#include <petsc/private/dmfieldimpl.h> /*I "petscdmfield.h" I*/
#include <petsc/private/dmimpl.h>      /*I "petscdm.h" I*/
#include <petscdmda.h>

typedef struct _n_DMField_DA {
  PetscScalar *cornerVals;
  PetscScalar *cornerCoeffs;
  PetscScalar *work;
  PetscReal    coordRange[3][2];
} DMField_DA;

static PetscErrorCode DMFieldDestroy_DA(DMField field)
{
  DMField_DA *dafield;

  PetscFunctionBegin;
  dafield = (DMField_DA *)field->data;
  PetscCall(PetscFree3(dafield->cornerVals, dafield->cornerCoeffs, dafield->work));
  PetscCall(PetscFree(dafield));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode DMFieldView_DA(DMField field, PetscViewer viewer)
{
  DMField_DA *dafield = (DMField_DA *)field->data;
  PetscBool   isascii;

  PetscFunctionBegin;
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
  if (isascii) {
    PetscInt i, dim;
    PetscInt nc;
    DM       dm = field->dm;

    PetscCall(PetscViewerASCIIPrintf(viewer, "Field corner values:\n"));
    PetscCall(PetscViewerASCIIPushTab(viewer));
    PetscCall(DMGetDimension(dm, &dim));
    nc = field->numComponents;
    for (i = 0; i < (1 << dim); i++) {
      PetscInt j;

      for (j = 0; j < nc; j++) {
        PetscScalar val = dafield->cornerVals[nc * i + j];

#if !defined(PETSC_USE_COMPLEX)
        PetscCall(PetscViewerASCIIPrintf(viewer, "%g ", (double)val));
#else
        PetscCall(PetscViewerASCIIPrintf(viewer, "%g+i%g ", (double)PetscRealPart(val), (double)PetscImaginaryPart(val)));
#endif
      }
      PetscCall(PetscViewerASCIIPrintf(viewer, "\n"));
    }
    PetscCall(PetscViewerASCIIPopTab(viewer));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

#define MEdot(y, A, x, m, c, cast) \
  do { \
    PetscInt _k, _l; \
    for (_k = 0; _k < (c); _k++) (y)[_k] = 0.; \
    for (_l = 0; _l < (m); _l++) { \
      for (_k = 0; _k < (c); _k++) (y)[_k] += cast((A)[(c) * _l + _k]) * (x)[_l]; \
    } \
  } while (0)

#define MEHess(out, cf, etaB, etaD, dim, nc, cast) \
  do { \
    PetscInt _m, _j, _k; \
    for (_m = 0; _m < (nc) * (dim) * (dim); _m++) (out)[_m] = 0.; \
    for (_j = 0; _j < (dim); _j++) { \
      for (_k = _j + 1; _k < (dim); _k++) { \
        PetscInt _ind = (1 << _j) + (1 << _k); \
        for (_m = 0; _m < (nc); _m++) { \
          PetscScalar c = (cf)[_m] * (etaB)[_ind] * (etaD)[_ind]; \
          (out)[(_m * (dim) + _k) * (dim) + _j] += cast(c); \
          (out)[(_m * (dim) + _j) * (dim) + _k] += cast(c); \
        } \
      } \
    } \
  } while (0)

static void MultilinearEvaluate(PetscInt dim, PetscReal (*coordRange)[2], PetscInt nc, PetscScalar *cf, PetscScalar *cfWork, PetscInt nPoints, const PetscScalar *points, PetscDataType datatype, void *B, void *D, void *H)
{
  PetscInt i, j, k, l, m;
  PetscInt whol = 1 << dim;
  PetscInt half = whol >> 1;

  PetscFunctionBeginHot;
  if (!B && !D && !H) PetscFunctionReturnVoid();
  for (i = 0; i < nPoints; i++) {
    const PetscScalar *point   = &points[dim * i];
    PetscReal          deta[3] = {0.};
    PetscReal          etaB[8] = {1., 1., 1., 1., 1., 1., 1., 1.};
    PetscReal          etaD[8] = {1., 1., 1., 1., 1., 1., 1., 1.};
    PetscReal          work[8];

    for (j = 0; j < dim; j++) {
      PetscReal e, d;

      e       = (PetscRealPart(point[j]) - coordRange[j][0]) / coordRange[j][1];
      deta[j] = d = 1. / coordRange[j][1];
      for (k = 0; k < whol; k++) work[k] = etaB[k];
      for (k = 0; k < half; k++) {
        etaB[k]        = work[2 * k] * e;
        etaB[k + half] = work[2 * k + 1];
      }
      if (H) {
        for (k = 0; k < whol; k++) work[k] = etaD[k];
        for (k = 0; k < half; k++) {
          etaD[k + half] = work[2 * k];
          etaD[k]        = work[2 * k + 1] * d;
        }
      }
    }
    if (B) {
      if (datatype == PETSC_SCALAR) {
        PetscScalar *out = &((PetscScalar *)B)[nc * i];

