/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/python/gpu/gpu_py_shader.c
 *  \ingroup bpygpu
 *
 * - Use ``bpygpu_`` for local API.
 * - Use ``BPyGPU`` for public API.
 */

#include <Python.h>

#include "BLI_utildefines.h"

#include "GPU_shader.h"
#include "GPU_shader_interface.h"

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

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


 /* -------------------------------------------------------------------- */

 /** \name Enum Conversion.
 * \{ */

static void bpygpu_shader_add_enum_objects(PyObject *submodule)
{
	PyObject *dict = PyModule_GetDict(submodule);
	PyObject *item;

#define PY_DICT_ADD_INT(x) PyDict_SetItemString(dict, #x, item = PyLong_FromLong(x)); Py_DECREF(item)

	/* Shaders */
	PY_DICT_ADD_INT(GPU_SHADER_2D_UNIFORM_COLOR);
	PY_DICT_ADD_INT(GPU_SHADER_2D_FLAT_COLOR);
	PY_DICT_ADD_INT(GPU_SHADER_2D_SMOOTH_COLOR);
	PY_DICT_ADD_INT(GPU_SHADER_3D_UNIFORM_COLOR);
	PY_DICT_ADD_INT(GPU_SHADER_3D_FLAT_COLOR);
	PY_DICT_ADD_INT(GPU_SHADER_3D_SMOOTH_COLOR);

#undef PY_DICT_ADD_INT
}

static int bpygpu_pyLong_as_shader_enum(PyObject *o)
{
	uint id = (uint)PyLong_AsUnsignedLong(o);

	if (id >= GPU_NUM_BUILTIN_SHADERS) {
		PyErr_SetString(PyExc_ValueError,
		                "not a builtin shader identifier");
		return -1;
	}

	return (int)id;
}

/** \} */


/* -------------------------------------------------------------------- */

/** \name Shader Type
 * \{ */

static PyObject *bpygpu_shader_new(PyTypeObject *UNUSED(type), PyObject *args, PyObject *kwds)
{
	static const char *kwlist[] = {
	        "vertexcode", "fragcode", "geocode",
	        "libcode", "defines", NULL};

	struct {
		const char *vertexcode;
		const char *fragcode;
		const char *geocode;
		const char *libcode;
		const char *defines;
	} params = {0};

	if (!PyArg_ParseTupleAndKeywords(
	        args, kwds, "ss|$sss:GPUShader.__new__", (char **)kwlist,
	        &params.vertexcode, &params.fragcode, &params.geocode,
	        &params.libcode, &params.defines))
	{
		return NULL;
	}

	GPUShader *shader = GPU_shader_create(
	        params.vertexcode,
	        params.fragcode,
	        params.geocode,
	        params.libcode,
	        params.defines,
	        NULL);

	if (shader == NULL) {
		PyErr_SetString(PyExc_Exception,
		                "Shader Compile Error, see console for more details");
		return NULL;
	}

	return BPyGPUShader_CreatePyObject(shader);
}

PyDoc_STRVAR(bpygpu_shader_bind_doc,
".. method:: bind()\n"
"\n"
"   Bind the Shader object.\n"
);
static PyObject *bpygpu_shader_bind(BPyGPUShader *self)
{
	GPU_shader_bind(self->shader);
	Py_RETURN_NONE;
}

PyDoc_STRVAR(bpygpu_shader_transform_feedback_enable_doc,
".. method:: transform_feedback_enable(vbo_id)\n"
"\n"
"   Start transform feedback operation.\n"
"\n"
"   :return: true if transform feedback was succesfully enabled.\n"
"   :rtype: `bool`\n"
);
static PyObject *bpygpu_shader_transform_feedback_enable(
        BPyGPUShader *self, PyObject *arg)
{
	uint vbo_id;
	if ((vbo_id = PyC_Long_AsU32(arg)) == (uint)-1) {
		return NULL;
	}
	return PyBool_FromLong(GPU_shader_transform_feedback_enable(self->shader, vbo_id));
}

