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A (very) simple chat service using MQTT
require "rubygems"
require "ncurses"
require 'mqtt/client'
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)
mqtt = MQTT::Client.new('localhost')
mqtt.connect do |client|
client.subscribe('chat/public')
client.subscribe('chat/system')
client.subscribe("chat/private/#{nickname}")
client.publish 'chat/public', "** #{nickname} enter"
Thread.new do
gui.run do |message|
case message
when /^\/quit\s*(.*)/
client.publish 'chat/public', "** #{nickname} has quit (#{$1})"
client.disconnect
gui.quit
exit 1
when /^\/privmsg\s*([^\s]*)\s*(.*)/
client.publish "chat/private/#{$1}", ">> [#{Time.now.strftime('%H:%M:%S')}] #{nickname} : #{$2}"
client.publish "chat/private/#{nickname}", ">> [#{Time.now.strftime('%H:%M:%S')}] #{nickname} : #{$2}"
when /^\/who/
client.publish "chat/system", nickname
when /^\/help/
help gui
else
client.publish 'chat/public', "[#{Time.now.strftime('%H:%M:%S')}] #{nickname} : #{message}"
end
end
end
loop do
topic,message = client.get
if topic =~ /chat\/system/
client.publish "chat/private/#{message}", "-- #{nickname} is here"
else
gui.add_message message
end
end
end

Run

  1. Install and run an MQTT server (mosquitto is a good choise)

  2. Install mqtt and ncurses-ruby gems

    sudo gem install ruby-mqtt ncurses-ruby

  3. Run the client

    ruby ./mqtt-chat.rb

FYI I made a number of changes to this and have committed to a new repo on Github andypiper/mqtt-chat@aa66df7

This makes the code work with the current version of the ruby-mqtt gem and adds a nicer exit handler as well as improving docs.

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