        MEdot(out, cf, etaB, (1 << dim), nc, (PetscScalar));
      } else {
        PetscReal *out = &((PetscReal *)B)[nc * i];

        MEdot(out, cf, etaB, (1 << dim), nc, PetscRealPart);
      }
    }
    if (D) {
      if (datatype == PETSC_SCALAR) {
        PetscScalar *out = &((PetscScalar *)D)[nc * dim * i];

        for (m = 0; m < nc * dim; m++) out[m] = 0.;
      } else {
        PetscReal *out = &((PetscReal *)D)[nc * dim * i];

        for (m = 0; m < nc * dim; m++) out[m] = 0.;
      }
      for (j = 0; j < dim; j++) {
        PetscReal d = deta[j];

        for (k = 0; k < whol * nc; k++) cfWork[k] = cf[k];
        for (k = 0; k < whol; k++) work[k] = etaB[k];
        for (k = 0; k < half; k++) {
          PetscReal e;

          etaB[k]        = work[2 * k];
          etaB[k + half] = e = work[2 * k + 1];

          for (l = 0; l < nc; l++) {
            cf[k * nc + l]          = cfWork[2 * k * nc + l];
            cf[(k + half) * nc + l] = cfWork[(2 * k + 1) * nc + l];
          }
          if (datatype == PETSC_SCALAR) {
            PetscScalar *out = &((PetscScalar *)D)[nc * dim * i];

            for (l = 0; l < nc; l++) out[l * dim + j] += d * e * cf[k * nc + l];
          } else {
            PetscReal *out = &((PetscReal *)D)[nc * dim * i];

            for (l = 0; l < nc; l++) out[l * dim + j] += d * e * PetscRealPart(cf[k * nc + l]);
          }
        }
      }
    }
    if (H) {
      if (datatype == PETSC_SCALAR) {
        PetscScalar *out = &((PetscScalar *)H)[nc * dim * dim * i];

        MEHess(out, cf, etaB, etaD, dim, nc, (PetscScalar));
      } else {
        PetscReal *out = &((PetscReal *)H)[nc * dim * dim * i];

        MEHess(out, cf, etaB, etaD, dim, nc, PetscRealPart);
      }
    }
  }
  PetscFunctionReturnVoid();
}

static PetscErrorCode DMFieldEvaluate_DA(DMField field, Vec points, PetscDataType datatype, void *B, void *D, void *H)
{
  DM                 dm;
  DMField_DA        *dafield;
  PetscInt           dim;
  PetscInt           N, n, nc;
  const PetscScalar *array;
  PetscReal (*coordRange)[2];

  PetscFunctionBegin;
  dm      = field->dm;
  nc      = field->numComponents;
  dafield = (DMField_DA *)field->data;
  PetscCall(DMGetDimension(dm, &dim));
  PetscCall(VecGetLocalSize(points, &N));
  PetscCheck(N % dim == 0, PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Point vector size %" PetscInt_FMT " not divisible by coordinate dimension %" PetscInt_FMT, N, dim);
  n          = N / dim;
  coordRange = &dafield->coordRange[0];
  PetscCall(VecGetArrayRead(points, &array));
  MultilinearEvaluate(dim, coordRange, nc, dafield->cornerCoeffs, dafield->work, n, array, datatype, B, D, H);
  PetscCall(VecRestoreArrayRead(points, &array));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode DMFieldEvaluateFE_DA(DMField field, IS cellIS, PetscQuadrature points, PetscDataType datatype, void *B, void *D, void *H)
{
  PetscInt  c, i, j, k, dim, cellsPer[3] = {0}, first[3] = {0}, whol, half;
  PetscReal stepPer[3]           = {0.};
  PetscReal cellCoordRange[3][2] = {
    {0., 1.},
    {0., 1.},
    {0., 1.}
  };
  PetscScalar     *cellCoeffs, *work;
  DM               dm;
  DMDALocalInfo    info;
  PetscInt         cStart, cEnd;
  PetscInt         nq, nc;
  const PetscReal *q;
#if defined(PETSC_USE_COMPLEX)
  PetscScalar *qs;
#else
  const PetscScalar *qs;
#endif
  DMField_DA     *dafield;
  PetscBool       isStride;
  const PetscInt *cells  = NULL;
  PetscInt        sfirst = -1, stride = -1, nCells;

