import dlib.aliases;
import dlib.util;
import dlib.alloc;

static if(NativeTarget)
{
	       import dlibincludes;
	public import opengl_native;
}
else
{
	public import opengl_wasm;
}

public import glenum;

__gshared bool FUNCS_LOADED = false;

version(linux)
{
	alias GLLoadFunc = glXGetProcAddressARB;
}
else static assert(false, "GL function loader alias not set for platform");

bool
GLLoadFuncs()
{
	glDeleteRenderbuffers      = cast(typeof(glDeleteRenderbuffers))GLLoadFunc(cast(u8*)"glDeleteRenderbuffers".ptr);
	glGenRenderbuffers         = cast(typeof(glGenRenderbuffers))GLLoadFunc(cast(u8*)"glGenRenderbuffers".ptr);
	glGenVertexArrays          = cast(typeof(glGenVertexArrays))GLLoadFunc(cast(u8*)"glGenVertexArrays".ptr);
	glDeleteVertexArrays       = cast(typeof(glDeleteVertexArrays))GLLoadFunc(cast(u8*)"glDeleteVertexArrays".ptr);
	glGenBuffers               = cast(typeof(glGenBuffers))GLLoadFunc(cast(u8*)"glGenBuffers".ptr);
	glCompileShader            = cast(typeof(glCompileShader))GLLoadFunc(cast(u8*)"glCompileShader".ptr);
	glUseProgram               = cast(typeof(glUseProgram))GLLoadFunc(cast(u8*)"glUseProgram".ptr);
	glValidateProgram          = cast(typeof(glValidateProgram))GLLoadFunc(cast(u8*)"glValidateProgram".ptr);
	glBindBufferBase           = cast(typeof(glBindBufferBase))GLLoadFunc(cast(u8*)"glBindBufferBase".ptr);
	glGetUniformBlockIndex     = cast(typeof(glGetUniformBlockIndex))GLLoadFunc(cast(u8*)"glGetUniformBlockIndex".ptr);
	glEnableVertexAttribArray  = cast(typeof(glEnableVertexAttribArray))GLLoadFunc(cast(u8*)"glEnableVertexAttribArray".ptr);
	glDisableVertexAttribArray = cast(typeof(glDisableVertexAttribArray))GLLoadFunc(cast(u8*)"glDisableVertexAttribArray".ptr);
	glBlendFuncSeparate        = cast(typeof(glBlendFuncSeparate))GLLoadFunc(cast(u8*)"glBlendFuncSeparate".ptr);
	glBindVertexArray          = cast(typeof(glBindVertexArray))GLLoadFunc(cast(u8*)"glBindVertexArray".ptr);
	glBindBuffer               = cast(typeof(glBindBuffer))GLLoadFunc(cast(u8*)"glBindBuffer".ptr);
	glBufferData               = cast(typeof(glBufferData))GLLoadFunc(cast(u8*)"glBufferData".ptr);
	glBufferSubData            = cast(typeof(glBufferSubData))GLLoadFunc(cast(u8*)"glBufferSubData".ptr);
	glVertexAttribDivisor      = cast(typeof(glVertexAttribDivisor))GLLoadFunc(cast(u8*)"glVertexAttribDivisor".ptr);
	glVertexAttribPointer      = cast(typeof(glVertexAttribPointer))GLLoadFunc(cast(u8*)"glVertexAttribPointer".ptr);
	glDrawArraysInstanced      = cast(typeof(glDrawArraysInstanced))GLLoadFunc(cast(u8*)"glDrawArraysInstanced".ptr);
	glDrawElementsInstanced    = cast(typeof(glDrawElementsInstanced))GLLoadFunc(cast(u8*)"glDrawElementsInstanced".ptr);
	glGetUniformLocation       = cast(typeof(glGetUniformLocation))GLLoadFunc(cast(u8*)"glGetUniformLocation".ptr);
	glUniform1f                = cast(typeof(glUniform1f))GLLoadFunc(cast(u8*)"glUniform1f".ptr);
	glUniform2f                = cast(typeof(glUniform2f))GLLoadFunc(cast(u8*)"glUniform2f".ptr);
	glUniform3f                = cast(typeof(glUniform3f))GLLoadFunc(cast(u8*)"glUniform3f".ptr);
	glUniform4f                = cast(typeof(glUniform4f))GLLoadFunc(cast(u8*)"glUniform4f".ptr);
	glUniform1i                = cast(typeof(glUniform1i))GLLoadFunc(cast(u8*)"glUniform1i".ptr);
	glUniform2i                = cast(typeof(glUniform2i))GLLoadFunc(cast(u8*)"glUniform2i".ptr);
	glUniform3i                = cast(typeof(glUniform3i))GLLoadFunc(cast(u8*)"glUniform3i".ptr);
	glUniform4i                = cast(typeof(glUniform4i))GLLoadFunc(cast(u8*)"glUniform4i".ptr);
	glCreateProgram            = cast(typeof(glCreateProgram))GLLoadFunc(cast(u8*)"glCreateProgram".ptr);
	glCreateShader             = cast(typeof(glCreateShader))GLLoadFunc(cast(u8*)"glCreateShader".ptr);
	glDeleteFramebuffers       = cast(typeof(glDeleteFramebuffers))GLLoadFunc(cast(u8*)"glDeleteFramebuffers".ptr);
	glDeleteProgram            = cast(typeof(glDeleteProgram))GLLoadFunc(cast(u8*)"glDeleteProgram".ptr);
	glDeleteShader             = cast(typeof(glDeleteShader))GLLoadFunc(cast(u8*)"glDeleteShader".ptr);
	glShaderSource             = cast(typeof(glShaderSource))GLLoadFunc(cast(u8*)"glShaderSource".ptr);
	glGetProgramiv             = cast(typeof(glGetProgramiv))GLLoadFunc(cast(u8*)"glGetProgramiv".ptr);
	glGetProgramInfoLog        = cast(typeof(glGetProgramInfoLog))GLLoadFunc(cast(u8*)"glGetProgramInfoLog".ptr);
	glGetShaderiv              = cast(typeof(glGetShaderiv))GLLoadFunc(cast(u8*)"glGetShaderiv".ptr);
	glGetShaderInfoLog         = cast(typeof(glGetShaderInfoLog))GLLoadFunc(cast(u8*)"glGetShaderInfoLog".ptr);
	glAttachShader             = cast(typeof(glAttachShader))GLLoadFunc(cast(u8*)"glAttachShader".ptr);
	glLinkProgram              = cast(typeof(glLinkProgram))GLLoadFunc(cast(u8*)"glLinkProgram".ptr);

