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 something in the "' + fieldLabel +'" field.');
    formField.focus();
    result = false;
  }
  return result;
}

function allDigits(str) {
  return inValidCharSet(str,"0123456789");
}

function inValidCharSet(str,charset) {
  var result = true;

  // Note: doesn't use regular expressions to avoid early Mac browser bugs
  for (var i=0;i<str.length;i++)
    if (charset.indexOf(str.substr(i,1))<0) {
      result = false;
      break;
    }
  return result;
}

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

  if (!required && (formField.value.length < 1))
    return 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 this format: yourname@yourdomain.com");
    formField.focus();
    result = false;
  }
  return result;
}

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

  if (!required && (formField.value.length < 1))
    return true;

  if (required && !validRequired(formField,fieldLabel))
    result = false;

  if (result) {
    if (!allDigits(formField.value)) {
      alert('Please enter a number for the "' + fieldLabel +'" field.');
      formField.focus();
      result = false;
    }
  }
  return result;
}

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

  if (!required && (formField.value.length < 1))
    return true;

  if (required && !validRequired(formField,fieldLabel))
    result = false;

  if (result) {
    var num = parseInt(formField.value,10);
    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 && (formField.value.length < 1))
    return 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],10);
       var day = parseInt(elems[1],10);
       var year = parseInt(elems[2],10);
       result = allDigits(elems[0]) && (month > 0) && (month < 13) &&
         allDigits(elems[1]) && (day > 0) && (day < 32) &&
         allDigits(elems[2]) && ((elems[2].length == 2) || (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 validComment(formField, fieldLabel, required) {
  var result = true;
  var maxchars = 2000;

  if (!required && (formField.value.length < 1))
    return true;

  if (required && !validRequired(formField,fieldLabel))
    result = false;

  if (result && (formField.value.length > maxchars)) { // if too long...trim it!
    alert('You\'ve entered too much data in the Comments text box. Please remove '+
      (formField.value.length - maxchars)+ ' characters.');

    formField.focus();
    result = false;
  }
  return result;
}

function validateForm(theForm) {
  if (!validEmail(theForm.email,"Email Address",false))
    return false;
  if (!validComment(theForm.comment,"Comments", true))
    return false;
  return true;
}