/**
 * How many try-ons this browser has already spent on the demo.
 *
 * Kept separate from the gallery on purpose: the gallery is the shopper's to
 * delete, and deleting a picture must not hand out another try-on.
 *
 * The authority is still the server. The brain caps the demo per IP and answers
 * 429 when that cap is hit, which the widget already turns into its own screen.
 * This counter exists so the number is on screen BEFORE the visitor starts,
 * instead of only when they walk into the wall.
 */
const COUNT_KEY = 'aisthetix-demo-tryons';

export function countDemoTryOns(): number {
  try {
    const raw = Number( localStorage.getItem( COUNT_KEY ) );
    if ( ! Number.isFinite( raw ) || raw < 0 ) {
      return 0;
    }
    return Math.floor( raw );
  } catch {
    return 0;
  }
}

/** Records one spent try-on and returns the new total. */
export function recordDemoTryOn(): number {
  const next = countDemoTryOns() + 1;
  try {
    localStorage.setItem( COUNT_KEY, String( next ) );
  } catch {
    // A browser that refuses storage loses the counter, not the try-on.
  }
  return next;
}

/**
 * Try-ons left, never below zero. A limit of 0 means the demo did not
 * advertise one, and callers should show nothing rather than "0 left".
 */
export function remainingDemoTryOns( limit: number ): number {
  return Math.max( 0, limit - countDemoTryOns() );
}