docuseal/lib/templates/process_document.rb

# frozen_string_literal: true

module Templates
  module ProcessDocument
    DPI = 200
    FORMAT = '.jpg'
    ATTACHMENT_NAME = 'preview_images'

    PDF_CONTENT_TYPE = 'application/pdf'
    Q = 35
    MAX_WIDTH = 1400
    MAX_NUMBER_OF_PAGES_PROCESSED = 15

    module_function

    def call(attachment, data)
      if attachment.content_type == PDF_CONTENT_TYPE
        generate_pdf_preview_images(attachment, data)
      elsif attachment.image?
        generate_preview_image(attachment, data)
      end

      attachment
    end

    def generate_preview_image(attachment, data)
      ActiveStorage::Attachment.where(name: ATTACHMENT_NAME, record: attachment).destroy_all

      image = Vips::Image.new_from_buffer(data, '')
      image = image.autorot.resize(MAX_WIDTH / image.width.to_f)

      io = StringIO.new(image.write_to_buffer(FORMAT, Q: Q, interlace: true))

      ActiveStorage::Attachment.create!(
        blob: ActiveStorage::Blob.create_and_upload!(
          io:, filename: "0#{FORMAT}",
          metadata: { analyzed: true, identified: true, width: image.width, height: image.height }
        ),
        name: ATTACHMENT_NAME,
        record: attachment
      )
    end

    def generate_pdf_preview_images(attachment, data)
      ActiveStorage::Attachment.where(name: ATTACHMENT_NAME, record: attachment).destroy_all
      number_of_pages = HexaPDF::Document.new(io: StringIO.new(data)).pages.size

      attachment.metadata['pdf'] ||= {}
      attachment.metadata['pdf']['number_of_pages'] = number_of_pages

      attachment.save!

      (0..[number_of_pages - 1, MAX_NUMBER_OF_PAGES_PROCESSED].min).each do |page_number|
        page = Vips::Image.new_from_buffer(data, '', dpi: DPI, page: page_number)
        page = page.resize(MAX_WIDTH / page.width.to_f)

        io = StringIO.new(page.write_to_buffer(FORMAT, Q: Q, interlace: true))

        ApplicationRecord.no_touching do
          ActiveStorage::Attachment.create!(
            blob: ActiveStorage::Blob.create_and_upload!(
              io:, filename: "#{page_number}#{FORMAT}",
              metadata: { analyzed: true, identified: true, width: page.width, height: page.height }
            ),
            name: ATTACHMENT_NAME,
            record: attachment
          )
        end
      end
    end

    def generate_pdf_preview_from_file(attachment, file_path, page_number)
      io = StringIO.new

      command = [
        'pdftocairo', '-jpeg', '-jpegopt', "progressive=y,quality=#{Q},optimize=y",
        '-scale-to-x', MAX_WIDTH, '-scale-to-y', '-1',
        '-r', DPI, '-f', page_number + 1, '-l', page_number + 1,
        '-singlefile', Shellwords.escape(file_path), '-'
      ].join(' ')

      Open3.popen3(command) do |_, stdout, _, _|
        io.write(stdout.read)

        io.rewind
      end

      page = Vips::Image.new_from_buffer(io.read, '')

      io.rewind

      ApplicationRecord.no_touching do
        ActiveStorage::Attachment.create!(
          blob: ActiveStorage::Blob.create_and_upload!(
            io:, filename: "#{page_number}#{FORMAT}",
            metadata: { analyzed: true, identified: true, width: page.width, height: page.height }
          ),
          name: ATTACHMENT_NAME,
          record: attachment
        )
      end
    end
  end
end