// whitespace characters: ' ', '\t', '\r', '\n'
var whitespace = " \t\n\r";

// isEmpty: Check whether string strVal is empty
function isEmpty(strVal)
{
  return ((strVal == null) || (strVal.length == 0));
}

// isWhitespace: Check if string strVal has only the whitespace characters
function isWhitespace(strVal)
{
  var nPos = 0;

  if (isEmpty(strVal))
    return false;

  for (nPos = 0; nPos < strVal.length; nPos++)
    if (whitespace.indexOf(strVal.charAt(nPos)) == -1)
      return false;

  return true;
}

// rtrim: Right trim the string and return the trimmed value
function rtrim(strVal)
{
  var nPos = 0;

  if (isEmpty(strVal))
    return strVal;

  for (nPos = strVal.length-1; nPos >= 0; nPos--) {
    if (whitespace.indexOf(strVal.charAt(nPos)) == -1)
      break;
  }

  return (nPos == strVal.length-1 ? strVal.substring(0) : strVal.substring(0, nPos+1));
}

// ltrim: Left trim the string and return the trimmed value
function ltrim(strVal)
{
  var nPos = 0;

  if (isEmpty(strVal))
    return strVal;

  for (nPos = 0; nPos < strVal.length; nPos++) {
    if (whitespace.indexOf(strVal.charAt(nPos)) == -1)
      break;
  }

  return strVal.substring(nPos);
}

// alltrim: Trim the string on left and right, and return the trimmed value
function alltrim(strVal)
{
  return (isEmpty(strVal) ? strVal:ltrim(rtrim(strVal)));
}

/********************************************************
 replace: useful for JavaScript 1.0 and 1.1 where replace 
    is not available. With JavaScript 1.2 (and above)
    replace function is available.
  : replaces one occurrence of strVal with strWith in strSrc
********************************************************/
function replace(strSrc, strVal, strWith)
{
  var nPos = 0, strLeft="", strRight="";

  // check if empty (or) no string is found to replace
  if (isEmpty(strSrc) || (strSrc.indexOf(strVal) < 0))
    return strSrc;

  nPos = strSrc.indexOf(strVal);
  strLeft = strSrc.substring(0, nPos);
  nPos += strVal.length;
  strRight = strSrc.substring(nPos);

  return (strLeft + strWith + strRight);
}

// replaceall : replace all occurrences of strVal with strWith in strSrc
function replaceall(strSrc, strVal, strWith)
{
  var strBuffer=strSrc;

  while (strBuffer.indexOf(strVal) >= 0)
    strBuffer = replace(strBuffer, strVal, strWith);

  return (strBuffer);
}

// occurs: return no of occurrences of strVal within strSrc
function occurs(strVal, strSrc)
{
  var nCnt = 0, strBuffer=strSrc;

  while (strBuffer.indexOf(strVal) >= 0)
  {
    strBuffer = replace(strBuffer, strVal, "");
    nCnt++;
  }

  return (nCnt);
}

// replicate: returns string that contains strVal repeated nCnt times
function replicate(strVal, nCnt)
{
  var i = 0, strBuffer = "";

  for (i = 0; i < nCnt; i++)
    strBuffer += strVal;

  return (strBuffer);
}

/**************************************************************
 stuff: returns string after replacing nCnt characters (starting
  from nStartPos) with strReplacement in strSrc. 

 NOTE: starting position is 0
**************************************************************/
function stuff(strSrc, nStartPos, nCnt, strReplacement)
{
  var strLeft= "", strRight="";

  // check boundary values
  if (nCnt < 0 || nStartPos < 0 || (nStartPos > strSrc.length-1))
    return strSrc;

  strLeft = strSrc.substring(0, nStartPos);
  strRight = strSrc.substring(nStartPos+nCnt);

  return (strLeft + strReplacement + strRight);
}
// whitespace characters: ' ', '\t', '\r', '\n'
var whitespace = " \t\n\r";

