/*
 GAMG geometric-algebric multigrid PC - Mark Adams 2011
 */
#include <petsc/private/matimpl.h>
#include <../src/ksp/pc/impls/gamg/gamg.h> /*I "petscpc.h" I*/
#include <petsc/private/kspimpl.h>

// PetscClangLinter pragma disable: -fdoc-sowing-chars
/*
  PCGAMGGetDataWithGhosts - Get array of local + ghost data with local data
  hacks into Mat MPIAIJ so this must have size > 1

  Input Parameters:
+ Gmat    - MPIAIJ matrix for scatters
. data_sz - number of data terms per node (# cols in output)
- data_in - column-oriented local data of size nloc*data_sz

  Output Parameters:
+ a_stride - number of rows of output (locals+ghosts)
- a_data_out - output data with ghosts of size stride*data_sz

*/
PetscErrorCode PCGAMGGetDataWithGhosts(Mat Gmat, PetscInt data_sz, PetscReal data_in[], PetscInt *a_stride, PetscReal **a_data_out)
{
  Vec          tmp_crds;
  Mat_MPIAIJ  *mpimat;
  PetscInt     nnodes, num_ghosts, dir, kk, jj, my0, Iend, nloc;
  PetscScalar *data_arr;
  PetscReal   *datas;
  PetscBool    isMPIAIJ;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(Gmat, MAT_CLASSID, 1);
  mpimat = (Mat_MPIAIJ *)Gmat->data;
  PetscCall(PetscObjectBaseTypeCompare((PetscObject)Gmat, MATMPIAIJ, &isMPIAIJ));
  PetscCall(MatGetOwnershipRange(Gmat, &my0, &Iend));
  nloc = Iend - my0;
  PetscCall(VecGetLocalSize(mpimat->lvec, &num_ghosts));
  nnodes    = num_ghosts + nloc;
  *a_stride = nnodes;
  PetscCall(MatCreateVecs(Gmat, &tmp_crds, NULL));

  PetscCall(PetscMalloc1(data_sz * nnodes, &datas));
  for (dir = 0; dir < data_sz; dir++) {
    /* set local, and global */
    for (kk = 0; kk < nloc; kk++) {
      PetscInt    gid          = my0 + kk;
      PetscScalar crd          = (PetscScalar)data_in[dir * nloc + kk]; /* col oriented */
      datas[dir * nnodes + kk] = PetscRealPart(crd);                    // get local part now

      PetscCall(VecSetValues(tmp_crds, 1, &gid, &crd, INSERT_VALUES));
    }
    PetscCall(VecAssemblyBegin(tmp_crds));
    PetscCall(VecAssemblyEnd(tmp_crds));
    /* scatter / gather ghost data and add to end of output data */
    PetscCall(VecScatterBegin(mpimat->Mvctx, tmp_crds, mpimat->lvec, INSERT_VALUES, SCATTER_FORWARD));
    PetscCall(VecScatterEnd(mpimat->Mvctx, tmp_crds, mpimat->lvec, INSERT_VALUES, SCATTER_FORWARD));
    PetscCall(VecGetArray(mpimat->lvec, &data_arr));
    for (kk = nloc, jj = 0; jj < num_ghosts; kk++, jj++) datas[dir * nnodes + kk] = PetscRealPart(data_arr[jj]);
    PetscCall(VecRestoreArray(mpimat->lvec, &data_arr));
  }
  PetscCall(VecDestroy(&tmp_crds));
  *a_data_out = datas;
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PCGAMGHashTableCreate(PetscInt a_size, PCGAMGHashTable *a_tab)
{
  PetscInt kk;

  PetscFunctionBegin;
  a_tab->size = a_size;
  PetscCall(PetscMalloc2(a_size, &a_tab->table, a_size, &a_tab->data));
  for (kk = 0; kk < a_size; kk++) a_tab->table[kk] = -1;
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PCGAMGHashTableDestroy(PCGAMGHashTable *a_tab)
{
  PetscFunctionBegin;
  PetscCall(PetscFree2(a_tab->table, a_tab->data));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PCGAMGHashTableAdd(PCGAMGHashTable *a_tab, PetscInt a_key, PetscInt a_data)
{
  PetscInt kk, idx;

  PetscFunctionBegin;
  PetscCheck(a_key >= 0, PETSC_COMM_SELF, PETSC_ERR_USER, "Negative key %" PetscInt_FMT ".", a_key);
  for (kk = 0, idx = GAMG_HASH(a_key); kk < a_tab->size; kk++, idx = (idx == (a_tab->size - 1)) ? 0 : idx + 1) {
    if (a_tab->table[idx] == a_key) {
      /* exists */
      a_tab->data[idx] = a_data;
      break;
    } else if (a_tab->table[idx] == -1) {
      /* add */
      a_tab->table[idx] = a_key;
      a_tab->data[idx]  = a_data;
      break;
    }
  }
  if (kk == a_tab->size) {
    /* this is not to efficient, waiting until completely full */
    PetscInt oldsize = a_tab->size, new_size = 2 * a_tab->size + 5, *oldtable = a_tab->table, *olddata = a_tab->data;

    a_tab->size = new_size;
    PetscCall(PetscMalloc2(a_tab->size, &a_tab->table, a_tab->size, &a_tab->data));
    for (kk = 0; kk < a_tab->size; kk++) a_tab->table[kk] = -1;
    for (kk = 0; kk < oldsize; kk++) {
      if (oldtable[kk] != -1) PetscCall(PCGAMGHashTableAdd(a_tab, oldtable[kk], olddata[kk]));
    }
    PetscCall(PetscFree2(oldtable, olddata));
    PetscCall(PCGAMGHashTableAdd(a_tab, a_key, a_data));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}