# cf) xray-rails : xray/middleware.rb

module CopyTunerClient
  class CopyrayMiddleware
    def initialize(app)
      @app = app
    end

    def call(env)
      CopyTunerClient::TranslationLog.clear
      status, headers, response = @app.call(env)
      if html_headers?(status, headers) && body = response_body(response)
        body = append_css(body)
        body = append_js(body)
        body = append_translation_logs(body)
        body = inject_copy_tuner_bar(body)
        content_length = body.bytesize.to_s
        headers['Content-Length'] = content_length
        # maintains compatibility with other middlewares
        if defined?(ActionDispatch::Response::RackBody) && ActionDispatch::Response::RackBody === response
          ActionDispatch::Response.new(status, headers, [body]).to_a
        else
          [status, headers, [body]]
        end
      else
        [status, headers, response]
      end
    end

    private

    def helpers
      ActionController::Base.helpers
    end

    def append_translation_logs(html)
      if CopyTunerClient::TranslationLog.initialized?
        json = CopyTunerClient::TranslationLog.translations.to_json
        # Use block to avoid back reference \?
        append_to_html_body(html, "<div id='copy-tuner-data' data-copy-tuner-translation-log='#{ERB::Util.html_escape json}' data-copy-tuner-url='#{CopyTunerClient.configuration.project_url}'></div>")
      else
        html
      end
    end

    def inject_copy_tuner_bar(html)
      append_to_html_body(html, render_copy_tuner_bar)
    end

    def render_copy_tuner_bar
      if ApplicationController.respond_to?(:render)
        # Rails 5
        ApplicationController.render(:partial => "/copy_tuner_bar").html_safe
      else
        # Rails <= 4.2
        ac = ActionController::Base.new
        ac.render_to_string(:partial => '/copy_tuner_bar').html_safe
      end
    end

    def append_css(html)
      append_to_html_body(html, css_tag)
    end

    def append_js(html)
      append_to_html_body(html, helpers.javascript_include_tag(:copyray))
    end

    def css_tag
      helpers.stylesheet_link_tag :copyray, media: :all
    end

    def append_to_html_body(html, content)
      content = content.html_safe if content.respond_to?(:html_safe)
      return html unless html.include?('</body>')

      position = html.rindex('</body>')
      html.insert(position, content + "\n")
    end

    def file?(headers)
      headers["Content-Transfer-Encoding"] == "binary"
    end

    def html_headers?(status, headers)
      status == 200 &&
      headers['Content-Type'] &&
      headers['Content-Type'].include?('text/html') &&
      !file?(headers)
    end

    def response_body(response)
      body = ''
      response.each { |s| body << s.to_s }
      body
    end
  end
end