CLAN_ID = 1

clan = Clan.find(CLAN_ID)

character_ids = ClanMember.connection.select_values(
  ClanMember.send(:sanitize_sql, ["SELECT character_id FROM clan_members WHERE clan_id = :clan", :clan => clan.id])
)

position = 0

Character.transaction do
  Character.order("level DESC").find(character_ids, :lock => true).each do |character|
    position += 1

    if character_ids.size <= 20 && position <= 10
      character.chips += 2
    elsif character_ids.size > 20 && position <= 20
      character.chips += 2
    else
      character.chips += 1
    end

    character.save!
  end

  clan.chips = 0
  clan.save!
end