/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright 2012 Blender Foundation. All rights reserved. */

/** \file
 * \ingroup pybmesh
 *
 * This file provides __call__ aka BPy_BMO_call for
 * the bmesh operator and has been given its own file
 * because argument conversion is involved.
 */

#include <Python.h>

#include "BLI_utildefines.h"

#include "../mathutils/mathutils.h"

#include "bmesh.h"

#include "bmesh_py_ops_call.h" /* own include */

#include "bmesh_py_types.h"

#include "../generic/py_capi_utils.h"
#include "../generic/python_utildefines.h"

BLI_STATIC_ASSERT(sizeof(PyC_FlagSet) == sizeof(BMO_FlagSet), "size mismatch");

static int bpy_bm_op_as_py_error(BMesh *bm)
{
  if (BMO_error_occurred_at_level(bm, BMO_ERROR_FATAL)) {
    /* NOTE: we could have multiple errors. */
    const char *errmsg;
    if (BMO_error_get(bm, &errmsg, NULL, NULL)) {
      PyErr_Format(PyExc_RuntimeError, "bmesh operator: %.200s", errmsg);
      BMO_error_clear(bm);
      return -1;
    }
  }
  return 0;
}

/**
 * \brief Utility function to check BMVert/BMEdge/BMFace's
 *
 * \param value:
 * \param bm: Check the \a value against this.
 * \param htype: Test \a value matches this type.
 * \param descr: Description text.
 */
static int bpy_slot_from_py_elem_check(BPy_BMElem *value,
                                       BMesh *bm,
                                       const char htype,
                                       /* for error messages */
                                       const char *opname,
                                       const char *slot_name,
                                       const char *descr)
{
  if (!BPy_BMElem_Check(value) || !(value->ele->head.htype & htype)) {
    PyErr_Format(PyExc_TypeError,
                 "%.200s: keyword \"%.200s\" %.200s, expected a %.200s not *.200s",
                 opname,
                 slot_name,
                 descr,
                 BPy_BMElem_StringFromHType(htype),
                 Py_TYPE(value)->tp_name);
    return -1;
  }
  if (value->bm == NULL) {
    PyErr_Format(PyExc_TypeError,
                 "%.200s: keyword \"%.200s\" %.200s invalidated element",
                 opname,
                 slot_name,
                 descr);
    return -1;
  }
  if (value->bm != bm) { /* we may want to make this check optional by setting 'bm' to NULL */
    PyErr_Format(PyExc_TypeError,
                 "%.200s: keyword \"%.200s\" %.200s invalidated element",
                 opname,
                 slot_name,
                 descr);
    return -1;
  }
  return 0;
}

/**
 * \brief Utility function to check BMVertSeq/BMEdgeSeq/BMFaceSeq's
 *
 * \param value: Caller must check its a BMeshSeq
 * \param bm: Check the \a value against this.
 * \param htype_py: The type(s) of \a value.
 * \param htype_bmo: The type(s) supported by the target slot.
 * \param descr: Description text.
 */
static int bpy_slot_from_py_elemseq_check(BPy_BMGeneric *value,
                                          BMesh *bm,
                                          const char htype_py,
                                          const char htype_bmo,
                                          /* for error messages */
                                          const char *opname,
                                          const char *slot_name,
                                          const char *descr)
{
  if (value->bm == NULL) {
    PyErr_Format(PyExc_TypeError,
                 "%.200s: keyword \"%.200s\" %.200s, invalidated sequence",
                 opname,
                 slot_name,
                 descr);
    return -1;
  }
  if (value->bm != bm) { /* we may want to make this check optional by setting 'bm' to NULL */
    PyErr_Format(PyExc_TypeError,
                 "%.200s: keyword \"%.200s\" %.200s, invalidated sequence",
                 opname,
                 slot_name,
                 descr);
    return -1;
  }
  if ((htype_py & htype_bmo) == 0) {
    char str_bmo[32];
    char str_py[32];
    PyErr_Format(PyExc_TypeError,
                 "%.200s: keyword \"%.200s\" %.200s, expected "
                 "a sequence of %.200s not %.200s",
                 opname,
                 slot_name,
                 descr,
                 BPy_BMElem_StringFromHType_ex(htype_bmo, str_bmo),
                 BPy_BMElem_StringFromHType_ex(htype_py, str_py));
    return -1;
  }

