! Copyright 2011-13 Max-Planck-Institut für Eisenforschung GmbH
!
! This file is part of DAMASK,
! the Düsseldorf Advanced MAterial Simulation Kit.
!
! DAMASK is free software: you can redistribute it and/or modify
! it under the terms of the GNU General Public License as published by
! the Free Software Foundation, either version 3 of the License, or
! (at your option) any later version.
!
! DAMASK is distributed in the hope that it will be useful,
! but WITHOUT ANY WARRANTY; without even the implied warranty of
! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
! GNU General Public License for more details.
!
! You should have received a copy of the GNU General Public License
! along with DAMASK. If not, see <http://www.gnu.org/licenses/>.
!
!--------------------------------------------------------------------------------------------------
! $Id: DAMASK_spectral_SolverAL.f90 1654 2012-08-03 09:25:48Z MPIE\m.diehl $
!--------------------------------------------------------------------------------------------------
!> @author Pratheek Shanthraj, Max-Planck-Institut für Eisenforschung GmbH
!> @author Martin Diehl, Max-Planck-Institut für Eisenforschung GmbH
!> @author Philip Eisenlohr, Max-Planck-Institut für Eisenforschung GmbH
!> @brief Basic scheme PETSc solver
!--------------------------------------------------------------------------------------------------
module DAMASK_spectral_SolverBasicPETSc
 use prec, only: & 
   pInt, &
   pReal
 use math, only: &
   math_I3
 use DAMASK_spectral_Utilities, only: &
   tSolutionState

 implicit none
 private
#include <finclude/petscsys.h>
#include <finclude/petscdmda.h>
#include <finclude/petscsnes.h>
 character (len=*), parameter, public :: &
   DAMASK_spectral_SolverBasicPETSC_label = 'basicpetsc'
   
!--------------------------------------------------------------------------------------------------
! derived types
 type tSolutionParams 
   real(pReal), dimension(3,3) :: P_BC, rotation_BC
   real(pReal) :: timeinc
   real(pReal) :: temperature
 end type tSolutionParams
 
 type(tSolutionParams), private :: params

!--------------------------------------------------------------------------------------------------
! PETSc data
 DM,   private :: da
 SNES, private :: snes
 Vec,  private :: solution_vec

!--------------------------------------------------------------------------------------------------
! common pointwise data
 real(pReal), private, dimension(:,:,:,:,:), allocatable ::  F_lastInc, Fdot

!--------------------------------------------------------------------------------------------------
! stress, stiffness and compliance average etc.
 real(pReal), private, dimension(3,3) :: &
   F_aim = math_I3, &
   F_aim_lastIter = math_I3, &
   F_aim_lastInc = math_I3, &
   P_av = 0.0_pReal, &
   F_aimDot=0.0_pReal
 character(len=1024), private :: incInfo   
 real(pReal), private, dimension(3,3,3,3) :: &
   C = 0.0_pReal, C_minmaxAvg = 0.0_pReal, C_lastInc= 0.0_pReal, &
   S = 0.0_pReal

 real(pReal), private :: err_stress, err_div
 logical, private :: ForwardData
 integer(pInt), private :: reportIter = 0_pInt
 real(pReal), private, dimension(3,3) :: mask_stress = 0.0_pReal

 public :: &
   basicPETSc_init, &
   basicPETSc_solution ,&
   basicPETSc_destroy
 external :: &
   VecDestroy, &
   DMDestroy, &
   DMDACreate3D, &
   DMCreateGlobalVector, &
   DMDASetLocalFunction, &
   PETScFinalize, &
   SNESDestroy, &
   SNESGetNumberFunctionEvals, &
   SNESGetIterationNumber, &
   SNESSolve, &
   SNESSetDM, &
   SNESGetConvergedReason, &
   SNESSetConvergenceTest, &
   SNESSetFromOptions, &
   SNESCreate, &
   MPI_Abort