// isEmpty: Check whether string strVal is empty
function isEmpty(strVal)
{
  return ((strVal == null) || (strVal.length == 0));
}

// isWhitespace: Check if string strVal has only the whitespace characters
function isWhitespace(strVal)
{
  var nPos = 0;

  if (isEmpty(strVal))
    return false;

  for (nPos = 0; nPos < strVal.length; nPos++)
    if (whitespace.indexOf(strVal.charAt(nPos)) == -1)
      return false;

  return true;
}

// rtrim: Right trim the string and return the trimmed value
function rtrim(strVal)
{
  var nPos = 0;

  if (isEmpty(strVal))
    return strVal;

  for (nPos = strVal.length-1; nPos >= 0; nPos--) {
    if (whitespace.indexOf(strVal.charAt(nPos)) == -1)
      break;
  }

  return (nPos == strVal.length-1 ? strVal.substring(0) : strVal.substring(0, nPos+1));
}

// ltrim: Left trim the string and return the trimmed value
function ltrim(strVal)
{
  var nPos = 0;

  if (isEmpty(strVal))
    return strVal;

  for (nPos = 0; nPos < strVal.length; nPos++) {
    if (whitespace.indexOf(strVal.charAt(nPos)) == -1)
      break;
  }

  return strVal.substring(nPos);
}

// alltrim: Trim the string on left and right, and return the trimmed value
function alltrim(strVal)
{
  return (isEmpty(strVal) ? strVal:ltrim(rtrim(strVal)));
}

/********************************************************
 replace: useful for JavaScript 1.0 and 1.1 where replace 
    is not available. With JavaScript 1.2 (and above)
    replace function is available.
  : replaces one occurrence of strVal with strWith in strSrc
********************************************************/
function replace(strSrc, strVal, strWith)
{
  var nPos = 0, strLeft="", strRight="";

  // check if empty (or) no string is found to replace
  if (isEmpty(strSrc) || (strSrc.indexOf(strVal) < 0))
    return strSrc;

  nPos = strSrc.indexOf(strVal);
  strLeft = strSrc.substring(0, nPos);
  nPos += strVal.length;
  strRight = strSrc.substring(nPos);

  return (strLeft + strWith + strRight);
}

// replaceall : replace all occurrences of strVal with strWith in strSrc
function replaceall(strSrc, strVal, strWith)
{
  var strBuffer=strSrc;

  while (strBuffer.indexOf(strVal) >= 0)
    strBuffer = replace(strBuffer, strVal, strWith);

  return (strBuffer);
}

// occurs: return no of occurrences of strVal within strSrc
function occurs(strVal, strSrc)
{
  var nCnt = 0, strBuffer=strSrc;

  while (strBuffer.indexOf(strVal) >= 0)
  {
    strBuffer = replace(strBuffer, strVal, "");
    nCnt++;
  }

  return (nCnt);
}

// replicate: returns string that contains strVal repeated nCnt times
function replicate(strVal, nCnt)
{
  var i = 0, strBuffer = "";

  for (i = 0; i < nCnt; i++)
    strBuffer += strVal;

  return (strBuffer);
}

/**************************************************************
 stuff: returns string after replacing nCnt characters (starting
  from nStartPos) with strReplacement in strSrc. 

 NOTE: starting position is 0
**************************************************************/
function stuff(strSrc, nStartPos, nCnt, strReplacement)
{
  var strLeft= "", strRight="";

  // check boundary values
  if (nCnt < 0 || nStartPos < 0 || (nStartPos > strSrc.length-1))
    return strSrc;

  strLeft = strSrc.substring(0, nStartPos);
  strRight = strSrc.substring(nStartPos+nCnt);

  return (strLeft + strReplacement + strRight);
}

// isDigit: check if val has digits (0-9)
function isDigit(val)
{
  var strBuffer = new String(val);
  var nPos = 0;

  if (isEmpty(strBuffer))
    return false;

  for (nPos = 0; nPos < strBuffer.length; nPos++)
    if (strBuffer.charAt(nPos) < '0' || strBuffer.charAt(nPos) > '9')
      return false;

