gistfile1.rb

class Photo < ActiveRecord::Base
  belongs_to :listing, :counter_cache => true

	scope :by_landlord, lambda {|landlord_id| joins(:listing).where('landlord_id = ?', landlord_id)}
	default_scope order('"photos"."index" ASC')

	attr_accessible :index, :image, :image_url, :image_processing
    attr_accessor :is_pre_listing

	validates_presence_of :listing_id, :unless => :is_pre_listing

	validate :validate_listing_photo_count, :unless => :is_pre_listing

	def validate_listing_photo_count
		errors[:base] << "This listing already has 9 photos" if listing.photos.length >= 9
	end

	after_save :cleanup_photo_indices, :unless => :is_pre_listing

	after_destroy :cleanup_photo_indices, :unless => :is_pre_listing

	def cleanup_photo_indices
		listing.photos.order(:index, 'created_at DESC').each_with_index do |p, i|
			p.update_column(:index, i)
		end
	end

	def image_url_for(size)
		"http://s3.amazonaws.com/#{S3_CREDENTIALS[:bucket]}/photos/#{id}/#{size}/#{image_file_name}"
	end

  # How to implement on Heroku with processing in the background
  # http://madeofcode.com/posts/42-paperclip-s3-delayed-job-in-rails

	has_attached_file :image,
		:styles => {
			:large => "640x960>",
			:small => "320x480>",
			:thumbnail => "160x240>",
			:feed => "550x380>"
			},
		:convert_options => { :all => '-auto-orient' },
		:storage => :s3,
		:s3_credentials => S3_CREDENTIALS,
		:s3_permissions => :public_read,
		:path => "photos/:id/:style/:filename"

	validates_attachment_presence :image
	before_validation :download_image

	def download_image
		if self.image_url.present? && new_record?
		puts "DOWNLOADING IMAGE", id
		  self.image = URI.parse(image_url)
		end
		true
	end

     # generate styles (downloads original first)
     def regenerate_styles!
       self.image.reprocess!
       self.update_column(:image_processing, false)
     end


  # cancel post-processing now, and set flag...
     before_image_post_process do |photo|
       if !photo.image_processing && photo.image_changed?
         photo.image_processing = true
         false # halts processing
       end
     end

     # call method from after_save that will be processed in the background
     after_save do
       if self.image_processing && self.image_changed?
         self.delay.regenerate_styles!
       end
     end


      def image_changed?
       image_file_size_changed? ||
       image_file_name_changed? ||
       image_content_type_changed? ||
       image_url_changed?
     end


     def calculate_dimensions
      self.image.reprocess!
      self.save
     end

end