#include <../src/ksp/pc/impls/factor/icc/icc.h> /*I "petscpc.h" I*/

static PetscErrorCode PCSetUp_ICC(PC pc)
{
  PC_ICC        *icc  = (PC_ICC *)pc->data;
  IS             perm = NULL, cperm = NULL;
  MatInfo        info;
  MatSolverType  stype;
  MatFactorError err;
  PetscBool      canuseordering;
  const char    *prefix;

  PetscFunctionBegin;
  pc->failedreason = PC_NOERROR;

  PetscCall(PCGetOptionsPrefix(pc, &prefix));
  PetscCall(MatSetOptionsPrefixFactor(pc->pmat, prefix));

  PetscCall(MatSetErrorIfFailure(pc->pmat, pc->erroriffailure));
  if (!pc->setupcalled) {
    PetscCall(PCFactorSetUpMatSolverType(pc));
    PetscCall(MatFactorGetCanUseOrdering(((PC_Factor *)icc)->fact, &canuseordering));
    if (canuseordering) {
      PetscCall(PCFactorSetDefaultOrdering_Factor(pc));
      PetscCall(MatGetOrdering(pc->pmat, ((PC_Factor *)icc)->ordering, &perm, &cperm));
    }
    PetscCall(MatICCFactorSymbolic(((PC_Factor *)icc)->fact, pc->pmat, perm, &((PC_Factor *)icc)->info));
  } else if (pc->flag != SAME_NONZERO_PATTERN) {
    PetscCall(MatDestroy(&((PC_Factor *)icc)->fact));
    PetscCall(PCFactorSetUpMatSolverType(pc));
    PetscCall(MatFactorGetCanUseOrdering(((PC_Factor *)icc)->fact, &canuseordering));
    if (canuseordering) {
      PetscCall(PCFactorSetDefaultOrdering_Factor(pc));
      PetscCall(MatGetOrdering(pc->pmat, ((PC_Factor *)icc)->ordering, &perm, &cperm));
    }
    PetscCall(MatICCFactorSymbolic(((PC_Factor *)icc)->fact, pc->pmat, perm, &((PC_Factor *)icc)->info));
  }
  PetscCall(MatGetInfo(((PC_Factor *)icc)->fact, MAT_LOCAL, &info));
  icc->hdr.actualfill = info.fill_ratio_needed;

  PetscCall(ISDestroy(&cperm));
  PetscCall(ISDestroy(&perm));

  PetscCall(MatFactorGetError(((PC_Factor *)icc)->fact, &err));
  if (err) { /* FactorSymbolic() fails */
    pc->failedreason = (PCFailedReason)err;
    PetscFunctionReturn(PETSC_SUCCESS);
  }

  PetscCall(MatCholeskyFactorNumeric(((PC_Factor *)icc)->fact, pc->pmat, &((PC_Factor *)icc)->info));
  PetscCall(MatFactorGetError(((PC_Factor *)icc)->fact, &err));
  if (err) { /* FactorNumeric() fails */
    pc->failedreason = (PCFailedReason)err;
  }

  PetscCall(PCFactorGetMatSolverType(pc, &stype));
  if (!stype) {
    MatSolverType solverpackage;

    PetscCall(MatFactorGetSolverType(((PC_Factor *)icc)->fact, &solverpackage));
    PetscCall(PCFactorSetMatSolverType(pc, solverpackage));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCReset_ICC(PC pc)
{
  PC_ICC *icc = (PC_ICC *)pc->data;

  PetscFunctionBegin;
  PetscCall(MatDestroy(&((PC_Factor *)icc)->fact));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCDestroy_ICC(PC pc)
{
  PC_ICC *icc = (PC_ICC *)pc->data;

  PetscFunctionBegin;
  PetscCall(PCReset_ICC(pc));
  PetscCall(PetscFree(((PC_Factor *)icc)->ordering));
  PetscCall(PetscFree(((PC_Factor *)icc)->solvertype));
  PetscCall(PCFactorClearComposedFunctions(pc));
  PetscCall(PetscFree(pc->data));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCApply_ICC(PC pc, Vec x, Vec y)
{
  PC_ICC *icc = (PC_ICC *)pc->data;

  PetscFunctionBegin;
  PetscCall(MatSolve(((PC_Factor *)icc)->fact, x, y));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCMatApply_ICC(PC pc, Mat X, Mat Y)
{
  PC_ICC *icc = (PC_ICC *)pc->data;

  PetscFunctionBegin;
  PetscCall(MatMatSolve(((PC_Factor *)icc)->fact, X, Y));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCApplySymmetricLeft_ICC(PC pc, Vec x, Vec y)
{
  PC_ICC *icc = (PC_ICC *)pc->data;

