#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

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

  Calling sequence of `solve`:
. tao - the optimizer, get the application context with `TaoShellGetContext()`

  Level: advanced

.seealso: `Tao`, `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(PETSC_SUCCESS);
}

/*@
  TaoShellGetContext - Returns the user-provided context associated with a `TAOSHELL`

  Not Collective

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

  Output Parameter:
. ctx - the user provided context

  Level: advanced

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

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

  PetscFunctionBegin;
  PetscValidHeaderSpecific(tao, TAO_CLASSID, 1);
  PetscAssertPointer(ctx, 2);
  PetscCall(PetscObjectTypeCompare((PetscObject)tao, TAOSHELL, &flg));
  if (!flg) *(void **)ctx = NULL;
  else *(void **)ctx = ((Tao_Shell *)tao->data)->ctx;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  TaoShellSetContext - sets the context for a `TAOSHELL`

  Logically Collective

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

  Level: advanced

  Fortran Notes:
  The context can only be an integer or a `PetscObject`

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

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

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

  PetscFunctionBegin;
  PetscCheck(shell->solve, PetscObjectComm((PetscObject)tao), PETSC_ERR_ARG_WRONGSTATE, "Must call TaoShellSetSolve() first");
  tao->reason = TAO_CONVERGED_USER;
  PetscCall((*shell->solve)(tao));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode TaoDestroy_Shell(Tao tao)
{
  PetscFunctionBegin;
  PetscCall(PetscFree(tao->data));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode TaoSetUp_Shell(Tao tao)
{
  PetscFunctionBegin;
  PetscFunctionReturn(PETSC_SUCCESS);
}

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

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

/*MC
  TAOSHELL - a user provided optimizer

   Level: advanced

.seealso: `TaoCreate()`, `Tao`, `TaoSetType()`, `TaoType`
M*/
PETSC_EXTERN PetscErrorCode TaoCreate_Shell(Tao tao)
{
  Tao_Shell *shell;

  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;

  PetscCall(PetscNew(&shell));
  tao->data = (void *)shell;
  PetscFunctionReturn(PETSC_SUCCESS);
}
