import type { RulesEdition } from "@initiative/domain";
import { useCallback, useSyncExternalStore } from "react";

const STORAGE_KEY = "initiative:rules-edition";

const listeners = new Set<() => void>();
let currentEdition: RulesEdition = loadEdition();

function loadEdition(): RulesEdition {
	try {
		const raw = localStorage.getItem(STORAGE_KEY);
		if (raw === "5e" || raw === "5.5e") return raw;
	} catch {
		// storage unavailable
	}
	return "5.5e";
}

function saveEdition(edition: RulesEdition): void {
	try {
		localStorage.setItem(STORAGE_KEY, edition);
	} catch {
		// quota exceeded or storage unavailable
	}
}

function notifyAll(): void {
	for (const listener of listeners) {
		listener();
	}
}

function subscribe(callback: () => void): () => void {
	listeners.add(callback);
	return () => listeners.delete(callback);
}

function getSnapshot(): RulesEdition {
	return currentEdition;
}

export function useRulesEdition() {
	const edition = useSyncExternalStore(subscribe, getSnapshot);

	const setEdition = useCallback((next: RulesEdition) => {
		currentEdition = next;
		saveEdition(next);
		notifyAll();
	}, []);

	return { edition, setEdition } as const;
}