/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

/** \file
 * \ingroup bpygpu
 *
 * This file defines the gpu.matrix stack API.
 *
 * \warning While these functions attempt to ensure correct stack usage.
 * Mixing Python and C functions may still crash on invalid use.
 *
 * - Use `bpygpu_` for local API.
 * - Use `BPyGPU` for public API.
 */

#include <Python.h>

#include "BLI_utildefines.h"

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

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

#define USE_GPU_PY_MATRIX_API
#include "GPU_matrix.h"
#undef USE_GPU_PY_MATRIX_API

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

/* -------------------------------------------------------------------- */
/** \name Helper Functions
 * \{ */

static bool pygpu_stack_is_push_model_view_ok_or_error(void)
{
  if (GPU_matrix_stack_level_get_model_view() >= GPU_PY_MATRIX_STACK_LEN) {
    PyErr_SetString(
        PyExc_RuntimeError,
        "Maximum model-view stack depth " STRINGIFY(GPU_PY_MATRIX_STACK_DEPTH) " reached");
    return false;
  }
  return true;
}

static bool pygpu_stack_is_push_projection_ok_or_error(void)
{
  if (GPU_matrix_stack_level_get_projection() >= GPU_PY_MATRIX_STACK_LEN) {
    PyErr_SetString(
        PyExc_RuntimeError,
        "Maximum projection stack depth " STRINGIFY(GPU_PY_MATRIX_STACK_DEPTH) " reached");
    return false;
  }
  return true;
}

static bool pygpu_stack_is_pop_model_view_ok_or_error(void)
{
  if (GPU_matrix_stack_level_get_model_view() == 0) {
    PyErr_SetString(PyExc_RuntimeError, "Minimum model-view stack depth reached");
    return false;
  }
  return true;
}

static bool pygpu_stack_is_pop_projection_ok_or_error(void)
{
  if (GPU_matrix_stack_level_get_projection() == 0) {
    PyErr_SetString(PyExc_RuntimeError, "Minimum projection stack depth reached");
    return false;
  }
  return true;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Manage Stack
 * \{ */

PyDoc_STRVAR(pygpu_matrix_push_doc,
             ".. function:: push()\n"
             "\n"
             "   Add to the model-view matrix stack.\n");
static PyObject *pygpu_matrix_push(PyObject *UNUSED(self))
{
  if (!pygpu_stack_is_push_model_view_ok_or_error()) {
    return NULL;
  }
  GPU_matrix_push();
  Py_RETURN_NONE;
}

PyDoc_STRVAR(pygpu_matrix_pop_doc,
             ".. function:: pop()\n"
             "\n"
             "   Remove the last model-view matrix from the stack.\n");
static PyObject *pygpu_matrix_pop(PyObject *UNUSED(self))
{
  if (!pygpu_stack_is_pop_model_view_ok_or_error()) {
    return NULL;
  }
  GPU_matrix_pop();
  Py_RETURN_NONE;
}

PyDoc_STRVAR(pygpu_matrix_push_projection_doc,
             ".. function:: push_projection()\n"
             "\n"
             "   Add to the projection matrix stack.\n");
static PyObject *pygpu_matrix_push_projection(PyObject *UNUSED(self))
{
  if (!pygpu_stack_is_push_projection_ok_or_error()) {
    return NULL;
  }
  GPU_matrix_push_projection();
  Py_RETURN_NONE;
}

