// JavaScript Form Validation Document
//calls this form the form in html
//to get required fields use
//<input type="hidden" name="required_fields" value="name,phone_no,ClassName,ClassDate,people_attending">	
function validateFormOnSubmit(theForm) {
  if(!document.getElementById || !document.createTextNode){return;}
  if(!theForm.required_fields){return;}
  
  var reason = "";
  var reqfields = theForm.required_fields.value.split(',');
  
  //alert(theForm.elements[reqfields[1]].value);

  // loop over required fields
  for(var i=0;i<reqfields.length;i++)
  {
    // check if required field is there    
    reason += validateEmpty(theForm.elements[reqfields[i]]);
    //validate email
    if (reqfields[i] == 'email' && theForm.elements[reqfields[i]].value != "")
    {
     reason += validateEmail(theForm.elements[reqfields[i]]);
    }  
  }

  if (reason != "") {
    alert("Some fields need correction:\n" + reason);
    return false;
  }

  return true;
} 

function validateDate(fld) {
    var error = "";
	
    if (isDate(fld.value)==false){
		fld.style.background = 'Yellow';
		error = "Please enter a date in the correct format.\n" 
	} else {
        fld.style.background = 'White';
    }
		
	return error;
}

function validateEmpty(fld) {
    var error = "";

    if (fld.value.length == 0) {
        fld.style.background = 'Yellow'; 
        error = "The required field, " + fld.name + ", has not been filled in.\n"
    } else {
        fld.style.background = 'White';
    }
    return error;  
}

function trim(s)
{
  return s.replace(/^\s+|\s+$/, '');
}

function validateEmail(fld) {
    var error="";
    var tfld = trim(fld.value);                        // value of field with whitespace trimmed off
    var emailFilter = /^[^@]+@[^@.]+\.[^@]*\w\w$/ ;
    var illegalChars= /[\(\)\<\>\,\;\:\\\"\[\]]/ ;
   
    if (fld.value == "") {
        fld.style.background = 'Yellow';
        error = "You didn't enter an email address.\n";
    } else if (!emailFilter.test(tfld)) {              //test email for illegal characters
        fld.style.background = 'Yellow';
        error = "Please enter a valid email address.\n";
    } else if (fld.value.match(illegalChars)) {
        fld.style.background = 'Yellow';
        error = "The email address contains illegal characters.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}

function validatePhone(fld) {
    var error = "";
    var stripped = fld.value.replace(/[\(\)\.\-\ ]/g, '');    

   if (fld.value == "") {
        error = "Please enter your phone number.\n";
        fld.style.background = 'Yellow';
    } else if (isNaN(parseInt(stripped))) {
        error = "The phone number contains illegal characters.\n";
        fld.style.background = 'Yellow';
    } else if (!(stripped.length == 10)) {
        error = "The phone number is the wrong length. Make sure you included an area code.\n";
        fld.style.background = 'Yellow';
    }
    return error;
}

/**
 * DHTML date validation script. Courtesy of SmartWebby.com (http://www.smartwebby.com/dhtml/)
 */
// Declaring valid date character, minimum year and maximum year
var dtCh= "/";
var minYear=1900;
var maxYear=2100;

function isInteger(s){
	var i;
    for (i = 0; i < s.length; i++){   
        // Check that current character is number.
        var c = s.charAt(i);
        if (((c < "0") || (c > "9"))) return false;
    }
    // All characters are numbers.
    return true;
}

function stripCharsInBag(s, bag){
	var i;
    var returnString = "";
    // Search through string's characters one by one.
    // If character is not in bag, append to returnString.
    for (i = 0; i < s.length; i++){   
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) returnString += c;
    }
    return returnString;
}

function daysInFebruary (year){
	// February has 29 days in any year evenly divisible by four,
    // EXCEPT for centurial years which are not also divisible by 400.
    return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
}
function DaysArray(n) {
	for (var i = 1; i <= n; i++) {
		this[i] = 31
		if (i==4 || i==6 || i==9 || i==11) {this[i] = 30}
		if (i==2) {this[i] = 29}
   } 
   return this
}

function isDate(dtStr){
	var daysInMonth = DaysArray(12)
	var pos1=dtStr.indexOf(dtCh)
	var pos2=dtStr.indexOf(dtCh,pos1+1)
	var strMonth=dtStr.substring(0,pos1)
	var strDay=dtStr.substring(pos1+1,pos2)
	var strYear=dtStr.substring(pos2+1)
	strYr=strYear
	if (strDay.charAt(0)=="0" && strDay.length>1) strDay=strDay.substring(1)
	if (strMonth.charAt(0)=="0" && strMonth.length>1) strMonth=strMonth.substring(1)
	for (var i = 1; i <= 3; i++) {
		if (strYr.charAt(0)=="0" && strYr.length>1) strYr=strYr.substring(1)
	}
	month=parseInt(strMonth)
	day=parseInt(strDay)
	year=parseInt(strYr)
	if (pos1==-1 || pos2==-1){
		/*alert("The date format should be : mm/dd/yyyy")*/
		return false
	}
	if (strMonth.length<1 || month<1 || month>12){
		/*alert("Please enter a valid month")*/
		return false
	}
	if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]){
		/*alert("Please enter a valid day")*/
		return false
	}
	if (strYear.length != 4 || year==0 || year<minYear || year>maxYear){
		/*alert("Please enter a valid 4 digit year between "+minYear+" and "+maxYear)*/
		return false
	}
	if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false){
		/*alert("Please enter a valid date")*/
		return false
	}
return true
}