#include <stdlib.h>
#include <stdbool.h>
#include "gl/glad/glad.h"
#include <GLFW/glfw3.h>
#include <lua.h>
#include <honeysuckle.h>
#include "gl.h"

/* needs to be here because glad uses macros to define glBufferData */
#ifdef HONEY_TEST_H
#undef glBufferData
#define glBufferData mock_glBufferData_
#endif


int gl_init(lua_State *L);
int glad_init(lua_State *L);
int gl_terminate(lua_State *L);
int gl_get_error(lua_State *L);

/* buffers */
int gl_create_buffer(lua_State *L);
int gl_bind_buffer(lua_State *L);
int gl_buffer_data(lua_State *L);

int gl_vertex_array_create(lua_State *L);
int gl_vertex_array_bind(lua_State *L);
int gl_vertex_attrib_pointer(lua_State *L);
int gl_vertex_array_enable_attrib(lua_State *L);

void setup_gl(lua_State *L, int honey_index)
{
	int data_types = hs_create_table(L,
		hs_str_int("integer", GL_INT),
		hs_str_int("float", GL_FLOAT),
	);

	int error_types = hs_create_table(L,
		hs_str_int("noError", GL_NO_ERROR),
		hs_str_int("invalidEnum", GL_INVALID_ENUM),
		hs_str_int("invalidValue", GL_INVALID_VALUE),
		hs_str_int("invalidOperation", GL_INVALID_OPERATION),
		hs_str_int("invalidFramebufferOperation", GL_INVALID_FRAMEBUFFER_OPERATION),
		hs_str_int("outOfMemory", GL_OUT_OF_MEMORY),
	);

	int buffer_binding_targets = hs_create_table(L,
		hs_str_int("arrayBuffer", GL_ARRAY_BUFFER),
		hs_str_int("elementArrayBuffer", GL_ELEMENT_ARRAY_BUFFER),
	);

	int buffer_usage_patterns = hs_create_table(L,
		hs_str_int("streamDraw", GL_STREAM_DRAW),
		hs_str_int("staticDraw", GL_STATIC_DRAW),
		hs_str_int("dynamicDraw", GL_DYNAMIC_DRAW),
	);

	int gl_index = hs_create_table(L,
		hs_str_cfunc("init", gl_init),
		hs_str_cfunc("initGlad", glad_init),
		hs_str_cfunc("terminate", gl_terminate),
		hs_str_cfunc("getError", gl_get_error),

		hs_str_tbl("dataType", data_types),
		hs_str_tbl("errorType", error_types),

		/* buffer */
		hs_str_cfunc("createBuffer", gl_create_buffer),
		hs_str_cfunc("bindBuffer", gl_bind_buffer),
		hs_str_cfunc("bufferData", gl_buffer_data),

		hs_str_cfunc("createVertexArray", gl_vertex_array_create),
		hs_str_cfunc("bindVertexArray", gl_vertex_array_bind),
		hs_str_cfunc("vertexAttribPointer", gl_vertex_attrib_pointer),
		hs_str_cfunc("vertexArrayEnableAttrib", gl_vertex_array_enable_attrib),

		hs_str_tbl("bufferTarget", buffer_binding_targets),
		hs_str_tbl("bufferUsage", buffer_usage_patterns),
	);

	setup_shader(L, gl_index);
	setup_drawing(L, gl_index);
	lua_setfield(L, honey_index, "gl");
}


int gl_init(lua_State *L)
{
	if (!glfwInit()) {
		hs_throw_error(L, "failed to initialize GLFW");
	}
	return 0;
}


int glad_init(lua_State *L)
{
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
		hs_throw_error(L, "failed to initialize GLAD");
	}
}


int gl_terminate(lua_State *L)
{
	glfwTerminate();
	return 0;
}


int gl_get_error(lua_State *L)
{
	lua_pushinteger(L, glGetError());
	return 1;
}


int gl_create_buffer(lua_State *L)
{
	int buf;
	glGenBuffers(1, &buf);
	lua_pushinteger(L, buf);
	return 1;
}


int gl_bind_buffer(lua_State *L)
{
	lua_Integer target, buf;
	hs_parse_args(L, hs_int(target), hs_int(buf));
	glBindBuffer(target, buf);
	return 0;
}


int gl_buffer_data(lua_State *L)
{
	lua_Integer target, type, usage;
	int table;
	hs_parse_args(L, hs_int(target), hs_int(type), hs_tbl(table), hs_int(usage));

	if (type != GL_INT && type != GL_FLOAT) {
		hs_throw_error(L, "invalid type");
	}

	/* build raw buffer */
	size_t len = lua_objlen(L, table);
	void *buf;
	if (type == GL_FLOAT) {
		float *fbuf = malloc(len * sizeof(float));
		if (fbuf == NULL)
			hs_throw_error(L, "failed to allocate intermediary fbuffer");
		for (int i=0; i<len; i++) {
			lua_rawgeti(L, table, i+1);
			if (!lua_isnumber(L, -1)) {
				hs_throw_error(L, "all table items must be numbers (failed at index %d)", i);
			}
			fbuf[i] = lua_tonumber(L, -1);
			lua_pop(L, 1);
		}
		len = len * sizeof(float);
		buf = fbuf;
	}
	else {
		int *ibuf = malloc(len * sizeof(int));
		if (ibuf == NULL)
			hs_throw_error(L, "failed to allocate intermediary ibuffer");
		for (int i=0; i<len; i++) {
			lua_rawgeti(L, table, i+1);
			if (!lua_isnumber(L, -1)) {
				hs_throw_error(L, "all table items must be integers (failed at index %d)", i);
			}
			ibuf[i] = lua_tointeger(L, -1);
			lua_pop(L, 1);
		}
		len = len * sizeof(int);
		buf = ibuf;
	}

	/* call */
	glBufferData(target, len, buf, usage);
	free(buf);
	return 0;
}


int gl_vertex_array_create(lua_State *L)
{
	int array;
	glGenVertexArrays(1, &array);
	lua_pushinteger(L, array);
	return 1;
}


int gl_vertex_array_bind(lua_State *L)
{
	lua_Integer array;
	hs_parse_args(L, hs_int(array));
	glBindVertexArray(array);
	return 0;
}


int gl_vertex_attrib_pointer(lua_State *L)
{
	lua_Integer index, size, stride, offset;
	bool normalized;
	hs_parse_args(L, hs_int(index), hs_int(size), hs_bool(normalized), hs_int(stride), hs_int(offset));
	glVertexAttribPointer(index, size, GL_FLOAT, 
	                      normalized, stride*sizeof(float), 
	                      (void*) (offset*sizeof(float)));
	return 0;
}


int gl_vertex_array_enable_attrib(lua_State *L)
{
	lua_Integer index;
	hs_parse_args(L, hs_int(index));
	glEnableVertexAttribArray(index);
	return 0;
}