var mPrefix = "El campo ";
var mSuffix = " es un dato necesario. Por favor coloquelo ahora.";
var defaultEmptyOK = false;
var whitespace = " \t\n\r";
var iEmail = " debe contener una dirección de e-mail valida.\nEjm: info@editorialintenso.com.\nPor favor revise.";
var iNumber = " debe contener valores numéricos.\nPor favor revise.";

function isEmpty(s) {
	return ((s == null) || (s.length == 0))
}

function isWhitespace (s) {
	var i;

    if (isEmpty(s)) return true;
    for (i = 0; i < s.length; i++) {   
        var c = s.charAt(i);
        if (whitespace.indexOf(c) == -1) return false;
    }
    return true;
}

function warnInvalid (theField, s) {
	theField.focus()
    theField.select()
    alert(mPrefix + s + iEmail)
    return false
}

function warnNumber (theField, s) {
	theField.focus()
	theField.select()
	alert(mPrefix + s + iNumber)
	return false
}

function warnEmpty (theField, s) {
	theField.focus()
    alert(mPrefix + s + mSuffix)
    return false
}

function isEmail (s) {
	if (isEmpty(s)) 
       if (isEmail.arguments.length == 1) return defaultEmptyOK;
       else return (isEmail.arguments[1] == true);
   
    if (isWhitespace(s)) return false;
    
    var i = 1;
    var sLength = s.length;

    while ((i < sLength) && (s.charAt(i) != "@")){
		i++
    }

    if ((i >= sLength) || (s.charAt(i) != "@")) return false;
    else i += 2;

    while ((i < sLength) && (s.charAt(i) != ".")){
		i++
    }

    if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;
    else return true;
}

function isNumber(s) {
	if (isEmpty(s)) 
       if (isNumber.arguments.length == 1) return defaultEmptyOK;
       else return (isNumber.arguments[1] == true);
	   
	   if (isWhitespace(s)) return false;
	   
	   if (isNaN(s)) return false;
	   else return true;
}

function checkString (theField, s, emptyOK){
    if (checkString.arguments.length == 2) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    if (isWhitespace(theField.value)) 
       return warnEmpty (theField, s);
    else return true;
}

function checkEmail (theField, s, emptyOK){
	if (checkEmail.arguments.length == 2) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else if (!isEmail(theField.value, false)) 
       return warnInvalid (theField, s);
    else return true;
}

function checkNumber (theField, s, emptyOK){
	if(checkNumber.arguments.length == 2) emptyOK = defaultEmptyOK;
	if((emptyOK == true) && (isEmpty(theField.value))) return true;
	else if(!isNumber(theField.value, false))
		return warnNumber (theField, s);
	else return true;
}

function CerrarSession() {
	var entrar = confirm("¿De verdad desea entrar en esta\npagina?");
	if(!entrar){
		document.location.href="index.php";
	}
}