// Common Form Validation functions
function isEmailAddr(email)
{
  var result = false;
  var theStr = new String(email);
  var index = theStr.indexOf("@");
  if (index > 0)
  {
    var pindex = theStr.indexOf(".",index);
    if ((pindex > index+1) && (theStr.length > pindex+1))
  result = true;
  }

  return result;
}

function validRequired(formField,fieldLabel)
{
  var result = true;
  
  if (formField.value == "")
  {
    alert('Please enter a value for the "' + fieldLabel +'" field.');
    formField.focus();
    result = false;
  }
  
  return result;
}

function validChecked(formField,fieldLabel)
{
  var result = true;
	var isChecked = false;
	var isNotChecked = false;
  
  for(i=0;i<formField.length;i++) { 
		if(formField[i].checked)
			isChecked = true;
		else
			isNotChecked = true
	}
	if(!isChecked) {
  	result = false;
		alert('Please enter a value for the "' + fieldLabel +'" field.');
		formField[0].focus();
	}
  return result;
}

function validEmail(formField,fieldLabel,required)
{
  var result = true;
  
  if (required && !validRequired(formField,fieldLabel))
    result = false;

  if (result && ((formField.value.length < 3) || !isEmailAddr(formField.value)) )
  {
    alert("Please enter a complete email address in the form: yourname@yourdomain.com");
    formField.focus();
    result = false;
  }
   
  return result;

}


function validNum(formField,fieldLabel,required)
{
  var result = true;

  if (required && !validRequired(formField,fieldLabel))
    result = false;
  
   if (result)
   {
     var num = parseInt(formField.value);
     if (isNaN(num))
     {
       alert('Please enter a number for the "' + fieldLabel +'" field.');
      formField.focus();    
      result = false;
    }
  } 
  
  return result;
}

function validDate(formField,fieldLabel,required)
{
  var result = true;

  if (required && !validRequired(formField,fieldLabel))
    result = false;
  
   if (result)
   {
     var elems = formField.value.split("/");
     
     result = (elems.length == 3); // should be three components
     
     if (result)
     {
       var month = parseInt(elems[0]);
        var day = parseInt(elems[1]);
       var year = parseInt(elems[2]);
      result = !isNaN(month) && (month > 0) && (month < 13) &&
            !isNaN(day) && (day > 0) && (day < 32) &&
            !isNaN(year) && (elems[2].length == 4);
     }
     
      if (!result)

     {
       alert('Please enter a date in the format MM/DD/YYYY for the "' + fieldLabel +'" field.');
      formField.focus();    
    }
  } 
  
  return result;
}

// Function assumes field already validated for date
function validOver13(formField)
{
  var result = true;
  
  // Create date object using birth date str
  var birthDate = new Date(formField.value);
  
  // Create todays date
  var today = new Date();
  
  // getTime returns date in milliseconds, so need
  // to divide by number of milliseconds in year
  var age = (today.getTime() - birthDate.getTime())
        /(365*24*60*60*1000)


  if (age < 13)
  {
     alert('You must be over age 13 to register.');
     result = false;
  }
  
  return result;
}
// End Common Form Validation functions