import type { SukebeiMagnet } from "@/crawlers/sukebei.db";

export interface MagnetDiff {
  added: SukebeiMagnet[];
  stillPresent: SukebeiMagnet[];
}

/**
 * Split the current sukebei result against a known set of magnetIds.
 *
 * - `added` are magnets we have never seen before for this work.
 * - `stillPresent` are already-known magnets re-observed this run.
 *
 * Sukebei never "unlists" cleanly, so we do not surface a `removed` set.
 */
export const diffMagnets = (previousIds: Set<string>, current: SukebeiMagnet[]): MagnetDiff => {
  const added: SukebeiMagnet[] = [];
  const stillPresent: SukebeiMagnet[] = [];
  for (const m of current) {
    if (previousIds.has(m.magnetId)) stillPresent.push(m);
    else added.push(m);
  }
  return { added, stillPresent };
};