!--------------------------------------------------------------------------------------------------!
! Copyright (C) by the DBCSR developers group - All rights reserved                                !
! This file is part of the DBCSR library.                                                          !
!                                                                                                  !
! For information on the license, see the LICENSE file.                                            !
! For further information please visit https://dbcsr.cp2k.org                                      !
! SPDX-License-Identifier: GPL-2.0+                                                                !
!--------------------------------------------------------------------------------------------------!

MODULE dbcsr_acc_event
   !! Accelerator support
#if defined (__DBCSR_ACC)
   USE ISO_C_BINDING, ONLY: C_INT, C_NULL_PTR, C_PTR, C_ASSOCIATED, C_NULL_PTR
#endif
   USE dbcsr_acc_stream, ONLY: acc_stream_cptr, &
                               acc_stream_type
#include "base/dbcsr_base_uses.f90"

   IMPLICIT NONE

   PRIVATE

   CHARACTER(len=*), PARAMETER, PRIVATE :: moduleN = 'dbcsr_acc_event'

   PUBLIC :: acc_event_type
   PUBLIC :: acc_event_create, acc_event_destroy
   PUBLIC :: acc_event_record, acc_event_query
   PUBLIC :: acc_stream_wait_event, acc_event_synchronize

   TYPE acc_event_type
      PRIVATE
#if defined (__DBCSR_ACC)
      TYPE(C_PTR) :: cptr = C_NULL_PTR
#else
      INTEGER :: dummy = 1
#endif
   END TYPE acc_event_type

#if defined (__DBCSR_ACC)

   INTERFACE
      FUNCTION acc_interface_event_create(event_ptr) RESULT(istat) BIND(C, name="c_dbcsr_acc_event_create")
         IMPORT
         TYPE(C_PTR)                              :: event_ptr
         INTEGER(KIND=C_INT)                      :: istat

      END FUNCTION acc_interface_event_create
   END INTERFACE

   INTERFACE
      FUNCTION acc_interface_event_destroy(event_ptr) RESULT(istat) BIND(C, name="c_dbcsr_acc_event_destroy")
         IMPORT
         TYPE(C_PTR), VALUE                       :: event_ptr
         INTEGER(KIND=C_INT)                      :: istat

      END FUNCTION acc_interface_event_destroy
   END INTERFACE

   INTERFACE
      FUNCTION acc_interface_event_query(event_ptr, has_occurred) RESULT(istat) BIND(C, name="c_dbcsr_acc_event_query")
         IMPORT
         TYPE(C_PTR), VALUE                       :: event_ptr
         INTEGER(KIND=C_INT)                      :: has_occurred, istat

      END FUNCTION acc_interface_event_query
   END INTERFACE

   INTERFACE
      FUNCTION acc_interface_event_record(event_ptr, stream_ptr) RESULT(istat) BIND(C, name="c_dbcsr_acc_event_record")
         IMPORT
         TYPE(C_PTR), VALUE                       :: event_ptr, stream_ptr
         INTEGER(KIND=C_INT)                      :: istat

      END FUNCTION acc_interface_event_record
   END INTERFACE

   INTERFACE
      FUNCTION acc_interface_stream_wait_event(stream_ptr, event_ptr) RESULT(istat) BIND(C, name="c_dbcsr_acc_stream_wait_event")
         IMPORT
         TYPE(C_PTR), VALUE                       :: stream_ptr, event_ptr
         INTEGER(KIND=C_INT)                      :: istat

      END FUNCTION acc_interface_stream_wait_event
   END INTERFACE

   INTERFACE
      FUNCTION acc_interface_event_synchronize(event_ptr) RESULT(istat) BIND(C, name="c_dbcsr_acc_event_synchronize")
         IMPORT
         TYPE(C_PTR), VALUE                       :: event_ptr
         INTEGER(KIND=C_INT)                      :: istat

      END FUNCTION acc_interface_event_synchronize
   END INTERFACE
#endif

CONTAINS

   SUBROUTINE acc_stream_wait_event(stream, event)
      !! Fortran-wrapper for making a GPU compute stream wait on an event.
      !! Because of fortran circular dependency restriction this can not go into acc_stream.F

      TYPE(acc_stream_type), INTENT(IN) :: stream
      TYPE(acc_event_type), INTENT(IN)  :: event

#if ! defined (__DBCSR_ACC)
      MARK_USED(stream)
      MARK_USED(event)
      DBCSR_ABORT("__DBCSR_ACC not compiled in.")
#else
      INTEGER                                  :: istat
      TYPE(C_PTR)                              :: stream_cptr

      stream_cptr = acc_stream_cptr(stream)
      IF (.NOT. C_ASSOCIATED(event%cptr)) &
         DBCSR_ABORT("acc_stream_wait_event: event not allocated")
      IF (.NOT. C_ASSOCIATED(stream_cptr)) &
         DBCSR_ABORT("acc_stream_wait_event: stream not allocated")
      istat = acc_interface_stream_wait_event(stream_cptr, event%cptr)
      IF (istat /= 0) &
         DBCSR_ABORT("acc_stream_wait_event failed")
#endif
   END SUBROUTINE acc_stream_wait_event

   SUBROUTINE acc_event_record(this, stream)
      !! Fortran-wrapper for recording a CUDA/HIP event.

