A (very) simple chat service using AMQP

README.md

Run

1. Install and run an AMQP server (RabbitMQ is a good choise)

2. Install amqp and ncurses-ruby gems

   sudo gem install amqp ncurses-ruby

3. Run the client

   ruby ./amqp-chat.rb

amqp-chat.rb

require "rubygems"
require "ncurses"
require "amqp"

class ChatGui
   def read_line(y, x,
                 window     = Ncurses.stdscr,
                 max_len    = (window.getmaxx - x - 1), 
                 string     = "", 
                 cursor_pos = 0)
      loop do
         window.mvaddstr(y,x,string)
         window.move(y,x+cursor_pos)
         ch = window.getch
         case ch
         when Ncurses::KEY_ENTER, ?\n.ord, ?\r.ord
            return string
         when Ncurses::KEY_BACKSPACE, 127 
            string = string[0...([0, cursor_pos-1].max)] + string[cursor_pos..-1]
            cursor_pos = [0, cursor_pos-1].max
            window.mvaddstr(y, x+string.length, " ")
         when (" "[0].ord..255)
            if (cursor_pos < max_len)
               string[cursor_pos,0] = ch.chr
               cursor_pos += 1
            else
               Ncurses.beep
            end 
         else
            Ncurses.beep
         end 
      end 
   end 

   def add_message(message)
      @messages += message.split("\n")
      if @messages.size > @max_messages
         @messages.shift
      end

      refresh_messages_window
   end

   def refresh_messages_window
      @messages_window.clear
      y = 0
      @messages.each do |message|
         @messages_window.mvaddstr(y, 0, message)
         y = y + 1
      end
      @messages_window.refresh
   end

   def initialize(nick)
      @messages = []
      Ncurses.initscr
      Ncurses.cbreak
      Ncurses.noecho
      Ncurses.keypad(Ncurses.stdscr, true)

      @window = Ncurses.stdscr
      @maxy = @window.getmaxy - 1
      @maxx = @window.getmaxx - 1

      @prompt_window = Ncurses.newwin(2, @maxx, @maxy - 2, 0)
      @prompt = "#{nick} >"

      @messages_window = Ncurses.newwin(@maxy - 2, @maxx, 0, 0)
      @max_messages = @messages_window.getmaxy
   end

   def run(&b)
      loop do
         # refresh_messages_window

         @prompt_window.mvaddstr(0, 0, "-"*@maxx)
         @prompt_window.mvaddstr(1, 0, @prompt)
         message = read_line(1, @prompt.length + 1, @prompt_window)
         yield message
         @prompt_window.clear
      end
   end

   def quit
      Ncurses.endwin
   end
end

# -- main --

def help(gui)
   gui.add_message <<EOH
   /help : display this help
   /me <message> : send an action message
   /privmsg <nickname> <message> : send a private message
   /quit : Quit AMQP chat
   /who : ask who is here
EOH
end

nickname = ARGV[0]
raise "Usage : #{$0} <nickname>" if nickname.nil?

gui = ChatGui.new(nickname)

AMQP.start("amqp://localhost") do |connection|
   channel  = AMQP::Channel.new(connection)
   exchange = channel.headers("amqp.chat.v3")

   public_queue = channel.queue("public.#{nickname}", :auto_delete => true)
   public_queue.bind(exchange, :arguments => { :type => 'public' }).subscribe do |headers, payload|
      gui.add_message payload.to_s
   end
   private_queue = channel.queue("private.#{nickname}", :auto_delete => true)
   private_queue.bind(exchange, :arguments => { :type => 'private', :nick => nickname }).subscribe do |headers, payload|
      gui.add_message payload.to_s
   end
   system_queue = channel.queue("system.#{nickname}", :auto_delete => true)
   system_queue.bind(exchange, :arguments => { :type => 'system' }).subscribe do |headers, payload|
      exchange.publish "-- #{nickname} is here", :headers => {:type => 'private', :nick => payload.to_s}
   end

   exchange.publish "** #{nickname} enter", :headers => {:type => 'public'}

   Thread.new do
      gui.run do |message|
         case message
         when /^\/quit\s*(.*)/
            exchange.publish "** #{nickname} has quit (#{$1})", :headers => {:type => 'public'}
            connection.close {
               EventMachine.stop
            }
            break
         when /^\/me\s*(.*)/
            exchange.publish "** #{nickname} #{$1}", :headers => {:type => "public"}
         when /^\/privmsg\s*([^\s]*)\s*(.*)/
            exchange.publish ">> [#{Time.now.strftime('%H:%M:%S')}] #{nickname} : #{$2}", :headers => {:type => 'private', :nick => $1}
            exchange.publish ">> [#{Time.now.strftime('%H:%M:%S')}] #{nickname} : #{$2}", :headers => {:type => 'private', :nick => nickname}
         when /^\/who/
            exchange.publish nickname, :headers => {:type => "system"}
         when /^\/help/
            help gui
         else
            exchange.publish "[#{Time.now.strftime('%H:%M:%S')}] #{nickname} : #{message}", :headers => {:type => 'public'}
         end
      end
   end
end

gui.quit