  return true;
}

// isAlpha: check if val has alphabets only (a-z, A-Z)
function isAlpha(val)
{
  var strBuffer = new String(val);
  var nPos = 0;

  if (isEmpty(strBuffer))
    return false;

  for (nPos = 0; nPos < strBuffer.length; nPos++)
    if (!((strBuffer.charAt(nPos) >= 'a' && strBuffer.charAt(nPos) <= 'z') ||
      (strBuffer.charAt(nPos) >= 'A' && strBuffer.charAt(nPos) <= 'Z')))
      return false;

  return true;
}

// isInteger: check if nVal is integer type
function isInteger(nVal)
{
  var strBuffer = new String(nVal);
  var nPos = 0, nStart = 0;

  if (isEmpty(strBuffer))
    return true;
  if (isWhitespace(strBuffer))
    return false;

  // check if -ve or +ve sign occurs in the beginning
  if ((strBuffer.charAt(0) == '-') || (strBuffer.charAt(0) == '+'))
    nStart = 1;
  else
    nStart = 0;

  for (nPos = nStart; nPos < strBuffer.length; nPos++)
    if (strBuffer.charAt(nPos) < '0' || strBuffer.charAt(nPos) > '9')
      return false;

  return true;	
}

// isFloat: check if fVal is floating-point type
//	LIMITATION: no scientific notation (for eg: xxxx.xxE+xx)
function isFloat(fVal)
{
  var strBuffer = new String(fVal);
  var nPos = 0, nStart = 0;

  if (isEmpty(strBuffer))
    return true;
  if (isWhitespace(strBuffer))
    return false;

  // check if -ve or +ve sign occurs in the beginning
  if ((strBuffer.charAt(0) == '-') || (strBuffer.charAt(0) == '+'))
    nStart = 1;
  else
    nStart = 0;

  for (nPos = nStart; nPos < strBuffer.length; nPos++)
    if ((strBuffer.charAt(nPos) < '0' || strBuffer.charAt(nPos) > '9') && 
	(strBuffer.charAt(nPos) != '.'))
      return false;

  return true;
}

/************************************************************
isDate	: Check if dVal is valid date
  : valid date format - 
    MM (or) M / DD (or) D / Y (or) YY (or) YYYY
  : YY > 50 should be 19YY
  : YY <= 50 should be 20YY
*************************************************************/
function isDate(dVal)
{
  var strBuffer= new String(dVal);
  var cDelimiter='';
  var strMonth=0, strDay=0, strYear=0;
  var nPos=-1;

  if (isEmpty(strBuffer))
    return true;
  if (isWhitespace(strBuffer))
    return false;

  // Get the delimiter used
  if (occurs('/', strBuffer) == 2)
    cDelimiter = '/';
  else if (occurs('-', strBuffer) == 2)
    cDelimiter = '-';

  // If no '/' or '-' found return false
  if (cDelimiter == '')
    return false;

  // validate month, date, and year (Y, YY, YYYY are valid year formats)
  nPos = strBuffer.indexOf(cDelimiter);
  strMonth = strBuffer.substring(0, nPos);
  if (strMonth.length > 2 || !isDigit(strMonth))
    return false;
  strBuffer = strBuffer.substring(nPos+1);
  nPos = strBuffer.indexOf(cDelimiter);
  strDay = strBuffer.substring(0, nPos);
  if (strDay.length > 2 || !isDigit(strDay))
    return false;
  strBuffer = strBuffer.substring(nPos+1);
  strYear = strBuffer;
  if ((strYear.length > 4) || (strYear.length == 3) || !isDigit(strYear))
    return false;

  // if YY < 50 then YYYY=20YY, else if YY >= 50 then YYYY=19YY
  var iYear = parseInt(strYear);
  if (iYear < 50)
    strYear = "20" + (strYear < 10 ? '0' + strYear:strYear);
  else if (iYear >= 50 && iYear < 100)
    strYear = "19" + strYear;

  strBuffer = strMonth + cDelimiter + strDay + cDelimiter + strYear;

