# File lib/ajaxim.rb, line 306
  def pingroom
    sql = "SELECT room FROM {ajaxim_chats} WHERE uid = '" + @user['uid'] + "'"
    res = @db.query(sql)
    user_chats = Array.new
    while uchat = res.fetch_hash do
      user_chats.push(uchat["room"]) 
    end
    #
    # getting available chatrooms by criteria
    criteria_users_num = get_variable("ajaxim_client_chatrooms_user_number" , 10)
    chats = Array.new
    sql = "SELECT room, COUNT(*) as num 
           FROM {ajaxim_chats} 
           WHERE uid != #{@user['uid']} 
           GROUP BY room"
    res = @db.query(sql)
    while chat = res.fetch_hash do
      if chat["num"].to_i >= criteria_users_num.to_i && !user_chats.include?(chat["room"])
        chats.push(chat['room'])
      end
    end
    

    output = {"rooms" => chats.sort.to_json}
    output.to_json
  end