class ActionView::Base
  TM_URL = 'txmt://open?url=file://%s&line=%d&column=%d'

  def _render_partial_with_dev(options, &block)
    result = _render_partial_without_dev(options, &block)
    template = @renderer.send(:find_template)
    filepath = template.identifier
    fileurl = TM_URL % [filepath, 0, 0]
    filelink = '<a href="%s" class="dev-tool-txmt" title="%s">&#9998;</a>' % [fileurl, template.virtual_path]
    filelink.html_safe + result
  end
  alias_method_chain :_render_partial, :dev
end

class MyFilter
  def self.filter(controller)
    insert_text controller, :before, /<\/head>/i, <<-HTML
      <style type="text/css">
        a.dev-tool-txmt { display: none; margin: 0 2px; text-decoration: none; color: red; }
        #dev-tool { position: fixed; bottom: 2px; right: 2px; z-index: 1000; }
        #dev-tool a { text-decoration: none; color: red; }
      </style>
    HTML
    insert_text controller, :before, /<\/body>/i, <<-HTML
      <div id="dev-tool">
        <a href="javascript:void(0);" onclick="$('.dev-tool-txmt').toggle()" title="Show dev tools">&#10037</a>
      </div>
    HTML
  end

  def self.insert_text(controller, position, pattern, new_text)
    index = if match = controller.response.body.match(pattern)
      match.offset(0)[position == :before ? 0 : 1]
    else
      controller.response.body.size
    end
    controller.response.body = controller.response.body.insert index, new_text
  end
end

class ActionController::Base
  after_filter MyFilter
end