job.rb

class S3FileCopier < Struct.new(:model_file, :filepath, :bucket_name, :additional_transformations)
  def initialize(model_file, filepath, bucket_name, additional_transformations = [])
    super
  end

  def copy
    expected_file.write(transformed_file, content_encoding: :deflate)
  end
  handle_asynchronously :copy

  private

  def expected_file
    bucket.objects[model_file.path.gsub(/^\//, '')]
  end

  def transformed_file
    additional_transformations.reduce(original_file.read) do |file, transformer|
      transformer.apply(file)
    end
  end

  def original_file
    bucket.objects[original_file_path]
  end

  def bucket
    AWS.s3.buckets[bucket_name]
  end

  def original_file_path
    CGI.unescape(stripped_file_name)
  end

  def stripped_file_name
    filepath.gsub(/^\/#{bucket_name}\//, '')
  end
end

module NullFileTransformer
  def self.apply(data)
    data
  end
end

class ZlibFileTransformer
  def initialize(level)
    # Yes, this really does vary, we have a case where we can't use
    # BEST_COMPRESSION
    @level = level
  end

  def apply(data)
    Zlib.deflate(data, level)
  end
end

class BinaryFileConverter
  def initialize(json_format_verson = 3)
    @json_format_verson = json_format_version
  end

  def apply(json_string)
    # Lots of intense binary conversion!
  end
end

class ImageCompressor
  def apply(image_data)
    # Shells out to ImageMagick
  end
end

class CodeMinifier
  def initialize(whitelisted_method_names = [], include_block_arguments = true)
  end

  def apply(ruby_code)
    # You get the picture
  end
end