_review_request.html.slim

= content_for :sender
  = @store.name

= content_for :branding
  = render 'layouts/front/store_branding', store: @store

= content_for :excuse
  = t             'review_request_html',
    scope:        'front.mailer.excuses',
    helpfulcrowd: link_to('HelpfulCrowd', 'https://www.helpfulcrowd.com'),
    store:        "<b>#{ @store.name }</b>".html_safe

== @presenter.parsed_template

placeholder_presenter.rb

class ReviewRequestBodyPresenter < TemplatePresenter

  def initialize(review_request, store)
    @store = store
    @review_request
  end
  
  def parsed_template
    parse_template template, safe, paragraphize
  end
  
  private
  def template
    @store.settings(:reviews).review_request_mail_body
  end

  def supported_placeholders
    [:customer_name, :store_url]
  end

  def customer_name
    @review_request.customer.name
  end

  def store_url
    @store.url
  end
end

template_presenter.rb

class TemplatePresenter
  def supported_placeholders
    []
  end
  
  def template
    ''
  end
  
  protected
  
  def parse_template(safe, paragraphize)
    template = CGI::escape_html(template) unless safe
    template = template.paragraphize if paragraphize

    supported_placeholders.select{ |x| template.include?("[#{x }]") }.each do |key|
      replacement = send(key)

      has_tags = ["<table>", "<div>", "<p>"].any? { |tag| replacement.include?(tag) }
      template = template.gsub("<p>[#{ key }]</p>", replacement) if has_tags && template.include?("<p>[#{ key }]</p>")
      template = template.gsub("[#{ key }]", replacement)
    end
    template
  end
end