  return 0;
}

/**
 * Use for giving py args to an operator.
 */
static int bpy_slot_from_py(BMesh *bm,
                            BMOperator *bmop,
                            BMOpSlot *slot,
                            PyObject *value,
                            /* the are just for exception messages */
                            const char *opname,
                            const char *slot_name)
{
  switch (slot->slot_type) {
    case BMO_OP_SLOT_BOOL: {
      const int param = PyC_Long_AsBool(value);

      if (param == -1) {
        PyErr_Format(PyExc_TypeError,
                     "%.200s: keyword \"%.200s\" expected True/False or 0/1, not %.200s",
                     opname,
                     slot_name,
                     Py_TYPE(value)->tp_name);
        return -1;
      }

      BMO_SLOT_AS_BOOL(slot) = param;

      break;
    }
    case BMO_OP_SLOT_INT: {
      if (slot->slot_subtype.intg == BMO_OP_SLOT_SUBTYPE_INT_ENUM) {
        int enum_val = -1;
        PyC_FlagSet *items = (PyC_FlagSet *)slot->data.enum_data.flags;
        const char *enum_str = PyUnicode_AsUTF8(value);

        if (enum_str == NULL) {
          PyErr_Format(PyExc_TypeError,
                       "%.200s: keyword \"%.200s\" expected a string, not %.200s",
                       opname,
                       slot_name,
                       Py_TYPE(value)->tp_name);
          return -1;
        }

        if (PyC_FlagSet_ValueFromID(items, enum_str, &enum_val, slot_name) == -1) {
          return -1;
        }

        BMO_SLOT_AS_INT(slot) = enum_val;
      }
      else if (slot->slot_subtype.intg == BMO_OP_SLOT_SUBTYPE_INT_FLAG) {
        int flag = 0;
        PyC_FlagSet *items = (PyC_FlagSet *)slot->data.enum_data.flags;

        if (PyC_FlagSet_ToBitfield(items, value, &flag, slot_name) == -1) {
          return -1;
        }

        BMO_SLOT_AS_INT(slot) = flag;
      }
      else {
        const int param = PyC_Long_AsI32(value);

        if (param == -1 && PyErr_Occurred()) {
          PyErr_Format(PyExc_TypeError,
                       "%.200s: keyword \"%.200s\" expected an int, not %.200s",
                       opname,
                       slot_name,
                       Py_TYPE(value)->tp_name);
          return -1;
        }

        BMO_SLOT_AS_INT(slot) = param;
      }
      break;
    }
    case BMO_OP_SLOT_FLT: {
      const float param = PyFloat_AsDouble(value);
      if (param == -1 && PyErr_Occurred()) {
        PyErr_Format(PyExc_TypeError,
                     "%.200s: keyword \"%.200s\" expected a float, not %.200s",
                     opname,
                     slot_name,
                     Py_TYPE(value)->tp_name);
        return -1;
      }

      BMO_SLOT_AS_FLOAT(slot) = param;

      break;
    }
    case BMO_OP_SLOT_MAT: {
      /* XXX: BMesh operator design is crappy here, operator slot should define matrix size,
       * not the caller! */
      MatrixObject *pymat;
      if (!Matrix_ParseAny(value, &pymat)) {
        return -1;
      }
      const ushort size = pymat->col_num;
      if ((size != pymat->row_num) || !ELEM(size, 3, 4)) {
        PyErr_Format(PyExc_TypeError,
                     "%.200s: keyword \"%.200s\" expected a 3x3 or 4x4 matrix",
                     opname,
                     slot_name);
        return -1;
      }

      BMO_slot_mat_set(bmop, bmop->slots_in, slot_name, pymat->matrix, size);
      break;
    }
    case BMO_OP_SLOT_VEC: {
      /* passing slot name here is a bit non-descriptive */
      if (mathutils_array_parse(BMO_SLOT_AS_VECTOR(slot), 3, 3, value, slot_name) == -1) {
        return -1;
      }
      break;
    }
    case BMO_OP_SLOT_ELEMENT_BUF: {
      if (slot->slot_subtype.elem & BMO_OP_SLOT_SUBTYPE_ELEM_IS_SINGLE) {
        if (bpy_slot_from_py_elem_check((BPy_BMElem *)value,
                                        bm,
                                        (slot->slot_subtype.elem & BM_ALL_NOLOOP),
                                        opname,
                                        slot_name,
                                        "single element") == -1) {
          return -1; /* error is set in bpy_slot_from_py_elem_check() */
        }

