def bench(label = nil)
  Rack::Bench.close_bench_item(Kernel.caller[0])
  Rack::Bench.on
  
  if label
    Rack::Bench.push_bench_item(
      :label => label,
      :start_time => Time.now,
      :start_context => Kernel.caller[0]
    )
  end
end

module Rack
  # Rack::Bench adds benchmarking capabilities to Kiss applications.
  #
  # bench(label) starts a new timer, which ends upon the next call to
  # bench, or when execution returns to Rack::Bench.
  #
  # bench can be called without a label to end the previous timer 
  # without starting a new one.
  #
  # Total request duration is also displayed for any request in which
  # the bench function is called.
  class Bench
    def self.on
      @@bench = true
    end
    
    def self.close_bench_item(end_context = nil)
      if @@bench_items[-1] && !@@bench_items[-1][:end_time]
        @@bench_items[-1][:end_time] = Time.now
        @@bench_items[-1][:end_context] = end_context
      end
    end
    
    def self.push_bench_item(item)
      @@bench_items.push(item)
    end
    
    def initialize(app)
      @app = app
    end

    def call(env)
      @@bench = false
      @@bench_items = []
      
      start_time = Time.now
      code, headers, body = @app.call(env)
      end_time = Time.now
      
      if @@bench
        Rack::Bench.close_bench_item
        contents = <<-EOT
<style>
.kiss_bench {
  text-align: left;
  padding: 3px 7px;
  border: 1px solid #ec4;
  border-top: 1px solid #fff4bb;
  border-bottom: 1px solid #d91;
  background-color: #ffe590;
  font-size: 12px;
  color: #101;
}
.kiss_bench a {
  color: #930;
  text-decoration: none;
}
.kiss_bench a:hover {
  color: #930;
  text-decoration: underline;
}
</style>
EOT
        
        contents += @@bench_items.map do |item|
          start_link = context_link(item[:start_context])
          end_link = context_link(item[:end_context])
          
          <<-EOT
<div class="kiss_bench">
<tt><b>#{item[:label].gsub(/\</,'&lt;')} duration: #{sprintf("%0.3f",item[:end_time].to_f - item[:start_time].to_f)} s</b></tt>
<small style="line-height: 105%; display: block; padding-bottom: 3px">kiss bench<br/>started at #{start_link}<br/>ended at #{end_link || 'return to kiss bench'}</small>
</div>
EOT
        end.join
        
        contents += <<-EOT
<div class="kiss_bench">
<tt><b>TOTAL request duration: #{sprintf("%0.3f",end_time.to_f - start_time.to_f)} s</b></tt>
<br><small>kiss bench request total</small>
</div>
EOT
      else
        contents = ''
      end
      
      body.each {|p| contents += p }
      headers['Content-Length'] = contents.length.to_s
    
      [ code, headers, contents ]
    end
    
    def absolute_path(filename)
      filename = ( filename =~ /\A\// ? '' : (Dir.pwd + '/') ) + filename
    end
    
    def context_link(context)
      return nil unless context
      
      filename, line, method = context.split(/:/)
      textmate_url = "txmt://open?url=file://" + h(absolute_path(filename)) + '&amp;line=' + line
      %Q(<a href="#{textmate_url}">#{filename}:#{line}</a> #{method})
    end
    
    def textmate_href(frame)
      "txmt://open?url=file://" + h(absolute_path(context)).sub(/:/,'&amp;line=')
    end

    def h(obj)                  # :nodoc:
      case obj
      when String
        Utils.escape_html(obj).gsub(/^(\s+)/) {'&nbsp;' * $1.length}
      else
        Utils.escape_html(obj.inspect)
      end
    end
  end
end