// SPDX-License-Identifier: BSD-3-Clause
/* Copyright 2018-2021, Intel Corporation */

/**
 * @file
 * Persistent pointer for pool handle.
 */

#ifndef PMEMOBJ_PERSISTENT_POOL_PTR_HPP
#define PMEMOBJ_PERSISTENT_POOL_PTR_HPP

#include <cassert>
#include <cstddef>
#include <type_traits>

#include <libpmemobj++/detail/specialization.hpp>
#include <libpmemobj++/persistent_ptr.hpp>

namespace pmem
{
namespace detail
{

template <typename T>
class persistent_pool_ptr {
	template <typename Y>
	friend class persistent_pool_ptr;

	typedef persistent_pool_ptr<T> this_type;

public:
	/**
	 * Type of an actual object with all qualifier removed,
	 * used for easy underlying type access
	 */
	typedef typename pmem::detail::sp_element<T>::type element_type;

	persistent_pool_ptr() : off(0)
	{
		verify_type();
	}

	/**
	 *  Default null constructor, zeroes the off.
	 */
	persistent_pool_ptr(std::nullptr_t) noexcept : off(0)
	{
		verify_type();
	}

	/**
	 * PMEMoid constructor.
	 *
	 * Provided for easy interoperability between C++ and C API's.
	 *
	 * @param oid C-style persistent pointer
	 */
	persistent_pool_ptr(PMEMoid oid) noexcept : off(oid.off)
	{
		verify_type();
	}

	/**
	 * PMEMoid constructor.
	 *
	 * Provided for easy interoperability between C++ and C API's.
	 *
	 * @param off offset inside persistent memory pool
	 */
	persistent_pool_ptr(uint64_t _off) noexcept : off(_off)
	{
		verify_type();
	}

	/**
	 * Copy constructor from a different persistent_pool_ptr<>.
	 *
	 * Available only for convertible types.
	 *
	 */
	template <typename Y,
		  typename = typename std::enable_if<
			  std::is_convertible<Y *, T *>::value>::type>
	persistent_pool_ptr(const persistent_pool_ptr<Y> &r) noexcept
	    : off(r.off)
	{
		verify_type();
	}

	/**
	 * Copy constructor from a different persistent_ptr<>.
	 *
	 * Available only for convertible types.
	 *
	 */
	template <typename Y,
		  typename = typename std::enable_if<
			  std::is_convertible<Y *, T *>::value>::type>
	persistent_pool_ptr(const pmem::obj::persistent_ptr<Y> &r) noexcept
	    : off(r.raw().off)
	{
		verify_type();
	}

	/*
	 * Copy constructor.
	 *
	 * @param r Persistent pool pointer to the same type.
	 */
	persistent_pool_ptr(const persistent_pool_ptr &r) noexcept : off(r.off)
	{
		verify_type();
	}

	/*
	 * Copy constructor from a persistent_ptr.
	 *
	 * @param r Persistent pointer to the same type.
	 */
	persistent_pool_ptr(const pmem::obj::persistent_ptr<T> &r) noexcept
	    : off(r.raw().off)
	{
		verify_type();
	}

	/**
	 * Move constructor.
	 */
	persistent_pool_ptr(persistent_pool_ptr &&r) noexcept
	    : off(std::move(r.off))
	{
		verify_type();
	}

	/**
	 * Move assignment operator.
	 */
	persistent_pool_ptr &
	operator=(persistent_pool_ptr &&r)
	{
		conditional_add_to_tx(this);
		this->off = std::move(r.off);

		return *this;
	}

	persistent_pool_ptr &operator=(std::nullptr_t)
	{
		conditional_add_to_tx(this);
		this->off = 0;

		return *this;
	}

	/**
	 * Assignment operator.
	 *
	 * Persistent pool pointer assignment within a transaction
	 * automatically registers this operation so that a rollback
	 * is possible.
	 *
	 * @throw pmem::transaction_error when adding the object to the
	 *	transaction failed.
	 */
	persistent_pool_ptr &
	operator=(const persistent_pool_ptr &r)
	{
		conditional_add_to_tx(this);
		this->off = r.off;

