module Merb

  module RenderMixin
  
    # shortcut to a template path based on name.
    def template_dir(loc)
      File.expand_path(Merb::Server.config[:merb_root] + "/dist/app/views/#{loc}")
    end  
    
    # returns the current method name. Used for
    # auto discovery of which template to render
    # based on the action name.
    def current_method_name(depth=0)
      caller[depth] =~ /`(.*)'$/; $1
    end
    
    def template_extension_for(ext)
      Merb::Server.config[:template_ext][ext]
    end
    
    # does a render with no layout. Also sets the
    # content type header to text/javascript
    def render_js(template=current_method_name(1), b=binding)
      headers['Content-Type'] = "text/javascript"
      template = Erubis::Eruby.new(IO.read( template_dir(self.class.name.snake_case) + "/#{template}.#{template_extension_for(:js)}" )) 
      template.result(b)
    end
    
    # set the @layout. Use this right before a render to
    # set the name of the layout to use minus the .rhtml
    def layout(l)
       @layout = l 
    end
    
    # renders nothing but sets the status
    def render_nothing(status=200)
      @status = status
      return "\n"
    end
    
    # renders the action without wrapping it in a layout.
    def render_no_layout(template=current_method_name(1), b=binding)
      template = Erubis::Eruby.new( IO.read( template_dir(self.class.name.snake_case) + "/#{template}.#{template_extension_for(:html)}" ) ) 
      template.result(b)
    end 
    
    def partial(template)
      template = Erubis::Eruby.new( IO.read( template_dir(self.class.name.snake_case) + "/_#{template}.#{template_extension_for(:html)}" ) ) 
      template.result(binding)
    end 
    
    def render_xml(template=current_method_name(1))
      xml = Builder::XmlMarkup.new :indent => 2
      xml.instruct! :xml, :version=>"1.0", :encoding=>"UTF-8"
      eval IO.read( template_dir(self.class.name.snake_case) + "/#{template}.#{template_extension_for(:xml)}" ) 
      @headers['Content-Type'] = 'application/xml'
      @headers['Encoding']     = 'UTF-8'
      xml.target!
    end
    
    # renders a template based on the current action name
    # you can pass the name of a template if you want to
    # render a template with a different name then then 
    # current action name. Wraps the rendered template in
    # the layout. Uses layout/application.rhtml unless
    # there is a layout named after the current controller
    # or @layout has been set to another value.
    def render(template=current_method_name(1), b=binding)
      tmpl_ext = template_extension_for(:html)
      MERB_LOGGER.info("Rendering template: #{template_dir(template)}..#{tmpl_ext}")
      name = self.class.name.snake_case
      template = Erubis::Eruby.new( IO.read( template_dir(name) + "/#{template}.#{tmpl_ext}" ) ) 
      layout_content = template.result(b)
      return layout_content if (@layout.to_s == 'none')
      if ['application', name].include?(@layout.to_s)
        if File.exist?(template_dir("layout/#{name}.#{tmpl_ext}"))
          layout = name
        else
          layout = 'application'
        end
      else
        layout = @layout.to_s
      end
      MERB_LOGGER.info("With Layout: #{template_dir('layout')}/#{layout}.#{tmpl_ext}")
      @layout_content = layout_content
      layout_tmpl = Erubis::Eruby.new( IO.read( "#{template_dir('layout')}/#{layout}.#{tmpl_ext}" ) )      
      layout_tmpl.result(b)
    end
    
  end  
end