//-----------------------------------------------------------------------
// Funcoes de AJAX
//-----------------------------------------------------------------------
// Programador: Claudio Monteoliva
//-----------------------------------------------------------------------
// seta variaveis global
var READY_STATE_UNINITIALISED = 0;
var READY_STATE_LOADING       = 1;
var READY_STATE_LOADED        = 2;
var READY_STATE_INTERACTIVE   = 3;
var READY_STATE_COMPLETE      = 4;

//--------------------------------------------------------
// funcao que chama o AJAX
//--------------------------------------------------------
// Parametro recebido:
// url ........: URL a ser executada
// funcRet ....: Funcao de retorno
// HttpMethod .: method da pesquisa (GET|POST) [opcional]
//--------------------------------------------------------
function ajax_request(url, funcRet, HttpMethod)
{
  // verifica o parāmetro do HttpMethod (default)
  if (!HttpMethod) { HttpMethod = "GET"; }

  // inicia variavel do objeto XMLHttpRequest
  var xRequest = null;

  // Procura por um objeto nativo
  if (window.XMLHttpRequest) { xRequest = new XMLHttpRequest();                   }  // Mozilla/Safari
  else                       { xRequest = new ActiveXObject("Microsoft.XMLHTTP"); }  // Internet Explorer

  // method
  xRequest.open(HttpMethod, url, true);
  xRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

  // ReadyStateChange (onReadyStateChange)
  xRequest.onreadystatechange = function()
  {
    // apenas quando o estado for "completado"
    if (xRequest.readyState == READY_STATE_COMPLETE)
    {
      // pega o retorno
      var resposta = xRequest.responseText;

      // apenas se o servidor retornar "OK"
      if (xRequest.status == 200) { if (resposta != "") { if (funcRet) { funcRet(resposta); } if (setLoading) { setLoading(0); }}}

      // apaga o objeto do Request
      delete xRequest;
    }
    else { if (setLoading) { setLoading(1); }}
  }

  // Send
  xRequest.send(null);
}