// VARIABLE DECLARATIONS

var digits = "0123456789";

var lowercaseLetters = "abcdefghijklmnopqrstuvwxyz";

var uppercaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";


// whitespace characters
var whitespace = " \t\n\r";

// non-digit characters which are allowed in phone numbers
var phoneNumberDelimiters = "()- ";


// characters which are allowed in US phone numbers
var validUSPhoneChars = digits + phoneNumberDelimiters;

// U.S. phone numbers have 10 digits.
// They are formatted as 123 456 7890 or (123) 456-7890.
var digitsInUSPhoneNumber = 10;

// CONSTANT STRING DECLARATIONS
// (grouped for ease of translation and localization)

// m is an abbreviation for "missing"

var mPrefix = "You did not enter a value into the ";
var mSuffix = " field. This is a required field. Please enter it now.";

// s is an abbreviation for "string"

var sUSLastName = "Last Name";
var sUSFirstName = "First Name";
var sCity = "City";
var sPhone = "Home Phone Number";
var sWorkPhone = "Work Phone Number";
var sEmail = "Email";
var sBestTime = "Best time to call";

// i is an abbreviation for "invalid"

var iUSPhone = "This field must be a 10 digit U.S. phone number (like 415 555 1212). Please reenter it now.";
var iEmail = "This field must be a valid email address (like foo@bar.com). Please reenter it now.";

// p is an abbreviation for "prompt"

var pEntryPrompt = "Please enter a ";
var pUSPhone = "10 digit U.S. phone number (like 415 555 1212).";
var pEmail = "valid email address (like foo@bar.com).";
var pBestTime = "Best time to call.";

var defaultEmptyOK = false;


// non-digit characters which are allowed in phone numbers
var phoneNumberDelimiters = "()- ";

// Display data entry prompt string s in status bar.

function promptEntry (s)
{   window.status = pEntryPrompt + s;
}


function isWhitespace (s)

{   var i;

    // Is s empty?
    if (isEmpty(s)) return true;

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);

        if (whitespace.indexOf(c) == -1) return false;
    }

    // All characters are whitespace.
    return true;
}

function warnEmpty (theField, s)
{   
    alert(mPrefix + s + mSuffix);
    theField.focus();
    theField.select(); 
    return false;
}

function warnInvalid (theField, s)
{   
    alert(s);
    theField.focus();
    theField.select();    
    return false;
}

function reformat (s)

{   var arg;
    var sPos = 0;
    var resultString = "";

    for (var i = 1; i < reformat.arguments.length; i++) {
       arg = reformat.arguments[i];
       if (i % 2 == 1) resultString += arg;
       else {
           resultString += s.substring(sPos, sPos + arg);
           sPos += arg;
       }
    }
    return resultString;
}

function reformatUSPhone (USPhone)
{   return (reformat (USPhone, "(", 3, ") ", 3, "-", 4));
}

// Check whether string s is empty.

function isEmpty(s)
{   return ((s == null) || (s.length == 0));
}

// Removes all characters which appear in string bag from string s.

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++)
    {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) returnString += c;
    }

    return returnString;
}

function isDigit (c)
{   return ((c >= "0") && (c <= "9"));
}

function isInteger (s)

{   var i;

    if (isEmpty(s)) 
       if (isInteger.arguments.length == 1) return defaultEmptyOK;
       else return (isInteger.arguments[1] == true);

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character is number.
        var c = s.charAt(i);

        if (!isDigit(c)) return false;
    }

    // All characters are numbers.
    return true;
}

function isEmail (s)
{   if (isEmpty(s)) 
       if (isEmail.arguments.length == 1) return defaultEmptyOK;
       else return (isEmail.arguments[1] == true);
   
    // is s whitespace?
    if (isWhitespace(s)) return false;
    
    // 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 false;
    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 false;
    else return true;
}

function isUSPhoneNumber (s)
{   if (isEmpty(s)) 
       if (isUSPhoneNumber.arguments.length == 1) return defaultEmptyOK;
       else return (isUSPhoneNumber.arguments[1] == true);
    return (isInteger(s) && s.length == digitsInUSPhoneNumber);
}

function checkUSPhone (theField, emptyOK)
{   if (checkUSPhone.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else
    {  var normalizedPhone = stripCharsInBag(theField.value, phoneNumberDelimiters)
       if (!isUSPhoneNumber(normalizedPhone, false)) 
          return warnInvalid (theField, iUSPhone);
       else 
       {  // if you don't want to reformat as (123) 456-789, comment next line out
          theField.value = reformatUSPhone(normalizedPhone)
          return true;
       }
    }
}

function checkPhone (theField)
{   
    if (isEmpty(theField.value)) return false;
    else
    {  var normalizedPhone = stripCharsInBag(theField.value, phoneNumberDelimiters)
       if (!isUSPhoneNumber(normalizedPhone, false)) 
          return false;
       else 
       {  // if you don't want to reformat as (123) 456-789, comment next line out
          //theField.value = reformatUSPhone(normalizedPhone)
          return true;
       }
    }
}

function checkString (theField, s, emptyOK)
{   // Next line is needed on NN3 to avoid "undefined is not a number" error
    // in equality comparison below.
    if (checkString.arguments.length == 2) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    if (isWhitespace(theField.value)) 
       return warnEmpty (theField, s);
    else return true;
}


function checkEmail (theField, emptyOK)
{   if (checkEmail.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else if (!isEmail(theField.value, false)) 
       return warnInvalid (theField, iEmail);
    else return true;
}