
    std::conjunction_v<std::is_same<CONFDATATYPE, _CONFDATATYPE>...>,
    CONFDATATYPE>
fuzzyOR(const CONFDATATYPE Data, const _CONFDATATYPE...  Datan) noexcept {
  return fuzzyOR(
      std::array<CONFDATATYPE, sizeof...(Datan) + 1>{Data, Datan...});
}


template <typename INDATATYPE, typename PROCDATATYPE>
PROCDATATYPE relativeDistance(INDATATYPE NewValue,
                              INDATATYPE HistoryValue) noexcept {
  PROCDATATYPE Dist = HistoryValue - NewValue;

  if (Dist == 0) {
    return 0;
  } else {
    Dist = Dist / NewValue;
    if (Dist < 0) {
      // TODO: I guess this multiplication here should not be done because
      // it could be that the distance fuzzy functions are not symetrical
      //(negative and positive side)
      Dist = Dist * (-1);
    }
    return (Dist);
  }
}

} // End namespace rosa

#endif // ROSA_SUPPORT_MATH_HPP