contains

!--------------------------------------------------------------------------------------------------
!> @brief allocates all neccessary fields and fills them with data, potentially from restart info
!--------------------------------------------------------------------------------------------------
subroutine basicPETSc_init(temperature)
 use, intrinsic :: iso_fortran_env                                                                  ! to get compiler_version and compiler_options (at least for gfortran >4.6 at the moment)
 use IO, only: &
   IO_read_JobBinaryFile, &
   IO_write_JobBinaryFile, &
   IO_intOut, &
   IO_timeStamp
 use debug, only: &
   debug_level, &
   debug_spectral, &
   debug_spectralRestart
 use FEsolving, only: &
   restartInc
 use DAMASK_interface, only: &
   getSolverJobName
 use DAMASK_spectral_Utilities, only: &
   Utilities_init, &
   Utilities_constitutiveResponse, &
   Utilities_updateGamma, &
   grid, &
   wgt, &
   geomSize
 use numerics, only: &
   petsc_options  
 use mesh, only: &
   mesh_ipCoordinates, &
   mesh_deformedCoordsFFT
 use math, only: &
   math_invSym3333
      
 implicit none
 real(pReal), intent(inout) :: &
   temperature
#include <finclude/petscdmda.h90>
#include <finclude/petscsnes.h90>
 real(pReal), dimension(:,:,:,:,:), allocatable :: P
 PetscScalar,  dimension(:,:,:,:), pointer     ::  F
 PetscErrorCode :: ierr
 PetscObject    :: dummy
 real(pReal), dimension(3,3) :: &
   temp33_Real = 0.0_pReal
 real(pReal), dimension(3,3,3,3) :: &
   temp3333_Real = 0.0_pReal

 call Utilities_init()
 write(6,'(/,a)') ' <<<+-  DAMASK_spectral_solverBasicPETSc init  -+>>>'
 write(6,'(a)') ' $Id: DAMASK_spectral_SolverBasicPETSC.f90 1654 2012-08-03 09:25:48Z MPIE\m.diehl $'
 write(6,'(a15,a)')   ' Current time: ',IO_timeStamp()
#include "compilation_info.f90"

 allocate (P        (3,3,grid(1),grid(2),grid(3)),source = 0.0_pReal)
!--------------------------------------------------------------------------------------------------
! allocate global fields
 allocate (F_lastInc(3,3,grid(1),grid(2),grid(3)),source = 0.0_pReal)
 allocate (Fdot     (3,3,grid(1),grid(2),grid(3)),source = 0.0_pReal)
    
!--------------------------------------------------------------------------------------------------
! initialize solver specific parts of PETSc
 call SNESCreate(PETSC_COMM_WORLD,snes,ierr); CHKERRQ(ierr)
 call DMDACreate3d(PETSC_COMM_WORLD, &
        DMDA_BOUNDARY_NONE, DMDA_BOUNDARY_NONE, DMDA_BOUNDARY_NONE, &
        DMDA_STENCIL_BOX,grid(1),grid(2),grid(3),PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE, &
        9,1,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,da,ierr)
 CHKERRQ(ierr)
 call DMCreateGlobalVector(da,solution_vec,ierr); CHKERRQ(ierr)
 call DMDASetLocalFunction(da,BasicPETSC_formResidual,ierr); CHKERRQ(ierr)
 call SNESSetDM(snes,da,ierr); CHKERRQ(ierr)
 call SNESSetConvergenceTest(snes,BasicPETSC_converged,dummy,PETSC_NULL_FUNCTION,ierr)
 CHKERRQ(ierr)
 call SNESSetFromOptions(snes,ierr); CHKERRQ(ierr)