  PetscFunctionBegin;
  dafield = (DMField_DA *)field->data;
  dm      = field->dm;
  nc      = field->numComponents;
  PetscCall(DMDAGetLocalInfo(dm, &info));
  dim         = info.dim;
  work        = dafield->work;
  stepPer[0]  = 1. / info.mx;
  stepPer[1]  = 1. / info.my;
  stepPer[2]  = 1. / info.mz;
  first[0]    = info.gxs;
  first[1]    = info.gys;
  first[2]    = info.gzs;
  cellsPer[0] = info.gxm;
  cellsPer[1] = info.gym;
  cellsPer[2] = info.gzm;
  /* TODO: probably take components into account */
  PetscCall(PetscQuadratureGetData(points, NULL, NULL, &nq, &q, NULL));
#if defined(PETSC_USE_COMPLEX)
  PetscCall(DMGetWorkArray(dm, nq * dim, MPIU_SCALAR, &qs));
  for (i = 0; i < nq * dim; i++) qs[i] = q[i];
#else
  qs = q;
#endif
  PetscCall(DMDAGetHeightStratum(dm, 0, &cStart, &cEnd));
  PetscCall(DMGetWorkArray(dm, (1 << dim) * nc, MPIU_SCALAR, &cellCoeffs));
  whol = (1 << dim);
  half = whol >> 1;
  PetscCall(ISGetLocalSize(cellIS, &nCells));
  PetscCall(PetscObjectTypeCompare((PetscObject)cellIS, ISSTRIDE, &isStride));
  if (isStride) PetscCall(ISStrideGetInfo(cellIS, &sfirst, &stride));
  else PetscCall(ISGetIndices(cellIS, &cells));
  for (c = 0; c < nCells; c++) {
    PetscInt cell   = isStride ? (sfirst + c * stride) : cells[c];
    PetscInt rem    = cell;
    PetscInt ijk[3] = {0};
    void    *cB, *cD, *cH;

    if (datatype == PETSC_SCALAR) {
      cB = PetscSafePointerPlusOffset((PetscScalar *)B, nc * nq * c);
      cD = PetscSafePointerPlusOffset((PetscScalar *)D, nc * nq * dim * c);
      cH = PetscSafePointerPlusOffset((PetscScalar *)H, nc * nq * dim * dim * c);
    } else {
      cB = PetscSafePointerPlusOffset((PetscReal *)B, nc * nq * c);
      cD = PetscSafePointerPlusOffset((PetscReal *)D, nc * nq * dim * c);
      cH = PetscSafePointerPlusOffset((PetscReal *)H, nc * nq * dim * dim * c);
    }
    PetscCheck(cell >= cStart && cell < cEnd, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Point %" PetscInt_FMT " not a cell [%" PetscInt_FMT ",%" PetscInt_FMT "), not implemented yet", cell, cStart, cEnd);
    for (i = 0; i < nc * whol; i++) work[i] = dafield->cornerCoeffs[i];
    for (j = 0; j < dim; j++) {
      PetscReal e, d;
      ijk[j] = (rem % cellsPer[j]);
      rem /= cellsPer[j];

      e = 2. * (ijk[j] + first[j] + 0.5) * stepPer[j] - 1.;
      d = stepPer[j];
      for (i = 0; i < half; i++) {
        for (k = 0; k < nc; k++) {
          cellCoeffs[i * nc + k]          = work[2 * i * nc + k] * d;
          cellCoeffs[(i + half) * nc + k] = work[2 * i * nc + k] * e + work[(2 * i + 1) * nc + k];
        }
      }
      for (i = 0; i < whol * nc; i++) work[i] = cellCoeffs[i];
    }
    MultilinearEvaluate(dim, cellCoordRange, nc, cellCoeffs, dafield->work, nq, qs, datatype, cB, cD, cH);
  }
  if (!isStride) PetscCall(ISRestoreIndices(cellIS, &cells));
  PetscCall(DMRestoreWorkArray(dm, (1 << dim) * nc, MPIU_SCALAR, &cellCoeffs));
#if defined(PETSC_USE_COMPLEX)
  PetscCall(DMRestoreWorkArray(dm, nq * dim, MPIU_SCALAR, &qs));
#endif
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode DMFieldEvaluateFV_DA(DMField field, IS cellIS, PetscDataType datatype, void *B, void *D, void *H)
{
  PetscInt        c, i, dim, cellsPer[3] = {0}, first[3] = {0};
  PetscReal       stepPer[3] = {0.};
  DM              dm;
  DMDALocalInfo   info;
  PetscInt        cStart, cEnd, numCells;
  PetscInt        nc;
  PetscScalar    *points;
  DMField_DA     *dafield;
  PetscBool       isStride;
  const PetscInt *cells  = NULL;
  PetscInt        sfirst = -1, stride = -1;

