!  
!   
!                             AMG4PSBLAS version 1.0
!    Algebraic Multigrid Package
!               based on PSBLAS (Parallel Sparse BLAS version 3.7)
!    
!    (C) Copyright 2021 
!  
!        Salvatore Filippone  
!        Pasqua D'Ambra   
!        Fabio Durastante        
!   
!    Redistribution and use in source and binary forms, with or without
!    modification, are permitted provided that the following conditions
!    are met:
!      1. Redistributions of source code must retain the above copyright
!         notice, this list of conditions and the following disclaimer.
!      2. Redistributions in binary form must reproduce the above copyright
!         notice, this list of conditions, and the following disclaimer in the
!         documentation and/or other materials provided with the distribution.
!      3. The name of the AMG4PSBLAS group or the names of its contributors may
!         not be used to endorse or promote products derived from this
!         software without specific written permission.
!   
!    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
!    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
!    TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
!    PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AMG4PSBLAS GROUP OR ITS CONTRIBUTORS
!    BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
!    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
!    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
!    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
!    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
!    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
!    POSSIBILITY OF SUCH DAMAGE.
!   
!  
subroutine amg_s_ilu_solver_apply(alpha,sv,x,beta,y,desc_data,&
     & trans,work,info,init,initu)
  
  use psb_base_mod
  use amg_s_ilu_solver, amg_protect_name => amg_s_ilu_solver_apply
  implicit none 
  type(psb_desc_type), intent(in)       :: desc_data
  class(amg_s_ilu_solver_type), intent(inout) :: sv
  real(psb_spk_),intent(inout)         :: x(:)
  real(psb_spk_),intent(inout)         :: y(:)
  real(psb_spk_),intent(in)            :: alpha,beta
  character(len=1),intent(in)           :: trans
  real(psb_spk_),target, intent(inout) :: work(:)
  integer(psb_ipk_), intent(out)        :: info
  character, intent(in), optional       :: init
  real(psb_spk_),intent(inout), optional :: initu(:)

  integer(psb_ipk_)   :: n_row,n_col
  real(psb_spk_), pointer :: ww(:), aux(:), tx(:),ty(:)
  integer(psb_ipk_)   :: i, err_act
  character           :: trans_
  character(len=20)   :: name='s_ilu_solver_apply'

  call psb_erractionsave(err_act)

  info = psb_success_

  trans_ = psb_toupper(trans)
  select case(trans_)
  case('N')
  case('T','C')
  case default
    call psb_errpush(psb_err_iarg_invalid_i_,name)
    goto 9999
  end select
  !
  ! For non-iterative solvers, init and initu are ignored.
  !

  n_row = desc_data%get_local_rows()
  n_col = desc_data%get_local_cols()

  if (n_col <= size(work)) then 
    ww => work(1:n_col)
    if ((4*n_col+n_col) <= size(work)) then 
      aux => work(n_col+1:)
    else
      allocate(aux(4*n_col),stat=info)
      if (info /= psb_success_) then 
        info=psb_err_alloc_request_
        call psb_errpush(info,name,& 
             & i_err=(/4*n_col,izero,izero,izero,izero/),&
             & a_err='real(psb_spk_)')
        goto 9999      
      end if
    endif
  else
    allocate(ww(n_col),aux(4*n_col),stat=info)
    if (info /= psb_success_) then 
      info=psb_err_alloc_request_
      call psb_errpush(info,name,& 
           & i_err=(/5*n_col,izero,izero,izero,izero/),&
           & a_err='real(psb_spk_)')
      goto 9999      
    end if
  endif

  select case(trans_)
  case('N')
    call psb_spsm(sone,sv%l,x,szero,ww,desc_data,info,&
         & trans=trans_,scale='L',diag=sv%d,choice=psb_none_,work=aux)

    if (info == psb_success_) call psb_spsm(alpha,sv%u,ww,beta,y,desc_data,info,&
         & trans=trans_,scale='U',choice=psb_none_, work=aux)

  case('T')
    call psb_spsm(sone,sv%u,x,szero,ww,desc_data,info,&
         & trans=trans_,scale='L',diag=sv%d,choice=psb_none_,work=aux)
    if (info == psb_success_) call psb_spsm(alpha,sv%l,ww,beta,y,desc_data,info,&
         & trans=trans_,scale='U',choice=psb_none_,work=aux)
  case('C')
    call psb_spsm(sone,sv%u,x,szero,ww,desc_data,info,&
         & trans=trans_,scale='L',diag=sv%d,choice=psb_none_,work=aux)
    if (info == psb_success_) call psb_spsm(alpha,sv%l,ww,beta,y,desc_data,info,&
         & trans=trans_,scale='U',choice=psb_none_,work=aux)
  case default
    call psb_errpush(psb_err_internal_error_,name,&
         & a_err='Invalid TRANS in ILU subsolve')
    goto 9999
  end select


  if (info /= psb_success_) then

    call psb_errpush(psb_err_internal_error_,name,& 
         & a_err='Error in subsolve')
    goto 9999
  endif

  if (n_col <= size(work)) then 
    if ((4*n_col+n_col) <= size(work)) then 
    else
      deallocate(aux)
    endif
  else
    deallocate(ww,aux)
  endif

  call psb_erractionrestore(err_act)
  return

9999 call psb_error_handler(err_act)

  return

end subroutine amg_s_ilu_solver_apply