Fiddled-together IRC - Discord bridge bot

cord.ls

# Fiddled-together IRC - Discord bridge bot
# Currently set up to relay messages to channels of the same name.
# Discord APIs are very likely to change, and so this will probably break.

require! {
  irc                     # npm install node-irc
  "discord.js": Discord   # npm install discord.js
  "prelude-ls": { find }  # npm install prelude-ls
  "./auth" # Configuration goes in auth.json file
           # auth.irc contains IRC information, see clientIrc
           # auth.discord contains "email" and "password" field
}

messageLimit = 200
String.prototype.limit = (repl) ->
  if @length > messageLimit
    then "#{@substr 0, messageLimit - 4} #{repl or '...'}"
    else @

String.prototype.splice = (index, count, str) ->
  "#{@slice 0, index}#str#{@slice index + count}"


# See here for options that may be contained in auth.irc:
#   autoConnect MUST be set to false. I've seen strange
#   things happen if connect is called a second time.
# https://node-irc.readthedocs.org/en/latest/API.html#client
clientIrc = new irc.Client auth.irc.server, auth.irc.nick, auth.irc

clientIrc.on \registered, !->
  # IRC client has no "disconnect" event, so we have to make do with this.
  # (clientIrc.conn is not initialized until clientItc.connect is called.)
  clientIrc.conn.on \close, !->
    console.log "[= IRC =] Sir, they spotted us, I have to kill the connection!"
  
  console.log "[= IRC =] We hacked into their mainframes, sir!"
  
  # Identify with nickserv. This requires the account to be set up already.
  clientIrc.say "NickServ", "IDENTIFY #auth.irc.password" if auth.irc.password

clientIrc.on \message#, (nick, channel, message) !->
  response = "<#nick> #{message.limit!}"
  console.log "[= IRC =] [#channel] #response"
  clientDiscord.sendToChannel channel, response

clientIrc.on \action, (nick, channel, message) !->
  # Ignore actions not sent channel a channel.
  if !channel.startsWith "#" then return
  response = "\\* #nick *#{message.limit!}*"
  clientDiscord.sendToChannel channel, response

clientDiscord = new Discord.Client!

clientDiscord.sendToChannel = (channelName, message, callback) !->
  # Find the Discord channel with a matching name, or don't send it.
  channel = clientDiscord.channels |> find (ch) -> "##{ch.name}" == channelName
  clientDiscord.sendMessage channel, message, callback if channel

clientDiscord.on \ready, !->
  console.log "[Discord] Ready to serve, copy-sensei."

clientDiscord.on \disconnected, !->
  console.log "[Discord] I have failed you, copy-sensei..."

clientDiscord.on \message, (msg) !->
  # You receive message events from your own sent messages, so ignore those.
  if msg.author.id == clientDiscord.user.id then return
  # Only relay messages to channels that the bot is actually in.
  if !("##{msg.channel.name}" of clientIrc.chans) then return
  
  from = msg.author.username
  text = msg.content
  
  # Replace user mentions (<@long-ass user id>) with actual user name (@username).
  # TODO: Do the same for #channel "mentions" (currently displays <#long-ass channel id>)
  for user in msg.mentions
    text .= replace (new RegExp "<@#{user.id}>", "g"), "@#{user.username}"
  
  # Format message differently if it seems to be a message generated by /me:
  # Needs to start and end with a *, no *'s in the message itself, so
  # "*this* is *bullshit*" or "*this *is* bullshit* don't count.
  response = if /^\*[^\*]+\*$/g.test text
    "* #from #{text.substr 1, text.length - 2 .limit!}"
  else "<#from> #{text.limit!}"
  
  console.log "[Discord] [##{msg.channel.name}] #response"
  # Insert zero-width space in name to avoid
  # highlighting IRC users with the same name.
  # Because lazyness, this only works for 3+ char nicks.
  response .= splice 3, 0, "\u200B"
  clientIrc.say "##{msg.channel.name}", response

clientIrc.connect 0  # retryCount = 0
clientDiscord.login auth.discord.email, auth.discord.password


exitHandler = !->
  # Wait for both clients to disconnect.
  num = 0
  onLogout = !->
    if ++num >= 2
      process.exit!
  
  clientIrc.disconnect "I have been terminated T_T", onLogout
  clientDiscord.logout onLogout

process.on \exit, exitHandler
process.on \SIGINT, exitHandler  # ctrl-c