MODULE compute_geopot_mod
  USE prec, ONLY : rstd
  USE grid_param
  USE earth_const
  USE disvert_mod
  USE omp_para
  USE trace
  IMPLICIT NONE
  PRIVATE
  SAVE

  PUBLIC :: compute_geopot_hex, compute_geopot_manual

CONTAINS

  !**************************** Geopotential *****************************

  SUBROUTINE compute_geopot_hex(rhodz,theta, ps,pk,geopot) 
    REAL(rstd),INTENT(IN)    :: rhodz(iim*jjm,llm)
    REAL(rstd),INTENT(IN)    :: theta(iim*jjm,llm,nqdyn) ! active scalars : theta/entropy, moisture, ...
    REAL(rstd),INTENT(INOUT) :: ps(iim*jjm)
    REAL(rstd),INTENT(OUT)   :: pk(iim*jjm,llm)       ! Exner function (compressible) /Lagrange multiplier (Boussinesq)
    REAL(rstd),INTENT(INOUT) :: geopot(iim*jjm,llm+1) ! geopotential

    INTEGER :: i,j,ij,l
    REAL(rstd) :: p_ik, exner_ik, Cp_ik, temp_ik, qv, chi, Rmix, gv
    INTEGER    :: ij_omp_begin_ext, ij_omp_end_ext

    CALL trace_start("compute_geopot")
    !$OMP BARRIER
    CALL distrib_level(ij_begin_ext,ij_end_ext, ij_omp_begin_ext,ij_omp_end_ext)
#include "../kernels_hex/compute_geopot.k90"
    !$OMP BARRIER

    CALL trace_end("compute_geopot")
  END SUBROUTINE compute_geopot_hex

  SUBROUTINE compute_geopot_manual(rhodz,theta, ps,pk,geopot) 
    REAL(rstd),INTENT(IN)    :: rhodz(iim*jjm,llm)
    REAL(rstd),INTENT(IN)    :: theta(iim*jjm,llm,nqdyn) ! active scalars : theta/entropy, moisture, ...
    REAL(rstd),INTENT(INOUT) :: ps(iim*jjm)
    REAL(rstd),INTENT(OUT)   :: pk(iim*jjm,llm)       ! Exner function (compressible) /Lagrange multiplier (Boussinesq)
    REAL(rstd),INTENT(INOUT) :: geopot(iim*jjm,llm+1) ! geopotential

    INTEGER :: i,j,ij,l
    REAL(rstd) :: p_ik, exner_ik, Cp_ik, temp_ik, qv, chi, Rmix, gv
    INTEGER    :: ij_omp_begin_ext, ij_omp_end_ext

    CALL trace_start("compute_geopot")

!$OMP BARRIER

    CALL distrib_level(ij_begin_ext,ij_end_ext, ij_omp_begin_ext,ij_omp_end_ext)

    ! Pressure is computed first top-down (temporarily stored in pk)
    ! Then Exner pressure and geopotential are computed bottom-up
    ! Works also when caldyn_eta=eta_mass          

    IF(boussinesq) THEN ! compute geopotential and pk=Lagrange multiplier
       ! specific volume 1 = dphi/g/rhodz
       !         IF (is_omp_level_master) THEN ! no openMP on vertical due to dependency
       DO l = 1,llm
          !DIR$ SIMD
          DO ij=ij_omp_begin_ext,ij_omp_end_ext         
             geopot(ij,l+1) = geopot(ij,l) + g*rhodz(ij,l)
          ENDDO
       ENDDO
       ! use hydrostatic balance with theta*rhodz to find pk (Lagrange multiplier=pressure) 
       ! uppermost layer
       !DIR$ SIMD
       DO ij=ij_begin_ext,ij_end_ext         
          pk(ij,llm) = ptop + (.5*g)*theta(ij,llm,1)*rhodz(ij,llm)
       END DO
       ! other layers
       DO l = llm-1, 1, -1
          !          !$OMP DO SCHEDULE(STATIC) 
          !DIR$ SIMD
          DO ij=ij_begin_ext,ij_end_ext         
             pk(ij,l) = pk(ij,l+1) + (.5*g)*(theta(ij,l,1)*rhodz(ij,l)+theta(ij,l+1,1)*rhodz(ij,l+1))
          END DO
       END DO
       ! now pk contains the Lagrange multiplier (pressure)
    ELSE ! non-Boussinesq, compute pressure, Exner pressure or temperature, then geopotential
       ! uppermost layer
       
