module Mindee::PDF::PDFCompressor

def self.compress_pdf(pdf_data, quality: 85, force_source_text_compression: false, disable_source_text: true)
  if PDFTools.source_text?(pdf_data)
    if force_source_text_compression
      if disable_source_text
        logger.warn('Re-writing PDF source-text is an EXPERIMENTAL feature.')
      else
        logger.warn('Source-file contains text, but disable_source_text flag is ignored. ' \
                    'Resulting file will not contain any embedded text.')
      end
    else
      logger.warn('Source-text detected in input PDF. Aborting operation.')
      return pdf_data
    end
  end
  pdf_data.rewind
  pdf = Origami::PDF.read(pdf_data)
  pages = process_pdf_pages(pdf, quality)
  output_pdf = create_output_pdf(pages, disable_source_text, pdf_data)
  output_stream = StringIO.new
  output_pdf.save(output_stream)
  output_stream
end

def self.create_output_pdf(pages, disable_source_text, pdf_data)
  output_pdf = Origami::PDF.new
  pages.rotate!(1) if pages.count >= 2
  inject_text(pdf_data, pages) unless disable_source_text
  pages.each { |page| output_pdf.append_page(page) }
  output_pdf
end

def self.inject_text(pdf_data, pages)
  reader = PDFReader::Reader.new(pdf_data)
  reader.pages.each_with_index do |original_page, index|
    break if index >= pages.length
    receiver = PDFReader::Reader::PageTextReceiver.new
    original_page.walk(receiver)
    receiver.runs.each do |text_run|
      x = text_run.origin.x
      y = text_run.origin.y
      text = text_run.text
      font_size = text_run.font_size
      content_stream = Origami::Stream.new
      content_stream.dictionary[:Filter] = :FlateDecode
      content_stream.data = "BT\n/F1 #{font_size} Tf\n#{x} #{y} Td\n(#{text}) Tj\nET\n"
      pages[index].Contents.data += content_stream.data
    end
  end
end

def self.process_pdf_page(page_stream, page_index, image_quality, media_box)
  new_page = Origami::Page.new
  compressed_image = Mindee::Image::ImageUtils.pdf_to_magick_image(page_stream, image_quality)
  width, height = Mindee::Image::ImageUtils.calculate_dimensions_from_media_box(compressed_image, media_box)
  compressed_xobject = PDF::PDFTools.create_xobject(compressed_image)
  PDF::PDFTools.set_xobject_properties(compressed_xobject, compressed_image)
  xobject_name = "X#{page_index + 1}"
  PDF::PDFTools.add_content_to_page(new_page, xobject_name, width, height)
  new_page.add_xobject(compressed_xobject, xobject_name)
  PDF::PDFTools.set_page_dimensions(new_page, width, height)
  new_page
end

def self.process_pdf_pages(pdf, quality)
  pdf.pages.map.with_index do |page, index|
    retrieved_page = Mindee::PDF::PDFProcessor.get_page(pdf, index)
    process_pdf_page(retrieved_page, index, quality, page[:MediaBox])
  end
end