// The MIT License (MIT)
//
// Copyright (c) 2018 Mateusz Pusz
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#pragma once

#include <units/concepts.h>
#include <limits>
#include <type_traits>

namespace units {

/**
 * @brief Specifies if a value of a type should be treated as a floating-point value
 * 
 * This type trait should be specialized for a custom representation type to specify
 * that values fo this type should be treated by the library as a floating-point ones
 * which will enable implicit conversions between quantities.
 * 
 * @tparam Rep a representation type for which a type trait is defined
 */
template<Scalar Rep>
inline constexpr bool treat_as_floating_point = std::is_floating_point_v<Rep>;

/**
 * @brief A type trait that defines zero, one, min, and max for a representation type
 * 
 * The zero, one, min, and max member functions in units::quantity forward their work to
 * these methods. This type can be specialized if the representation Rep requires a specific
 * implementation to return these quantity objects.
 * 
 * @tparam Rep a representation type for which a type trait is defined
 */
template<Scalar Rep>
struct quantity_values {
  static constexpr Rep zero() noexcept { return Rep(0); }
  static constexpr Rep one() noexcept { return Rep(1); }
  static constexpr Rep min() noexcept { return std::numeric_limits<Rep>::lowest(); }
  static constexpr Rep max() noexcept { return std::numeric_limits<Rep>::max(); }
};



// // isnan
// namespace isnan_impl {

//   // non-ADL lookup block
//   void isnan(); // undefined

//   template<typename>
//   inline constexpr bool has_customization = false;

//   template<typename T>
//     requires requires(const T& t) {
//       { isnan(t) } -> bool;
//     }
//   inline constexpr bool has_customization<T> = true;

//   struct fn {
//     template<typename T>
//     constexpr bool operator()(const T&) const
//     {
//       return false;
//     }

//     template<typename T>
//       requires treat_as_floating_point<T>
//     constexpr bool operator()(const T& value) const
//     {
//       return std::isnan(value);
//     }

//     template<typename T>
//       requires treat_as_floating_point<T> && has_customization<T>
//     constexpr bool operator()(const T& value) const
//     {
//       return isnan(value);  // uses ADL
//     }
//   };
// }

// inline constexpr isnan_impl::fn isnan{};

// // isfinite
// namespace isfinite_impl {

//   // non-ADL lookup block
//   void isfinite(); // undefined

//   template<typename>
//   inline constexpr bool has_customization = false;

//   template<typename T>
//     requires requires(const T& t) {
//       { isfinite(t) } -> bool;
//     }
//   inline constexpr bool has_customization<T> = true;

//   struct fn {
//     template<typename T>
//     constexpr bool operator()(const T&) const
//     {
//       return true;
//     }

//     template<typename T>
//       requires treat_as_floating_point<T>
//     constexpr bool operator()(const T& value) const
//     {
//       return std::isfinite(value);
//     }

//     template<typename T>
//       requires treat_as_floating_point<T> && has_customization<T>
//     constexpr bool operator()(const T& value) const
//     {
//       return isfinite(value);  // uses ADL
//     }
//   };
// }

// inline constexpr isfinite_impl::fn isfinite{};

} // namespace units