import { on } from "svelte/events";
import { createSubscriber } from "svelte/reactivity";

let held = false;

const subscribe = createSubscriber((update) => {
	const set = (next: boolean) => {
		if (held === next) return;
		held = next;
		update();
	};
	const track = (event: KeyboardEvent) => set(event.shiftKey);
	const offs = [
		on(window, "keydown", track),
		on(window, "keyup", track),
		on(window, "blur", () => set(false))
	];
	return () => {
		for (const off of offs) off();
		held = false;
	};
});

export const shiftKey = {
	get held() {
		subscribe();
		return held;
	}
};