        BMO_slot_buffer_from_single(bmop, slot, &((BPy_BMElem *)value)->ele->head);
      }
      else {
        /* there are many ways we could interpret arguments, for now...
         * - verts/edges/faces from the mesh direct,
         *   this way the operator takes every item.
         * - `TODO` a plain python sequence (list) of elements.
         * - `TODO`  an iterator. eg.
         *   face.verts
         * - `TODO`  (type, flag) pair, eg.
         *   ('VERT', {'TAG'})
         */

        if (BPy_BMVertSeq_Check(value)) {
          if (bpy_slot_from_py_elemseq_check((BPy_BMGeneric *)value,
                                             bm,
                                             BM_VERT,
                                             (slot->slot_subtype.elem & BM_ALL_NOLOOP),
                                             opname,
                                             slot_name,
                                             "element buffer") == -1) {
            return -1; /* error is set in bpy_slot_from_py_elem_check() */
          }

          BMO_slot_buffer_from_all(bm, bmop, bmop->slots_in, slot_name, BM_VERT);
        }
        else if (BPy_BMEdgeSeq_Check(value)) {
          if (bpy_slot_from_py_elemseq_check((BPy_BMGeneric *)value,
                                             bm,
                                             BM_EDGE,
                                             (slot->slot_subtype.elem & BM_ALL_NOLOOP),
                                             opname,
                                             slot_name,
                                             "element buffer") == -1) {
            return -1; /* error is set in bpy_slot_from_py_elem_check() */
          }

          BMO_slot_buffer_from_all(bm, bmop, bmop->slots_in, slot_name, BM_EDGE);
        }
        else if (BPy_BMFaceSeq_Check(value)) {
          if (bpy_slot_from_py_elemseq_check((BPy_BMGeneric *)value,
                                             bm,
                                             BM_FACE,
                                             (slot->slot_subtype.elem & BM_ALL_NOLOOP),
                                             opname,
                                             slot_name,
                                             "element buffer") == -1) {
            return -1; /* error is set in bpy_slot_from_py_elem_check() */
          }
          BMO_slot_buffer_from_all(bm, bmop, bmop->slots_in, slot_name, BM_FACE);
        }

        else if (BPy_BMElemSeq_Check(value)) {
          BMIter iter;
          BMHeader *ele;
          int tot;
          uint i;

          if (bpy_slot_from_py_elemseq_check(
                  (BPy_BMGeneric *)value,
                  bm,
                  bm_iter_itype_htype_map[((BPy_BMElemSeq *)value)->itype],
                  (slot->slot_subtype.elem & BM_ALL_NOLOOP),
                  opname,
                  slot_name,
                  "element buffer") == -1) {
            return -1; /* error is set in bpy_slot_from_py_elem_check() */
          }

          /* this will loop over all elements which is a shame but
           * we need to know this before alloc */
          /* calls bpy_bmelemseq_length() */
          tot = Py_TYPE(value)->tp_as_sequence->sq_length(value);

          BMO_slot_buffer_alloc(bmop, bmop->slots_in, slot_name, tot);

          i = 0;
          BM_ITER_BPY_BM_SEQ (ele, &iter, ((BPy_BMElemSeq *)value)) {
            slot->data.buf[i] = ele;
            i++;
          }
        }
        /* keep this last */
        else if (PySequence_Check(value)) {
          BMElem **elem_array = NULL;
          Py_ssize_t elem_array_len;

          elem_array = BPy_BMElem_PySeq_As_Array(&bm,
                                                 value,
                                                 0,
                                                 PY_SSIZE_T_MAX,
                                                 &elem_array_len,
                                                 (slot->slot_subtype.elem & BM_ALL_NOLOOP),
                                                 true,
                                                 true,
                                                 slot_name);

          /* error is set above */
          if (elem_array == NULL) {
            return -1;
          }

