#pragma once

// -----------------------------------------------------------------------
// GLFunctions
//
// Linux distributions only ship GL/gl.h with legacy (<=1.1/1.2) function
// declarations; everything from OpenGL 1.5 onward (VAOs/VBOs, GLSL
// shaders, etc.) must be resolved at runtime as function pointers. This
// is a small, self-contained loader for exactly the subset of OpenGL 3.3
// core functions this project's renderer uses. It is intentionally
// separate from Dear ImGui's own bundled loader (imgui_impl_opengl3_loader.h)
// to avoid the multiple-definition problems that occur when two GL
// loaders are mixed in the same program - see the comment at the top of
// that file for details.
//
// Usage: call planetarium::gl::loadGLFunctions() exactly once, right
// after the GLFW OpenGL context has been made current and before any
// other GL call in the project's own rendering code.
// -----------------------------------------------------------------------

#include <GL/gl.h>
#include <cstddef>

#ifndef GL_ARRAY_BUFFER
#define GL_ARRAY_BUFFER 0x8892
#endif
#ifndef GL_ELEMENT_ARRAY_BUFFER
#define GL_ELEMENT_ARRAY_BUFFER 0x8893
#endif
#ifndef GL_STATIC_DRAW
#define GL_STATIC_DRAW 0x88E4
#endif
#ifndef GL_DYNAMIC_DRAW
#define GL_DYNAMIC_DRAW 0x88E8
#endif
#ifndef GL_FRAGMENT_SHADER
#define GL_FRAGMENT_SHADER 0x8B30
#endif
#ifndef GL_VERTEX_SHADER
#define GL_VERTEX_SHADER 0x8B31
#endif
#ifndef GL_COMPILE_STATUS
#define GL_COMPILE_STATUS 0x8B81
#endif
#ifndef GL_LINK_STATUS
#define GL_LINK_STATUS 0x8B82
#endif
#ifndef GL_TEXTURE0
#define GL_TEXTURE0 0x84C0
#endif
#ifndef GL_PROGRAM_POINT_SIZE
#define GL_PROGRAM_POINT_SIZE 0x8642
#endif
#ifndef GL_CLAMP_TO_EDGE
#define GL_CLAMP_TO_EDGE 0x812F
#endif
#ifndef GL_MULTISAMPLE
#define GL_MULTISAMPLE 0x809D
#endif
#ifndef GL_MAJOR_VERSION
#define GL_MAJOR_VERSION 0x821B
#endif
#ifndef GL_MINOR_VERSION
#define GL_MINOR_VERSION 0x821C
#endif

typedef char GLchar;
typedef ptrdiff_t GLsizeiptr;
typedef ptrdiff_t GLintptr;

namespace planetarium::gl {

using PFNGLGENVERTEXARRAYS = void (*)(GLsizei, GLuint*);
using PFNGLBINDVERTEXARRAY = void (*)(GLuint);
using PFNGLDELETEVERTEXARRAYS = void (*)(GLsizei, const GLuint*);
using PFNGLGENBUFFERS = void (*)(GLsizei, GLuint*);
using PFNGLBINDBUFFER = void (*)(GLenum, GLuint);
using PFNGLBUFFERDATA = void (*)(GLenum, GLsizeiptr, const void*, GLenum);
using PFNGLDELETEBUFFERS = void (*)(GLsizei, const GLuint*);
using PFNGLVERTEXATTRIBPOINTER = void (*)(GLuint, GLint, GLenum, GLboolean, GLsizei, const void*);
using PFNGLENABLEVERTEXATTRIBARRAY = void (*)(GLuint);
using PFNGLDISABLEVERTEXATTRIBARRAY = void (*)(GLuint);

