sul-dlss/assembly-image

# frozen_string_literal: true

require 'assembly-objectfile'
require 'tempfile'
require 'English' # see https://github.com/rubocop-hq/rubocop/issues/1747 (not #MAGA related)
require 'active_support/core_ext/module/delegation'

module Assembly
  class Image < Assembly::ObjectFile
    # Creates jp2 derivatives
    class Jp2Creator
      # Create a JP2 file for the current image.
      # Important note: this will not work for multipage TIFFs.
      #
      # @return [Assembly::Image] object containing the generated JP2 file
      #
      # @param [Assembly::Image] the image file
      # @param [String] output path to the output JP2 file (default: mirrors the source file name and path, but with a .jp2 extension)
      # @param [Boolean] overwrite if set to false, an existing JP2 file with the same name won't be overwritten (default: false)
      # @param [Dir] tmp_folder the temporary folder to use when creating the jp2 (default: '/tmp'); also used by imagemagick
      #
      # Example:
      #   source_img = Assembly::Image.new('/input/path_to_file.tif')
      #   derivative_img = source_img.create_jp2(overwrite: true)
      #   puts derivative_img.mimetype # 'image/jp2'
      #   puts derivative_image.path # '/input/path_to_file.jp2'
      def self.create(image, **args)
        new(image, **args).create
      end

      def initialize(image, overwrite: false, output: image.jp2_filename, tmp_folder: Dir.tmpdir)
        @image = image
        @output_path = output
        @tmp_folder = tmp_folder
        @overwrite = overwrite
      end

      attr_reader :image, :output_path, :tmp_folder

      delegate :vips_image, to: :image

      # @return [Assembly::Image] object containing the generated JP2 file
      def create
        create_jp2_checks

        Dir.mktmpdir('assembly-image', tmp_folder) do |tmp_tiff_dir|
          tmp_tiff_path = File.join(tmp_tiff_dir, 'temp.tif')

          # KDUcompress doesn’t support arbitrary image types, so we make a temporary tiff
          make_tmp_tiff(tmp_tiff_path)
          make_jp2(tmp_tiff_path)
        end

        # create output response object, which is an Assembly::Image type object
        Image.new(output_path)
      end

      private

      def overwrite?
        @overwrite
      end

      def jp2_create_command(source_path:, output:)
        options = []
        # CMYK becomes sRGB in make_tmp_tiff, so jp2_space option will be set for sRGB and CMYK
        #   TODO: we're not sure at this time what happens for grayscale (or what Tony C. wants for grayscale)
        #   see https://github.com/sul-dlss/assembly-image/issues/98
        options << '-jp2_space sRGB' if image.srgb?
        options += KDU_COMPRESS_DEFAULT_OPTIONS
        options << "Clayers=#{layers}"
        "kdu_compress #{options.join(' ')} -i '#{source_path}' -o '#{output}' 2>&1"
      end

      # Get the number of JP2 layers to generate
      def layers
        pixdem = [image.width, image.height].max
        ((Math.log(pixdem) / Math.log(2)) - (Math.log(96) / Math.log(2))).ceil + 1
      end

      KDU_COMPRESS_DEFAULT_OPTIONS = [
        '-num_threads 2', # forces Kakadu to only use 2 threads
        '-quiet', # suppress informative messages.
        'Creversible=no', # Disable reversible compression
        'Corder=RPCL', # R=resolution P=position C=component L=layer
        'Cblk=\\{64,64\\}', # code-block dimensions; 64x64 happens to also be the default
        'Cprecincts=\\{256,256\\},\\{256,256\\},\\{128,128\\}', # Precinct dimensions; 256x256 for the 2 highest resolution levels, defaults to 128x128 for the rest
        '-rate -', # Ratio of compressed bits to the image size
        'Clevels=5' # Number of wavelet decomposition levels, or stages
      ].freeze

      # rubocop:disable Metrics/AbcSize
      # rubocop:disable Metrics/CyclomaticComplexity
      def create_jp2_checks
        raise "tmp_folder #{tmp_folder} does not exist" unless File.exist?(tmp_folder)

        image.send(:check_for_file)
        raise 'input file is not a valid image, or is the wrong mimetype' unless image.jp2able?

        raise SecurityError, "output #{output_path} exists, cannot overwrite" if !overwrite? && File.exist?(output_path)
        raise SecurityError, 'cannot recreate jp2 over itself' if overwrite? && image.mimetype == 'image/jp2' && output_path == image.path
      end
      # rubocop:enable Metrics/AbcSize
      # rubocop:enable Metrics/CyclomaticComplexity

      # We do this because we need to reliably compress the tiff and KDUcompress doesn’t support arbitrary image types
      def make_tmp_tiff(tmp_tiff_path)
        tmp_tiff_image = if vips_image.interpretation.eql?(:cmyk)
                           vips_image.icc_transform(SRGB_ICC, input_profile: CMYK_ICC)
                         elsif image.has_profile?
                           vips_image.icc_transform(SRGB_ICC, embedded: true)
                         else
                           vips_image
                         end

        tmp_tiff_image.tiffsave(tmp_tiff_path, bigtiff: true) # Use bigtiff so we can support images > 4GB

        # For troublshooting JP2 creation problems. See https://github.com/sul-dlss/common-accessioning/issues/1079
        raise "Temp tiff files #{tmp_tiff_path} does not exist" unless File.exist?(tmp_tiff_path)
      end

      def make_jp2(tmp_tiff_path)
        jp2_command = jp2_create_command(source_path: tmp_tiff_path, output: output_path)
        result = `#{jp2_command}`
        return if $CHILD_STATUS.success?

        # Clean up any partial result
        FileUtils.rm_rf(output_path)
        raise "JP2 creation command failed: #{jp2_command} with result #{result}"
      end
    end
  end
end