#foreign_system_library "opengl32" when ODIN_OS == "windows"
#import "win32.odin" when ODIN_OS == "windows"
#include "opengl_constants.odin"

Clear          :: proc(mask: u32)                                #foreign "glClear"
ClearColor     :: proc(r, g, b, a: f32)                          #foreign "glClearColor"
Begin          :: proc(mode: i32)                                #foreign "glBegin"
End            :: proc()                                         #foreign "glEnd"
Finish         :: proc()                                         #foreign "glFinish"
BlendFunc      :: proc(sfactor, dfactor: i32)                    #foreign "glBlendFunc"
Enable         :: proc(cap: i32)                                 #foreign "glEnable"
Disable        :: proc(cap: i32)                                 #foreign "glDisable"
GenTextures    :: proc(count: i32, result: ^u32)                 #foreign "glGenTextures"
DeleteTextures :: proc(count: i32, result: ^u32)                 #foreign "glDeleteTextures"
TexParameteri  :: proc(target, pname, param: i32)                #foreign "glTexParameteri"
TexParameterf  :: proc(target: i32, pname: i32, param: f32)      #foreign "glTexParameterf"
BindTexture    :: proc(target: i32, texture: u32)                #foreign "glBindTexture"
LoadIdentity   :: proc()                                         #foreign "glLoadIdentity"
Viewport       :: proc(x, y, width, height: i32)                 #foreign "glViewport"
Ortho          :: proc(left, right, bottom, top, near, far: f64) #foreign "glOrtho"
Color3f        :: proc(r, g, b: f32)                             #foreign "glColor3f"
Vertex3f       :: proc(x, y, z: f32)                             #foreign "glVertex3f"
TexImage2D     :: proc(target, level, internal_format,
                       width, height, border,
                       format, _type: i32, pixels: rawptr) #foreign "glTexImage2D"

GetError    :: proc() -> i32            #foreign "glGetError"
GetString   :: proc(name: i32) -> ^byte #foreign "glGetString"
GetIntegerv :: proc(name: i32, v: ^i32) #foreign "glGetIntegerv"



_libgl := win32.LoadLibraryA(("opengl32.dll\x00" as string).data)

GetProcAddress :: proc(name: string) -> proc() {
	assert(name[name.count-1] == 0)
	res := win32.wglGetProcAddress(name.data)
	if res == nil {
		res = win32.GetProcAddress(_libgl, name.data)
	}
	return res
}


GenBuffers:      proc(count: i32, buffers: ^u32)
GenVertexArrays: proc(count: i32, buffers: ^u32)
GenSamplers:     proc(count: i32, buffers: ^u32)
BindBuffer:      proc(target: i32, buffer: u32)
BindVertexArray: proc(buffer: u32)
BindSampler:     proc(position: i32, sampler: u32)
BufferData:      proc(target: i32, size: int, data: rawptr, usage: i32)
BufferSubData:   proc(target: i32, offset, size: int, data: rawptr)

DrawArrays:      proc(mode, first: i32, count: u32)
DrawElements:    proc(mode: i32, count: u32, type_: i32, indices: rawptr)

MapBuffer:       proc(target, access: i32) -> rawptr
UnmapBuffer:     proc(target: i32)

VertexAttribPointer: proc(index: u32, size, type_: i32, normalized: i32, stride: u32, pointer: rawptr)
EnableVertexAttribArray: proc(index: u32)

CreateShader:  proc(shader_type: i32) -> u32
ShaderSource:  proc(shader: u32, count: u32, string: ^^byte, length: ^i32)
CompileShader: proc(shader: u32)
CreateProgram: proc() -> u32
AttachShader:  proc(program, shader: u32)
DetachShader:  proc(program, shader: u32)
DeleteShader:  proc(shader: u32)
LinkProgram:   proc(program: u32)
UseProgram:    proc(program: u32)
DeleteProgram: proc(program: u32)


GetShaderiv:       proc(shader:  u32, pname: i32, params: ^i32)
GetProgramiv:      proc(program: u32, pname: i32, params: ^i32)
GetShaderInfoLog:  proc(shader:  u32, max_length: u32, length: ^u32, info_long: ^byte)
GetProgramInfoLog: proc(program: u32, max_length: u32, length: ^u32, info_long: ^byte)

ActiveTexture:  proc(texture: i32)
GenerateMipmap: proc(target: i32)