  PetscFunctionBegin;
  dafield = (DMField_DA *)field->data;
  dm      = field->dm;
  nc      = field->numComponents;
  PetscCall(DMDAGetLocalInfo(dm, &info));
  dim         = info.dim;
  stepPer[0]  = 1. / info.mx;
  stepPer[1]  = 1. / info.my;
  stepPer[2]  = 1. / info.mz;
  first[0]    = info.gxs;
  first[1]    = info.gys;
  first[2]    = info.gzs;
  cellsPer[0] = info.gxm;
  cellsPer[1] = info.gym;
  cellsPer[2] = info.gzm;
  PetscCall(DMDAGetHeightStratum(dm, 0, &cStart, &cEnd));
  PetscCall(ISGetLocalSize(cellIS, &numCells));
  PetscCall(DMGetWorkArray(dm, dim * numCells, MPIU_SCALAR, &points));
  PetscCall(PetscObjectTypeCompare((PetscObject)cellIS, ISSTRIDE, &isStride));
  if (isStride) PetscCall(ISStrideGetInfo(cellIS, &sfirst, &stride));
  else PetscCall(ISGetIndices(cellIS, &cells));
  for (c = 0; c < numCells; c++) {
    PetscInt cell   = isStride ? (sfirst + c * stride) : cells[c];
    PetscInt rem    = cell;
    PetscInt ijk[3] = {0};

    PetscCheck(cell >= cStart && cell < cEnd, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Point %" PetscInt_FMT " not a cell [%" PetscInt_FMT ",%" PetscInt_FMT "), not implemented yet", cell, cStart, cEnd);
    for (i = 0; i < dim; i++) {
      ijk[i] = (rem % cellsPer[i]);
      rem /= cellsPer[i];
      points[dim * c + i] = (ijk[i] + first[i] + 0.5) * stepPer[i];
    }
  }
  if (!isStride) PetscCall(ISRestoreIndices(cellIS, &cells));
  MultilinearEvaluate(dim, dafield->coordRange, nc, dafield->cornerCoeffs, dafield->work, numCells, points, datatype, B, D, H);
  PetscCall(DMRestoreWorkArray(dm, dim * numCells, MPIU_SCALAR, &points));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode DMFieldGetDegree_DA(DMField field, IS pointIS, PetscInt *minDegree, PetscInt *maxDegree)
{
  DM       dm;
  PetscInt dim, h, imin;

  PetscFunctionBegin;
  dm = field->dm;
  PetscCall(ISGetMinMax(pointIS, &imin, NULL));
  PetscCall(DMGetDimension(dm, &dim));
  for (h = 0; h <= dim; h++) {
    PetscInt hEnd;

    PetscCall(DMDAGetHeightStratum(dm, h, NULL, &hEnd));
    if (imin < hEnd) break;
  }
  dim -= h;
  if (minDegree) *minDegree = 1;
  if (maxDegree) *maxDegree = dim;
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode DMFieldCreateDefaultQuadrature_DA(DMField field, IS cellIS, PetscQuadrature *quad)
{
  PetscInt h, dim, imax, imin;
  DM       dm;

  PetscFunctionBegin;
  dm = field->dm;
  PetscCall(ISGetMinMax(cellIS, &imin, &imax));
  PetscCall(DMGetDimension(dm, &dim));
  *quad = NULL;
  for (h = 0; h <= dim; h++) {
    PetscInt hStart, hEnd;

    PetscCall(DMDAGetHeightStratum(dm, h, &hStart, &hEnd));
    if (imin >= hStart && imax < hEnd) break;
  }
  dim -= h;
  if (dim > 0) PetscCall(PetscDTGaussTensorQuadrature(dim, 1, 1, -1.0, 1.0, quad));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode DMFieldInitialize_DA(DMField field)
{
  DM          dm;
  Vec         coords = NULL;
  PetscInt    dim, i, j, k;
  DMField_DA *dafield = (DMField_DA *)field->data;