PyDoc_STRVAR(bpygpu_shader_transform_feedback_disable_doc,
".. method:: transform_feedback_disable()\n"
"\n"
"   Disable transform feedback.\n"
);
static PyObject *bpygpu_transform_feedback_disable(BPyGPUShader *self)
{
	GPU_shader_transform_feedback_disable(self->shader);
	Py_RETURN_NONE;
}

PyDoc_STRVAR(bpygpu_shader_uniform_from_name_doc,
".. method:: uniform_from_name(name)\n"
"\n"
"   Get uniform location by name.\n"
"\n"
"   :param name: name of the uniform variable whose location is to be queried.\n"
"   :type name: `str`\n"
"   :return: the location of the uniform variable.\n"
"   :rtype: `int`\n"
);
static PyObject *bpygpu_shader_uniform_from_name(
        BPyGPUShader *self, PyObject *arg)
{
	const char *name = PyUnicode_AsUTF8(arg);
	if (name == NULL) {
		return NULL;
	}

	int uniform = GPU_shader_get_uniform(self->shader, name);

	if (uniform == -1) {
		PyErr_SetString(PyExc_SyntaxError,
		                "GPUShader.get_uniform: uniform not found.");
		return NULL;
	}

	return PyLong_FromLong(uniform);
}

PyDoc_STRVAR(bpygpu_shader_uniform_block_from_name_doc,
".. method:: uniform_block_from_name(name)\n"
"\n"
"   Get uniform block location by name.\n"
"\n"
"   :param name: name of the uniform block variable whose location is to be queried.\n"
"   :type name: `str`\n"
"   :return: the location of the uniform block variable.\n"
"   :rtype: `int`\n"
);
static PyObject *bpygpu_shader_uniform_block_from_name(
        BPyGPUShader *self, PyObject *arg)
{
	const char *name = PyUnicode_AsUTF8(arg);
	if (name == NULL) {
		return NULL;
	}

	int uniform = GPU_shader_get_uniform_block(self->shader, name);

	if (uniform == -1) {
		PyErr_SetString(PyExc_SyntaxError,
		                "GPUShader.get_uniform_block: uniform not found");
		return NULL;
	}

	return PyLong_FromLong(uniform);
}

static bool bpygpu_shader_uniform_vector_imp(
        PyObject *args, int elem_size,
        int *r_location, int *r_length, int *r_count, Py_buffer *r_pybuffer)
{
	PyObject *buffer;

	*r_count = 1;
	if (!PyArg_ParseTuple(
	        args, "iOi|i:GPUShader.uniform_vector_*",
	        r_location, &buffer, r_length, r_count))
	{
		return false;
	}

	if (PyObject_GetBuffer(buffer, r_pybuffer, PyBUF_SIMPLE) == -1) {
		/* PyObject_GetBuffer raise a PyExc_BufferError */
		return false;
	}

	if (r_pybuffer->len != (*r_length * *r_count * elem_size)) {
		PyErr_SetString(
		        PyExc_BufferError,
		        "GPUShader.uniform_vector_*: buffer size does not match.");
		return false;
	}

	return true;
}

PyDoc_STRVAR(bpygpu_shader_uniform_vector_float_doc,
".. method:: uniform_vector_float(location, buffer, length, count)\n"
"\n"
"   Set the buffer to fill the uniform.\n"
"\n"
"   :param location: location of the uniform variable to be modified.\n"
"   :type location:  `int`\n"
"   :param buffer:   buffer object with format float.\n"
"   :type buffer:    `buffer object`\n"
"   :param length:   size of the uniform data type:\n"
"                    1: float\n"
"                    2: vec2 or float[2]\n"
"                    3: vec3 or float[3]\n"
"                    4: vec4 or float[4]\n"
"                    9: mat3\n"
"                    16: mat4\n"
"   :type length:    `int`\n"
"   :param count:    specifies the number of elements, vector or matrices that are to be modified.\n"
"   :type count:     `int`\n"
);
static PyObject *bpygpu_shader_uniform_vector_float(
        BPyGPUShader *self, PyObject *args)
{
	int location, length, count;

