!--------------------------------------------------------------------------------------------------!
!   CP2K: A general program to perform molecular dynamics simulations                              !
!   Copyright (C) 2000 - 2017  CP2K developers group                                               !
!--------------------------------------------------------------------------------------------------!

! **************************************************************************************************
!> \brief perform biased molecular dynamics (H= k H1 + (1-k) H2 [linear or general mixing)
!> \author fschiff 11.06
! **************************************************************************************************
MODULE mixed_main
   USE cp_files,                        ONLY: open_file
   USE cp_log_handling,                 ONLY: cp_get_default_logger,&
                                              cp_logger_create,&
                                              cp_logger_set,&
                                              cp_logger_type,&
                                              cp_to_string
   USE cp_output_handling,              ONLY: cp_print_key_unit_nr
   USE cp_para_env,                     ONLY: cp_para_env_create
   USE cp_para_types,                   ONLY: cp_para_env_type
   USE input_section_types,             ONLY: section_vals_type,&
                                              section_vals_val_get
   USE kinds,                           ONLY: default_path_length
   USE message_passing,                 ONLY: mp_comm_split
   USE mixed_environment,               ONLY: mixed_init
   USE mixed_environment_types,         ONLY: mixed_env_create,&
                                              mixed_environment_type,&
                                              set_mixed_env
#include "./base/base_uses.f90"

   IMPLICIT NONE

   PRIVATE

! *** Global parameters ***
   CHARACTER(len=*), PARAMETER, PRIVATE :: moduleN = 'mixed_main'

   PUBLIC :: mixed_create_force_env

CONTAINS
! **************************************************************************************************
!> \brief Controls program flow for mixed calculations
!> \param mixed_env ...
!> \param root_section ...
!> \param para_env ...
!> \param force_env_section ...
!> \param n_subforce_eval ...
!> \param use_motion_section ...
!> \author fschiff
! **************************************************************************************************
   SUBROUTINE mixed_create_force_env(mixed_env, root_section, para_env, &
                                     force_env_section, n_subforce_eval, use_motion_section)

      TYPE(mixed_environment_type), POINTER              :: mixed_env
      TYPE(section_vals_type), POINTER                   :: root_section
      TYPE(cp_para_env_type), POINTER                    :: para_env
      TYPE(section_vals_type), POINTER                   :: force_env_section
      INTEGER, INTENT(IN)                                :: n_subforce_eval
      LOGICAL, INTENT(IN)                                :: use_motion_section

      CHARACTER(LEN=*), PARAMETER :: routineN = 'mixed_create_force_env', &
         routineP = moduleN//':'//routineN

      CHARACTER(len=default_path_length)                 :: c_val, input_file_path, output_file_path
      INTEGER                                            :: group_size_wish, handle, i, lp, &
                                                            n_rep_val, ngroup_wish, output_unit, &
                                                            unit_nr
      INTEGER, DIMENSION(:), POINTER                     :: group_partition, i_vals
      LOGICAL                                            :: group_size_wish_set, ngroup_wish_set
      TYPE(cp_logger_type), POINTER                      :: logger

      CALL timeset(routineN, handle)
      logger => cp_get_default_logger()
      output_unit = cp_print_key_unit_nr(logger, force_env_section, "MIXED%PRINT%PROGRAM_RUN_INFO", &
                                         extension=".log")

      CALL mixed_env_create(mixed_env, para_env=para_env)
      ! Setup the new parallel env
      NULLIFY (group_partition)
      group_size_wish_set = .FALSE.
      ngroup_wish_set = .FALSE.
      CALL section_vals_val_get(force_env_section, "MIXED%GROUP_PARTITION", n_rep_val=n_rep_val)
      IF (n_rep_val > 0) THEN
         CALL section_vals_val_get(force_env_section, "MIXED%GROUP_PARTITION", i_vals=i_vals)
         ALLOCATE (group_partition(0:SIZE(i_vals)-1))
         group_partition(:) = i_vals
         ngroup_wish_set = .TRUE.
         ngroup_wish = SIZE(i_vals)
      ELSE
         CALL section_vals_val_get(force_env_section, "MIXED%NGROUPS", n_rep_val=n_rep_val)
         IF (n_rep_val > 0) THEN
            CALL section_vals_val_get(force_env_section, "MIXED%NGROUPS", i_val=ngroup_wish)
         ELSE
            ngroup_wish = n_subforce_eval
         END IF
         group_size_wish_set = .TRUE.
         group_size_wish = MAX(1, para_env%num_pe/ngroup_wish)
      END IF

