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#ifndef TEMPLAT_LATTICE_ALGEBRA_OPERATORS_SQUAREROOT_H
#define TEMPLAT_LATTICE_ALGEBRA_OPERATORS_SQUAREROOT_H

/* This file is part of TempLat, available at https://cosmolattice.github.io/templat .
   Copyright 2021-2026 The TempLat authors, see AUTHORS.md.
   Released under the MIT license, see LICENSE.md. */

// File info: Main contributor(s): Wessel Valkenburg, Franz R. Sattler, Year: 2025

#include "TempLat/lattice/algebra/operators/power.h"

#include "TempLat/lattice/algebra/constants/halftype.h"

namespace TempLat
{
  using device::sqrt;

  namespace Operators
  {
    template <typename R> struct SafeSqrt : public UnaryOperator<R> {
    public:
      using UnaryOperator<R>::mR;

      SafeSqrt(const R &pR) : UnaryOperator<R>(pR) {}

      template <typename... IDX>
        requires requires(std::decay_t<R> r, IDX... idx) {
          requires IsVariadicIndex<IDX...>;
          DoEval::eval(r, idx...);
        }
      DEVICE_INLINE_FUNCTION auto eval(const IDX &...idx) const
      {
        const auto a = DoEval::eval(mR, idx...);
        constexpr decltype(a) zero{};
        return (a < zero) ? zero : sqrt(a);
      }

      virtual std::string operatorString() const override { return "safe_sqrt"; }

      template <typename U> void d(const U &other) = delete;
    };
  } // namespace Operators

  template <typename R>
    requires ConditionalUnaryGetter<R>
  auto safeSqrt(const R &r)
  {
    return Operators::SafeSqrt<R>(r);
  }

  template <typename T>
    requires(ConditionalBinaryGetter<T, HalfType> && !std::is_arithmetic_v<T>)
  auto sqrt(T a)
  {
    return Operators::Power<T, HalfType>(a, HalfType());
  }

  constexpr inline ZeroType sqrt(ZeroType a) { return a; }

  constexpr inline OneType sqrt(OneType a) { return a; }
} // namespace TempLat

#endif