	Py_buffer pybuffer;

	if (!bpygpu_shader_uniform_vector_imp(
	        args, sizeof(float),
	        &location, &length, &count, &pybuffer))
	{
		return NULL;
	}

	GPU_shader_uniform_vector(
	        self->shader, location, length,
	        count, pybuffer.buf);

	PyBuffer_Release(&pybuffer);

	Py_RETURN_NONE;
}

PyDoc_STRVAR(bpygpu_shader_uniform_vector_int_doc,
".. method:: uniform_vector_int(location, buffer, length, count)\n"
"\n"
"   See GPUShader.uniform_vector_float(...) description.\n."
);
static PyObject *bpygpu_shader_uniform_vector_int(
        BPyGPUShader *self, PyObject *args)
{
	int location, length, count;

	Py_buffer pybuffer;

	if (!bpygpu_shader_uniform_vector_imp(
	        args, sizeof(int),
	        &location, &length, &count, &pybuffer))
	{
		return NULL;
	}

	GPU_shader_uniform_vector_int(
	        self->shader, location, length,
	        count, pybuffer.buf);

	PyBuffer_Release(&pybuffer);

	Py_RETURN_NONE;
}

PyDoc_STRVAR(bpygpu_shader_uniform_int_doc,
".. method:: uniform_int(location, value)\n"
"\n"
"   Set uniform value.\n"
"\n"
"   :param location: builtin identifier.\n"
"   :type location: `int`\n"
"   :param value: builtin identifier.\n"
"   :type value: `int`\n"
);
static PyObject *bpygpu_shader_uniform_int(
        BPyGPUShader *self, PyObject *args)
{
	int location, value;

	if (!PyArg_ParseTuple(
	        args, "ii:GPUShader.uniform_int",
	        &location, &value))
	{
		return NULL;
	}

	GPU_shader_uniform_int(self->shader, location, value);

	Py_RETURN_NONE;
}

PyDoc_STRVAR(bpygpu_shader_attr_from_name_doc,
".. method:: attr_from_name(name)\n"
"\n"
"   Get attribute location by name.\n"
"\n"
"   :param name: the name of the attribute variable whose location is to be queried.\n"
"   :type name: `str`\n"
"   :return: the location of an attribute variable.\n"
"   :rtype: `int`\n"
);
static PyObject *bpygpu_shader_attr_from_name(
        BPyGPUShader *self, PyObject *arg)
{
	const char *name = PyUnicode_AsUTF8(arg);
	if (name == NULL) {
		return NULL;
	}

	int attrib = GPU_shader_get_attribute(self->shader, name);

	if (attrib == -1) {
		PyErr_SetString(PyExc_SyntaxError,
		                "GPUShader.attr_from_name: attribute not found.");
		return NULL;
	}

	return PyLong_FromLong(attrib);
}

PyDoc_STRVAR(bpygpu_shader_program_doc,
".. method:: The name of the program object for use by the OpenGL API (read-only).\n"
"\n"
"   :rtype: `int`\n"
);
static PyObject *bpygpu_shader_program_get(BPyGPUShader *self, void *UNUSED(closure))
{
	return PyLong_FromLong(GPU_shader_get_program(self->shader));
}

static struct PyMethodDef bpygpu_shader_methods[] = {
	{"bind", (PyCFunction)bpygpu_shader_bind,
	 METH_NOARGS, bpygpu_shader_bind_doc},
	{"transform_feedback_enable",
	 (PyCFunction)bpygpu_shader_transform_feedback_enable,
	 METH_O, bpygpu_shader_transform_feedback_enable_doc},
	{"transform_feedback_disable",
	 (PyCFunction)bpygpu_transform_feedback_disable,
	 METH_NOARGS, bpygpu_shader_transform_feedback_disable_doc},
	{"uniform_from_name",
	 (PyCFunction)bpygpu_shader_uniform_from_name,
	 METH_O, bpygpu_shader_uniform_from_name_doc},
	{"uniform_block_from_name",
	 (PyCFunction)bpygpu_shader_uniform_block_from_name,
	 METH_O, bpygpu_shader_uniform_block_from_name_doc},
	{"uniform_vector_float",
	 (PyCFunction)bpygpu_shader_uniform_vector_float,
	 METH_VARARGS, bpygpu_shader_uniform_vector_float_doc},
	{"uniform_vector_int",
	 (PyCFunction)bpygpu_shader_uniform_vector_int,
	 METH_VARARGS, bpygpu_shader_uniform_vector_int_doc},
	{"uniform_int",
	 (PyCFunction)bpygpu_shader_uniform_int,
	 METH_VARARGS, bpygpu_shader_uniform_int_doc},
	{"attr_from_name",
	 (PyCFunction)bpygpu_shader_attr_from_name,
	 METH_O, bpygpu_shader_attr_from_name_doc},
	{NULL, NULL, 0, NULL}
};