!--------------------------------------------------------------------------------------------------
! init fields                 
 call DMDAVecGetArrayF90(da,solution_vec,F,ierr); CHKERRQ(ierr)                                     ! get the data out of PETSc to work with

 if (restartInc == 1_pInt) then                                                                     ! no deformation (no restart)
   F_lastInc = spread(spread(spread(math_I3,3,grid(1)),4,grid(2)),5,grid(3))                           ! initialize to identity
   F = reshape(F_lastInc,[9,grid(1),grid(2),grid(3)])
 elseif (restartInc > 1_pInt) then                                                                  ! using old values from file                                                      
   if (iand(debug_level(debug_spectral),debug_spectralRestart)/= 0) &
     write(6,'(/,a,'//IO_intOut(restartInc-1_pInt)//',a)') &
     'reading values of increment', restartInc - 1_pInt, 'from file'
   flush(6)
   call IO_read_jobBinaryFile(777,'F',&
                                                trim(getSolverJobName()),size(F))
   read (777,rec=1) F
   close (777)
   call IO_read_jobBinaryFile(777,'F_lastInc',&
                                                trim(getSolverJobName()),size(F_lastInc))
   read (777,rec=1) F_lastInc
   close (777)
   F_aim         = reshape(sum(sum(sum(F,dim=4),dim=3),dim=2) * wgt, [3,3])                         ! average of F
   F_aim_lastInc = sum(sum(sum(F_lastInc,dim=5),dim=4),dim=3) * wgt                                 ! average of F_lastInc 

   call IO_read_jobBinaryFile(777,'F_aimDot',trim(getSolverJobName()),size(f_aimDot))
   read (777,rec=1) f_aimDot
   close (777)
   call IO_read_jobBinaryFile(777,'C',trim(getSolverJobName()),size(C))
   read (777,rec=1) C
   close (777)
   call IO_read_jobBinaryFile(777,'C_lastInc',trim(getSolverJobName()),size(C_lastInc))
   read (777,rec=1) C_lastInc
   close (777)
   call IO_read_jobBinaryFile(777,'C_ref',trim(getSolverJobName()),size(temp3333_Real))
   read (777,rec=1) temp3333_Real
   close (777)
 endif
 mesh_ipCoordinates = reshape(mesh_deformedCoordsFFT(geomSize,reshape(&
                                              F,[3,3,grid(1),grid(2),grid(3)])),[3,1,product(grid)])
 call Utilities_constitutiveResponse(&
    reshape(F(0:8,0:grid(1)-1_pInt,0:grid(2)-1_pInt,0:grid(3)-1_pInt),[3,3,grid(1),grid(2),grid(3)]),&
    reshape(F(0:8,0:grid(1)-1_pInt,0:grid(2)-1_pInt,0:grid(3)-1_pInt),[3,3,grid(1),grid(2),grid(3)]),&
    temperature,0.0_pReal,P,C,C_minmaxAvg,temp33_Real,.false.,math_I3)
 call DMDAVecRestoreArrayF90(da,solution_vec,F,ierr); CHKERRQ(ierr)                                 ! write data back into PETSc
 if (restartInc == 1_pInt) then                                                                     ! use initial stiffness as reference stiffness
   temp3333_Real = C_minmaxAvg
 endif 
   
 call Utilities_updateGamma(temp3333_Real,.True.)

end subroutine basicPETSc_init
  
!--------------------------------------------------------------------------------------------------
!> @brief solution for the Basic PETSC scheme with internal iterations
!--------------------------------------------------------------------------------------------------
type(tSolutionState) function basicPETSc_solution( &
             incInfoIn,guess,timeinc,timeinc_old,loadCaseTime,P_BC,F_BC,temperature_bc,rotation_BC)
 use numerics, only: &
   update_gamma, &
   itmax
 use math, only: &
   math_mul33x33 ,&
   math_rotate_backward33
 use mesh, only: &
   mesh_ipCoordinates,&
   mesh_deformedCoordsFFT
 use IO, only: &
   IO_write_JobBinaryFile
 use DAMASK_spectral_Utilities, only: &
   grid, &
   geomSize, &
   tBoundaryCondition, &
   Utilities_calculateRate, &
   Utilities_forwardField, &
   Utilities_maskedCompliance, &
   Utilities_updateGamma, &
   cutBack
 use FEsolving, only: &
   restartWrite, &
   terminallyIll

 implicit none
#include <finclude/petscdmda.h90>
#include <finclude/petscsnes.h90>
!--------------------------------------------------------------------------------------------------
! input data for solution
  real(pReal), intent(in) :: &
   timeinc, &                                                                                       !< increment in time for current solution
   timeinc_old, &                                                                                   !< increment in time of last increment
   loadCaseTime, &                                                                                  !< remaining time of current load case
   temperature_bc
 logical, intent(in):: guess
 type(tBoundaryCondition),      intent(in) :: P_BC,F_BC
 real(pReal), dimension(3,3), intent(in) :: rotation_BC
 character(len=*), intent(in) :: incInfoIn
 
