impress/app/models/outfit.rb

class Outfit < ActiveRecord::Base
  has_many :item_outfit_relationships, :dependent => :destroy
  has_many :worn_item_outfit_relationships, :class_name => 'ItemOutfitRelationship',
    :conditions => {:is_worn => true}
  has_many :worn_items, :through => :worn_item_outfit_relationships, :source => :item
  belongs_to :pet_state
  belongs_to :user

  validates :name, :presence => {:if => :user_id}, :uniqueness => {:scope => :user_id, :if => :user_id}
  validates :pet_state, :presence => true

  attr_accessible :name, :pet_state_id, :starred, :worn_and_unworn_item_ids

  scope :wardrobe_order, order('starred DESC', :name)
  
  mount_uploader :image, OutfitImageUploader
  
  after_commit :enqueue_image!

  def as_json(more_options={})
    serializable_hash :only => [:id, :name, :pet_state_id, :starred],
      :methods => [:color_id, :species_id, :worn_and_unworn_item_ids,
                   :image_versions]
  end
  
  def image_versions
    {}.tap do |versions|
      versions[:large] = image.url
      image.versions.each { |name, version| versions[name] = version.url }
    end
  end

  def closet_item_ids
    item_outfit_relationships.map(&:item_id)
  end

  def color_id
    pet_state.pet_type.color_id
  end

  def species_id
    pet_state.pet_type.species_id
  end

  def to_query
    {
      :closet => closet_item_ids,
      :color => color_id,
      :objects => worn_item_ids,
      :species => species_id,
      :state => pet_state_id
    }.to_query
  end

  def worn_and_unworn_item_ids
    {:worn => [], :unworn => []}.tap do |output|
      item_outfit_relationships.each do |rel|
        key = rel.is_worn? ? :worn : :unworn
        output[key] << rel.item_id
      end
    end
  end

  def worn_and_unworn_item_ids=(all_item_ids)
    new_rels = []
    all_item_ids.each do |key, item_ids|
      worn = key == 'worn'
      unless item_ids.blank?
        item_ids.each do |item_id|
          rel = ItemOutfitRelationship.new
          rel.item_id = item_id
          rel.is_worn = worn
          new_rels << rel
        end
      end
    end
    self.item_outfit_relationships = new_rels
  end
  
  # Returns the array of SwfAssets representing each layer of the output image,
  # ordered from bottom to top. Careful: this method is memoized, so if the
  # image layers change after its first call we'll get bad results.
  def image_layers
    @image_layers ||= visible_assets_with_images.sort { |a, b| a.zone.depth <=> b.zone.depth }
  end
  
  # Creates and writes the thumbnail images for this outfit iff the new image
  # would be different than the current one. (Writes to file in development,
  # S3 in production.) If the image is updated, updates the image layers hash
  # and runs #save! on the record, so any other changes will also be saved.
  def write_image!
    if image_layers_dirty?
      Tempfile.open(['outfit_image', '.png']) do |image|
        create_image! image
        self.image_layers_hash = generate_image_layers_hash
        self.image = image
        save!
      end
    end
    
    self.image
  end
  
  # Enqueue an image write iff the new image would be different than the
  # current one.
  def enqueue_image!
    Resque.enqueue(OutfitImageUpdate, id) if image_layers_dirty?
  end
  
  def s3_key(size)
    URI.encode("#{id}/#{size.join 'x'}.png")
  end

  def self.build_for_user(user, params)
    Outfit.new.tap do |outfit|
      name = params.delete(:name)
      starred = params.delete(:starred)
      anonymous = params.delete(:anonymous) == "true"
      if user && !anonymous
        outfit.user = user
        outfit.name = name
        outfit.starred = starred
      end
      outfit.attributes = params
    end
  end
  
  protected
  
  # Creates a 600x600 PNG image of this outfit, writing to the given output
  # file.
  def create_image!(output)
    unless image_layers.empty?
      base_layer = image_layers.first
      above_layers = image_layers[1..-1]
      write_temp_swf_asset_image!(base_layer, output)
      output.close

      unless above_layers.empty?
        Tempfile.open(['outfit_overlay', '.png']) do |overlay|
          above_layers.each do |layer|
            overlay.open
            write_temp_swf_asset_image! layer, overlay
            overlay.close
            
            previous_image = MiniMagick::Image.open(output.path)
            overlay_image = MiniMagick::Image.open(overlay.path)
            output_image = previous_image.composite(overlay_image)
            output_image.write output.path
          end
        end
      end
    else
      output.close
    end
  end
  
  def visible_assets
    biology_assets = pet_state.swf_assets
    object_assets = SwfAsset.object_assets.
      fitting_body_id(pet_state.pet_type.body_id).for_item_ids(worn_item_ids)
    
    # Now for fun with bitmasks! Rather than building a bunch of integer arrays
    # here, we instead go low-level and use bit-level operations. Build the
    # bitmask by parsing the binary string (reversing it to get the lower zone
    # numbers on the right), then OR them all together to get the mask
    # representing all the restricted zones. (Note to self: why not just store
    # in this format in the first place?)
    restrictors = biology_assets + worn_items
    restricted_zones_mask = restrictors.inject(0) do |mask, restrictor|
      mask | restrictor.zones_restrict.reverse.to_i(2)
    end
    
    # Now, check each asset's zone is not restricted in the bitmask using
    # bitwise operations: shift 1 to the zone_id position, then AND it with
    # the restricted zones mask. If we get 0, then the bit for that zone ID was
    # not turned on, so the zone is not restricted and this asset is visible.
    all_assets = biology_assets + object_assets
    all_assets.select { |a| (1 << (a.zone_id - 1)) & restricted_zones_mask == 0 }
  end
  
  def visible_assets_with_images
    visible_assets.select(&:has_image?)
  end
  
  # Generate 8-char hex digest representing visible image layers for this outfit.
  # Hash function should be decently collision-resistant.
  def generate_image_layers_hash
    @generated_image_layers_hash ||=
      Digest::MD5.hexdigest(image_layers.map(&:id).join(',')).first(8)
  end
  
  def image_layers_dirty?
    generate_image_layers_hash != self.image_layers_hash
  end
  
  IMAGE_BASE_SIZE = [600, 600]
  def write_temp_swf_asset_image!(swf_asset, file)
    key = swf_asset.s3_key(IMAGE_BASE_SIZE)
    bucket = SwfAsset::IMAGE_BUCKET
    data = bucket.get(key)
    file.binmode # write in binary mode
    file.truncate(0) # clear the file
    file.write data # write the new data
  end
end