static PyGetSetDef bpygpu_shader_getseters[] = {
	{"program",
	 (getter)bpygpu_shader_program_get, (setter)NULL,
	 bpygpu_shader_program_doc, NULL},
	{NULL, NULL, NULL, NULL, NULL} /* Sentinel */
};


static void bpygpu_shader_dealloc(BPyGPUShader *self)
{
	GPU_shader_free(self->shader);
	Py_TYPE(self)->tp_free((PyObject *)self);
}


PyDoc_STRVAR(bpygpu_shader_doc,
"GPUShader(vertexcode, fragcode, geocode=None, libcode=None, defines=None)\n"
"\n"
"GPUShader combines multiple GLSL shaders into a program used for drawing.\n"
"It must contain a vertex and fragment shaders, with an optional geometry shader.\n"
"\n"
"The GLSL #version directive is automatically included at the top of shaders, and set to 330.\n"
"\n"
"Some preprocessor directives are automatically added according to the Operating System or availability.\n"
"These are:\n"
"        \"#define GPU_ATI\\n\"\n"
"        \"#define GPU_NVIDIA\\n\"\n"
"        \"#define GPU_INTEL\\n\"\n"
"\n"
"The following extensions are enabled by default if supported by the GPU:\n"
"        \"#extension GL_ARB_texture_gather: enable\\n\"\n"
"        \"#extension GL_ARB_texture_query_lod: enable\\n\"\n"
"\n"
"To debug shaders, use the --debug-gpu-shaders command line option"
" to see full GLSL shader compilation and linking errors.\n"
"\n"
"   :param vertexcode: vertex Shader Code.\n"
"   :type vertexcode: `str`\n"
"   :param fragcode: fragment Shader Code.\n"
"   :type value: `str`\n"
"   :param geocode: geometry Shader Code.\n"
"   :type value: `str`\n"
"   :param libcode: code with functions and presets to be shared between shaders.\n"
"   :type value: `str`\n"
"   :param defines: preprocessor directives.\n"
"   :type value: `str`\n"
);
PyTypeObject BPyGPUShader_Type = {
	PyVarObject_HEAD_INIT(NULL, 0)
	.tp_name = "GPUShader",
	.tp_basicsize = sizeof(BPyGPUShader),
	.tp_dealloc = (destructor)bpygpu_shader_dealloc,
	.tp_flags = Py_TPFLAGS_DEFAULT,
	.tp_doc = bpygpu_shader_doc,
	.tp_methods = bpygpu_shader_methods,
	.tp_getset = bpygpu_shader_getseters,
	.tp_new = bpygpu_shader_new,
};

/** \} */


/* -------------------------------------------------------------------- */

/** \name gpu.shader Module API
 * \{ */

PyDoc_STRVAR(bpygpu_shader_unbind_doc,
".. function:: unbind()\n"
"\n"
"   Unbind the bound shader object.\n"
);
static PyObject *bpygpu_shader_unbind(BPyGPUShader *UNUSED(self))
{
	GPU_shader_unbind();
	Py_RETURN_NONE;
}

PyDoc_STRVAR(bpygpu_shader_from_builtin_doc,
".. function:: shader_from_builtin(shader_id)\n"
"\n"
"   :param shader_id: shader identifier.\n"
"   :type shader_id: `int`\n"
);
static PyObject *bpygpu_shader_from_builtin(PyObject *UNUSED(self), PyObject *arg)
{
	int shader_id = bpygpu_pyLong_as_shader_enum(arg);
	if (shader_id == -1) {
		return NULL;
	}

