'use client';
/**
 * Owner token for watchlists and alerts (no account, spec §55): a random string generated once in the browser
 * (`crypto.randomUUID()` twice → 72 chars) and kept in localStorage. Sent as `X-CA-Owner-Token`; the API stores a hash.
 * Losing the browser storage loses the watchlist — the /watchlist page says so and offers export/import of the token.
 */
import { useEffect, useState } from 'react';

export const OWNER_KEY = 'ca-owner-token';
const EVENT = 'ca-owner-change';

export function readOwnerToken(): string | null {
  if (typeof window === 'undefined') return null;
  try {
    const v = window.localStorage.getItem(OWNER_KEY);
    return v && v.length >= 24 ? v : null;
  } catch {
    return null;
  }
}

export function ensureOwnerToken(): string {
  const cur = readOwnerToken();
  if (cur) return cur;
  const t = `${crypto.randomUUID()}${crypto.randomUUID()}`.replace(/-/g, '');
  try {
    window.localStorage.setItem(OWNER_KEY, t);
    window.dispatchEvent(new CustomEvent(EVENT));
  } catch {
    /* storage disabled: token lives for this page only */
  }
  return t;
}

export function setOwnerToken(t: string): boolean {
  if (t.trim().length < 24) return false;
  try {
    window.localStorage.setItem(OWNER_KEY, t.trim());
    window.dispatchEvent(new CustomEvent(EVENT));
    return true;
  } catch {
    return false;
  }
}

/** Token after mount (null during SSR / first paint). `create` generates one when absent. */
export function useOwnerToken(create = false): string | null {
  const [token, setToken] = useState<string | null>(null);
  useEffect(() => {
    const read = () => setToken(create ? ensureOwnerToken() : readOwnerToken());
    read();
    window.addEventListener(EVENT, read);
    window.addEventListener('storage', read);
    return () => {
      window.removeEventListener(EVENT, read);
      window.removeEventListener('storage', read);
    };
  }, [create]);
  return token;
}

/** Local mirror of watched slugs so watch buttons render instantly and work when the API is briefly unavailable. */
export const WATCHED_KEY = 'ca-watched';
const WATCHED_EVENT = 'ca-watched-change';
export function readWatched(): string[] {
  if (typeof window === 'undefined') return [];
  try {
    const arr = JSON.parse(window.localStorage.getItem(WATCHED_KEY) ?? '[]') as unknown;
    return Array.isArray(arr) ? arr.filter((x): x is string => typeof x === 'string') : [];
  } catch {
    return [];
  }
}
export function writeWatched(slugs: string[]) {
  try {
    window.localStorage.setItem(WATCHED_KEY, JSON.stringify([...new Set(slugs)]));
  } catch {
    /* ignore */
  }
  window.dispatchEvent(new CustomEvent(WATCHED_EVENT));
}
export function useWatched(): string[] {
  const [w, setW] = useState<string[]>([]);
  useEffect(() => {
    const read = () => setW(readWatched());
    read();
    window.addEventListener(WATCHED_EVENT, read);
    window.addEventListener('storage', read);
    return () => {
      window.removeEventListener(WATCHED_EVENT, read);
      window.removeEventListener('storage', read);
    };
  }, []);
  return w;
}