!--------------------------------------------------------------------------------------------------
! 
 PetscScalar, pointer :: F(:,:,:,:)
 PetscErrorCode :: ierr   
 SNESConvergedReason :: reason
 incInfo = incInfoIn

 call DMDAVecGetArrayF90(da,solution_vec,F,ierr)
!--------------------------------------------------------------------------------------------------
! write restart information for spectral solver
 if (restartWrite) then
   write(6,'(/,a)') ' writing converged results for restart'
   flush(6)
   call IO_write_jobBinaryFile(777,'F',size(F))                                                     ! writing deformation gradient field to file
   write (777,rec=1) F
   close (777)
   call IO_write_jobBinaryFile(777,'F_lastInc',size(F_lastInc))                                     ! writing F_lastInc field to file
   write (777,rec=1) F_lastInc
   close (777)
   call IO_write_jobBinaryFile(777,'F_aimDot',size(F_aimDot))
   write (777,rec=1) F_aimDot
   close(777)
   call IO_write_jobBinaryFile(777,'C',size(C))
   write (777,rec=1) C
   close(777)
   call IO_write_jobBinaryFile(777,'C_lastInc',size(C_lastInc))
   write (777,rec=1) C_lastInc
   close(777)
 endif 
 mesh_ipCoordinates = reshape(mesh_deformedCoordsFFT(geomSize,reshape(&
                                             F,[3,3,grid(1),grid(2),grid(3)])),[3,1,product(grid)])
 if ( cutBack) then 
   F_aim = F_aim_lastInc
   F = reshape(F_lastInc,[9,grid(1),grid(2),grid(3)]) 
   C = C_lastInc
 else
   C_lastInc = C
   mesh_ipCoordinates = reshape(mesh_deformedCoordsFFT(geomSize,reshape(&
                                             F,[3,3,grid(1),grid(2),grid(3)])),[3,1,product(grid)])

!--------------------------------------------------------------------------------------------------
! calculate rate for aim
   if (F_BC%myType=='l') then                                                                       ! calculate f_aimDot from given L and current F
     f_aimDot = F_BC%maskFloat * math_mul33x33(F_BC%values, F_aim)
   elseif(F_BC%myType=='fdot')   then                                                               ! f_aimDot is prescribed
     f_aimDot = F_BC%maskFloat * F_BC%values
   elseif(F_BC%myType=='f') then                                                                    ! aim at end of load case is prescribed
     f_aimDot = F_BC%maskFloat * (F_BC%values -F_aim)/loadCaseTime
  endif
   if (guess) f_aimDot  = f_aimDot + P_BC%maskFloat * (F_aim - F_aim_lastInc)/timeinc_old
   F_aim_lastInc = F_aim
  
!--------------------------------------------------------------------------------------------------
! update rate and forward last inc
   Fdot =  Utilities_calculateRate(math_rotate_backward33(f_aimDot,params%rotation_BC), &
                                 timeinc_old,guess,F_lastInc,reshape(F,[3,3,grid(1),grid(2),grid(3)]))
   F_lastInc = reshape(F,[3,3,grid(1),grid(2),grid(3)])
 endif
 F_aim = F_aim + f_aimDot * timeinc

 F = reshape(Utilities_forwardField(timeinc,F_lastInc,Fdot,math_rotate_backward33(F_aim, &
                                                            rotation_BC)),[9,grid(1),grid(2),grid(3)])
 call DMDAVecRestoreArrayF90(da,solution_vec,F,ierr); CHKERRQ(ierr)
  
!--------------------------------------------------------------------------------------------------
! update stiffness (and gamma operator)
 S = Utilities_maskedCompliance(rotation_BC,P_BC%maskLogical,C)
 if (update_gamma) call Utilities_updateGamma(C_minmaxAvg,restartWrite)
 
 ForwardData = .True.

