cobot.rb

require 'net/http'
require 'base64'
require 'cgi'
require 'json'

class CoBot
  HEADERS = {
    'Accept'        => 'application/json',
    'Content-Type'  => 'application/json; charset=utf-8',
    'User-Agent'    => 'Harvest Twitter Script' }

  def initialize(group_id, group_key)
    @group_id = group_id
    @group_key = group_key
    @connection = Net::HTTP.new("coopapp.com", 80)
    @connection.open_timeout = 10
  end

  def post(message, message_src)
    message_src_pattern = /#{Regexp.escape(message_src)}$/
    unless statuses.any?{|m| message_src_pattern =~ m}
      status = "#{message}<br />Source: #{message_src}"
      @connection.post("/groups/#{@group_id}/notes", {:status => status, :key => @group_key}.to_json, HEADERS)
      statuses << status
    end
  end

  private

  def statuses
    @statuses ||= retrieve_statuses
  end

  def retrieve_statuses
    response = @connection.get("/groups/#{@group_id}/users/cobot?key=#{@group_key}", HEADERS)
    JSON.parse(response.body).map{|s| s['text']}
  end
end

cobot_twitter.rb

#!/usr/bin/env ruby
$KCODE = 'U'

require 'rubygems'
require 'twitter'
require 'cobot'

MAX_TWEETS = 3

cobot = CoBot.new(<group_id>, <group_secret>)

%w{mobalean kanjidamage keitai-dev}.each do |keyword|
  Twitter::Search.new(keyword).per_page(MAX_TWEETS).each do |r|
    cobot.post("@#{r['from_user']} mentioned #{keyword}: \"#{r['text']}\"", 
      "http://twitter.com/#{r['from_user']}/status/#{r['id']}")
  end
end