"use client";

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

// Single "analytics" bucket, not one bool per TrackingCodes.consentCategory
// — a plain binary accept/reject banner (TTDSG's own bar for "equally
// prominent" only requires two options) rather than a granular per-category
// settings panel. A tracking-codes row's `marketing` category is gated by
// the same flag as `analytics`; `necessary` always renders regardless of
// this cookie (see TrackingScripts.tsx).
export type Consent = { analytics: boolean };

const COOKIE_NAME = "cookie_consent";
const COOKIE_MAX_AGE_DAYS = 180;

function readConsentCookie(): Consent | null {
  if (typeof document === "undefined") return null;
  const match = document.cookie.match(new RegExp(`(?:^|; )${COOKIE_NAME}=([^;]*)`));
  if (!match) return null;
  try {
    const parsed = JSON.parse(decodeURIComponent(match[1]));
    return typeof parsed?.analytics === "boolean" ? { analytics: parsed.analytics } : null;
  } catch {
    return null;
  }
}

function writeConsentCookie(consent: Consent) {
  const maxAge = COOKIE_MAX_AGE_DAYS * 24 * 60 * 60;
  document.cookie = `${COOKIE_NAME}=${encodeURIComponent(JSON.stringify(consent))}; path=/; max-age=${maxAge}; SameSite=Lax`;
}

/**
 * `consent === null` means "no decision made yet" (CookieBanner.tsx should
 * show) — distinct from `{ analytics: false }`, an explicit reject.
 * `loaded` gates on the client-only cookie read completing, so a server-
 * rendered page never briefly flashes the banner before hydration confirms
 * there's actually no cookie.
 */
export function useConsent() {
  const [consent, setConsentState] = useState<Consent | null>(null);
  const [loaded, setLoaded] = useState(false);

  useEffect(() => {
    setConsentState(readConsentCookie());
    setLoaded(true);
  }, []);

  const setConsent = useCallback((next: Consent) => {
    writeConsentCookie(next);
    setConsentState(next);
  }, []);

  return { consent, loaded, setConsent };
}