#pragma once

#include <stdexcept>
#include <type_traits>

namespace detail
{
template <typename Integer>
constexpr Integer intlog2_impl(Integer integer)
{
    auto degree = Integer{0};

    while ((integer >>= 1) > 0) { ++degree; }

    return degree;
}
} // namespace detail

template <typename Integer>
constexpr Integer intlog2(Integer integer)
{
    static_assert(std::is_integral_v<Integer>, "Input type must be an integral type.");

    return integer > 0 ? detail::intlog2_impl(integer)
                       : throw std::domain_error("The binary logarithm is not defined on non-positive numbers.");
}