#include <petsc/private/taoimpl.h> /*I "petsctao.h" I*/

typedef struct _n_TaoShell Tao_Shell;

struct _n_TaoShell
{
  PetscErrorCode (*solve)(Tao);
  void            *ctx;
};

/*@C
   TaoShellSetSolve - Sets routine to apply as solver

   Logically Collective on Tao

   Input Parameters:
+  tao - the nonlinear solver context
-  solve - the application-provided solver routine

   Calling sequence of solve:
.vb
   PetscErrorCode solve (Tao tao)
.ve

.  tao - the optimizer, get the application context with TaoShellGetContext()

   Notes:
    the function MUST return an error code of 0 on success and nonzero on failure.

   Level: advanced

.seealso: TAOSHELL, TaoShellSetContext(), TaoShellGetContext()
@*/
PetscErrorCode TaoShellSetSolve(Tao tao, PetscErrorCode (*solve) (Tao))
{
  Tao_Shell                    *shell = (Tao_Shell*)tao->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(tao, TAO_CLASSID, 1);
  shell->solve = solve;
  PetscFunctionReturn(0);
}

/*@
    TaoShellGetContext - Returns the user-provided context associated with a shell Tao

    Not Collective

    Input Parameter:
.   tao - should have been created with TaoSetType(tao,TAOSHELL);

    Output Parameter:
.   ctx - the user provided context

    Level: advanced

    Notes:
    This routine is intended for use within various shell routines

.seealso: TaoCreateShell(), TaoShellSetContext()
@*/
PetscErrorCode  TaoShellGetContext(Tao tao,void **ctx)
{
  PetscErrorCode ierr;
  PetscBool      flg;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(tao,TAO_CLASSID,1);
  PetscValidPointer(ctx,2);
  ierr = PetscObjectTypeCompare((PetscObject)tao,TAOSHELL,&flg);CHKERRQ(ierr);
  if (!flg) *ctx = NULL;
  else      *ctx = ((Tao_Shell*)(tao->data))->ctx;
  PetscFunctionReturn(0);
}

/*@
    TaoShellSetContext - sets the context for a shell Tao

   Logically Collective on Tao

    Input Parameters:
+   tao - the shell Tao
-   ctx - the context

   Level: advanced

   Fortran Notes:
    The context can only be an integer or a PetscObject
      unfortunately it cannot be a Fortran array or derived type.


.seealso: TaoCreateShell(), TaoShellGetContext()
@*/
PetscErrorCode  TaoShellSetContext(Tao tao,void *ctx)
{
  Tao_Shell     *shell = (Tao_Shell*)tao->data;
  PetscErrorCode ierr;
  PetscBool      flg;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(tao,TAO_CLASSID,1);
  ierr = PetscObjectTypeCompare((PetscObject)tao,TAOSHELL,&flg);CHKERRQ(ierr);
  if (flg) shell->ctx = ctx;
  PetscFunctionReturn(0);
}

static PetscErrorCode TaoSolve_Shell(Tao tao)
{
  Tao_Shell                    *shell = (Tao_Shell*)tao->data;
  PetscErrorCode               ierr;

  PetscFunctionBegin;
  if (!shell->solve) SETERRQ(PetscObjectComm((PetscObject)tao),PETSC_ERR_ARG_WRONGSTATE,"Must call TaoShellSetSolve() first");
  tao->reason = TAO_CONVERGED_USER;
  ierr = (*(shell->solve)) (tao);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

PetscErrorCode TaoDestroy_Shell(Tao tao)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  ierr = PetscFree(tao->data);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

PetscErrorCode TaoSetUp_Shell(Tao tao)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}

PetscErrorCode TaoSetFromOptions_Shell(PetscOptionItems *PetscOptionsObject,Tao tao)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}

PetscErrorCode TaoView_Shell(Tao tao, PetscViewer viewer)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}

/*MC
  TAOSHELL - a user provided nonlinear solver

   Level: advanced

.seealso: TaoCreate(), Tao, TaoSetType(), TaoType (for list of available types)
M*/
PETSC_EXTERN PetscErrorCode TaoCreate_Shell(Tao tao)
{
  Tao_Shell      *shell;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  tao->ops->destroy = TaoDestroy_Shell;
  tao->ops->setup = TaoSetUp_Shell;
  tao->ops->setfromoptions = TaoSetFromOptions_Shell;
  tao->ops->view = TaoView_Shell;
  tao->ops->solve = TaoSolve_Shell;

  ierr = PetscNewLog(tao,&shell);CHKERRQ(ierr);
  tao->data = (void*)shell;
  PetscFunctionReturn(0);
}