module Mailings
  class OpenPixel
    def self.call(html, recipient)
      new(html, recipient).call
    end

    def initialize(html, recipient)
      @html = html.to_s
      @recipient = recipient
    end

    def call
      return @html unless trackable?

      url = tracking_url
      return @html if url.blank?

      tag = %(<img src="#{ERB::Util.html_escape(url)}" width="1" height="1" alt="" style="display:block;border:0;width:1px;height:1px;opacity:0;" />)
      if @html.match?(/<\/body>/i)
        @html.sub(/<\/body>/i, "#{tag}</body>")
      else
        "#{@html}#{tag}"
      end
    end

    private

    def trackable?
      @recipient.respond_to?(:tracking_token) && @recipient.tracking_token.present?
    end

    def tracking_url
      Rails.application.routes.url_helpers.mail_open_url(@recipient.tracking_token, **PublicUrl.options)
    end
  end
end