Smart Status - keep updated status attribute depending on datetime model's attribute

readme.md

Smart Status usage:

event = Event.create
event.status # nil

event.scheduled_at = Time.now
event.save! 
event.status # scheduled

event.started_at = Time.now
event.save! 
event.status # started

For those events created before adding smart status, there is 'force_update_status' which is setting up the first value

event = Event.find 1
event.finished_at # '2015-07-08 18:21:23'
event.status # nil, created before smart status
event.force_update_status
event.save # true
event.satus # finished

create_events.rb

class CreateEvent < ActiveRecord::Migration
  def change
    create_table :events do |t|
      t.string :status
      t.datetime :scheduled_at
      t.datetime :started_at
      t.datetime :finished_at
      t.datetime :canceled_at
      
      t.timestamps
    end
  end
end

event.rb

class Event < ActiveRecord::Base
  include SmartStatus
  
  attr_accessible :scheduled_at, :started_at, :finished_at, :canceled_at
  status :scheduled, :started, :finished, :canceled
end

smart_status.rb

require 'active_support/concern'

module SmartStatus
  extend ActiveSupport::Concern

  included do
    before_save :update_status
  end

  def force_update_status
    self.class.monitored_status.each do |status|
      if self.send("#{status}_at").present?
        self.send("status=", status)
      end
    end
  end

  def update_status
    self.class.monitored_status.each do |status|
      if self.send("#{status}_at_changed?")
        self.send("status=", status)
      end
    end
  end

  module ClassMethods
    def monitored_status
      @monitored_status ||= []
    end

    def status(*args)
      args.each do |arg|
        monitored_status << arg
      end
    end
  end
end