	static if(!__traits(compiles, { glActiveTexture(0x84C0); }))
	{
		glActiveTexture            = cast(typeof(glActiveTexture))GLLoadFunc(cast(u8*)"glActiveTexture".ptr);
	}

	return glDeleteRenderbuffers != null;
}

u32
GLCreateShader(GLEnum shader_type, string[] shader_src)
{
	i32[32]              src_lengths;
	immutable(char)*[32] src_ptrs;
	for(usize i = 0; i < shader_src.length; i += 1)
	{
		src_ptrs[i]    = shader_src[i].ptr;
		src_lengths[i] = cast(i32)shader_src[i].length;
	}

	u32 shader = glCreateShader(shader_type);
	glShaderSource(shader, cast(u32)shader_src.length, src_ptrs.ptr, src_lengths.ptr);

	i32 success;
	glGetShaderiv(shader, GLE.COMPILE_STATUS, &success);
	if(!success)
	{
		char[512] info_log;
		i32       log_length;
		glGetShaderInfoLog(shader, cast(u32)info_log.length, &log_length, info_log.ptr);

		Errf("Error compiling shader: %s", Str(info_log[0 .. log_length]));
		shader = 0;
	}

	return shader;
}

u32
GLCreateProgramFromSources(string[] vertex_src, string[] fragment_src)
{
	u32 program;

	u32 vertex_shader   = GLCreateShader(GLE.VERTEX_SHADER,   vertex_src);
	u32 fragment_shader = GLCreateShader(GLE.FRAGMENT_SHADER, fragment_src);
	if(vertex_shader && fragment_shader)
	{
		program = glCreateProgram();
		glAttachShader(program, vertex_shader);
		glAttachShader(program, fragment_shader);
		glLinkProgram(program);

		i32 success;
		glGetProgramiv(program, GLE.LINK_STATUS, &success);
		if(!success)
		{
			char[512] info_log;
			i32       log_length;
			glGetProgramInfoLog(program, cast(u32)info_log.length, &log_length, info_log.ptr);

			Errf("Error compiling program: %s", Str(info_log[0 .. log_length]));

			program = 0;
		}
	}

	if(!program)
	{
		Errf("Failed to create program!");
	}

	return program;	
}