module Daemonic
  class Worker
    include Logging

    attr_reader :index, :config

    def initialize(options)
      @index        = options.fetch(:index)
      @config       = options.fetch(:config)
    end

    def start
      @pid = Process.spawn(
        {"DAEMON_WORKER_NUMBER" => index.to_s},
        *Array(config.command),
        {:chdir => config.working_dir}
      )
      sleep 0.1
      info "#{to_s} Starting."
      pidfile.write
      wait_for { running? }
      info "#{to_s} Started!"
    end

    def stop
      Process.kill("TERM", pid)
      info "#{to_s} Stopping."
      Process.waitpid(pid)
    rescue Errno::ECHILD, Errno::ESRCH
      warn "#{to_s} Already stopped."
    ensure
      pidfile.clean
      @pid = nil
    end

    def restart
      info "#{to_s} Restarting."
      stop
      start
    end

    def hup
      Process.kill("HUP", pid)
    end

    def monitor
      if not running?
        warn "#{to_s} Not running."
        start
      end
    end

    def running?
      if @pid
        !Process.waitpid(pid, Process::WNOHANG) rescue false
      else
        false
      end
    end

    private

    def pid
      @pid || raise("unknown pid")
    end

    def pidfile
      Pidfile.new(
        pid:       pid,
        config:    config,
        index:     index,
      )
    end

    def wait_for(timeout=2)
      deadline = Time.now + timeout
      until Time.now >= deadline
        result = yield
        if result
          return
        else
          sleep 0.1
        end
      end
      warn "#{to_s} It took too long to start."
    end

    def to_s
      "<Worker:#{index} pid:#{@pid.inspect} running:#{running?.inspect}>"
    end

  end
end