      ! Split the current communicator
      ALLOCATE (mixed_env%group_distribution(0:para_env%num_pe-1))
      IF (group_size_wish_set) THEN
         CALL mp_comm_split(para_env%group, mixed_env%new_group, mixed_env%ngroups, mixed_env%group_distribution, &
                            subgroup_min_size=group_size_wish)
      ELSE IF (ngroup_wish_set) THEN
         CALL mp_comm_split(para_env%group, mixed_env%new_group, mixed_env%ngroups, mixed_env%group_distribution, &
                            n_subgroups=ngroup_wish, &
                            group_partition=group_partition)
      ENDIF
      IF (output_unit > 0) THEN
         WRITE (output_unit, FMT="(T2,A,T71,I10)") "MIXED_ENV| Number of created MPI groups:", mixed_env%ngroups
         WRITE (output_unit, FMT="(T2,A)", ADVANCE="NO") "MIXED_ENV| Task to group correspondence:"
         DO i = 0, para_env%num_pe-1
            IF (MODULO(i, 4) == 0) WRITE (output_unit, *)
            WRITE (output_unit, FMT='(A3,I4,A3,I4,A1)', ADVANCE="NO") &
               "  (", i, " : ", mixed_env%group_distribution(i), ")"
         END DO
         WRITE (output_unit, *)
      ENDIF
      IF (ASSOCIATED(group_partition)) THEN
         DEALLOCATE (group_partition)
      END IF
      ! Allocate para_env and handle the several loggers
      ALLOCATE (mixed_env%sub_para_env(mixed_env%ngroups))
      ALLOCATE (mixed_env%sub_logger(mixed_env%ngroups))
      ALLOCATE (mixed_env%energies(n_subforce_eval))
      !
      DO i = 1, mixed_env%ngroups
         NULLIFY (mixed_env%sub_para_env(i)%para_env, logger)
         IF (MODULO(i-1, mixed_env%ngroups) == mixed_env%group_distribution(para_env%mepos)) THEN
            ! Create sub_para_env
            CALL cp_para_env_create(mixed_env%sub_para_env(i)%para_env, &
                                    group=mixed_env%new_group, &
                                    owns_group=.TRUE.)
            ! Create sub_logger
            IF (mixed_env%sub_para_env(i)%para_env%mepos == mixed_env%sub_para_env(i)%para_env%source) THEN
               ! Redirecting output of subforce_eval to file..
               CALL section_vals_val_get(root_section, "GLOBAL%PROJECT_NAME", &
                                         c_val=input_file_path)
               lp = LEN_TRIM(input_file_path)
               input_file_path(lp+1:LEN(input_file_path)) = "-r-"// &
                                                            ADJUSTL(cp_to_string(i))
               lp = LEN_TRIM(input_file_path)
               output_file_path = input_file_path(1:lp)//".out"
               CALL open_file(file_name=output_file_path, file_status="UNKNOWN", &
                              file_action="WRITE", file_position="APPEND", &
                              unit_number=unit_nr)
            ELSE
               unit_nr = -1
            END IF
            CALL cp_logger_create(mixed_env%sub_logger(i)%p, &
                                  para_env=mixed_env%sub_para_env(i)%para_env, &
                                  default_global_unit_nr=unit_nr, &
                                  close_global_unit_on_dealloc=.FALSE.)
            ! Try to use better names for the local log if it is not too late
            CALL section_vals_val_get(root_section, "GLOBAL%OUTPUT_FILE_NAME", &
                                      c_val=c_val)
            IF (c_val /= "") THEN
               CALL cp_logger_set(mixed_env%sub_logger(i)%p, &
                                  local_filename=TRIM(c_val)//"_localLog")
            END IF
            CALL section_vals_val_get(root_section, "GLOBAL%PROJECT", c_val=c_val)
            IF (c_val /= "") THEN
               CALL cp_logger_set(mixed_env%sub_logger(i)%p, &
                                  local_filename=TRIM(c_val)//"_localLog")
            END IF
            mixed_env%sub_logger(i)%p%iter_info%project_name = c_val
            CALL section_vals_val_get(root_section, "GLOBAL%PRINT_LEVEL", &
                                      i_val=mixed_env%sub_logger(i)%p%iter_info%print_level)

         END IF
      END DO

      ! *** initializations for the setup of the MIXED environment ***
      CALL set_mixed_env(mixed_env)
      CALL mixed_init(mixed_env, root_section, para_env, force_env_section, &
                      use_motion_section)
      CALL timestop(handle)

   END SUBROUTINE mixed_create_force_env

END MODULE mixed_main