!--------------------------------------------------------------------------------------------------
! set module wide availabe data 
 mask_stress = P_BC%maskFloat
 params%P_BC = P_BC%values
 params%rotation_BC = rotation_BC
 params%timeinc = timeinc
 params%temperature = temperature_BC

 call SNESSolve(snes,PETSC_NULL_OBJECT,solution_vec,ierr); CHKERRQ(ierr)
 call SNESGetConvergedReason(snes,reason,ierr); CHKERRQ(ierr)
 basicPETSc_solution%termIll = terminallyIll
 terminallyIll = .false.

 if (reason < 1) then
   basicPETSC_solution%converged = .false.
   basicPETSC_solution%iterationsNeeded = itmax
 else
   basicPETSC_solution%converged = .true.
   basicPETSC_solution%iterationsNeeded = reportIter - 1_pInt
 endif

end function BasicPETSc_solution


!--------------------------------------------------------------------------------------------------
!> @brief forms the AL residual vector
!--------------------------------------------------------------------------------------------------
subroutine BasicPETSC_formResidual(in,x_scal,f_scal,dummy,ierr)
 use numerics, only: &
   itmax, &
   itmin
 use math, only: &
   math_rotate_backward33, &
   math_transpose33, &
   math_mul3333xx33
 use debug, only: &
   debug_level, &
   debug_spectral, &
   debug_spectralRotation
 use DAMASK_spectral_Utilities, only: &
   grid, &
   wgt, &
   field_real, &
   Utilities_FFTforward, &
   Utilities_FFTbackward, &
   Utilities_fourierConvolution, &
   Utilities_constitutiveResponse, &
   Utilities_divergenceRMS
 use IO, only: &
   IO_intOut 

 implicit none
 DMDALocalInfo, dimension(DMDA_LOCAL_INFO_SIZE) :: &
   in
 PetscScalar,   dimension(3,3,grid(1),grid(2),grid(3)) :: &
   x_scal, &
   f_scal 
 PetscInt :: &
   iter, &
   nfuncs
 PetscObject :: dummy
 PetscErrorCode :: ierr
 integer(pInt), save :: callNo = 3_pInt

 call SNESGetNumberFunctionEvals(snes,nfuncs,ierr); CHKERRQ(ierr)
 call SNESGetIterationNumber(snes,iter,ierr); CHKERRQ(ierr)

!--------------------------------------------------------------------------------------------------
! report begin of new iteration
 if (iter == 0 .and. callNo>2) then
   callNo = 0_pInt
   reportIter = 0_pInt
 endif
 if (callNo == 0 .or. mod(callNo,2) == 1_pInt) then
   write(6,'(1x,a,3(a,'//IO_intOut(itmax)//'))') trim(incInfo), &
                    ' @ Iteration ', itmin, '≤',reportIter, '≤', itmax
   if (iand(debug_level(debug_spectral),debug_spectralRotation) /= 0) &
   write(6,'(/,a,/,3(3(f12.7,1x)/))',advance='no') ' deformation gradient aim (lab)=', &
                                 math_transpose33(math_rotate_backward33(F_aim,params%rotation_BC))
   write(6,'(/,a,/,3(3(f12.7,1x)/))',advance='no') ' deformation gradient aim =', &
                                 math_transpose33(F_aim)
   flush(6)
   reportIter = reportIter + 1_pInt
 endif
 callNo = callNo +1_pInt

!--------------------------------------------------------------------------------------------------
! evaluate constitutive response
 call Utilities_constitutiveResponse(F_lastInc,x_scal,params%temperature,params%timeinc, &
                                     f_scal,C,C_minmaxAvg,P_av,ForwardData,params%rotation_BC)
 ForwardData = .false.
  