	GPUShader *shader = GPU_shader_get_builtin_shader(shader_id);

	return BPyGPUShader_CreatePyObject(shader);
}

PyDoc_STRVAR(bpygpu_shader_code_from_builtin_doc,
".. function:: shader_code_from_builtin(shader_id)\n"
"\n"
"   :param shader_id: shader identifier.\n"
"   :type shader_id: `int`\n"
"   :return: vertex, fragment and geometry shader codes.\n"
"   :rtype: `dict`\n"
);
static PyObject *bpygpu_shader_code_from_builtin(BPyGPUShader *UNUSED(self), PyObject *arg)
{
	const char *vert;
	const char *frag;
	const char *geom;
	const char *defines;

	PyObject *item, *r_dict;

	int shader_id = bpygpu_pyLong_as_shader_enum(arg);
	if (shader_id == -1) {
		return NULL;
	}

	GPU_shader_get_builtin_shader_code(
	        shader_id, &vert, &frag, &geom, &defines);

	r_dict = PyDict_New();

	PyDict_SetItemString(r_dict, "vertex_shader", item = PyUnicode_FromString(vert));
	Py_DECREF(item);

	PyDict_SetItemString(r_dict, "fragment_shader", item = PyUnicode_FromString(frag));
	Py_DECREF(item);

	if (geom) {
		PyDict_SetItemString(r_dict, "geometry_shader", item = PyUnicode_FromString(geom));
		Py_DECREF(item);
	}
	if (defines) {
		PyDict_SetItemString(r_dict, "defines", item = PyUnicode_FromString(defines));
		Py_DECREF(item);
	}
	return r_dict;
}

static struct PyMethodDef bpygpu_shader_module_methods[] = {
	{"unbind",
	 (PyCFunction)bpygpu_shader_unbind,
	 METH_NOARGS, bpygpu_shader_unbind_doc},
	{"shader_from_builtin",
	 (PyCFunction)bpygpu_shader_from_builtin,
	 METH_O, bpygpu_shader_from_builtin_doc},
	{"shader_code_from_builtin",
	 (PyCFunction)bpygpu_shader_code_from_builtin,
	 METH_O, bpygpu_shader_code_from_builtin_doc},
	{NULL, NULL, 0, NULL}
};

PyDoc_STRVAR(bpygpu_shader_module_doc,
"This module provides access to GPUShader internal functions."
);
static PyModuleDef BPyGPU_shader_module_def = {
	PyModuleDef_HEAD_INIT,
	.m_name = "gpu.shader",
	.m_doc = bpygpu_shader_module_doc,
	.m_methods = bpygpu_shader_module_methods,
};

/** \} */


/* -------------------------------------------------------------------- */

/** \name gpu.shader.buitin Module API
 * \{ */

PyDoc_STRVAR(bpygpu_shader_builtin_module_doc,
"This module contains integers that identify the built-in shader ids."
);
static PyModuleDef BPyGPU_shader_builtin_module_def = {
	PyModuleDef_HEAD_INIT,
	.m_name = "gpu.shader.builtin",
	.m_doc = bpygpu_shader_builtin_module_doc,
};

/** \} */


/* -------------------------------------------------------------------- */

/** \name Public API
 * \{ */

PyObject *BPyGPUShader_CreatePyObject(GPUShader *shader)
{
	BPyGPUShader *self;

	self = PyObject_New(BPyGPUShader, &BPyGPUShader_Type);
	self->shader = shader;

	return (PyObject *)self;
}

PyObject *BPyInit_gpu_shader(void)
{
	PyObject *submodule;

	submodule = PyModule_Create(&BPyGPU_shader_module_def);

	return submodule;
}

PyObject *BPyInit_gpu_shader_builtin(void)
{
	PyObject *submodule;

	submodule = PyModule_Create(&BPyGPU_shader_builtin_module_def);
	bpygpu_shader_add_enum_objects(submodule);

	return submodule;
}

/** \} */