PyDoc_STRVAR(pygpu_matrix_pop_projection_doc,
             ".. function:: pop_projection()\n"
             "\n"
             "   Remove the last projection matrix from the stack.\n");
static PyObject *pygpu_matrix_pop_projection(PyObject *UNUSED(self))
{
  if (!pygpu_stack_is_pop_projection_ok_or_error()) {
    return NULL;
  }
  GPU_matrix_pop_projection();
  Py_RETURN_NONE;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Stack (Context Manager)
 *
 * Safer alternative to ensure balanced push/pop calls.
 *
 * \{ */

typedef struct {
  PyObject_HEAD /* Required Python macro. */
  int type;
  int level;
} BPyGPU_MatrixStackContext;

enum {
  PYGPU_MATRIX_TYPE_MODEL_VIEW = 1,
  PYGPU_MATRIX_TYPE_PROJECTION = 2,
};

static PyObject *pygpu_matrix_stack_context_enter(BPyGPU_MatrixStackContext *self);
static PyObject *pygpu_matrix_stack_context_exit(BPyGPU_MatrixStackContext *self, PyObject *args);

static PyMethodDef pygpu_matrix_stack_context__tp_methods[] = {
    {"__enter__", (PyCFunction)pygpu_matrix_stack_context_enter, METH_NOARGS},
    {"__exit__", (PyCFunction)pygpu_matrix_stack_context_exit, METH_VARARGS},
    {NULL},
};

static PyTypeObject PyGPUMatrixStackContext_Type = {
    PyVarObject_HEAD_INIT(NULL, 0).tp_name = "GPUMatrixStackContext",
    .tp_basicsize = sizeof(BPyGPU_MatrixStackContext),
    .tp_flags = Py_TPFLAGS_DEFAULT,
    .tp_methods = pygpu_matrix_stack_context__tp_methods,
};

static PyObject *pygpu_matrix_stack_context_enter(BPyGPU_MatrixStackContext *self)
{
  /* sanity - should never happen */
  if (self->level != -1) {
    PyErr_SetString(PyExc_RuntimeError, "Already in use");
    return NULL;
  }

  if (self->type == PYGPU_MATRIX_TYPE_MODEL_VIEW) {
    if (!pygpu_stack_is_push_model_view_ok_or_error()) {
      return NULL;
    }
    GPU_matrix_push();
    self->level = GPU_matrix_stack_level_get_model_view();
  }
  else if (self->type == PYGPU_MATRIX_TYPE_PROJECTION) {
    if (!pygpu_stack_is_push_projection_ok_or_error()) {
      return NULL;
    }
    GPU_matrix_push_projection();
    self->level = GPU_matrix_stack_level_get_projection();
  }
  else {
    BLI_assert_unreachable();
  }
  Py_RETURN_NONE;
}

static PyObject *pygpu_matrix_stack_context_exit(BPyGPU_MatrixStackContext *self,
                                                 PyObject *UNUSED(args))
{
  /* sanity - should never happen */
  if (self->level == -1) {
    fprintf(stderr, "Not yet in use\n");
    goto finally;
  }

  if (self->type == PYGPU_MATRIX_TYPE_MODEL_VIEW) {
    const int level = GPU_matrix_stack_level_get_model_view();
    if (level != self->level) {
      fprintf(stderr, "Level push/pop mismatch, expected %d, got %d\n", self->level, level);
    }
    if (level != 0) {
      GPU_matrix_pop();
    }
  }
  else if (self->type == PYGPU_MATRIX_TYPE_PROJECTION) {
    const int level = GPU_matrix_stack_level_get_projection();
    if (level != self->level) {
      fprintf(stderr, "Level push/pop mismatch, expected %d, got %d", self->level, level);
    }
    if (level != 0) {
      GPU_matrix_pop_projection();
    }
  }
  else {
    BLI_assert_unreachable();
  }
finally:
  Py_RETURN_NONE;
}

static PyObject *pygpu_matrix_push_pop_impl(int type)
{
  BPyGPU_MatrixStackContext *ret = PyObject_New(BPyGPU_MatrixStackContext,
                                                &PyGPUMatrixStackContext_Type);
  ret->type = type;
  ret->level = -1;
  return (PyObject *)ret;
}

