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#ifndef LIBRARY_SRC_BACKEND_TYPE_HPP_
#define LIBRARY_SRC_BACKEND_TYPE_HPP_

/**
 * @file backend_type.hpp
 * Defines the Backend derived class types and contains the DISPATCH macros.
 *
 * The type information is required to be known at compile time because
 * we use static dispatch to produce compile time polymorphism.
 *
 * The device cannot use runtime polymorphism because calls through virtual
 * functions are not supported at this time.
 */

#include "rocshmem_config.h"  // NOLINT(build/include_subdir)

namespace rocshmem {

/**
 * @brief Enumerates the Backend derived classes.
 *
 * @note Derived classes which use Backend as a base class must add
 * themselves to this enum class to support static polymorphism.
 */
enum class BackendType { RO_BACKEND, GPU_IB_BACKEND, IPC_BACKEND };

/**
 * @brief Helper macro for some dispatch calls
 */
#define PAIR(A, B) A, B

/**
 * @brief Device static dispatch method call.
 */
#ifdef USE_GPU_IB
#define DISPATCH(Func)                     \
  static_cast<GPUIBContext *>(this)->Func;
#elif defined(USE_RO)
#define DISPATCH(Func)                     \
  static_cast<ROContext *>(this)->Func;
#else
#define DISPATCH(Func)                     \
  static_cast<IPCContext *>(this)->Func;
#endif

/**
 * @brief Device static dispatch method call with a return value.
 */
#ifdef USE_GPU_IB
#define DISPATCH_RET(Func)                           \
  auto ret_val = static_cast<GPUIBContext *>(this)->Func; \
  return ret_val;
#elif defined(USE_RO)
#define DISPATCH_RET(Func)                        \
  auto ret_val = static_cast<ROContext *>(this)->Func; \
  return ret_val;
#else
#define DISPATCH_RET(Func)                        \
  auto ret_val{0};                                \
  ret_val = static_cast<IPCContext *>(this)->Func; \
  return ret_val;
#endif
/**
 * @brief Device static dispatch method call with a return type of pointer.
 */
#ifdef USE_GPU_IB
#define DISPATCH_RET_PTR(Func)                       \
  void *ret_val{nullptr};                            \
  ret_val = static_cast<GPUIBContext *>(this)->Func; \
  return ret_val;
#elif defined(USE_RO)
#define DISPATCH_RET_PTR(Func)                    \
  void *ret_val{nullptr};                         \
  ret_val = static_cast<ROContext *>(this)->Func; \
  return ret_val;
#else
#define DISPATCH_RET_PTR(Func)                    \
  void *ret_val{nullptr};                         \
  ret_val = static_cast<IPCContext *>(this)->Func; \
  return ret_val;
#endif

/**
 * @brief Host static dispatch method call.
 *
 * @note There is no need to lock-unlock on host since we are using
 * MPI_THREAD_MULTIPLE (for RMA and AMO operations) and the ordering and
 * threading semantics of collectives in OpenSHMEM match those of MPI.
 */
#ifdef USE_GPU_IB
#define HOST_DISPATCH(Func) static_cast<GPUIBHostContext *>(this)->Func;
#elif defined(USE_RO)
#define HOST_DISPATCH(Func) static_cast<ROHostContext *>(this)->Func;
#else
#define HOST_DISPATCH(Func) static_cast<IPCHostContext *>(this)->Func;
#endif
/**
 * @brief Host static dispatch method call with return value.
 *
 * @note There is no need to lock-unlock on host since we are using
 * MPI_THREAD_MULTIPLE (for RMA and AMO operations) and the ordering and
 * threading semantics of collectives in OpenSHMEM match those of MPI.
 */

#ifdef USE_GPU_IB
#define HOST_DISPATCH_RET(Func)                          \
  auto ret_val = static_cast<GPUIBHostContext *>(this)->Func; \
  return ret_val;
#elif defined(USE_RO)
#define HOST_DISPATCH_RET(Func)                       \
  auto ret_val = static_cast<ROHostContext *>(this)->Func; \
  return ret_val;
#else
#define HOST_DISPATCH_RET(Func)                       \
  auto ret_val{0};                                    \
  ret_val = static_cast<IPCHostContext *>(this)->Func; \
  return ret_val;
#endif

}  // namespace rocshmem

#endif  // LIBRARY_SRC_BACKEND_TYPE_HPP_