module SidekiqAlive

# File lib/sidekiq_alive.rb, line 91
def self.alive?
  redis.ttl(current_lifeness_key) != -2
end

# File lib/sidekiq_alive.rb, line 129
  def self.banner
    <<~BANNER

    =================== SidekiqAlive =================

    Hostname: #{hostname}
    Liveness key: #{current_lifeness_key}
    Port: #{config.port}
    Time to live: #{config.time_to_live}s
    Current instance register key: #{current_instance_register_key}
    Worker running on queue: #{@queue}


    starting ...
    BANNER
  end

# File lib/sidekiq_alive.rb, line 105
def self.config
  @config ||= SidekiqAlive::Config.instance
end

# File lib/sidekiq_alive.rb, line 77
def self.current_instance_register_key
  "#{config.registered_instance_key}::#{hostname}"
end

# File lib/sidekiq_alive.rb, line 109
def self.current_lifeness_key
  "#{config.liveness_key}::#{hostname}"
end

# File lib/sidekiq_alive.rb, line 39
def self.current_queue
  "#{config.queue_prefix}-#{hostname}"
end

# File lib/sidekiq_alive.rb, line 58
def self.deep_scan(keyword, keys = [], cursor = 0)
  next_cursor, found_keys = *redis { |r| r }.scan(cursor, match: keyword)
  keys += found_keys
  return keys if next_cursor == "0" || found_keys.blank?
  deep_scan(keyword, keys, next_cursor)
end

# File lib/sidekiq_alive.rb, line 113
def self.hostname
  ENV['HOSTNAME'] || 'HOSTNAME_NOT_SET'
end

# File lib/sidekiq_alive.rb, line 101
def self.logger
  Sidekiq.logger
end

# File lib/sidekiq_alive.rb, line 65
def self.purge_pending_jobs
  # TODO:
  # Sidekiq 6 allows better way to find scheduled jobs:
  # https://github.com/mperham/sidekiq/wiki/API#scan
  scheduled_set = Sidekiq::ScheduledSet.new
  jobs = scheduled_set.select { |job| job.klass == 'SidekiqAlive::Worker' && job.queue == current_queue }
  logger.info("[SidekiqAlive] Purging #{jobs.count} pending for #{hostname}")
  jobs.each(&:delete)
  logger.info("[SidekiqAlive] Removing queue #{current_queue}")
  Sidekiq::Queue.new(current_queue).clear
end

# File lib/sidekiq_alive.rb, line 87
def self.redis
  Sidekiq.redis { |r| r }
end

# File lib/sidekiq_alive.rb, line 43
def self.register_current_instance
  register_instance(current_instance_register_key)
end

# File lib/sidekiq_alive.rb, line 156
def self.register_instance(instance_name)
  redis.set(instance_name,
            Time.now.to_i,
            ex: config.registration_ttl.to_i)
end

# File lib/sidekiq_alive.rb, line 54
def self.registered_instances
  deep_scan("#{config.registered_instance_key}::*")
end

# File lib/sidekiq_alive.rb, line 97
def self.setup
  yield(config)
end

# File lib/sidekiq_alive.rb, line 117
  def self.shutdown_info
    <<~BANNER

    =================== Shutting down SidekiqAlive =================

    Hostname: #{hostname}
    Liveness key: #{current_lifeness_key}
    Current instance register key: #{current_instance_register_key}

    BANNER
  end

# File lib/sidekiq_alive.rb, line 8
def self.start
  SidekiqAlive::Worker.sidekiq_options queue: current_queue
  Sidekiq.configure_server do |sq_config|

    sq_config.options[:queues].unshift(current_queue)

    sq_config.on(:startup) do
      SidekiqAlive.tap do |sa|
        sa.logger.info(banner)
        sa.register_current_instance
        sa.store_alive_key
        sa::Worker.perform_async(hostname)
        @server_pid = fork do
          sa::Server.run!
        end
        sa.logger.info(successful_startup_text)
      end
    end

    sq_config.on(:quiet) do
      SidekiqAlive.unregister_current_instance
    end

    sq_config.on(:shutdown) do
      Process.kill('TERM', @server_pid) unless @server_pid.nil?
      Process.wait(@server_pid) unless @server_pid.nil?
      SidekiqAlive.unregister_current_instance
    end
  end
end

# File lib/sidekiq_alive.rb, line 81
def self.store_alive_key
  redis.set(current_lifeness_key,
            Time.now.to_i,
            ex: config.time_to_live.to_i)
end

# File lib/sidekiq_alive.rb, line 146
  def self.successful_startup_text
    <<~BANNER
    Registered instances:

    - #{registered_instances.join("\n\s\s- ")}

    =================== SidekiqAlive Ready! =================
    BANNER
  end

# File lib/sidekiq_alive.rb, line 47
def self.unregister_current_instance
  # Delete any pending jobs for this instance
  logger.info(shutdown_info)
  purge_pending_jobs
  redis.del(current_instance_register_key)
end