//*******************************************************
// JavaScript generic form validation script
//
// Dave Fisher, 03-10-2001
// v1.0
//
//
// The return values are based on the logic:
// Is there an ERROR?
//   yes = return true
//   no  = return false
//
// To add to HTML:
//
// <script src="/javascript/FormValidate.js"></script>
//
// Example usage script is in <dir> called ValidateExample.htm
//
//*******************************************************
// Functions:        Description:
//
// -- require strings --
// isEmpty           Check if value is empty
// isNotType         Checks for digits, alphanumerics etc
// isWhitespace      Checks for new line, tabs, spaces etc
// isEmail           Checks email address structure is vallid
// isPasswordError   Checks pwd has:
//                     1 uppercase char
//                     1 lowercase char
//                     1 numeric char
//                     Only alphanumerics 
// minChars          Check to see string has min set of chars
// maxChars          Check to see string does not exceed set of chars
// firstAlpha        Checks to make sure first two chars are 
//                   alphabetical
//
// -- require objects --
// isSelected        Checks if selection on select box as been made
// isDate            Checks date is valid
// isUnderAge        Checks to see if date is less than 18yrs old
//
// isNotChecked      Has the check box been checked
// isNotRadioChecked Checks to see if any radiobuttons enabled
//
//

// vars used for validating strings
var digits     = "0123456789";
var lowercase  = "abcdefghijklmnopqrstuvwxyz";
var uppercase  = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
var whitespace= " \t\n\r";


//*******************************************************
// Generic checks 
//*******************************************************

// Check whether string s is empty.
// returns true if empty
function isEmpty(s) {
  if((s == null) || (s.length == 0)) return true;

	// check for whitespace only
  for(var i=0; i < s.length; ++i){
		var thechar = s.charAt(i);
		if((thechar == ' ' || thechar == '\n' || thechar == '\t') == false){
			return false;
		}
	}

  return true; // it's just all whitespace
}

// Check string for whitespace
function isWhitespace(s){
  // Is the string 's' empty?
  if (isEmpty(s)) return true;

  for(var i=0; i < whitespace.length; ++i)
    if (s.indexOf(whitespace.charAt(i)) > -1) return true;

  // All chars are valid 
  return false;
}

// check min chars exists
// return true if less than minimum 
function minChars(s, i){
  if(s.length < i) return true;
  return false;
}

// check max chars exists
// return true if exceeded
function maxChars(s, i){
  if(s.length > i) return true;
  return false;
}

// check first 2 chars are alphanumeric
function firstAlpha(s){
  var test = lowercase+uppercase;

  var a = s.charAt(0);
  var b = s.charAt(1);

  if(test.indexOf(a) > -1 && test.indexOf(b) > -1) return false;

  return true;
}

////
// check from DOB that person is minimum age (18)
// slightly bespoke function, but most financial packages
// require a min age of 18.
//
// This run via accessing select boxes
//
// ! Check date is valid by running isDate before calling this function !
//
function isUnderAge(pDAY, pMONTH, pYEAR){
  var minAge=18; // could have a param if required

  var pday   = pDAY.options[pDAY.selectedIndex].value;
  var pmonth = pMONTH.options[pMONTH.selectedIndex].value;
  var pyear  = pYEAR.options[pYEAR.selectedIndex].value;

  // Ensure numeric context.
  // Can't use parseInt as values beginning with '0' will be treated as octal.
  pday   = pday - 0;
  pmonth = pmonth - 0;
  pyear  = pyear - 0;

  // get todays date
  var today = new Date();
  var day   = today.getDate();
  var month = today.getMonth()+1;     // some odd reason months are 0-11
  var year  = today.getYear()-minAge; // today xx years ago

  // make sure we have a 4 digit year!
  year += (year < 100) ? 1900 : 0

  // check year is min
  if(year < pyear) return true; // under age

  // if same year, check month 
  if(year == pyear){
    if(month < pmonth) return true;
    if(month == pmonth){
      // check day is min
      if(day < pday) return true;
    }
  }
  return false; // DoB shows age is 18+
}