PyDoc_STRVAR(
    pygpu_matrix_push_pop_doc,
    ".. function:: push_pop()\n"
    "\n"
    "   Context manager to ensure balanced push/pop calls, even in the case of an error.\n");
static PyObject *pygpu_matrix_push_pop(PyObject *UNUSED(self))
{
  return pygpu_matrix_push_pop_impl(PYGPU_MATRIX_TYPE_MODEL_VIEW);
}

PyDoc_STRVAR(
    pygpu_matrix_push_pop_projection_doc,
    ".. function:: push_pop_projection()\n"
    "\n"
    "   Context manager to ensure balanced push/pop calls, even in the case of an error.\n");
static PyObject *pygpu_matrix_push_pop_projection(PyObject *UNUSED(self))
{
  return pygpu_matrix_push_pop_impl(PYGPU_MATRIX_TYPE_PROJECTION);
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Manipulate State
 * \{ */

PyDoc_STRVAR(pygpu_matrix_multiply_matrix_doc,
             ".. function:: multiply_matrix(matrix)\n"
             "\n"
             "   Multiply the current stack matrix.\n"
             "\n"
             "   :param matrix: A 4x4 matrix.\n"
             "   :type matrix: :class:`mathutils.Matrix`\n");
static PyObject *pygpu_matrix_multiply_matrix(PyObject *UNUSED(self), PyObject *value)
{
  MatrixObject *pymat;
  if (!Matrix_Parse4x4(value, &pymat)) {
    return NULL;
  }
  GPU_matrix_mul(pymat->matrix);
  Py_RETURN_NONE;
}

PyDoc_STRVAR(pygpu_matrix_scale_doc,
             ".. function:: scale(scale)\n"
             "\n"
             "   Scale the current stack matrix.\n"
             "\n"
             "   :param scale: Scale the current stack matrix.\n"
             "   :type scale: sequence of 2 or 3 floats\n");
static PyObject *pygpu_matrix_scale(PyObject *UNUSED(self), PyObject *value)
{
  float scale[3];
  int len;
  if ((len = mathutils_array_parse(
           scale, 2, 3, value, "gpu.matrix.scale(): invalid vector arg")) == -1) {
    return NULL;
  }
  if (len == 2) {
    GPU_matrix_scale_2fv(scale);
  }
  else {
    GPU_matrix_scale_3fv(scale);
  }
  Py_RETURN_NONE;
}

PyDoc_STRVAR(pygpu_matrix_scale_uniform_doc,
             ".. function:: scale_uniform(scale)\n"
             "\n"
             "   :param scale: Scale the current stack matrix.\n"
             "   :type scale: float\n");
static PyObject *pygpu_matrix_scale_uniform(PyObject *UNUSED(self), PyObject *value)
{
  float scalar;
  if ((scalar = PyFloat_AsDouble(value)) == -1.0f && PyErr_Occurred()) {
    PyErr_Format(PyExc_TypeError, "expected a number, not %.200s", Py_TYPE(value)->tp_name);
    return NULL;
  }
  GPU_matrix_scale_1f(scalar);
  Py_RETURN_NONE;
}

PyDoc_STRVAR(pygpu_matrix_translate_doc,
             ".. function:: translate(offset)\n"
             "\n"
             "   Scale the current stack matrix.\n"
             "\n"
             "   :param offset: Translate the current stack matrix.\n"
             "   :type offset: sequence of 2 or 3 floats\n");
static PyObject *pygpu_matrix_translate(PyObject *UNUSED(self), PyObject *value)
{
  float offset[3];
  int len;
  if ((len = mathutils_array_parse(
           offset, 2, 3, value, "gpu.matrix.translate(): invalid vector arg")) == -1) {
    return NULL;
  }
  if (len == 2) {
    GPU_matrix_translate_2fv(offset);
  }
  else {
    GPU_matrix_translate_3fv(offset);
  }
  Py_RETURN_NONE;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Write State
 * \{ */