          BMO_slot_buffer_alloc(bmop, bmop->slots_in, slot_name, elem_array_len);
          memcpy(slot->data.buf, elem_array, sizeof(void *) * elem_array_len);
          PyMem_FREE(elem_array);
        }
        else {
          PyErr_Format(PyExc_TypeError,
                       "%.200s: keyword \"%.200s\" expected "
                       "a bmesh sequence, list, (htype, flag) pair, not %.200s",
                       opname,
                       slot_name,
                       Py_TYPE(value)->tp_name);
          return -1;
        }
      }
      break;
    }
    case BMO_OP_SLOT_MAPPING: {
      /* first check types */
      if (slot->slot_subtype.map != BMO_OP_SLOT_SUBTYPE_MAP_EMPTY) {
        if (!PyDict_Check(value)) {
          PyErr_Format(PyExc_TypeError,
                       "%.200s: keyword \"%.200s\" expected "
                       "a dict, not %.200s",
                       opname,
                       slot_name,
                       Py_TYPE(value)->tp_name);
          return -1;
        }
      }
      else {
        if (!PySet_Check(value)) {
          PyErr_Format(PyExc_TypeError,
                       "%.200s: keyword \"%.200s\" expected "
                       "a set, not %.200s",
                       opname,
                       slot_name,
                       Py_TYPE(value)->tp_name);
          return -1;
        }
      }

      switch (slot->slot_subtype.map) {
        case BMO_OP_SLOT_SUBTYPE_MAP_ELEM: {
          if (PyDict_Size(value) > 0) {
            PyObject *arg_key, *arg_value;
            Py_ssize_t arg_pos = 0;
            while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
              if (bpy_slot_from_py_elem_check((BPy_BMElem *)arg_key,
                                              bm,
                                              BM_ALL_NOLOOP,
                                              opname,
                                              slot_name,
                                              "invalid key in dict") == -1) {
                return -1; /* error is set in bpy_slot_from_py_elem_check() */
              }

              if (bpy_slot_from_py_elem_check((BPy_BMElem *)arg_value,
                                              bm,
                                              BM_ALL_NOLOOP,
                                              opname,
                                              slot_name,
                                              "invalid value in dict") == -1) {
                return -1; /* error is set in bpy_slot_from_py_elem_check() */
              }

              BMO_slot_map_elem_insert(
                  bmop, slot, ((BPy_BMElem *)arg_key)->ele, ((BPy_BMElem *)arg_value)->ele);
            }
          }
          break;
        }
        case BMO_OP_SLOT_SUBTYPE_MAP_FLT: {
          if (PyDict_Size(value) > 0) {
            PyObject *arg_key, *arg_value;
            Py_ssize_t arg_pos = 0;
            while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
              float value_f;

              if (bpy_slot_from_py_elem_check((BPy_BMElem *)arg_key,
                                              bm,
                                              BM_ALL_NOLOOP,
                                              opname,
                                              slot_name,
                                              "invalid key in dict") == -1) {
                return -1; /* error is set in bpy_slot_from_py_elem_check() */
              }

              value_f = PyFloat_AsDouble(arg_value);

              if (value_f == -1.0f && PyErr_Occurred()) {
                PyErr_Format(PyExc_TypeError,
                             "%.200s: keyword \"%.200s\" expected "
                             "a dict with float values, not %.200s",
                             opname,
                             slot_name,
                             Py_TYPE(arg_value)->tp_name);
                return -1;
              }

              BMO_slot_map_float_insert(bmop, slot, ((BPy_BMElem *)arg_key)->ele, value_f);
            }
          }
          break;
        }
        case BMO_OP_SLOT_SUBTYPE_MAP_INT: {
          if (PyDict_Size(value) > 0) {
            PyObject *arg_key, *arg_value;
            Py_ssize_t arg_pos = 0;
            while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
              int value_i;

              if (bpy_slot_from_py_elem_check((BPy_BMElem *)arg_key,
                                              bm,
                                              BM_ALL_NOLOOP,
                                              opname,
                                              slot_name,
                                              "invalid key in dict") == -1) {
                return -1; /* error is set in bpy_slot_from_py_elem_check() */
              }

              value_i = PyC_Long_AsI32(arg_value);

              if (value_i == -1 && PyErr_Occurred()) {
                PyErr_Format(PyExc_TypeError,
                             "%.200s: keyword \"%.200s\" expected "
                             "a dict with int values, not %.200s",
                             opname,
                             slot_name,
                             Py_TYPE(arg_value)->tp_name);
                return -1;
              }

