# <<*>> -^v- SNOWARE APPLICATION
# usage: MINESENTINEL mainloop.
# 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.

def main
  puts '              ___  __   ___      ___         ___      '
  puts ' |\/| | |\ | |__  /__` |__  |\ |  |  | |\ | |__  |    '
  puts ' |  | | | \| |___ .__/ |___ | \|  |  | | \| |___ |___ '
  puts " MineSentinel dev-rolling version by <*> S.A. [@SNOWARE] and owned by SCU team."
  puts " Copyleft (c) 2026 S.A. SNOWARE-SCU. This program is licensed under Mulan PubL v2."
  puts " E-mail: SALflake@qq.com | QQ: 758522192 | Website: https://swe-iss.rth1.xyz/softwares/minesentinel."
  puts

  require_relative 'method_executor' # 日志系统在此时初始化
  MethodExecutor.record("debug", "init", "Initialized MethodExecutor, which implements logging system and intervening functions.")
  require_relative 'server_status_detector'
  require_relative 'systemd_notifier' # 心跳系统在此时初始化
  require_relative 'config'
  MethodExecutor.record("debug", "init", "Initialized SystemdNotifier, which implements systemd watchdog feeder.")

  # 确认是否具有展开干预操作的权限 如果因场景不同不需要请注释这部分内容
  unless Process.euid == 0
    MethodExecutor.record("error", "init", "Permission denied: root required to intervene Systemd Services.")
    raise Errno::EPERM
  end

  MethodExecutor.record("info", "mainloop", "MineSentinel started, entering mainloop.")

  # 初次启动：MineSentinel 先于 minecraft 启动（systemd Before=），
  # 等待服务器端口就绪，避免误判为崩溃
  MethodExecutor.record("info", "mainloop",
    "Initial startup grace period #{INITIAL_GRACE}s — waiting for server to come up...")
  grace_deadline = Time.now + INITIAL_GRACE
  while Time.now < grace_deadline
    sleep 5
    if ServerStatusDetector::MinecraftServer.self_diag[:type]
      MethodExecutor.record("info", "mainloop",
        "Server port is open during grace period, resuming normal monitoring.")
      break
    end
  end
  MethodExecutor.record("info", "mainloop", "Grace period ended.")
  main_loop
end

# Functional mainloop.
def main_once
  chkrslts = []
  for i in 0..TRY_TIMES
    chkrslt = ServerStatusDetector::MinecraftServer.self_diag
    chkrslts.append(chkrslt)
  end
  if chkrslts.all? { |chkrslt_in| chkrslt_in[:type] }
    MethodExecutor.record("debug", "mainloop", "Server health check passed.")
  else
    for chkrslt_in in chkrslts
      MethodExecutor.record("warn", "mainloop", "Server health check FAILED: #{chkrslt_in[:message]}")
    end
    MethodExecutor.record("info", "mainloop", "Checked #{TRY_TIMES} time.")
    if chkrslts.any? { |chkrslt_in| chkrslt_in[:operation] == "Record" }
      MethodExecutor.record("warn", "mainloop", "Action: Record -> Server died!")
      if chkrslts.any? { |chkrslt_in| chkrslt_in[:message] == "Server died for unknown reason, and will be restarted." }
        MethodExecutor.record("info", "mainloop", "Action: ForceResetServerProcess triggered.")
        MethodExecutor.reset_minecraft_server
        # 重启后等待服务器启动（MC服务器启动通常需要30秒~2分钟）
        cooldown_beg = Time.now
        MethodExecutor.record("info", "mainloop", "Cooling down #{RST_COOLDOWN_DURATION}s for server startup...")
        while Time.now < cooldown_beg + RST_COOLDOWN_DURATION
          sleep 1
          SystemdNotifier.notify("WATCHDOG=1")
        end
        MethodExecutor.record("info", "mainloop", "Cooldown finished, resuming monitoring.")
      end
    end
  end
end

def main_loop
  while true
    sleep CHECK_INTERVAL
    SystemdNotifier.notify("WATCHDOG=1")
    main_once
  end
end

begin
  main
rescue => e
  # 强制输出到stderr
  $stderr.puts "[CRITICAL] Unhandled exception: #{e.message}"
  $stderr.puts e.backtrace.join("\n")
  exit 1
end