!--------------------------------------------------------------------------------------------------
! stress BC handling
 F_aim_lastIter = F_aim
 F_aim = F_aim - math_mul3333xx33(S, ((P_av - params%P_BC)))                                        ! S = 0.0 for no bc
 err_stress = maxval(abs(mask_stress * (P_av - params%P_BC)))                                       ! mask = 0.0 for no bc
 
!--------------------------------------------------------------------------------------------------
! updated deformation gradient using fix point algorithm of basic scheme
 field_real = 0.0_pReal
 field_real(1:grid(1),1:grid(2),1:grid(3),1:3,1:3) = reshape(f_scal,[grid(1),grid(2),grid(3),3,3],&
                                                             order=[4,5,1,2,3]) ! field real has a different order
 call Utilities_FFTforward()
 err_div = Utilities_divergenceRMS()
 call Utilities_fourierConvolution(math_rotate_backward33(F_aim_lastIter-F_aim,params%rotation_BC))
 call Utilities_FFTbackward()
 
!--------------------------------------------------------------------------------------------------
! constructing residual                         
 f_scal = reshape(field_real(1:grid(1),1:grid(2),1:grid(3),1:3,1:3),shape(x_scal),order=[3,4,5,1,2]) 

end subroutine BasicPETSc_formResidual


!--------------------------------------------------------------------------------------------------
!> @brief convergence check
!--------------------------------------------------------------------------------------------------
subroutine BasicPETSc_converged(snes_local,it,xnorm,snorm,fnorm,reason,dummy,ierr)
 use numerics, only: &
   itmax, &
   itmin, &
   err_div_tol, &
   err_stress_tolrel, &
   err_stress_tolabs
 use math, only: &
   math_mul33x33, &
   math_eigenvalues33, &
   math_transpose33
 use FEsolving, only: &
   terminallyIll
 
 implicit none
 SNES :: snes_local
 PetscInt :: it
 PetscReal :: &
   xnorm, &
   snorm, &
   fnorm
 SNESConvergedReason :: reason
 PetscObject :: dummy
 PetscErrorCode :: ierr
 logical :: Converged
 real(pReal) :: &
   pAvgDivL2, &
   err_stress_tol 
 
 err_stress_tol =max(maxval(abs(P_av))*err_stress_tolrel,err_stress_tolabs)
 pAvgDivL2 = sqrt(maxval(math_eigenvalues33(math_mul33x33(P_av,math_transpose33(P_av)))))
 Converged = (it >= itmin .and. &
                           all([ err_div/pAvgDivL2/err_div_tol, &
                                 err_stress/err_stress_tol       ] < 1.0_pReal)) &
             .or.    terminallyIll                 
 
 if (Converged) then
   reason = 1
 elseif (it >= itmax) then
   reason = -1
 else  
   reason = 0
 endif 
 write(6,'(1/,a)') ' ... reporting .............................................................'
 write(6,'(/,a,f8.2,a,es11.5,a,es11.4,a)') ' error divergence = ', &
            err_div/pAvgDivL2/err_div_tol, ' (',err_div/pAvgDivL2,' / m,  tol =',err_div_tol,')'
 write(6,'(a,f8.2,a,es11.5,a,es11.4,a)')   ' error stress BC =  ', &
                   err_stress/err_stress_tol, ' (',err_stress, ' Pa  , tol =',err_stress_tol,')' 
 write(6,'(/,a)')  ' ==========================================================================='
 flush(6)
 
end subroutine BasicPETSc_converged


!--------------------------------------------------------------------------------------------------
!> @brief destroy routine
!--------------------------------------------------------------------------------------------------
subroutine BasicPETSc_destroy()
 use DAMASK_spectral_Utilities, only: &
   Utilities_destroy

 implicit none
 PetscErrorCode :: ierr
  
 call VecDestroy(solution_vec,ierr); CHKERRQ(ierr)
 call SNESDestroy(snes,ierr); CHKERRQ(ierr)
 call DMDestroy(da,ierr); CHKERRQ(ierr)
 call PetscFinalize(ierr); CHKERRQ(ierr)
 call Utilities_destroy()

end subroutine BasicPETSc_destroy

end module DAMASK_spectral_SolverBasicPETSc