# <<*>> -^v- SNOWARE APPLICATION
# usage: Notify systemd.
# author: S.A.
# time: 2026-06-07
# Copyright (c) [2026] [S.A. SNOWARE-SCU]
# [MineSentinel] is licensed under Mulan PubL v2.
# You can use this software according to the terms and conditions of the Mulan PubL v2.
# You may obtain a copy of Mulan PubL v2 at:
#          http://license.coscl.org.cn/MulanPubL-2.0
# THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
# EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
# MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
# See the Mulan PubL v2 for more details.

# frozen_string_literal: true

# Sends keep-alive notifications (including WATCHDOG=1) to systemd
# via the NOTIFY_SOCKET datagram socket, enabling service supervision.
class SystemdNotifier
  require_relative 'method_executor'


  @notify_socket = ENV.fetch('NOTIFY_SOCKET', nil)
  @watchdog_usec = (ENV['WATCHDOG_USEC'] || '0').to_i

  if @notify_socket && File.socket?(@notify_socket)
    MethodExecutor.record('debug', 'heartbeat', 'Found NOTIFY_SOCKET, enabling heartbeat')
    @enable_heartbeat = true
    # Fix(2026-06-08): 将 UNIXSocket(SOCK_STREAM) 改为 SOCK_DGRAM
    # systemd NOTIFY_SOCKET 是 datagram socket，用 stream socket 连接会报
    #    Protocol wrong type for socket (Errno::EPROTOTYPE)
    @socket = Socket.new(Socket::AF_UNIX, Socket::SOCK_DGRAM)
    @socket.connect(Socket.pack_sockaddr_un(@notify_socket))
    MethodExecutor.record('debug', 'heartbeat', 'Heartbeat socket opened')
  else
    MethodExecutor.record('error', 'heartbeat', 'NOTIFY_SOCKET is not set or is not a socket, am I a service?')
    @enable_heartbeat = false
  end

  # @return [Boolean]
  def enabled?
    @enable_heartbeat
  end

  # @param message [String]
  # @return [void]
  def self.notify(message)
    return unless @enable_heartbeat

    begin
      @socket.send(message, 0)
      MethodExecutor.record('debug', 'heartbeat', "Heartbeat sent: #{message}")
    rescue StandardError => e
      MethodExecutor.record('error', 'heartbeat', "Failed to send heartbeat: #{e}")
      @enable_heartbeat = false
    end
  end
end