#!/usr/bin/env ruby

require 'fileutils'

class Sidekiqctl
  DEFAULT_TIMEOUT = 10

  attr_reader :stage, :pidfile, :timeout

  def self.print_usage
    puts
    puts "Usage: #{File.basename($0)} <command> <pidfile> <timeout>"
    puts " where <command> is either 'quiet', 'stop' or 'shutdown'"
    puts "       <pidfile> is path to a pidfile"
    puts "       <timeout> is number of seconds to wait till Sidekiq exits (default: #{Sidekiqctl::DEFAULT_TIMEOUT})"
    puts
  end

  def initialize(stage, pidfile, timeout)
    @stage = stage
    @pidfile = pidfile
    @timeout = timeout

    done('No pidfile given', :error) if !pidfile
    done("Pidfile #{pidfile} does not exist", :warn) if !File.exist?(pidfile)
    done('Invalid pidfile content', :error) if pid == 0

    fetch_process

    begin
      send(stage)
    rescue NoMethodError
      done 'Invalid control command', :error
    end
  end

  def fetch_process
    Process.getpgid(pid)
  rescue Errno::ESRCH
    done "Process doesn't exist", :error
  end

  def done(msg, error = nil)
    puts msg
    exit(exit_signal(error))
  end

  def exit_signal(error)
    (error == :error) ? 1 : 0
  end

  def pid
    @pid ||= File.read(pidfile).to_i
  end

  def quiet
    `kill -USR1 #{pid}`
  end

  def stop
    `kill -TERM #{pid}`
    timeout.times do
      begin
        Process.getpgid(pid)
      rescue Errno::ESRCH
        FileUtils.rm_f pidfile
        done 'Sidekiq shut down gracefully.'
      end
      sleep 1
    end
    `kill -9 #{pid}`
    FileUtils.rm_f pidfile
    done 'Sidekiq shut down forcefully.'
  end

  def shutdown
    quiet
    stop
  end
end

if ARGV.length < 2
  Sidekiqctl.print_usage
else
  stage = ARGV[0]
  pidfile = ARGV[1]
  timeout = ARGV[2].to_i
  timeout = Sidekiqctl::DEFAULT_TIMEOUT if timeout == 0

  Sidekiqctl.new(stage, pidfile, timeout)
end