  // validate date
  var dBuffer = new Date(strBuffer);
  if (dBuffer.getDate() != parseInt(strDay) || 
	dBuffer.getMonth()+1 != parseInt(strMonth) || 
	dBuffer.getFullYear() != parseInt(strYear))
    return false;

  return true;
}

// isZipcode: check if valid US zip code (##### or #####-####)
function isZipcode(strZip)
{
  var strLeft="", strRight="", strVal = new String(strZip);

  if (isEmpty(strVal))
    return true;
  if (isWhitespace(strVal))
    return false;

  if (strVal.length != 5 && strVal.length != 10)
    return false;

  if ((strVal.length == 5) && isDigit(strVal))
    return true;

  if ((strVal.length == 10) && isDigit(strVal.substring(0, 5)) && 
	isDigit(strVal.substring(6)))
    return true;

  return false;
}

// isDatePart: check if nVal is valid day: 1-31, month:1-12, year:YYYY
function isDatePart(nVal, strType)
{
  var strBuffer = new String(nVal);

  if (isEmpty(strBuffer) || isWhitespace(strBuffer))
    return false;
  
  nVal = parseInt(strBuffer);
  if (!isDigit(nVal))
    return false;

  if ((strType == "Year") && (nVal < 0 || (nVal > 99 && nVal < 1000) || nVal > 9999))
    return false;
  else if ((strType == "Month") && (nVal < 1 || nVal > 12))
    return false;
  else if ((strType == "Day") && (nVal < 1 || nVal > 31))
    return false;

  return true;
}

/**********************************************************************
Depends on: 	alltrim(), isEmpty(), replaceall()
  	isFloat(), isDigit(), isZipcode()
    
NOTE: 
  -- always alltrim field value before calling any of these functions
  -- if field is empty, the function call will return true
**********************************************************************/

function checkField(objFld, strType)
{
  objFld.value = alltrim(objFld.value);
  if (isEmpty(objFld.value))
    return true;

  // Remove commas from Integer and Float fields
  if ((strType == "Integer") || (strType == "Float"))
    objFld.value = replaceall(objFld.value, ",", "");

  if ((strType == "Digit") && !isDigit(objFld.value)) {
    alert("Please enter a response in numerical format (please " + 
      "exclude dollar signs, commas, parenthesis or any other " + 
      "non-numeric symbols).");
    objFld.value = "";
    objFld.focus();
    return false;
  }

  if (strType == "Integer") 
    if (!isInteger(parseInt(objFld.value))) {
      alert("Please enter a response in numerical format (please " + 
	"exclude dollar signs, commas, parenthesis or any other " + 
	"non-numeric symbols).");
      objFld.value = "";
      objFld.focus();
      return false;
    }
    else
      objFld.value = parseInt(objFld.value);

  if (strType == "Float") 
    if (!isFloat(parseFloat(objFld.value))) {
      alert("Please enter a response in numerical format (please " + 
	"exclude dollar signs, commas, parenthesis or any other " + 
	"non-numeric symbols).");
      objFld.value = "";
      objFld.focus();
      return false;
    }
    else
      objFld.value = parseFloat(objFld.value);

  if (strType == "ZIP") 
    if (!isZipcode(objFld.value)) {
      alert("Please enter valid zip code value");
      objFld.value = "";
      objFld.focus();
      return false;
    }

  if (strType == "Date") 
    if (!isDate(objFld.value)) {
      alert("Please enter valid date value (MM/DD/YYYY)");
      objFld.value = "";
      objFld.focus();
      return false;
    }

  if (strType == "DatePartYear" && checkField(objFld, "Digit")) {
    if (!isDatePart(objFld.value, "Year")) {
      alert("Please enter valid year value");
      objFld.value = "";
      objFld.focus();
      return false;
    }
    else if (objFld.value < 100)
      objFld.value = (objFld.value < 50 ? 2000:1900) + parseInt(objFld.value);
  }

  return true;
}