SamplerParameteri:    proc(sampler: u32, pname: i32, param: i32)
SamplerParameterf:    proc(sampler: u32, pname: i32, param: f32)
SamplerParameteriv:   proc(sampler: u32, pname: i32, params: ^i32)
SamplerParameterfv:   proc(sampler: u32, pname: i32, params: ^f32)
SamplerParameterIiv:  proc(sampler: u32, pname: i32, params: ^i32)
SamplerParameterIuiv: proc(sampler: u32, pname: i32, params: ^u32)


Uniform1i:        proc(loc: i32, v0: i32)
Uniform2i:        proc(loc: i32, v0, v1: i32)
Uniform3i:        proc(loc: i32, v0, v1, v2: i32)
Uniform4i:        proc(loc: i32, v0, v1, v2, v3: i32)
Uniform1f:        proc(loc: i32, v0: f32)
Uniform2f:        proc(loc: i32, v0, v1: f32)
Uniform3f:        proc(loc: i32, v0, v1, v2: f32)
Uniform4f:        proc(loc: i32, v0, v1, v2, v3: f32)
UniformMatrix4fv: proc(loc: i32, count: u32, transpose: i32, value: ^f32)

GetUniformLocation: proc(program: u32, name: ^byte) -> i32

init :: proc() {
	set_proc_address :: proc(p: rawptr, name: string) #inline { (p as ^proc())^ = GetProcAddress(name); }

	set_proc_address(^GenBuffers,      "glGenBuffers\x00")
	set_proc_address(^GenVertexArrays, "glGenVertexArrays\x00")
	set_proc_address(^GenSamplers,     "glGenSamplers\x00")
	set_proc_address(^BindBuffer,      "glBindBuffer\x00")
	set_proc_address(^BindSampler,     "glBindSampler\x00")
	set_proc_address(^BindVertexArray, "glBindVertexArray\x00")
	set_proc_address(^BufferData,      "glBufferData\x00")
	set_proc_address(^BufferSubData,   "glBufferSubData\x00")

	set_proc_address(^DrawArrays,      "glDrawArrays\x00")
	set_proc_address(^DrawElements,    "glDrawElements\x00")

	set_proc_address(^MapBuffer,   "glMapBuffer\x00")
	set_proc_address(^UnmapBuffer, "glUnmapBuffer\x00")

	set_proc_address(^VertexAttribPointer,     "glVertexAttribPointer\x00")
	set_proc_address(^EnableVertexAttribArray, "glEnableVertexAttribArray\x00")

	set_proc_address(^CreateShader,  "glCreateShader\x00")
	set_proc_address(^ShaderSource,  "glShaderSource\x00")
	set_proc_address(^CompileShader, "glCompileShader\x00")
	set_proc_address(^CreateProgram, "glCreateProgram\x00")
	set_proc_address(^AttachShader,  "glAttachShader\x00")
	set_proc_address(^DetachShader,  "glDetachShader\x00")
	set_proc_address(^DeleteShader,  "glDeleteShader\x00")
	set_proc_address(^LinkProgram,   "glLinkProgram\x00")
	set_proc_address(^UseProgram,    "glUseProgram\x00")
	set_proc_address(^DeleteProgram, "glDeleteProgram\x00")

	set_proc_address(^GetShaderiv,       "glGetShaderiv\x00")
	set_proc_address(^GetProgramiv,      "glGetProgramiv\x00")
	set_proc_address(^GetShaderInfoLog,  "glGetShaderInfoLog\x00")
	set_proc_address(^GetProgramInfoLog, "glGetProgramInfoLog\x00")

	set_proc_address(^ActiveTexture,  "glActiveTexture\x00")
	set_proc_address(^GenerateMipmap, "glGenerateMipmap\x00")

	set_proc_address(^Uniform1i,        "glUniform1i\x00")
	set_proc_address(^UniformMatrix4fv, "glUniformMatrix4fv\x00")

	set_proc_address(^GetUniformLocation, "glGetUniformLocation\x00")

	set_proc_address(^SamplerParameteri,    "glSamplerParameteri\x00")
	set_proc_address(^SamplerParameterf,    "glSamplerParameterf\x00")
	set_proc_address(^SamplerParameteriv,   "glSamplerParameteriv\x00")
	set_proc_address(^SamplerParameterfv,   "glSamplerParameterfv\x00")
	set_proc_address(^SamplerParameterIiv,  "glSamplerParameterIiv\x00")
	set_proc_address(^SamplerParameterIuiv, "glSamplerParameterIuiv\x00")
}