PyDoc_STRVAR(pygpu_matrix_reset_doc,
             ".. function:: reset()\n"
             "\n"
             "   Empty stack and set to identity.\n");
static PyObject *pygpu_matrix_reset(PyObject *UNUSED(self))
{
  GPU_matrix_reset();
  Py_RETURN_NONE;
}

PyDoc_STRVAR(pygpu_matrix_load_identity_doc,
             ".. function:: load_identity()\n"
             "\n"
             "   Empty stack and set to identity.\n");
static PyObject *pygpu_matrix_load_identity(PyObject *UNUSED(self))
{
  GPU_matrix_identity_set();
  Py_RETURN_NONE;
}

PyDoc_STRVAR(pygpu_matrix_load_matrix_doc,
             ".. function:: load_matrix(matrix)\n"
             "\n"
             "   Load a matrix into the stack.\n"
             "\n"
             "   :param matrix: A 4x4 matrix.\n"
             "   :type matrix: :class:`mathutils.Matrix`\n");
static PyObject *pygpu_matrix_load_matrix(PyObject *UNUSED(self), PyObject *value)
{
  MatrixObject *pymat;
  if (!Matrix_Parse4x4(value, &pymat)) {
    return NULL;
  }
  GPU_matrix_set(pymat->matrix);
  Py_RETURN_NONE;
}

PyDoc_STRVAR(pygpu_matrix_load_projection_matrix_doc,
             ".. function:: load_projection_matrix(matrix)\n"
             "\n"
             "   Load a projection matrix into the stack.\n"
             "\n"
             "   :param matrix: A 4x4 matrix.\n"
             "   :type matrix: :class:`mathutils.Matrix`\n");
static PyObject *pygpu_matrix_load_projection_matrix(PyObject *UNUSED(self), PyObject *value)
{
  MatrixObject *pymat;
  if (!Matrix_Parse4x4(value, &pymat)) {
    return NULL;
  }
  GPU_matrix_projection_set(pymat->matrix);
  Py_RETURN_NONE;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Read State
 * \{ */

PyDoc_STRVAR(pygpu_matrix_get_projection_matrix_doc,
             ".. function:: get_projection_matrix()\n"
             "\n"
             "   Return a copy of the projection matrix.\n"
             "\n"
             "   :return: A 4x4 projection matrix.\n"
             "   :rtype: :class:`mathutils.Matrix`\n");
static PyObject *pygpu_matrix_get_projection_matrix(PyObject *UNUSED(self))
{
  float matrix[4][4];
  GPU_matrix_projection_get(matrix);
  return Matrix_CreatePyObject(&matrix[0][0], 4, 4, NULL);
}

PyDoc_STRVAR(pygpu_matrix_get_model_view_matrix_doc,
             ".. function:: get_model_view_matrix()\n"
             "\n"
             "   Return a copy of the model-view matrix.\n"
             "\n"
             "   :return: A 4x4 view matrix.\n"
             "   :rtype: :class:`mathutils.Matrix`\n");
static PyObject *pygpu_matrix_get_model_view_matrix(PyObject *UNUSED(self))
{
  float matrix[4][4];
  GPU_matrix_model_view_get(matrix);
  return Matrix_CreatePyObject(&matrix[0][0], 4, 4, NULL);
}

PyDoc_STRVAR(pygpu_matrix_get_normal_matrix_doc,
             ".. function:: get_normal_matrix()\n"
             "\n"
             "   Return a copy of the normal matrix.\n"
             "\n"
             "   :return: A 3x3 normal matrix.\n"
             "   :rtype: :class:`mathutils.Matrix`\n");
static PyObject *pygpu_matrix_get_normal_matrix(PyObject *UNUSED(self))
{
  float matrix[3][3];
  GPU_matrix_normal_get(matrix);
  return Matrix_CreatePyObject(&matrix[0][0], 3, 3, NULL);
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Module
 * \{ */

static struct PyMethodDef pygpu_matrix__tp_methods[] = {
    /* Manage Stack */
    {"push", (PyCFunction)pygpu_matrix_push, METH_NOARGS, pygpu_matrix_push_doc},
    {"pop", (PyCFunction)pygpu_matrix_pop, METH_NOARGS, pygpu_matrix_pop_doc},

