class Mailings::InlineImages
  BLOB_PATH = %r{/rails/active_storage/blobs/(?:redirect/|proxy/)?([^/?#]+)}

  def self.call(mailer, html)
    new(mailer).call(html)
  end

  def initialize(mailer)
    @mailer = mailer
  end

  def call(html)
    fragment = Nokogiri::HTML::DocumentFragment.parse(html.to_s)
    fragment.css("img").each_with_index do |img, index|
      blob = blob_from(img["src"])
      next unless blob

      name = "inline-#{index}-#{blob.filename}"
      @mailer.attachments.inline[name] = {
        mime_type: blob.content_type,
        content: blob.download
      }
      img["src"] = @mailer.attachments[name].url
      width = img["width"].presence
      styles = ["max-width: 100%", "height: auto"]
      styles << "width: #{width}px" if width.present?
      img["style"] = [img["style"], *styles].compact.join("; ")
    end

    fragment.css("figure").each do |figure|
      image = figure.at_css("img")
      image ? figure.replace(image) : figure.remove
    end

    fragment.to_html
  end

  private

  def blob_from(src)
    signed_id = src.to_s[BLOB_PATH, 1]
    return if signed_id.blank?

    ActiveStorage::Blob.find_signed(signed_id)
  rescue ActiveSupport::MessageVerifier::InvalidSignature, ActiveRecord::RecordNotFound
    nil
  end
end