module L4dServer
  class HealthChecker
    def self.check(server)
      new(server).check
    end

    def initialize(server)
      @server = server
    end

    def check
      # First check if systemd thinks the service is active
      status = SystemdManager.status(@server)

      case status
      when "active"
        check_rcon
      when "inactive", "failed"
        :stopped
      else
        :unknown
      end
    end

    private

    def check_rcon
      # Try to connect via RCON to verify server is actually responding
      socket = UDPSocket.new
      socket.connect("127.0.0.1", @server.port)

      # Build a simple RCON auth packet for L4D2
      # Format: 0xFFFFFFFF + "challenge rcon_password"
      packet = "\xFF\xFF\xFF\xFFchallenge #{@server.rcon_password}\n"
      socket.send(packet, 0)

      socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_RCVTIMEO, 1) # 1 second timeout
      response = socket.recv(4096)
      socket.close

      response.length > 0 ? :running : :failed
    rescue Timeout::Error, Errno::ECONNREFUSED, StandardError => e
      Rails.logger.debug("RCON health check failed: #{e.message}")
      :failed
    end
  end
end