#ifndef ARBUTILS_OPTIONALOptionalUniquePtr_HPP
#define ARBUTILS_OPTIONALOptionalUniquePtr_HPP

#include "../Assert.hpp"

namespace ArbUt {
    /// @brief An optional unique pointer is used to indicate a pointer that is owned by its holder, and will be deleted
    /// when its owner is deleted.
    /// @details A unique pointer is used to indicate a pointer that is owned by an object, and that needs to be deleted
    /// when its owner is deleted.
    template <class T> class OptionalUniquePtr {
    private:
        T* _raw;

    public:
        /// @brief Initialise a OptionalUniquePtr with a specific raw pointer.
        inline OptionalUniquePtr<T>(__attribute__((nonnull)) T* ptr) : _raw(ptr){};
        /// @brief Initialise a OptionalUniquePtr from a copy.
        inline OptionalUniquePtr<T>(const OptionalUniquePtr<T>& other) : _raw(other._raw){};
        /// @brief Initialise a OptionalUniquePtr with a std unique_ptr.
        inline OptionalUniquePtr<T>(const std::unique_ptr<T>& other) : _raw(other.get()){};

        ~OptionalUniquePtr() noexcept { delete _raw; }

        /// @brief Copy operator.
        inline OptionalUniquePtr<T>& operator=(const OptionalUniquePtr<T>& rhs) {
            if (this == &rhs)
                return *this;
            _raw = rhs._raw;
            return *this;
        }

        inline OptionalUniquePtr<T>& operator=(__attribute__((nonnull)) T* rhs) {
            if (_raw == &rhs)
                return *this;
            AssertNotNull(rhs);
            _raw = rhs;
            return *this;
        }

        /// @brief Operator for access into underlying pointer.
        /// @warning Note that this asserts that the underlying pointer is not null first, to prevent segfaults.
        inline T* operator->() const noexcept { return _raw; }

        /// @brief Get the raw underlying pointer.
        inline T* GetRaw() const noexcept { return _raw; }

        /// @brief Check equality of two OptionalUniquePtr objects
        inline bool operator==(const OptionalUniquePtr& rhs) const noexcept { return _raw == rhs._raw; }
        /// @brief Check equality of pointers
        inline bool operator==(T* rhs) const noexcept { return _raw == rhs; }
        /// @brief Check equality of two OptionalUniquePtr objects
        inline bool operator!=(const OptionalUniquePtr& rhs) const noexcept { return _raw != rhs._raw; }
        /// @brief Check equality of pointers
        inline bool operator!=(T* rhs) const noexcept { return _raw == rhs; }

        /// @brief Implicit cast to retrieve raw pointer.
        inline operator T*() const noexcept {
            AssertNotNull(_raw);
            return _raw;
        }
    };
}

namespace std {
    /// @brief Helper class for allowing hashing of OptionalUniquePtr.
    template <class T> struct hash<ArbUt::OptionalUniquePtr<T>> {
        /// @brief Returns a hash of for a borrowed Pointer. Effectively just the raw memory address.
        /// @param k A borrowed pointer.
        /// @return The hash of the borrowed pointer.
        std::size_t operator()(const ArbUt::OptionalUniquePtr<T>& k) const { return (size_t)k.GetRaw(); }
    };
}

#endif // ARBUTILS_OPTIONALOptionalUniquePtr_HPP