              BMO_slot_map_int_insert(bmop, slot, ((BPy_BMElem *)arg_key)->ele, value_i);
            }
          }
          break;
        }
        case BMO_OP_SLOT_SUBTYPE_MAP_BOOL: {
          if (PyDict_Size(value) > 0) {
            PyObject *arg_key, *arg_value;
            Py_ssize_t arg_pos = 0;
            while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
              int value_i;

              if (bpy_slot_from_py_elem_check((BPy_BMElem *)arg_key,
                                              bm,
                                              BM_ALL_NOLOOP,
                                              opname,
                                              slot_name,
                                              "invalid key in dict") == -1) {
                return -1; /* error is set in bpy_slot_from_py_elem_check() */
              }

              value_i = PyC_Long_AsI32(arg_value);

              if (value_i == -1 && PyErr_Occurred()) {
                PyErr_Format(PyExc_TypeError,
                             "%.200s: keyword \"%.200s\" expected "
                             "a dict with bool values, not %.200s",
                             opname,
                             slot_name,
                             Py_TYPE(arg_value)->tp_name);
                return -1;
              }

              BMO_slot_map_bool_insert(bmop, slot, ((BPy_BMElem *)arg_key)->ele, value_i != 0);
            }
          }
          break;
        }
        case BMO_OP_SLOT_SUBTYPE_MAP_EMPTY: {
          if (PySet_Size(value) > 0) {
            PyObject *arg_key;
            Py_ssize_t arg_pos = 0;
            Py_ssize_t arg_hash = 0;
            while (_PySet_NextEntry(value, &arg_pos, &arg_key, &arg_hash)) {

              if (bpy_slot_from_py_elem_check((BPy_BMElem *)arg_key,
                                              bm,
                                              BM_ALL_NOLOOP,
                                              opname,
                                              slot_name,
                                              "invalid key in set") == -1) {
                return -1; /* error is set in bpy_slot_from_py_elem_check() */
              }

              BMO_slot_map_empty_insert(bmop, slot, ((BPy_BMElem *)arg_key)->ele);
            }
          }
          break;
        }
        case BMO_OP_SLOT_SUBTYPE_MAP_INTERNAL: {
          /* can't convert from these */
          PyErr_Format(PyExc_NotImplementedError,
                       "This arguments mapping subtype %d is not supported",
                       slot->slot_subtype.map);
          return -1;
        }
      }
      break;
    }
    default:
      /* TODO: many others. */
      PyErr_Format(PyExc_NotImplementedError,
                   "%.200s: keyword \"%.200s\" type %d not working yet!",
                   opname,
                   slot_name,
                   slot->slot_type);
      return -1;
  }

  /* all is well */
  return 0;
}

/**
 * Use for getting return values from an operator that's already executed.
 *
 * \note Don't throw any exceptions and should always return a valid (PyObject *).
 */
static PyObject *bpy_slot_to_py(BMesh *bm, BMOpSlot *slot)
{
  PyObject *item = NULL;

  /* keep switch in same order as above */
  switch (slot->slot_type) {
    case BMO_OP_SLOT_BOOL:
      item = PyBool_FromLong(BMO_SLOT_AS_BOOL(slot));
      break;
    case BMO_OP_SLOT_INT:
      item = PyLong_FromLong(BMO_SLOT_AS_INT(slot));
      break;
    case BMO_OP_SLOT_FLT:
      item = PyFloat_FromDouble((double)BMO_SLOT_AS_FLOAT(slot));
      break;
    case BMO_OP_SLOT_MAT:
      item = Matrix_CreatePyObject((float *)BMO_SLOT_AS_MATRIX(slot), 4, 4, NULL);
      break;
    case BMO_OP_SLOT_VEC:
      item = Vector_CreatePyObject(BMO_SLOT_AS_VECTOR(slot), slot->len, NULL);
      break;
    case BMO_OP_SLOT_PTR:
      BLI_assert(0); /* currently we don't have any pointer return values in use */
      item = Py_INCREF_RET(Py_None);
      break;
    case BMO_OP_SLOT_ELEMENT_BUF: {
      if (slot->slot_subtype.elem & BMO_OP_SLOT_SUBTYPE_ELEM_IS_SINGLE) {
        BMHeader *ele = BMO_slot_buffer_get_single(slot);
        item = ele ? BPy_BMElem_CreatePyObject(bm, ele) : Py_INCREF_RET(Py_None);
      }
      else {
        const int size = slot->len;
        void **buffer = BMO_SLOT_AS_BUFFER(slot);
        int j;

