Express compress

var Request = require('express/request').Request,
    deflate = require('./support/deflate').deflate,
statusBodies = require('http').STATUS_CODES,
gzipTest = /gzip/,

_long = function(n) {
  return String.fromCharCode(n & 0xFF)
       + String.fromCharCode(n >> 8 & 0xFF)
       + String.fromCharCode(n >> 16 & 0xFF)
       + String.fromCharCode(n >> 24 & 0xFF);
};

exports.Gzip = Plugin.extend({

  extend: {
    init: function(){
      var node_compress, oldRespond = Request.prototype.respond
      try {
        node_compress = require('compress')
      } catch(e){
        node_compress = null
      }
      
      Request.include({
        
        respond: function(code, body, encoding, callback) {
          var self = this, gzip, level = set('gzip compression level') || 4
          if (set('gzip output') && gzipTest.test(this.header('accept-encoding')) && body && typeof body == 'string'){
            this.header('Content-Encoding', 'gzip')
            encoding = 'binary'
            if (node_compress){
              gzip = new node_compress.Gzip
              gzip.init(level)
              body = gzip.deflate(body, 'binary') + gzip.end()
            } else {
              // per RFC 1952 http://tools.ietf.org/html/rfc1952
              // var size = body.length, crc = crc32(body);
              body = '\u001f\u008b\u0008\u0000' + _long(+new Date) + '\u0000\u0003' // |ID1|ID2|CM|FLG|MTIME|XFL|OS|
                    + deflate(body, level) // compressed blocks
                    // + _long(crc) + _long(size); // |CRC32|ISIZE|
            }
          }
          oldRespond.apply(this, [code, body, encoding, callback])
        }
        
      });
      
    }
  }
  
});