import type { PriceState } from "@/interfaces";

/**
 * Returns true when we should append a new row to price_history for `next`.
 *
 * - `next == null` means "price could not be observed this run" — not a change.
 * - `prev == null` (no history yet) and `next != null` is the first observation.
 */
export const isPriceChange = (prev: PriceState | null, next: PriceState | null): boolean => {
  if (next === null) return false;
  if (prev === null) return true;
  return prev.priceYen !== next.priceYen || prev.onPromo !== next.onPromo;
};