ForestAdmin/forest-rails

module ForestLiana
  class Base64StringIO < StringIO
    class ArgumentError < StandardError; end

    attr_accessor :file_format

    def initialize(encoded_file)
      description, encoded_bytes = encoded_file.split(",")

      raise ArgumentError unless encoded_bytes
      raise ArgumentError if encoded_bytes.eql?("(null)")

      @file_format = get_file_format description
      bytes = ::Base64.decode64 encoded_bytes

      super bytes
    end

    def original_filename
      File.basename("file.#{@file_format}")
    end

    private

    def get_file_format(description)
      regex = /([a-z0-9]+);base64\z/
      regex.match(description).try(:[], 1)
    end
  end
end