# Copyright (c) 2021 Contrast Security, Inc. See https://www.contrastsecurity.com/enduser-terms-0317a for more details.
# frozen_string_literal: true

require 'contrast/components/logger'

module Contrast
  module Api
    module Communication
      # Handles local service startup. As this should only ever be invoked by the Speedracer class, which includes
      # this, all methods here are private.
      module ServiceLifecycle
        include Contrast::Components::Logger::InstanceMethods

        private

        # Attempt to start up a local process with SpeedRacer. This will ensure the process isn't just a zombie and is
        # a real functioning process.
        #
        # @return [Boolean] Did the SpeedRacer process start?
        def attempt_local_service_startup
          zombie_check
          service_starter_thread.join(5)
          is_service_started = Contrast::Utils::OS.running?
          if is_service_started
            logger.info('The bundled service was successfully started.')
          else
            logger.error('The bundled service could not be started. The agent will not function properly.')
          end
          is_service_started
        end

        # Check if there's a zombie service that exists, and wait on it if so. Currently, this only happens when trying
        # to initialize SpeedRacer. If there is a zombie, we'll wait until the zombie completes.
        def zombie_check
          zombie_pid_list = Contrast::Utils::OS.zombie_pids
          zombie_pid_list.each do |pid|
            Process.wait(pid.to_i)
          rescue Errno::ECHILD => _e
            # Sometimes the zombie process dies between us finding it and killing it
          end
        end

        # Determine the options used to set up the SpeedRacer process. Specifically, this handles if we need to adjust
        # where the process needs to log.
        #
        # @return [Hash] options used to spawn the SpeedRacer process
        def determine_startup_options
          return { out: :out, err: :out } if ::Contrast::CONTRAST_SERVICE.logger_path == 'STDOUT'
          return { out: :err, err: :err } if ::Contrast::CONTRAST_SERVICE.logger_path == 'STDERR'

          { out: File::NULL, err: File::NULL }
        end

        # Create a new process for the SpeedRacer. This is a separate method so we can overwrite it globally in specs.
        def spawn_service
          options = determine_startup_options
          logger.debug('Spawning service')
          spawn 'contrast_service', options
        end

        # Create a thread to start the SpeedRacer, making calls to spawn until one starts successfully. As soon as the
        # SpeedRacer process starts, this thread terminates.
        def service_starter_thread
          Contrast::Agent::Thread.new do
            # Always check to see if it already started
            unless Contrast::Utils::OS.running?
              # Spawn the service process
              spawn_service
              # Block until service is running
              sleep(0.1) until Contrast::Utils::OS.running?
            end
          end
        end
      end
    end
  end
end