// xHttpRequest r4, Copyright 2006-2007 Michael Foster (Cross-Browser.com)
// Part of X, a Cross-Browser Javascript Library, Distributed under the terms of the GNU LGPL

function xHttpRequest() // object prototype
{
  // Private Properties
  var _i = this; // instance object
  var _r = null; // XMLHttpRequest object
  var _t = null; // timer
  var _f = null; // callback function
  var _x = false; // XML response pending
  var _o = null; // user data object passed to _f
  // Public Properties
  _i.OK 			= 0;
  _i.NOXMLOBJ 	= 1;
  _i.REQERR 	= 2;
  _i.TIMEOUT 	= 4;
  _i.RSPERR 	= 8;
  _i.NOXMLCT 	= 16;
  _i.status = _i.OK;
  _i.busy = false;

  // Private Event Listeners
  function _oc() // onReadyStateChange
  {
    if (_r.readyState == 4) 
    {
      if (_t) { clearTimeout(_t); }
      if (_r.status != 200) _i.status = _i.RSPERR;
      if (_x) 
      {
        var ct = _r.getResponseHeader('Content-Type');
        if (ct && ct.indexOf('xml') == -1) { _i.status |= _i.NOXMLCT; }
      }
      if (_f) _f(_r, _i.status, _o);
      _i.busy = false;
    }
  }

  function _ot() // onTimeout
  {
    _r.onreadystatechange = function(){};
    _r.abort();
    _i.status |= _i.TIMEOUT;
    if (_f) _f(_r, _i.status, _o);
    _i.busy = false;
  }

  // Public Method
  /* args: 
  	m method (GET POST)
  	u url
  	d url parameters
  	t timeout (milliseconds)
  	r set to nonzero if you want a uniqueing parameter to prevent cacheing by browser
  	x require xml content header to be returned if true
  	o user data object passed to callback function
  	f callback function
  */
  
this.send = function(m, u, d, t, r, x, o, f)
{
	if (!_r || _i.busy) { return false; }
	m = m.toUpperCase();
	if (m != 'POST') 
	{
		if (d) 
		{
			d = '?' + d;
			if (r) { d += '&' + r + '=' + Math.round(10000*Math.random()); }
		}
		else { d = ''; }
	}
	_x = x;
	_o = o;
	_f = f;
	_i.busy = true;
	_i.status = _i.OK;
	if (t) { _t = setTimeout(_ot, t); }
	try {
		if (m == 'GET') 
		{
			_r.open(m, u + d, true);
			d = null;
			_r.setRequestHeader('Cache-Control', 'no-cache');
			var ct = 'text/' + (x ? 'xml':'plain');
			if (_r.overrideMimeType) {_r.overrideMimeType(ct);}
			_r.setRequestHeader('Content-Type', ct);
		}
		else if (m == 'POST')
		{
			_r.open(m, u, true);
			_r.setRequestHeader('Method', 'POST ' + u + ' HTTP/1.1');
			_r.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
			}
		else {
			_r.open(m, u + d, true);
			d = null;
		}
		_r.onreadystatechange = _oc;
		_r.send(d);
	}
	catch(e) 
	{
		if (_t) { clearTimeout(_t); }
		_f = null;
		_i.busy = false;
		_i.status = _i.REQERR;
		_i.error = e;
		alert("status="+_i.status+", error="+_i.error);
		return false;
	}
	return true;
};

  // Constructor Code
  try { _r = new XMLHttpRequest(); }
  catch (e) { try { _r = new ActiveXObject('Msxml2.XMLHTTP'); }
  catch (e) { try { _r = new ActiveXObject('Microsoft.XMLHTTP'); }
  catch (e) { _r = null; }}}
  if (!_r) { _i.status = _i.NOXMLOBJ; }
}