/**
 * Team walking-distance aggregation.
 *
 * A team's distance is the average of the `UserTrack.distanceMeters` of its
 * _current_ participants (the team owner plus its team members) that actually
 * recorded a distance. Participants without a recorded track are excluded
 * rather than diluting the average with zeros.
 */
export function teamAverageDistance(
  participantIds: number[],
  tracks: Map<number, number>
): number {
  const unique = [...new Set(participantIds)];
  const distances = unique
    .map((id) => tracks.get(id))
    .filter((d): d is number => d !== undefined);

  if (distances.length === 0) return 0;

  const sum = distances.reduce((acc, d) => acc + d, 0);
  return Math.round(sum / distances.length);
}