use strings;
use types::c;
use trace;

use gl::*;

fn debug_callback(
	source: gl_enum,
	type_: gl_enum,
	id: uint,
	severity: gl_enum,
	length: i32,
	message: nullable *const c::char,
	user_data: nullable *opaque,
) void = {
	// (2024 note): I'm painfully aware of the data race present here:
	// The GL driver can call this from another thread, and the stdlib has
	// some non-thread-safe stuff in it that we use, in particular strconv.
	// I've seen it happen at times, but it's pretty rare.
	const message = (message: *const [*]u8)[..length];
	const message = strings::fromutf8(message)!;
	const message = strings::trimsuffix(message, "\n");
	trace::debug(&trace::root, "gl: {}", message);
};

export fn init_debug_logging() void = {
	let ctxflags = 0i32;
	glGetIntegerv(GL_CONTEXT_FLAGS, &ctxflags);

	if (ctxflags & GL_CONTEXT_FLAG_DEBUG_BIT: i32 != 0) {
		trace::info(&trace::root, "opengl debugging is enabled");
		glDebugMessageCallback(&debug_callback, null);
	};
};