using PFNGLCREATESHADER = GLuint (*)(GLenum);
using PFNGLSHADERSOURCE = void (*)(GLuint, GLsizei, const GLchar* const*, const GLint*);
using PFNGLCOMPILESHADER = void (*)(GLuint);
using PFNGLGETSHADERIV = void (*)(GLuint, GLenum, GLint*);
using PFNGLGETSHADERINFOLOG = void (*)(GLuint, GLsizei, GLsizei*, GLchar*);
using PFNGLDELETESHADER = void (*)(GLuint);
using PFNGLCREATEPROGRAM = GLuint (*)();
using PFNGLATTACHSHADER = void (*)(GLuint, GLuint);
using PFNGLLINKPROGRAM = void (*)(GLuint);
using PFNGLGETPROGRAMIV = void (*)(GLuint, GLenum, GLint*);
using PFNGLGETPROGRAMINFOLOG = void (*)(GLuint, GLsizei, GLsizei*, GLchar*);
using PFNGLUSEPROGRAM = void (*)(GLuint);
using PFNGLDELETEPROGRAM = void (*)(GLuint);

using PFNGLGETUNIFORMLOCATION = GLint (*)(GLuint, const GLchar*);
using PFNGLUNIFORMMATRIX4FV = void (*)(GLint, GLsizei, GLboolean, const GLfloat*);
using PFNGLUNIFORM3FV = void (*)(GLint, GLsizei, const GLfloat*);
using PFNGLUNIFORM4FV = void (*)(GLint, GLsizei, const GLfloat*);
using PFNGLUNIFORM1F = void (*)(GLint, GLfloat);
using PFNGLUNIFORM1I = void (*)(GLint, GLint);
using PFNGLACTIVETEXTURE = void (*)(GLenum);
using PFNGLGENERATEMIPMAP = void (*)(GLenum);

extern PFNGLGENVERTEXARRAYS glGenVertexArrays;
extern PFNGLBINDVERTEXARRAY glBindVertexArray;
extern PFNGLDELETEVERTEXARRAYS glDeleteVertexArrays;
extern PFNGLGENBUFFERS glGenBuffers;
extern PFNGLBINDBUFFER glBindBuffer;
extern PFNGLBUFFERDATA glBufferData;
extern PFNGLDELETEBUFFERS glDeleteBuffers;
extern PFNGLVERTEXATTRIBPOINTER glVertexAttribPointer;
extern PFNGLENABLEVERTEXATTRIBARRAY glEnableVertexAttribArray;
extern PFNGLDISABLEVERTEXATTRIBARRAY glDisableVertexAttribArray;

extern PFNGLCREATESHADER glCreateShader;
extern PFNGLSHADERSOURCE glShaderSource;
extern PFNGLCOMPILESHADER glCompileShader;
extern PFNGLGETSHADERIV glGetShaderiv;
extern PFNGLGETSHADERINFOLOG glGetShaderInfoLog;
extern PFNGLDELETESHADER glDeleteShader;
extern PFNGLCREATEPROGRAM glCreateProgram;
extern PFNGLATTACHSHADER glAttachShader;
extern PFNGLLINKPROGRAM glLinkProgram;
extern PFNGLGETPROGRAMIV glGetProgramiv;
extern PFNGLGETPROGRAMINFOLOG glGetProgramInfoLog;
extern PFNGLUSEPROGRAM glUseProgram;
extern PFNGLDELETEPROGRAM glDeleteProgram;

extern PFNGLGETUNIFORMLOCATION glGetUniformLocation;
extern PFNGLUNIFORMMATRIX4FV glUniformMatrix4fv;
extern PFNGLUNIFORM3FV glUniform3fv;
extern PFNGLUNIFORM4FV glUniform4fv;
extern PFNGLUNIFORM1F glUniform1f;
extern PFNGLUNIFORM1I glUniform1i;
extern PFNGLACTIVETEXTURE glActiveTexture;
extern PFNGLGENERATEMIPMAP glGenerateMipmap;

// Resolves every function pointer above via glfwGetProcAddress. Must be
// called once, after glfwMakeContextCurrent(). Returns false if any
// required entry point could not be resolved.
bool loadGLFunctions();

}  // namespace planetarium::gl