extensible IRC bot (requires suckless.org sic)

plugbot.rb

#!/usr/bin/env ruby
# vim:sw=2

# IRC bot (requires suckless.org sic).

# Each executable file in the current directory is treated as a command
# plugin for the bot, and is executed when a command corresponding to its
# filename is called. For example, a plugin with filename "greet" would be
# invoked via the command "!greet".

# The plugin is passed the channel, nick, and message of its invocation as
# 3 positional arguments. Any line printed to standard output by the plugin
# is forwarded to the channel of the invoking message.

require 'optparse'
require 'shellwords'

OPTIONS, CHANNELS = begin
  options, channels = [], []

  OptionParser.new do |opts|
    opts.on('-s', '--server <server>',
            'Overrides the default server') { |serv| options << '-h' << serv }
    
    opts.on('-p', '--port <port>', Integer,
            'Overrides the default port') { |port| options << '-p' << port }

    opts.on('-n', '--nick <nick>',
            'Override the default nick') { |nick| options << '-n' << nick }

    opts.on('-k', '--keyword <keyword>',
            'Specifies the keyword to authenticate your',
            'nick on the host') { |keyword| options << '-k' << keyword }

    opts.on('-c', '--channels <channels>',
            'Comma-separated list of channels to join') do |list|
      channels = list.split(',')
    end
  end.parse!

  [options.freeze, channels.freeze]
end

def join_channels(subprocess)
  subprocess.each_line do |line|
    if line.include? ' >< MODE ('
      CHANNELS.each { |chan| subprocess.write(":j ##{chan}\n") }
      subprocess.flush
      break
    end
  end
end

def run_plugin(subprocess, plugin, channel, nick, msg)
  args = [plugin, channel, nick, msg].map { |arg| arg.shellescape }
  IO.popen(args.join(' ')) do |plugin|
    plugin.each_line do |line|
      target = channel[0] == '#' ? channel : nick
      subprocess.write(":m #{target} #{line}")
      subprocess.flush
    end
  end
end

def loop_input(subprocess)
  subprocess.each_line do |line|
    begin
      line_match = /(\S+).+<(.+?)> (.+)/.match(line)
    rescue ArgumentError
      next
    end
    if line_match
      channel, nick, msg = line_match[1, 3]
      cmd, args = msg.split(' ', 2)
      args = '' if not args
      /^\W(.+)/.match(cmd) do |cmd_match|
        files = Dir.glob(cmd_match[1]).select do |file|
          File.executable? file and not File.directory? file
        end
        files.each do |plugin|
          Thread.new do
            run_plugin(subprocess, './' + plugin, channel, nick, args)
          end
        end
      end
    end
  end
end

if fork
  exit!
end

IO.popen("sic #{OPTIONS.join(' ')}", 'w+') do |subprocess|
  join_channels(subprocess)
  loop_input(subprocess)
end