/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup DNA
 *
 * Group generic defines for all DNA headers may use in this file.
 */

#pragma once

/* `makesdna` ignores. */
#ifdef DNA_DEPRECATED_ALLOW
/* allow use of deprecated items */
#  define DNA_DEPRECATED
#else
#  if defined(__GNUC__) || defined(__clang__) || defined(_MSC_VER)
#    define DNA_DEPRECATED [[deprecated]]
#  else
#    define DNA_DEPRECATED
#  endif
#endif

/* GCC considers default member initialization in constructors deprecated.
 * This macro helps silence that while still warning in other cases */
#if defined(__GNUC__) || defined(__clang__)
/* clang-format off */
#  define DNA_DEPRECATED_IGNORE(statement) \
    _Pragma("GCC diagnostic push") \
    _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"") \
    statement \
    _Pragma("GCC diagnostic pop")
/* clang-format on */
#else
#  define DNA_DEPRECATED_IGNORE(statement) statement
#endif

#ifdef __GNUC__
#  define DNA_PRIVATE_ATTR __attribute__((deprecated))
#else
#  define DNA_PRIVATE_ATTR
#endif

/* poison pragma */
#ifdef DNA_DEPRECATED_ALLOW
#  define DNA_DEPRECATED_GCC_POISON 0
#else
/* enable the pragma if we can */
#  ifdef __GNUC__
#    define DNA_DEPRECATED_GCC_POISON 1
#  else
#    define DNA_DEPRECATED_GCC_POISON 0
#  endif
#endif

/* hrmf, we need a better include then this */
#include "../blenlib/BLI_sys_types.h" /* needed for int64_t only! */

namespace blender {

/* non-id name variables should use this length */
#define MAX_NAME 64

/* #DNA_DEFINE_CXX_METHODS is used to define C++ methods which are needed for proper/safe resource
 * management, making unsafe (from an ownership perspective: i.e. pointers which sometimes needs to
 * be set to nullptr on copy, sometimes needs to be dupalloc-ed) operations explicit, and taking
 * care of compiler specific warnings when dealing with members marked with DNA_DEPRECATED.
 *
 * The `class_name` argument is to match the structure name the macro is used from.
 *
 * Typical usage example:
 *
 *   struct Object {
 *     DNA_DEFINE_CXX_METHODS(Object)
 *   };
 */

/* Forward-declared here since there is no simple header file to be pulled for this functionality.
 * Avoids pulling `string.h` from this header to get access to #memcpy. */
void _DNA_internal_memcpy(void *dst, const void *src, size_t size);
void _DNA_internal_memzero(void *dst, size_t size);
void _DNA_internal_swap(void *a, void *b, size_t size);

namespace dna::internal {

template<class T> class ShallowDataConstRef {
 public:
  constexpr explicit ShallowDataConstRef(const T &ref) : ref_(ref) {}

  const T *get_pointer() const
  {
    return &ref_;
  }

 private:
  const T &ref_;
};

class ShallowZeroInitializeTag {};

}  // namespace dna::internal

#define DNA_DEFINE_CXX_METHODS(class_name) \
  DNA_DEPRECATED_IGNORE(class_name() = default;) \
  ~class_name() = default; \
  /* Delete copy and assignment, which are not safe for resource ownership. */ \
  class_name(const class_name &other) = delete; \
  class_name(class_name &&other) noexcept = delete; \
  class_name &operator=(const class_name &other) = delete; \
  class_name &operator=(class_name &&other) = delete; \
  /* Support for shallow copy. */ \
  /* NOTE: Calling the default constructor works-around deprecated warning generated by GCC. */ \
  class_name(const dna::internal::ShallowDataConstRef<class_name> ref) : class_name() \
  { \
    _DNA_internal_memcpy(this, ref.get_pointer(), sizeof(class_name)); \
  } \
  class_name &operator=(const dna::internal::ShallowDataConstRef<class_name> ref) \
  { \
    if (this != ref.get_pointer()) { \
      _DNA_internal_memcpy(this, ref.get_pointer(), sizeof(class_name)); \
    } \
    return *this; \
  } \
  /* Create object which memory is filled with zeros. */ \
  class_name(const dna::internal::ShallowZeroInitializeTag /*tag*/) : class_name() \
  { \
    _DNA_internal_memzero(this, sizeof(class_name)); \
  } \
  class_name &operator=(const dna::internal::ShallowZeroInitializeTag /*tag*/) \
  { \
    _DNA_internal_memzero(this, sizeof(class_name)); \
    return *this; \
  }

namespace dna {

/* Creates shallow copy of the given object.
 * The entire object is copied as-is using memory copy.
 *
 * Typical usage:
 *   Object temp_object = dna::shallow_copy(*input_object);
 *
 * From the implementation detail go via copy constructor/assign operator defined in the structure.
 */
template<typename T>
[[nodiscard]] inline internal::ShallowDataConstRef<T> shallow_copy(const T &other)
{
  return internal::ShallowDataConstRef(other);
}

template<typename T> inline void shallow_copy_array(T *dst, const T *src, const int64_t size)
{
  _DNA_internal_memcpy(dst, src, sizeof(T) * size_t(size));
}

/* DNA object initializer which leads to an object which underlying memory is filled with zeroes.
 */
[[nodiscard]] inline internal::ShallowZeroInitializeTag shallow_zero_initialize()
{
  return internal::ShallowZeroInitializeTag();
}

template<typename T> inline void shallow_swap(T &a, T &b)
{
  _DNA_internal_swap(&a, &b, sizeof(T));
}

}  // namespace dna
}  // namespace blender