		return *this;
	}

	/**
	 * Assignment operator from a persistent_ptr.
	 *
	 * Persistent pool pointer assignment within a transaction
	 * automatically registers this operation so that a rollback
	 * is possible.
	 *
	 * @throw pmem::transaction_error when adding the object to the
	 *	transaction failed.
	 */
	persistent_pool_ptr &
	operator=(const pmem::obj::persistent_ptr<T> &r)
	{
		conditional_add_to_tx(this);
		this->off = r.raw().off;

		return *this;
	}

	/**
	 * Assignment operator from a PMEMoid.
	 *
	 * Persistent pool pointer assignment within a transaction
	 * automatically registers this operation so that a rollback
	 * is possible.
	 *
	 * @throw pmem::transaction_error when adding the object to the
	 *	transaction failed.
	 */
	persistent_pool_ptr &
	operator=(const PMEMoid &oid)
	{
		conditional_add_to_tx(this);
		this->off = oid.off;
		return *this;
	}

	/**
	 * Converting assignment operator from a different
	 * persistent_pool_ptr<>.
	 *
	 * Available only for convertible types.
	 * Just like regular assignment, also automatically registers
	 * itself in a transaction.
	 *
	 * @throw pmem::transaction_error when adding the object to the
	 *	transaction failed.
	 */
	template <typename Y,
		  typename = typename std::enable_if<
			  std::is_convertible<Y *, T *>::value>::type>
	persistent_pool_ptr &
	operator=(const persistent_pool_ptr<Y> &r)
	{
		conditional_add_to_tx(this);
		this->off = r.off;

		return *this;
	}

	/**
	 * Converting assignment operator from a different
	 * persistent_ptr<>.
	 *
	 * Available only for convertible types.
	 * Just like regular assignment, also automatically registers
	 * itself in a transaction.
	 *
	 * @throw pmem::transaction_error when adding the object to the
	 *	transaction failed.
	 */
	template <typename Y,
		  typename = typename std::enable_if<
			  std::is_convertible<Y *, T *>::value>::type>
	persistent_pool_ptr &
	operator=(const pmem::obj::persistent_ptr<Y> &r)
	{
		conditional_add_to_tx(this);
		this->off = r.raw().off;

		return *this;
	}

	/**
	 * Get a direct pointer.
	 *
	 * Performs a calculations on the underlying C-style pointer.
	 *
	 * @return a direct pointer to the object.
	 */
	element_type *
	get(uint64_t pool_uuid) const noexcept
	{
		PMEMoid oid = {pool_uuid, this->off};
		return static_cast<element_type *>(pmemobj_direct(oid));
	}

	element_type *
	operator()(uint64_t pool_uuid) const noexcept
	{
		return get(pool_uuid);
	}

	/**
	 * Get a persistent pointer.
	 *
	 * Performs a calculations on the underlying C-style pointer.
	 *
	 * @return a direct pointer to the object.
	 */
	pmem::obj::persistent_ptr<T>
	get_persistent_ptr(uint64_t pool_uuid) const noexcept
	{
		PMEMoid oid = {pool_uuid, this->off};
		return pmem::obj::persistent_ptr<T>(oid);
	}

	/**
	 * Swaps two persistent_pool_ptr objects of the same type.
	 */
	void
	swap(persistent_pool_ptr &other)
	{
		conditional_add_to_tx(this);
		conditional_add_to_tx(&other);
		std::swap(this->off, other.off);
	}

	/*
	 * Bool conversion operator.
	 */
	explicit operator bool() const noexcept
	{
		return this->off != 0;
	}

