Gemfile

source 'https://rubygems.org'
gem 'cinch', '< 1.2'

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    cinch (1.1.3)

PLATFORMS
  ruby

DEPENDENCIES
  cinch (< 1.2)

log_bot.rb

####################
### Dependencies ###
####################

require "optparse"

gem 'cinch', '< 1.2'
require "cinch"
require "cinch/logger/null_logger"

######################
### Option Parsing ###
######################

options = { channels:             [ ],
            debug:                false,
            nick:                 "#{ENV['USER']}s_log_bot",
            password:             nil,
            time_stamp_frequency: 5 }
ARGV.options do |opts|
  opts.banner = "Usage:  #{File.basename($PROGRAM_NAME)} [OPTIONS] CHANNELS"

  opts.separator ""
  opts.separator "Specific Options:"

  opts.on( "-d", "--[no-]debug",
           "Set to debug this bot." ) do |boolean|
    options[:debug] = boolean
  end
  opts.on( "-n", "--nick NICK", String,
           "The IRC nick to login with" ) do |nick|
    options[:nick] = nick
  end
  opts.on( "-p", "--password PASSWORD", String,
           "Set this to authenticate with NICKSERV." ) do |password|
    options[:password] = password
  end
  opts.on( "-t", "--time-stamp-frequency INT", Integer,
           "The delay between time stamps in minutes." ) do |minutes|
    options[:time_stamp_frequency] = minutes
  end

  opts.separator "Common Options:"

  opts.on( "-h", "--help",
           "Show this message." ) do
    puts opts
    exit
  end

  begin
    opts.parse!

    options[:channels].push(*ARGV)
    fail "You must list channels" if options[:channels].empty?
  rescue
    puts opts
    exit
  end
end

#############################
### Optional Dependencies ###
#############################

require "cinch/plugins/identify" if options[:password]

###############
### IRC Bot ###
###############

bot = Cinch::Bot.new do
  self.logger = Cinch::Logger::NullLogger.new unless options[:debug]

  configure do |c|
    c.server   = "irc.freenode.org"
    c.nick     = options[:nick]
    c.channels = options[:channels].map { |n| n.sub(/\A(?!#)/, "#") }

    if options[:password]
      c.plugins.plugins                           = [Cinch::Plugins::Identify]
      c.plugins.options[Cinch::Plugins::Identify] = {
        username: options[:nick],
        password: options[:password],
        type:     :nickserv
      }
    end

    @last_printed_time = nil
    @logs              = { }
  end

  on :channel do |message, _|
    if message.channel and message.user
      channel_name = message.channel.name
      message_time = Time.now

      day_of_message = message_time.strftime("%Y-%m-%d")
      if not @logs.include?(channel_name) or
        File.basename( @logs[channel_name].path,
                       ".log" ) !~ /-#{day_of_message}\z/
        @logs[channel_name].close if @logs[channel_name]
        clean_channel_name  = channel_name.sub(/\A#+/, "")
        log_file_name       = "#{clean_channel_name}-#{day_of_message}.log"
        @logs[channel_name] = open(log_file_name, "a")
        @last_printed_time  = nil
      end

      if @last_printed_time.nil? or
         message_time - @last_printed_time > options[:time_stamp_frequency] * 60
        @logs[channel_name].puts unless @last_printed_time.nil?
        @logs[channel_name].puts message_time.strftime("%Y-%m-%d %H:%M")
        @last_printed_time = message_time
      end
      @logs[channel_name].puts "#{message.user.nick}:  #{message.message}"
    end
  end
end

bot.start