video.rb

# encoding: UTF-8
require "open-uri"

class Video < ActiveRecord::Base
  class YoutubeVideoValidator < ActiveModel::Validator
    def validate(record)
      unless record.youtube_code.include? 'youtube.com/watch?v='
        record.errors[:base] << "URL não é um endereço válido de um vídeo do youtube"
      end
    end
  end

  after_create :set_position
  before_save :youtube_code_from_url, :download_video_thumb

  has_friendly_id :name, :use_slug => true, :approximate_ascii => true
  acts_as_list

  has_one :image, :as => :assetable, :class_name => 'VideoImage', :dependent => :destroy
  has_one :thumb, :as => :assetable, :class_name => 'VideoThumb', :dependent => :destroy

  accepts_nested_attributes_for :image, :reject_if => lambda { |a| a[:attachment].blank? }, :allow_destroy => true
  accepts_nested_attributes_for :thumb, :reject_if => lambda { |a| a[:attachment].blank? }, :allow_destroy => true

  validates_presence_of :name
  validates_with YoutubeVideoValidator

  protected
    def set_position
      self.move_to_top
    end

    def youtube_code_from_url
      unless youtube_code.blank?
        self.youtube_code = youtube_code.split('?v=')[1]
        self.youtube_code = youtube_code.split('&')[0] if youtube_code.include? '&'
      end
    end

    def download_video_thumb
      unless youtube_code.blank?
        build_thumb if thumb.blank?
        io = open("http://img.youtube.com/vi/" + youtube_code + "/2.jpg")
        io.original_filename = "thumb.jpg"
        thumb.attachment = io
      end
    end
end