# <<*>> -^v- SNOWARE APPLICATION
# usage: MINECRAFT Server monitoring.
# 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

module ServerStatusDetector
  require 'socket'
  require 'timeout'

  class TcpServer
    # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
    # @param host [String]
    # @param port [Integer]
    # @param timeout [Integer]
    # @return [Hash{Symbol=>Integer, Symbol=>Symbol, Symbol=>Float,nil}]
    def self.test_port(host = '127.0.0.1', port = 25_565, timeout = 10)
      result = {
        port: port,
        status: :unknown,
        response_time: nil
      }
      begin_time = Time.now
      # 带错误处理的代码需要使用 begin...end
      begin
        Timeout.timeout(timeout) do # 此方法接收整数和代码块作为参数，并在超时时引发错误
          socket = TCPSocket.new(host, port)
          result[:status] = :open
          result[:response_time] = (Time.now - begin_time).round(4)
          socket.close
        end
      rescue Timeout::Error
        result[:status] = :timeout
      rescue Errno::ECONNREFUSED
        result[:status] = :closed
      rescue Errno::ECONNRESET
        result[:status] = :interrupted
      rescue Errno::ENETUNREACH, Errno::EHOSTUNREACH
        result[:status] = :unreachable
      rescue StandardError => e
        result[:status] = :error
        result[:error] = e.message
      end

      result
    end
    # rubocop:enable Metrics/MethodLength, Metrics/AbcSize
  end

  # 继承为TcpServer编写的属性和方法
  class MinecraftServer < TcpServer
    # rubocop:disable Metrics/MethodLength
    # @return [Hash{Symbol=>Boolean, Symbol=>Array<String>, Symbol=>String}]
    def self_diag
      res = test_port('127.0.0.1', 25_565)

      unless res[:error].nil?
        message = "Unexpected ERROR when testing SMP by TCP: #{res[:status]},INFO: #{res[:error]}"
        puts message
        return {
          type: false,
          operation: %w[Record],
          message: message
        }
        # 立刻错误处理是好习惯
      end

      case res[:status]

      when :open
        MethodExecutor.record('debug', 'self_diag',
                              "TCP check OK — #{res[:response_time]}s")
        {
          type: true
        }
      when :timeout
        MethodExecutor.record('warn', 'self_diag',
                              'TCP check timed out.')
        {
          type: false,
          operation: %w[Record],
          message: 'We sent packet without response.'
        }
      when :closed
        MethodExecutor.record('warn', 'self_diag',
                              'TCP port closed — server is down.')
        {
          type: false,
          operation: %w[Record ForceResetServerProcess], # 重启时注意要设置最大尝试次数
          message: 'Server died for unknown reason, and will be restarted.'
        }
      else
        MethodExecutor.record('warn', 'self_diag',
                              "TCP check returned unexpected status: #{res[:status]}.")
        {
          type: false,
          operation: %w[Record],
          message: "Unexpected status: #{res[:status]}."
        }
      end
    end
    # rubocop:enable Metrics/MethodLength
  end
end