    {"push_projection",
     (PyCFunction)pygpu_matrix_push_projection,
     METH_NOARGS,
     pygpu_matrix_push_projection_doc},
    {"pop_projection",
     (PyCFunction)pygpu_matrix_pop_projection,
     METH_NOARGS,
     pygpu_matrix_pop_projection_doc},

    /* Stack (Context Manager) */
    {"push_pop", (PyCFunction)pygpu_matrix_push_pop, METH_NOARGS, pygpu_matrix_push_pop_doc},
    {"push_pop_projection",
     (PyCFunction)pygpu_matrix_push_pop_projection,
     METH_NOARGS,
     pygpu_matrix_push_pop_projection_doc},

    /* Manipulate State */
    {"multiply_matrix",
     (PyCFunction)pygpu_matrix_multiply_matrix,
     METH_O,
     pygpu_matrix_multiply_matrix_doc},
    {"scale", (PyCFunction)pygpu_matrix_scale, METH_O, pygpu_matrix_scale_doc},
    {"scale_uniform",
     (PyCFunction)pygpu_matrix_scale_uniform,
     METH_O,
     pygpu_matrix_scale_uniform_doc},
    {"translate", (PyCFunction)pygpu_matrix_translate, METH_O, pygpu_matrix_translate_doc},

/* TODO */
#if 0
    {"rotate", (PyCFunction)pygpu_matrix_rotate, METH_O, pygpu_matrix_rotate_doc},
    {"rotate_axis", (PyCFunction)pygpu_matrix_rotate_axis, METH_O, pygpu_matrix_rotate_axis_doc},
    {"look_at", (PyCFunction)pygpu_matrix_look_at, METH_O, pygpu_matrix_look_at_doc},
#endif

    /* Write State */
    {"reset", (PyCFunction)pygpu_matrix_reset, METH_NOARGS, pygpu_matrix_reset_doc},
    {"load_identity",
     (PyCFunction)pygpu_matrix_load_identity,
     METH_NOARGS,
     pygpu_matrix_load_identity_doc},
    {"load_matrix", (PyCFunction)pygpu_matrix_load_matrix, METH_O, pygpu_matrix_load_matrix_doc},
    {"load_projection_matrix",
     (PyCFunction)pygpu_matrix_load_projection_matrix,
     METH_O,
     pygpu_matrix_load_projection_matrix_doc},

    /* Read State */
    {"get_projection_matrix",
     (PyCFunction)pygpu_matrix_get_projection_matrix,
     METH_NOARGS,
     pygpu_matrix_get_projection_matrix_doc},
    {"get_model_view_matrix",
     (PyCFunction)pygpu_matrix_get_model_view_matrix,
     METH_NOARGS,
     pygpu_matrix_get_model_view_matrix_doc},
    {"get_normal_matrix",
     (PyCFunction)pygpu_matrix_get_normal_matrix,
     METH_NOARGS,
     pygpu_matrix_get_normal_matrix_doc},

    {NULL, NULL, 0, NULL},
};

PyDoc_STRVAR(pygpu_matrix__tp_doc, "This module provides access to the matrix stack.");
static PyModuleDef pygpu_matrix_module_def = {
    PyModuleDef_HEAD_INIT,
    .m_name = "gpu.matrix",
    .m_doc = pygpu_matrix__tp_doc,
    .m_methods = pygpu_matrix__tp_methods,
};

PyObject *bpygpu_matrix_init(void)
{
  PyObject *submodule;

  submodule = PyModule_Create(&pygpu_matrix_module_def);

  if (PyType_Ready(&PyGPUMatrixStackContext_Type) < 0) {
    return NULL;
  }

  return submodule;
}

/** \} */