       SELECT CASE(caldyn_thermo)
          CASE(thermo_theta, thermo_entropy)
             !DIR$ SIMD
             DO ij=ij_omp_begin_ext,ij_omp_end_ext
                pk(ij,llm) = ptop + (.5*g)*rhodz(ij,llm)
             END DO
             ! other layers
             DO l = llm-1, 1, -1
                !DIR$ SIMD
                DO ij=ij_omp_begin_ext,ij_omp_end_ext         
                   pk(ij,l) = pk(ij,l+1) + (.5*g)*(rhodz(ij,l)+rhodz(ij,l+1))
                END DO
             END DO
             ! surface pressure (for diagnostics)
             IF(caldyn_eta==eta_lag) THEN
                DO ij=ij_omp_begin_ext,ij_omp_end_ext         
                   ps(ij) = pk(ij,1) + (.5*g)*rhodz(ij,1)
                END DO
             END IF
          CASE(thermo_moist) ! theta(ij,l,2) = qv = mv/md
             !DIR$ SIMD
             DO ij=ij_omp_begin_ext,ij_omp_end_ext
                pk(ij,llm) = ptop + (.5*g)*rhodz(ij,llm)*(1.+theta(ij,l,2))
             END DO
             ! other layers
             DO l = llm-1, 1, -1
                !DIR$ SIMD
                DO ij=ij_omp_begin_ext,ij_omp_end_ext         
                   pk(ij,l) = pk(ij,l+1) + (.5*g)*(          &
                        rhodz(ij,l)  *(1.+theta(ij,l,2)) +   &
                        rhodz(ij,l+1)*(1.+theta(ij,l+1,2)) )
                END DO
             END DO
             ! surface pressure (for diagnostics)
             IF(caldyn_eta==eta_lag) THEN
                DO ij=ij_omp_begin_ext,ij_omp_end_ext         
                   ps(ij) = pk(ij,1) + (.5*g)*rhodz(ij,1)*(1.+theta(ij,l,2))
                END DO
             END IF
          END SELECT

       DO l = 1,llm
          SELECT CASE(caldyn_thermo)
          CASE(thermo_theta)
             !DIR$ SIMD
             DO ij=ij_omp_begin_ext,ij_omp_end_ext
                p_ik = pk(ij,l)
                exner_ik = cpp * (p_ik/preff) ** kappa
                pk(ij,l) = exner_ik
                ! specific volume v = kappa*theta*pi/p = dphi/g/rhodz
                geopot(ij,l+1) = geopot(ij,l) + (g*kappa)*rhodz(ij,l)*theta(ij,l,1)*exner_ik/p_ik
             ENDDO
          CASE(thermo_entropy) ! theta is in fact entropy = cpp*log(theta/Treff) = cpp*log(T/Treff) - Rd*log(p/preff)
             !DIR$ SIMD
             DO ij=ij_omp_begin_ext,ij_omp_end_ext
                p_ik = pk(ij,l)
                temp_ik = Treff*exp((theta(ij,l,1) + Rd*log(p_ik/preff))/cpp)
                pk(ij,l) = temp_ik
                ! specific volume v = Rd*T/p = dphi/g/rhodz
                geopot(ij,l+1) = geopot(ij,l) + (g*Rd)*rhodz(ij,l)*temp_ik/p_ik
             ENDDO
          CASE(thermo_moist) ! theta is moist pseudo-entropy per dry air mass
             DO ij=ij_omp_begin_ext,ij_omp_end_ext
                p_ik = pk(ij,l)
                qv = theta(ij,l,2) ! water vaper mixing ratio = mv/md
                Rmix = Rd+qv*Rv
                chi = ( theta(ij,l,1) + Rmix*log(p_ik/preff) ) / (cpp + qv*cppv) ! log(T/Treff)
                temp_ik = Treff*exp(chi)
                pk(ij,l) = temp_ik
                ! specific volume v = R*T/p = dphi/g/rhodz
                ! R = (Rd + qv.Rv)/(1+qv)
                geopot(ij,l+1) = geopot(ij,l) + g*Rmix*rhodz(ij,l)*temp_ik/(p_ik*(1+qv))
             ENDDO
          CASE DEFAULT
             STOP
          END SELECT
       ENDDO
    END IF

    !ym flush geopot
    !$OMP BARRIER

    CALL trace_end("compute_geopot")

  END SUBROUTINE compute_geopot_manual

END MODULE compute_geopot_mod