"use client";

// Which archives the hub's search covers, per browser. Every archive is in by
// default; the visitor takes one out with its scope chip. Stored as the set of
// origins switched OFF, so an archive the browser has never seen (a new
// official instance, a site added later) is searched until someone says not to.
// localStorage is a convenience here: when it is unavailable every archive is
// simply searched.

import { useCallback, useEffect, useRef, useState } from "react";

const STORAGE_KEY = "ytdlp-tb:hub-scope";

function readOff(): ReadonlySet<string> {
  if (typeof window === "undefined") return new Set();
  try {
    const raw = window.localStorage.getItem(STORAGE_KEY);
    const parsed: unknown = raw ? JSON.parse(raw) : null;
    const off =
      parsed && typeof parsed === "object" && Array.isArray((parsed as { off?: unknown }).off)
        ? (parsed as { off: unknown[] }).off
        : [];
    return new Set(off.filter((o): o is string => typeof o === "string"));
  } catch {
    return new Set();
  }
}

function writeOff(off: ReadonlySet<string>) {
  try {
    window.localStorage.setItem(
      STORAGE_KEY,
      JSON.stringify({ off: Array.from(off) }),
    );
  } catch {
    // Storage full / disabled — the choice still holds for this visit.
  }
}

export function useHubScope() {
  // Read on the client's first render. The registry's server snapshot is empty,
  // so nothing that depends on this renders during hydration.
  const [off, setOff] = useState<ReadonlySet<string>>(readOff);
  const first = useRef(true);
  useEffect(() => {
    if (first.current) {
      first.current = false;
      return;
    }
    writeOff(off);
  }, [off]);

  const toggle = useCallback((origin: string) => {
    setOff((prev) => {
      const next = new Set(prev);
      if (next.has(origin)) next.delete(origin);
      else next.add(origin);
      return next;
    });
  }, []);

  const isOn = useCallback((origin: string) => !off.has(origin), [off]);

  return { isOn, toggle };
}