var clientOffset = 0;
	 var ajaxwin;
	 
	 /*
	  * Funcion para crear objeto de conexion ajax
	  */   	
	  function makeRequest() {
		var http_request = false;
	
		if (window.XMLHttpRequest) { // Mozilla, Safari,...
			http_request = new XMLHttpRequest();
			if (http_request.overrideMimeType) {
				http_request.overrideMimeType('text/json');
			}
		} else if (window.ActiveXObject) { // IE
			try {
				http_request = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {
				try {
					http_request = new ActiveXObject("Msxml2.XMLHTTP");
				} catch (e) {}
			}
		}
		
		if (!http_request) {
			alert('Giving up :( Cannot create an XMLHTTP instance');
			return false;
		}
		
		return http_request;
	  }
	  
	  function login(){
	  		var usuario = document.getElementById("usuario").value;
	  		var clave = document.getElementById("clave").value;
	  		var data = "usuario="+usuario+"&clave="+clave+"&localOffset="+clientOffset;
	  
	  		var http_request = makeRequest();
  	
		  	http_request.onreadystatechange = function () {
		  		if (http_request.readyState == 4) {
					if (http_request.status == 200) {
						var result = http_request.responseText.parseJSON();
			
						if(result != false) {					
							if(result.success) {
								document.index_form.action = result.service+"/movilsat.php";
								document.getElementById("localOffset").value = clientOffset;
								document.index_form.submit();
							}
							else {
								alert(unescape(result.message));
							}		
						} 
					} 
				}
		  	}
		  	
			http_request.open("POST", "./login.php", true);
			http_request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
			http_request.send(data);
	  }
	  
	  function cambiarClave(){
	  		ajaxwin = dhtmlwindow.open("dialogo", "iframe", "nueva_clave.php", "Cambiar Clave", "width=650px,height=400px,resize=1,scrolling=1,center=1", "recal");
			ajaxwin.show();
	  }
	  
	  function cerrarVentana(){
			ajaxwin.hide();
	  }
	  
	 /*
	  * Funcion que hace login al presionar enter
	  */
	  function enterLogin(e) {
	  		var key;
	  		if (window.event)
	  			key = window.event.keyCode;
	  		else 
	  			key = e.which;
		
			if(key == 13) login();
	  }