// Make sure a checkbox has been enabled 
function isNotChecked(o){
  if(o.checked) return false;
  return true;
}

// Make sure a radiobutton has been enabled 
function isNotRadioChecked(o){
  // Loop through all radio buttons, return true if none
  // have been checked
  var i=0;
  while(o[i]){ 
    if(o[i].checked) return false;
    ++i;
  }
  return true;
}

////
// check if char is not in specified range
//
// s    = string
// type = AN (alphanumerics) <- default
//      = D  (digits)
//      = TXT(letter)
//      = LC (lowercase)
//      = UC (uppercase)
//      = ANU (AN + userdefined chars) 
//      = UD (user defined).. user_string must be specified
// user_string = user specifed string of chars to check against
//
function isNotType(s, type, user_string){
  if(isEmpty(s)) return true;
  
  var check = lowercase+uppercase+digits;
  
  if(type == 'D')        check = digits;
  else if(type == 'TXT') check = lowercase+uppercase;
  else if(type == 'LC')  check = lowercase;
  else if(type == 'UC')  check = uppercase;
  else if(type == 'ANU') check = check+user_string;
  else if(type == 'UD')  check = user_string; 

  for(var i=0; i < s.length; ++i)
    if (check.indexOf(s.charAt(i)) == -1) return true;

  return false;
}

////
// this checks the password contains atleast 1 of the following:
// uppercase, lowercase and digit
function isPasswordError(s){
  // check all is no more than alphanumerics and 'underscore'
  var check = lowercase+uppercase+digits;
  for(var i=0; i < s.length; ++i)
    if (check.indexOf(s.charAt(i)) == -1) return true;

  if(s.search(/[0-9]+/g)==-1) return true;
  if(s.search(/[a-z]+/g)==-1) return true;
  if(s.search(/[A-Z]+/g)==-1) return true;

  return false; // there was no error
}

////
// Date validator, based on dd,mm, yyyy via select boxes 
//
function isDate(pDAY, pMONTH, pYEAR){
  var daysinmonth = new Array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

  // Get date varaibles dd, mm, yyyy
  var startday   = pDAY.options[pDAY.selectedIndex].value;
  var startmonth = pMONTH.options[pMONTH.selectedIndex].value;
  var startyear  = pYEAR.options[pYEAR.selectedIndex].value;

  // is this a leap year?? .. reset value
  daysinmonth[1]=28;
  if(LeapYear(startyear)) daysinmonth[1]=29;

  // have we been sensible with the number of days in this month?
  if (startday > daysinmonth[startmonth-1]){
    alert("Only "+daysinmonth[startmonth-1]+" days in the specified month");
    return true; 
  }
  return false; // no errors 
}

// make sure data is valid (i.e. no 31/02/2000 please )
function LeapYear(year){
  if ((year/4)   != Math.floor(year/4))   return false;
  if ((year/100) != Math.floor(year/100)) return true;
  if ((year/400) != Math.floor(year/400)) return false;
  return true;
}

// email checker, mus be of format x@x.x
function isEmail(s){
  // is it blank or any white space chars??
  if (isWhitespace(s)) return true;

  // there must be >= 1 character before @, so we
  // start looking at character position 1
  // (i.e. second character)
  var i = 1;
  var sLength = s.length;

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

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

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

  // there must be at least one character after the .
  if ((i >= sLength - 1) || (s.charAt(i) != ".")) return true;
  else return false;
}

//*******************************************************
// Form element checks
//*******************************************************

// Check selection box has received a selection
function isSelected(o) {
  if (o.selectedIndex == 0) return true;
  return false; // one was selected
}
 
//*******************************************************
// Process forms
//*******************************************************

// Display the errors that occured
function error(s){
  alert("The following errors occurred:\n"
        +"------------------------------------------------------\n"
        +s
        +"------------------------------------------------------\n"
        +"Please check your entries"
        );
  return false;
}

//*******************************************************
//                      The end
//*******************************************************