gistfile1.rb

require 'yaml'

require 'rubygems'
gem 'twitter'
require 'twitter'

class AutoRetweet
  def initialize search_phrase, config_file_name = 'config.yml'
    @phrase = search_phrase
    @config_file = config_file_name
    @config = YAML.load(File.read(config_file_name))
  end

  def get_min_id
    @config[:min_id]
  end

  def set_min_id id
    old_id = @config[:min_id] || 0
    return unless id > old_id
    @config[:min_id] = id
    File.open(@config_file, 'w'){|f| f.write(@config.to_yaml)}
  end

  def search
    results = Twitter::Search.new.contains(@phrase).fetch.results
    results.each do |r|
      reply(r) unless r.from_user == @config[:username]
      set_min_id(r.id)
    end
  end

  def reply msg
    auth = Twitter::HTTPAuth.new(@config[:username], @config[:password])
    client = Twitter::Base.new(auth)

    header = "RT @#{msg.from_user}: "
    len = header.length

    m = msg.text
    if m.length + len > 120
      m= m[0, 120 - len - 3]
      m= "#{header}#{m}..."
    else
      m= "#{header}#{m}"
    end

    client.update(m, {:in_reply_to_status_id => msg.id})
  end
end

config = YAML.load(File.read('config.yml'))
s = AutoRetweet.new(config[:retweet_search])

while true
  s.search
  sleep(30 * 60 * 60)
end