gistfile1.rb

require 'rubygems'
require 'eventmachine'
require 'dataflow'

# Experimenting with dataflow + EM
def do_pop_stuff
  pop_client = EventMachine::POP::POP3Client.new('pop.gmail.com', 995, true, 'username', 'password')
  print "stat: #{pop_client.stat}\n"
  pop_client.mails.each do |m|
    print m.raw + "\n"
  end
end


module EventMachine
  module POP
    class POPMail
      attr_accessor :uidl

      def initialize(number, client)
        @number = number
        @client = client
      end

      def header
        @client.header(@number)
      end

      def raw 
        @client.retr(@number)
      end
    end

    class POP3Connection < EM::Connection
      include Protocols::LineText2
      include Dataflow

      attr_accessor :username, :password, :guard

      def self.connect(host, port, ssl, username, password, guard)
        p "connecting"
        EM.connect(host, port, self) do |c|
          c.username = username
          c.password = password 
          c.guard = guard
        end
      end

      def post_init
        start_tls
        @responder = :login
        @mails = []
        p "post init"
      end
      
      def login
        p "logging in"
        send_data "USER #{username}\r\n"
        @responder = :receive_user
      end

      def receive_user
        send_data "PASS #{password}\r\n"
        @responder = :receive_auth_response
      end

      def receive_auth_response
        if @line.match(/\+OK/)
          unify @guard, ""
        else
          raise StandardError, "Could not authenticate"
        end
      end

      def send_data(data)
        p "send: #{data}"
        super
      end
      
      def receive_line(line)
        p "recv: #{line}"
        @line = line
        send @responder if @responder
      end

      def auth_guard
        @guard.object_id # force wait on variable
      end

      def send_command(command, *args)
        auth_guard

        @responder = "receive_#{command.downcase}"

        data = command
        data += " " + args.join(" ") unless args.empty?
        send_data "#{data}\r\n"

        @result = Dataflow::Variable.new
      end

      def stat
        p "sSTAT"
        send_command("STAT")
      end

      def receive_stat
        matches = @line.match(/\+OK (\d+) (\d+)/)
        unify @result, matches[1].to_i
      end

      def retr(number)
        @body = []
        send_command("RETR", number)
      end

      def receive_retr
        if @line =~ /^\+OK/
          # ignore
        elsif @line == "."
          unify @result, @body.join("\n")
        else
          @body << @line
        end
      end

      def header(number)
        send_command("TOP", number, 0)
      end

      def receive_header
        if @line =~ /^\+OK/
          # ignore
        elsif @line == "."
          unify @result, @header.join("\n")
        else
          @header << @line
        end
      end

      def mails
        @mail ||= send_command("UIDL")
      end

      def receive_uidl
        if @line == "."
          unify @result, @mails
        elsif @line == "+OK"
          # ignore
        else
          matches = @line.match(/(\d+) (.*)/)
          mail = POPMail.new(matches[1], self)
          mail.uidl = matches[2]
          @mails << mail
        end
      end

      def queue_command(*args)
      end

      def do_next_command
      end

      def need_raw_mails
      end

    end
    
    class POP3Client
      include Dataflow

      def initialize(*args)
        @connection = nil
        guard = Dataflow::Variable.new

        EM.next_tick {
          @connection = EventMachine::POP::POP3Connection.connect(*args.push(guard))
        }

        guard.object_id # wait until connection is complete
        @connection 
      end

      def method_missing(*args)
        @connection.send(*args)
      end
    end
  end
end

EM.run {

  Thread.abort_on_exception = true
  EM.defer { 
    do_pop_stuff 
  }

}