        item = PyList_New(size);
        for (j = 0; j < size; j++) {
          BMHeader *ele = buffer[j];
          PyList_SET_ITEM(item, j, BPy_BMElem_CreatePyObject(bm, ele));
        }
      }
      break;
    }
    case BMO_OP_SLOT_MAPPING: {
      GHash *slot_hash = BMO_SLOT_AS_GHASH(slot);
      GHashIterator hash_iter;

      switch (slot->slot_subtype.map) {
        case BMO_OP_SLOT_SUBTYPE_MAP_ELEM: {
          item = _PyDict_NewPresized(slot_hash ? BLI_ghash_len(slot_hash) : 0);
          if (slot_hash) {
            GHASH_ITER (hash_iter, slot_hash) {
              BMHeader *ele_key = BLI_ghashIterator_getKey(&hash_iter);
              void *ele_val = BLI_ghashIterator_getValue(&hash_iter);

              PyObject *py_key = BPy_BMElem_CreatePyObject(bm, ele_key);
              PyObject *py_val = BPy_BMElem_CreatePyObject(bm, ele_val);

              PyDict_SetItem(item, py_key, py_val);
              Py_DECREF(py_key);
              Py_DECREF(py_val);
            }
          }
          break;
        }
        case BMO_OP_SLOT_SUBTYPE_MAP_FLT: {
          item = _PyDict_NewPresized(slot_hash ? BLI_ghash_len(slot_hash) : 0);
          if (slot_hash) {
            GHASH_ITER (hash_iter, slot_hash) {
              BMHeader *ele_key = BLI_ghashIterator_getKey(&hash_iter);
              void *ele_val = BLI_ghashIterator_getValue(&hash_iter);

              PyObject *py_key = BPy_BMElem_CreatePyObject(bm, ele_key);
              PyObject *py_val = PyFloat_FromDouble(*(float *)&ele_val);

              PyDict_SetItem(item, py_key, py_val);
              Py_DECREF(py_key);
              Py_DECREF(py_val);
            }
          }
          break;
        }
        case BMO_OP_SLOT_SUBTYPE_MAP_INT: {
          item = _PyDict_NewPresized(slot_hash ? BLI_ghash_len(slot_hash) : 0);
          if (slot_hash) {
            GHASH_ITER (hash_iter, slot_hash) {
              BMHeader *ele_key = BLI_ghashIterator_getKey(&hash_iter);
              void *ele_val = BLI_ghashIterator_getValue(&hash_iter);

              PyObject *py_key = BPy_BMElem_CreatePyObject(bm, ele_key);
              PyObject *py_val = PyLong_FromLong(*(int *)&ele_val);

              PyDict_SetItem(item, py_key, py_val);
              Py_DECREF(py_key);
              Py_DECREF(py_val);
            }
          }
          break;
        }
        case BMO_OP_SLOT_SUBTYPE_MAP_BOOL: {
          item = _PyDict_NewPresized(slot_hash ? BLI_ghash_len(slot_hash) : 0);
          if (slot_hash) {
            GHASH_ITER (hash_iter, slot_hash) {
              BMHeader *ele_key = BLI_ghashIterator_getKey(&hash_iter);
              void *ele_val = BLI_ghashIterator_getValue(&hash_iter);

              PyObject *py_key = BPy_BMElem_CreatePyObject(bm, ele_key);
              PyObject *py_val = PyBool_FromLong(*(bool *)&ele_val);

              PyDict_SetItem(item, py_key, py_val);
              Py_DECREF(py_key);
              Py_DECREF(py_val);
            }
          }
          break;
        }
        case BMO_OP_SLOT_SUBTYPE_MAP_EMPTY: {
          item = PySet_New(NULL);
          if (slot_hash) {
            GHASH_ITER (hash_iter, slot_hash) {
              BMHeader *ele_key = BLI_ghashIterator_getKey(&hash_iter);

