# <<*>> -^v- SNOWARE APPLICATION
# usage: Automatic operator implementation.
# 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

PERSISTENCE_PERIOD = 30 # Wait for systemctl to take the order.

require 'logger'
require_relative 'server_status_detector'
class MethodExecutor
  public
  RST_COUNTS_LIMIT = 10
  @@rst_counter = 0
  # Initialize the standard log system.
  @@logger = Logger.new(STDOUT) # This script will be launched as a systemd server.
  STDOUT.sync = true
  STDERR.sync = true
  # Fetch the environmental variable and convert it into log level.
  @@logger.level = case ENV["LOG_LEVEL"] # @为单个实例（半生不熟的概念，貌似是在不同的空间独立创建），@@为共享同一个
                      when nil # Default config.
                        Logger::Severity::DEBUG
                      when "debug"
                        Logger::Severity::DEBUG
                      when "info"
                        Logger::Severity::INFO
                      when "warn"
                        Logger::Severity::WARN
                      when "error"
                        Logger::Severity::ERROR
                      else
                        raise ArgumentError
                   end
  @@logger.progname = "MineSentinel"

  def self.record(level, module_name, message)
    case level
    when "info"
      @@logger.info("#{module_name}: #{message}")
    when "warn"
      @@logger.warn("#{module_name}: #{message}")
    when "error"
      @@logger.error("#{module_name}: #{message}")
    when "debug"
      @@logger.debug("#{module_name}: #{message}")
    else
      raise ArgumentError
    end
  end

  def self.reset_minecraft_server

    self.record("info", "reset", "Attempt ##{@@rst_counter + 1} to reset Minecraft server.")

    if @@rst_counter >= RST_COUNTS_LIMIT
      self.record("error", "reset",
                  "Tried #{RST_COUNTS_LIMIT} times and failed, now I'll idle until server is manually restarted.")
      while true
        sleep 10
        if ServerStatusDetector::MinecraftServer.self_diag[:type] == true
          self.record("info", "reset", "Server recovered! Resuming normal monitoring.")
          @@rst_counter = 0
          return
        end
      end
    end

    @@rst_counter += 1

      unless Process.euid == 0
        self.record("error", "reset", "Permission denied: root required to manage systemd services.")
        raise Errno::EPERM
      end

      self.record("info", "reset", "Spawning 'systemctl restart minecraft' (PID will be captured)...")
      pid = spawn "systemctl restart minecraft"
      self.record("debug", "reset", "systemctl restart spawned with PID #{pid}.")
      tick_beg = Time.now

      while true
        sleep 0.5
        begin
          SystemdNotifier.notify("WATCHDOG=1")
          proc_status = Process.waitpid2(pid, Process::WNOHANG)
        if proc_status # 子进程已退出，返回 [pid, status]
          _, status = proc_status
          elapsed = (Time.now - tick_beg).round(2)
          if status.success?
            self.record("info", "reset", "'systemctl restart' succeeded in #{elapsed}s.")
            @@rst_counter = 0 # 成功时重置计数器
            break
          else
            self.record("error", "reset", "'systemctl restart' failed with exitcode #{status.exitstatus} after #{elapsed}s.")
            break
          end
        else # 子进程仍在运行 (WNOHANG 返回 nil)
          if Time.now - tick_beg > PERSISTENCE_PERIOD then
            self.record("warn", "reset",
                        "'systemctl restart' timed out after #{PERSISTENCE_PERIOD}s. Force-killing PID #{pid}...")
            system "kill -9 #{pid}"
            self.record("warn", "reset", "Running 'systemctl kill minecraft' (last resort)...")
            system "systemctl kill minecraft" # 没招了，毁灭吧
            sleep 0.5
            self.record("info", "reset", "Running 'systemctl start minecraft' (rebirth)...")
            system "systemctl start minecraft" # 重生
            self.record("info", "reset", "Force-reset sequence completed.")
            break
          end
        end
        end
      end


  end

end