/**
 * Pure helpers for the bracket-scoring route action, extracted so the
 * knockout-detection logic can be unit-tested without the full action harness.
 */

/**
 * From a set of matches being scored this action, return the season_participant
 * ids knocked out for the FIRST time. A loser counts only when its match was NOT
 * already complete — a re-score/correction of a finished match must not
 * re-announce the exit (mirrors populateBracketFromDraw's first-completion rule in
 * the live-sync path). Entries with an unknown loser (`null`) are skipped.
 *
 * The ids are season_participant ids of the primary window (playoff_matches are
 * keyed by season_participant); the fan-out translates them to each mirror
 * window's own season_participant id before announcing the "Knocked Out" section.
 */
export function newlyDecidedLosers(
  entries: Array<{ wasComplete: boolean; loserId: string | null }>
): string[] {
  return entries
    .filter((e): e is { wasComplete: boolean; loserId: string } =>
      !e.wasComplete && e.loserId !== null
    )
    .map((e) => e.loserId);
}