  PetscFunctionBegin;
  PetscCall(MatForwardSolve(((PC_Factor *)icc)->fact, x, y));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCApplySymmetricRight_ICC(PC pc, Vec x, Vec y)
{
  PC_ICC *icc = (PC_ICC *)pc->data;

  PetscFunctionBegin;
  PetscCall(MatBackwardSolve(((PC_Factor *)icc)->fact, x, y));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PCSetFromOptions_ICC(PC pc, PetscOptionItems PetscOptionsObject)
{
  PC_ICC   *icc = (PC_ICC *)pc->data;
  PetscBool flg;
  /* PetscReal      dt[3];*/

  PetscFunctionBegin;
  PetscOptionsHeadBegin(PetscOptionsObject, "ICC Options");
  PetscCall(PCSetFromOptions_Factor(pc, PetscOptionsObject));

  PetscCall(PetscOptionsReal("-pc_factor_levels", "levels of fill", "PCFactorSetLevels", ((PC_Factor *)icc)->info.levels, &((PC_Factor *)icc)->info.levels, &flg));
  /*dt[0] = ((PC_Factor*)icc)->info.dt;
  dt[1] = ((PC_Factor*)icc)->info.dtcol;
  dt[2] = ((PC_Factor*)icc)->info.dtcount;
  PetscInt       dtmax = 3;
  PetscCall(PetscOptionsRealArray("-pc_factor_drop_tolerance","<dt,dtcol,maxrowcount>","PCFactorSetDropTolerance",dt,&dtmax,&flg));
  if (flg) PetscCall(PCFactorSetDropTolerance(pc,dt[0],dt[1],(PetscInt)dt[2]));
  */
  PetscOptionsHeadEnd();
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*MC
     PCICC - Incomplete Cholesky factorization preconditioners {cite}`chan1997approximate`

   Options Database Keys:
+  -pc_factor_levels <k>                                 - number of levels of fill for ICC(k)
.  -pc_factor_in_place                                   - only for ICC(0) with natural ordering, reuses the space of the matrix for
                                                         its factorization (overwrites original matrix)
.  -pc_factor_fill <nfill>                               - expected amount of fill in factored matrix compared to original matrix, nfill > 1
-  -pc_factor_mat_ordering_type <natural,nd,1wd,rcm,qmd> - set the row/column ordering of the factored matrix

   Level: beginner

   Notes:
   Only implemented for some matrix formats. Not implemented in parallel.

   For `MATSEQBAIJ` matrices this implements a point block ICC.

   By default, the Manteuffel shift {cite}`manteuffel1979shifted` is applied, for matrices with block size 1 only. Call `PCFactorSetShiftType`(pc,`MAT_SHIFT_POSITIVE_DEFINITE`);
   to turn off the shift.

.seealso: [](ch_ksp), `PCCreate()`, `PCSetType()`, `PCType`, `PC`, `PCSOR`, `MatOrderingType`, `PCILU`, `PCLU`, `PCCHOLESKY`,
          `PCFactorSetZeroPivot()`, `PCFactorSetShiftType()`, `PCFactorSetShiftAmount()`,
          `PCFactorSetFill()`, `PCFactorSetMatOrderingType()`, `PCFactorSetReuseOrdering()`,
          `PCFactorSetLevels()`
M*/

PETSC_EXTERN PetscErrorCode PCCreate_ICC(PC pc)
{
  PC_ICC *icc;

  PetscFunctionBegin;
  PetscCall(PetscNew(&icc));
  pc->data = (void *)icc;
  PetscCall(PCFactorInitialize(pc, MAT_FACTOR_ICC));

  ((PC_Factor *)icc)->info.fill      = 1.0;
  ((PC_Factor *)icc)->info.dtcol     = PETSC_DEFAULT;
  ((PC_Factor *)icc)->info.shifttype = (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE;

  pc->ops->apply               = PCApply_ICC;
  pc->ops->matapply            = PCMatApply_ICC;
  pc->ops->applytranspose      = PCApply_ICC;
  pc->ops->matapplytranspose   = PCMatApply_ICC;
  pc->ops->setup               = PCSetUp_ICC;
  pc->ops->reset               = PCReset_ICC;
  pc->ops->destroy             = PCDestroy_ICC;
  pc->ops->setfromoptions      = PCSetFromOptions_ICC;
  pc->ops->view                = PCView_Factor;
  pc->ops->applysymmetricleft  = PCApplySymmetricLeft_ICC;
  pc->ops->applysymmetricright = PCApplySymmetricRight_ICC;
  PetscFunctionReturn(PETSC_SUCCESS);
}