/**
 * Validate.js: unobtrusive HTML form validation.
 *
 * This is from David Flanagan's book on JavaScript.
 *
 */
(function() { // Do everything in this one anonymous function
    // When the document finishes loading, call init()
    if (window.addEventListener) window.addEventListener("load", init, false);
    else if (window.attachEvent) window.attachEvent("onload", init);

    // Define event handlers for any forms and form elements that need them.
    function init() {
        // Loop through all forms in the document
		// alert("form cnt="+document.forms.length);
        for(var i = 0; i < document.forms.length; i++) {
            var f = document.forms[i];  // the form we're working on now

            // Assume, for now, that this form does not need any validation
            var needsValidation = false;

            // Now loop through the elements in our form
            for(j = 0; j < f.elements.length; j++) {
                var e = f.elements[j];  // the element we're working on

                // We're only interested in <input type="text"> textfields
                if (e.type != "text") continue;

                // See if it has attributes that require validation
                var pattern = e.getAttribute("pattern");
                // We could use e.hasAttribute() but IE doesn't support it
                var required = e.getAttribute("required") != null;

                // Required is just a shortcut for a simple pattern
                if (required && !pattern) {
                    pattern = "\\S";
                    e.setAttribute("pattern", pattern);
                }

                // If this element requires validation,
                if (pattern) {
                    // validate the element each time it changes
                    // e.onchange = validateOnChange;
                    e.onblur = validateOnChange;
					e.onblur();	// initialize it
                    // Remember to add an onsubmit handler to this form
                    needsValidation = true;
                }
            }

            // If at least one of the form elements needed validation,
            // we also need an onsubmit event handler for the form
            if (needsValidation) f.onsubmit = validateOnSubmit;
        }
    }
          
    // This function is the onchange event handler for textfields that 
    // require validation.  Remember that we converted the required attribute
    // to a pattern attribute in init().
    function validateOnChange() {
        var textfield = this;                            // the textfield
        var pattern = textfield.getAttribute("pattern"); // the pattern
        var value = this.value;                          // the user's input

        // If the value does not match the pattern set the class to "invalid".
        if (value.search(pattern) == -1) textfield.className = "invalid";
        else textfield.className = "valid";
    }

    // This function is the onsubmit event handler for any form that 
    // requires validation.
    function validateOnSubmit() {
        // When the form is submitted, we revalidate all the fields in the
        // form and then check their classNames to see if they are invalid.
        // If any of those fields are invalid, display an alert and prevent
        // form submission.
        var invalid = false;  // Start by assuming everything is valid
        // Loop through all form elements
        for(var i = 0; i < this.elements.length; i++) {
            var e = this.elements[i];
            // If the element is a text field and has our onchange handler
            if (e.type == "text" && e.onblur == validateOnChange) {
                e.onblur(); // Invoke the handler to re-validate
                // If validation fails for the element, it fails for the form
                if (e.className == "invalid") {
					// alert("Error: "+e.name+"="+e.value);
					invalid = true;
				}
            }
        }

        // If the form is invalid, alert user and block submission
        if (invalid) {
            alert("The form is incompletely or incorrectly filled out.\n" +
                  "Please correct the  highlighted fields and try again.");
            return false;
        }
    }
})();