  PetscFunctionBegin;
  field->ops->destroy                 = DMFieldDestroy_DA;
  field->ops->evaluate                = DMFieldEvaluate_DA;
  field->ops->evaluateFE              = DMFieldEvaluateFE_DA;
  field->ops->evaluateFV              = DMFieldEvaluateFV_DA;
  field->ops->getDegree               = DMFieldGetDegree_DA;
  field->ops->createDefaultQuadrature = DMFieldCreateDefaultQuadrature_DA;
  field->ops->view                    = DMFieldView_DA;
  dm                                  = field->dm;
  PetscCall(DMGetDimension(dm, &dim));
  PetscCall(DMGetCoordinates(dm, &coords));
  if (coords) {
    PetscInt           n;
    const PetscScalar *array;
    PetscReal          mins[3][2] = {
      {PETSC_MAX_REAL, PETSC_MAX_REAL},
      {PETSC_MAX_REAL, PETSC_MAX_REAL},
      {PETSC_MAX_REAL, PETSC_MAX_REAL}
    };

    PetscCall(VecGetLocalSize(coords, &n));
    n /= dim;
    PetscCall(VecGetArrayRead(coords, &array));
    for (i = 0, k = 0; i < n; i++) {
      for (j = 0; j < dim; j++, k++) {
        PetscReal val = PetscRealPart(array[k]);

        mins[j][0] = PetscMin(mins[j][0], val);
        mins[j][1] = PetscMin(mins[j][1], -val);
      }
    }
    PetscCall(VecRestoreArrayRead(coords, &array));
    PetscCallMPI(MPIU_Allreduce(mins, &dafield->coordRange[0][0], 2 * dim, MPIU_REAL, MPI_MIN, PetscObjectComm((PetscObject)dm)));
    for (j = 0; j < dim; j++) dafield->coordRange[j][1] = -dafield->coordRange[j][1];
  } else {
    for (j = 0; j < dim; j++) {
      dafield->coordRange[j][0] = 0.;
      dafield->coordRange[j][1] = 1.;
    }
  }
  for (j = 0; j < dim; j++) {
    PetscReal avg = 0.5 * (dafield->coordRange[j][1] + dafield->coordRange[j][0]);
    PetscReal dif = 0.5 * (dafield->coordRange[j][1] - dafield->coordRange[j][0]);

    dafield->coordRange[j][0] = avg;
    dafield->coordRange[j][1] = dif;
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

PETSC_INTERN PetscErrorCode DMFieldCreate_DA(DMField field)
{
  DMField_DA *dafield;

  PetscFunctionBegin;
  PetscCall(PetscNew(&dafield));
  field->data = dafield;
  PetscCall(DMFieldInitialize_DA(field));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode DMFieldCreateDA(DM dm, PetscInt nc, const PetscScalar *cornerValues, DMField *field)
{
  DMField      b;
  DMField_DA  *dafield;
  PetscInt     dim, nv, i, j, k;
  PetscInt     half;
  PetscScalar *cv, *cf, *work;

  PetscFunctionBegin;
  PetscCall(DMFieldCreate(dm, nc, DMFIELD_VERTEX, &b));
  PetscCall(DMFieldSetType(b, DMFIELDDA));
  dafield = (DMField_DA *)b->data;
  PetscCall(DMGetDimension(dm, &dim));
  nv = (1 << dim) * nc;
  PetscCall(PetscMalloc3(nv, &cv, nv, &cf, nv, &work));
  for (i = 0; i < nv; i++) cv[i] = cornerValues[i];
  for (i = 0; i < nv; i++) cf[i] = cv[i];
  dafield->cornerVals   = cv;
  dafield->cornerCoeffs = cf;
  dafield->work         = work;
  half                  = (1 << (dim - 1));
  for (i = 0; i < dim; i++) {
    PetscScalar *w;

    w = work;
    for (j = 0; j < half; j++) {
      for (k = 0; k < nc; k++) w[j * nc + k] = 0.5 * (cf[(2 * j + 1) * nc + k] - cf[(2 * j) * nc + k]);
    }
    w = &work[j * nc];
    for (j = 0; j < half; j++) {
      for (k = 0; k < nc; k++) w[j * nc + k] = 0.5 * (cf[(2 * j) * nc + k] + cf[(2 * j + 1) * nc + k]);
    }
    for (j = 0; j < nv; j++) cf[j] = work[j];
  }
  *field = b;
  PetscFunctionReturn(PETSC_SUCCESS);
}