      TYPE(acc_event_type), INTENT(IN)  :: this
      TYPE(acc_stream_type), INTENT(IN) :: stream

#if ! defined (__DBCSR_ACC)
      MARK_USED(this)
      MARK_USED(stream)
      DBCSR_ABORT("__DBCSR_ACC not compiled in.")
#else
      INTEGER                                  :: istat
      TYPE(C_PTR)                              :: stream_cptr

      stream_cptr = acc_stream_cptr(stream)
      IF (.NOT. C_ASSOCIATED(this%cptr)) &
         DBCSR_ABORT("acc_event_record: event not allocated")
      IF (.NOT. C_ASSOCIATED(stream_cptr)) &
         DBCSR_ABORT("acc_event_record: stream not allocated")
      istat = acc_interface_event_record(this%cptr, stream_cptr)
      IF (istat /= 0) &
         DBCSR_ABORT("acc_event_record failed")
#endif
   END SUBROUTINE acc_event_record

   SUBROUTINE acc_event_create(this)
      !! Fortran-wrapper for creation of a CUDA/HIP event.

      TYPE(acc_event_type), &
         INTENT(INOUT)                          :: this

#if ! defined (__DBCSR_ACC)
      MARK_USED(this)
      DBCSR_ABORT("__DBCSR_ACC not compiled in.")
#else
      INTEGER                                  :: istat

      IF (C_ASSOCIATED(this%cptr)) &
         DBCSR_ABORT("acc_event_create: already allocated")
      istat = acc_interface_event_create(this%cptr)
      IF (istat /= 0 .OR. .NOT. C_ASSOCIATED(this%cptr)) &
         DBCSR_ABORT("acc_event_create: failed")
#endif
   END SUBROUTINE acc_event_create

   SUBROUTINE acc_event_destroy(this)
      !! Fortran-wrapper for destruction of a CUDA/HIP event.

      TYPE(acc_event_type), &
         INTENT(INOUT)                          :: this

#if ! defined (__DBCSR_ACC)
      MARK_USED(this)
      DBCSR_ABORT("__DBCSR_ACC not compiled in.")
#else
      INTEGER                                  :: istat
      IF (.NOT. C_ASSOCIATED(this%cptr)) &
         DBCSR_ABORT("acc_event_destroy: event not allocated")
      istat = acc_interface_event_destroy(this%cptr)
      IF (istat /= 0) &
         DBCSR_ABORT("acc_event_destroy failed")
      this%cptr = C_NULL_PTR
#endif
   END SUBROUTINE acc_event_destroy

   FUNCTION acc_event_query(this) RESULT(res)
      !! Fortran-wrapper for querying a CUDA/HIP event's status.

      TYPE(acc_event_type), INTENT(IN)         :: this
      LOGICAL                                  :: res
         !! true if event has occurred, false otherwise

#if ! defined (__DBCSR_ACC)
      res = .FALSE.
      MARK_USED(this)
      DBCSR_ABORT("__DBCSR_ACC not compiled in.")
#else
      INTEGER                                  :: istat, has_occurred
      IF (.NOT. C_ASSOCIATED(this%cptr)) &
         DBCSR_ABORT("acc_event_query: event not allocated")
      istat = acc_interface_event_query(this%cptr, has_occurred)
      IF (istat /= 0) &
         DBCSR_ABORT("acc_event_query failed")
      res = (has_occurred == 1)
#endif
   END FUNCTION acc_event_query

   SUBROUTINE acc_event_synchronize(this)
      !! Fortran-wrapper for waiting for the completion of a HIP/CUDA event.

      TYPE(acc_event_type), INTENT(IN)  :: this

#if ! defined (__DBCSR_ACC)
      MARK_USED(this)
      DBCSR_ABORT("__DBCSR_ACC not compiled in.")
#else
      INTEGER                                  :: istat
      IF (.NOT. C_ASSOCIATED(this%cptr)) &
         DBCSR_ABORT("acc_event_synchronize: event not allocated")
      istat = acc_interface_event_synchronize(this%cptr)
      IF (istat < 0) &
         DBCSR_ABORT("acc_event_synchronize failed")
#endif
   END SUBROUTINE acc_event_synchronize

END MODULE dbcsr_acc_event
