Simple global settings stored on Redis

settings.rb

# Redis persisted class to save global settings.
class Settings
  class << self
    SETTER_MATCHER = /=$/.freeze
    BOOLEAN_MATCHER = /\?$/.freeze
    def redis
      # TODO: use other redis instance?
      @redis ||= Redis.new(RedisConfig[:statistic_counter])
    end

    def method_missing(key, *args, &block)
      if key.to_s =~ SETTER_MATCHER
        redis.hset(namespace, key.to_s.gsub(SETTER_MATCHER, ''), *args)
        reload!
      elsif key.to_s =~ BOOLEAN_MATCHER
        key = key.to_s.gsub(BOOLEAN_MATCHER, '')
        ::Truth.true?(all[key])
      else
        all[key.to_s]
      end
    end

    def namespace
      'settings:members'.freeze
    end

    def all
      Rails.cache.fetch(cache_key, expires_in: 15.minutes) do
        redis.hgetall(namespace)
      end
    end

    def replace(settings_hash)
      redis.hmset(namespace, *settings_hash)
      reload!
    end

    def cache_key
      'global-settings'.freeze
    end

    def expire_cache
      Rails.cache.delete(cache_key)
    end

    def reload!
      expire_cache
      all
    end
  end
end

settings_spec.rb

require 'spec_helper'

describe Settings do
  it "behaves like a open struct" do
    Settings.hearts_count = 1
    Settings.hearts_count.should == "1"
  end

  it "gets the booleans value for keys ending with ?" do
    Settings.survey_active = true
    Settings.survey_active?.should == true
    Settings.survey_active = false
    Settings.survey_active?.should == false
  end

  describe "#all" do
    it "returns a hash with all the settings" do
      Settings.some_setting = "hello"
      Settings.another_setting = "world"
      Settings.all.should eql({"some_setting" => "hello", "another_setting" => "world"})
    end
  end

  describe "#replace" do
    it "replaces settings with a given hash" do
      Settings.some_setting = "hello"
      Settings.another_setting = "yeah"

      Settings.replace("some_setting" => "world", "another_setting" => "woot!")
      Settings.some_setting.should eql("world")
      Settings.another_setting.should eql("woot!")
    end
  end
end