	/**
	 * Get PMEMoid encapsulated by this object.
	 *
	 * For C API compatibility.
	 *
	 * @return const reference to the PMEMoid
	 */
	PMEMoid
	raw_oid(uint64_t pool_uuid) const noexcept
	{
		PMEMoid oid = {pool_uuid, this->off};
		return oid;
	}

	const uint64_t &
	raw() const noexcept
	{
		return this->off;
	}

	uint64_t &
	raw()
	{
		conditional_add_to_tx(this);
		return this->off;
	}

	/**
	 * Prefix increment operator.
	 */
	inline persistent_pool_ptr<T> &
	operator++()
	{
		conditional_add_to_tx(this);
		this->off += sizeof(T);

		return *this;
	}

	/**
	 * Postfix increment operator.
	 */
	inline persistent_pool_ptr<T>
	operator++(int)
	{
		persistent_pool_ptr<T> ret(*this);
		++(*this);

		return ret;
	}

	/**
	 * Prefix decrement operator.
	 */
	inline persistent_pool_ptr<T> &
	operator--()
	{
		conditional_add_to_tx(this);
		this->off -= sizeof(T);

		return *this;
	}

	/**
	 * Postfix decrement operator.
	 */
	inline persistent_pool_ptr<T>
	operator--(int)
	{
		persistent_pool_ptr<T> ret(*this);
		--(*this);

		return ret;
	}

	/**
	 * Addition assignment operator.
	 */
	inline persistent_pool_ptr<T> &
	operator+=(std::ptrdiff_t s)
	{
		conditional_add_to_tx(this);
		this->off += s * sizeof(T);

		return *this;
	}

	/**
	 * Subtraction assignment operator.
	 */
	inline persistent_pool_ptr<T> &
	operator-=(std::ptrdiff_t s)
	{
		conditional_add_to_tx(this);
		this->off -= s * sizeof(T);

		return *this;
	}

	inline persistent_pool_ptr<T>
	operator+(std::ptrdiff_t s)
	{
		persistent_pool_ptr<T> ret(*this);
		ret.off += s * sizeof(T);

		return ret;
	}

	inline persistent_pool_ptr<T>
	operator-(std::ptrdiff_t s)
	{
		persistent_pool_ptr<T> ret(*this);
		ret.off -= s * sizeof(T);

		return ret;
	}

private:
	/* offset of persistent object in a persistent memory pool */
	uint64_t off;

	void
	verify_type()
	{
		static_assert(!std::is_polymorphic<element_type>::value,
			      "Polymorphic types are not supported");
	}
};

/**
 * Equality operator.
 *
 * This checks if underlying PMEMoids are equal.
 * @relates persistent_pool_ptr
 */
template <typename T, typename Y>
inline bool
operator==(const persistent_pool_ptr<T> &lhs,
	   const persistent_pool_ptr<Y> &rhs) noexcept
{
	return lhs.raw() == rhs.raw();
}

/**
 * Inequality operator.
 * @relates persistent_pool_ptr
 */
template <typename T, typename Y>
inline bool
operator!=(const persistent_pool_ptr<T> &lhs,
	   const persistent_pool_ptr<Y> &rhs) noexcept
{
	return !(lhs == rhs);
}

/**
 * Inequality operator with nullptr.
 * @relates persistent_pool_ptr
 */
template <typename T>
inline bool
operator!=(const persistent_pool_ptr<T> &lhs, std::nullptr_t) noexcept
{
	return lhs.raw() != 0;
}

/**
 * Inequality operator with nullptr.
 * @relates persistent_pool_ptr
 */
template <typename T>
inline bool
operator!=(std::nullptr_t, const persistent_pool_ptr<T> &lhs) noexcept
{
	return lhs.raw() != 0;
}

/**
 * Equality operator with nullptr.
 * @relates persistent_pool_ptr
 */
template <typename T>
inline bool
operator==(const persistent_pool_ptr<T> &lhs, std::nullptr_t) noexcept
{
	return lhs.raw() == 0;
}

/**
 * Equality operator with nullptr.
 * @relates persistent_pool_ptr
 */
template <typename T>
inline bool
operator==(std::nullptr_t, const persistent_pool_ptr<T> &lhs) noexcept
{
	return lhs.raw() == 0;
}

template <class T, class U>
persistent_pool_ptr<T>
static_persistent_pool_pointer_cast(const persistent_pool_ptr<U> &r)
{
	static_assert(std::is_convertible<T *, U *>::value,
		      "Cannot cast persistent_pool_ptr");
	return persistent_pool_ptr<T>(r.raw());
}

} // namespace detail
} // namespace pmem

#endif // PMEMOBJ_PERSISTENT_POOL_PTR_HPP