              PyObject *py_key = BPy_BMElem_CreatePyObject(bm, ele_key);

              PySet_Add(item, py_key);

              Py_DECREF(py_key);
            }
          }
          break;
        }
        case BMO_OP_SLOT_SUBTYPE_MAP_INTERNAL:
          /* can't convert from these */
          item = Py_INCREF_RET(Py_None);
          break;
      }
      break;
    }
  }
  BLI_assert(item != NULL);

  return item;
}

PyObject *BPy_BMO_call(BPy_BMeshOpFunc *self, PyObject *args, PyObject *kw)
{
  PyObject *ret;
  BPy_BMesh *py_bm;
  BMesh *bm;

  BMOperator bmop;

  if ((PyTuple_GET_SIZE(args) == 1) && (py_bm = (BPy_BMesh *)PyTuple_GET_ITEM(args, 0)) &&
      BPy_BMesh_Check(py_bm)) {
    BPY_BM_CHECK_OBJ(py_bm);
    bm = py_bm->bm;

    if (bm->use_toolflags == false) {
      PyErr_SetString(PyExc_ValueError, "bmesh created with 'use_operators=False'");
      return NULL;
    }

    /* could complain about entering with exceptions... */
    BMO_error_clear(bm);
  }
  else {
    PyErr_SetString(PyExc_TypeError,
                    "bmesh operators expect a single BMesh positional argument, all other args "
                    "must be keywords");
    return NULL;
  }

  /* TODO: error check this!, though we do the error check on attribute access. */
  /* TODO: make flags optional. */
  BMO_op_init(bm, &bmop, BMO_FLAG_DEFAULTS, self->opname);

  if (kw && PyDict_Size(kw) > 0) {
    /* setup properties, see bpy_rna.c: pyrna_py_to_prop()
     * which shares this logic for parsing properties */

    PyObject *key, *value;
    Py_ssize_t pos = 0;
    while (PyDict_Next(kw, &pos, &key, &value)) {
      const char *slot_name = PyUnicode_AsUTF8(key);
      BMOpSlot *slot;

      if (!BMO_slot_exists(bmop.slots_in, slot_name)) {
        PyErr_Format(PyExc_TypeError,
                     "%.200s: keyword \"%.200s\" is invalid for this operator",
                     self->opname,
                     slot_name);
        BMO_op_finish(bm, &bmop);
        return NULL;
      }

      slot = BMO_slot_get(bmop.slots_in, slot_name);

      /* now assign the value */
      if (bpy_slot_from_py(bm, &bmop, slot, value, self->opname, slot_name) == -1) {
        BMO_op_finish(bm, &bmop);
        return NULL;
      }
    }
  }

  BMO_op_exec(bm, &bmop);

  /* from here until the end of the function, no returns, just set 'ret' */
  if (UNLIKELY(bpy_bm_op_as_py_error(bm) == -1)) {
    ret = NULL; /* exception raised above */
  }
  else if (bmop.slots_out[0].slot_name == NULL) {
    ret = Py_INCREF_RET(Py_None);
  }
  else {
    /* build return value */
    int i;
    ret = PyDict_New();

    for (i = 0; bmop.slots_out[i].slot_name; i++) {
      // BMOpDefine *op_def = opdefines[bmop.type];
      // BMOSlotType *slot_type = op_def->slot_types_out[i];
      BMOpSlot *slot = &bmop.slots_out[i];
      PyObject *item;

      /* this function doesn't throw exceptions */
      item = bpy_slot_to_py(bm, slot);
      if (item == NULL) {
        item = Py_INCREF_RET(Py_None);
      }

#if 1
      /* temp code, strip off '.out' while we keep this convention */
      {
        char slot_name_strip[MAX_SLOTNAME];
        const char *ch = strchr(slot->slot_name, '.'); /* can't fail! */
        const int tot = ch - slot->slot_name;
        BLI_assert(ch != NULL);
        memcpy(slot_name_strip, slot->slot_name, tot);
        slot_name_strip[tot] = '\0';
        PyDict_SetItemString(ret, slot_name_strip, item);
      }
#else
      PyDict_SetItemString(ret, slot->slot_name, item);
#endif
      Py_DECREF(item);
    }
  }

  BMO_op_finish(bm, &bmop);
  return ret;
}