require "fileutils"
require "pathname"
require "tempfile"
require "base64"
require "marcel"

module ReverseAdoc
  module Converters
    class Img < Base
      def image_number
        sprintf(
          ReverseAdoc.config.image_counter_pattern,
          ReverseAdoc.config.image_counter,
        )
      end

      def image_number_increment
        ReverseAdoc.config.image_counter += 1
      end

      def datauri2file(src)
        %r{^data:image/(?:[^;]+);base64,(?<imgdata>.+)$} =~ src

        dest_dir = Pathname.new(ReverseAdoc.config.destination).dirname
        images_dir = dest_dir.join("images")
        FileUtils.mkdir_p(images_dir)

        ext, image_src_path = determine_image_src_path(src, imgdata)
        image_dest_path = images_dir + "#{image_number}.#{ext}"

        # puts "image_dest_path: #{image_dest_path.to_s}"
        # puts "image_src_path: #{image_src_path.to_s}"

        FileUtils.cp(image_src_path, image_dest_path)
        image_number_increment

        image_dest_path.relative_path_from(dest_dir)
      end

      def determine_image_src_path(src, imgdata)
        return copy_temp_file(imgdata) if imgdata

        ext = File.extname(src).strip.downcase[1..-1]
        [ext, Pathname.new(ReverseAdoc.config.sourcedir).join(src)]
      end

      def copy_temp_file(imgdata)
        Tempfile.open(["radoc", ".jpg"]) do |f|
          f.binmode
          f.write(Base64.strict_decode64(imgdata))
          f.rewind
          ext = Marcel::MimeType.for(f).sub(%r{^[^/]+/}, "")
          [ext, f.path]
        end
      end

      def to_coradoc(node, _state = {})
        id = node["id"]
        alt   = node["alt"]
        src   = node["src"]
        width = node["width"]
        height = node["height"]

        title = extract_title(node)

        if ReverseAdoc.config.external_images
          # puts "external image conversion #{id}, #{src}"
          src = datauri2file(src)
        end

        attributes = Coradoc::Element::AttributeList.new
        # attributes.add_named("id", id) if id
        if alt # && !alt.to_s.empty?
          attributes.add_positional(alt)
        elsif width || height
          attributes.add_positional("\"\"")
        end
        # attributes.add_named("title", title) if title
        attributes.add_positional(width) if width
        attributes.add_positional(height) if height

        Coradoc::Element::Image::BlockImage.new(title, id, src,
                                                attributes: attributes)
      end

      def convert(node, state = {})
        Coradoc::Generator.gen_adoc(to_coradoc(node, state))
      end
    end

    register :img, Img.new
  end
end