panter/carrierwave-base64_image_content

# frozen_string_literal: true

# initially taken from
# https://github.com/lebedev-yury/carrierwave-base64/blob/master/lib/carrierwave/base64/base64_string_io.rb
module CarrierWave
  module Base64ImageContent
    class Base64StringIO < StringIO
      class ArgumentError < StandardError; end

      attr_accessor :file_format, :file_name

      # @param [String] encoded_file e.g.
      #   "data:image/jpg;base64,/9j/4AAQSkZJRgABAQEASABKdhH//2Q=="
      def initialize(encoded_file)
        description, encoded_bytes = encoded_file.split(',')

        raise ArgumentError unless encoded_bytes
        raise ArgumentError if encoded_bytes == '(null)'

        @file_name = Digest::SHA256.hexdigest(encoded_file)
        @file_format = get_file_format(description)
        bytes = Base64.strict_decode64(encoded_bytes)

        super(bytes)
      end

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

      private

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