/*********************************
        DATE VALIDATION
**********************************/

// Declaring valid date character, minimum year and maximum year
var dtCh = "/";
var MIN_YEAR = 2000;
var MAX_YEAR = 2100;
var DATE_FORMAT = "Date format should be mm/dd/yyyy";
var MONTH_VALIDATION = "Please enter a valid month!";
var DAY_VALIDATION = "Please enter a valid day!";
var DATE_VALIDATI0N = "Please enter a valid date!";
var YEAR_VALIDATION = "Please enter a valid 4-digit year between " + MIN_YEAR + " and " + MAX_YEAR + "!";
var INNER_HTML = "";

function ValidateDate(strInnerHTML, strDate)
{
    INNER_HTML = strInnerHTML;
    var date = strDate;
    if (isDate(date))
        return true;
    
    return false;        
}

function isInteger(s)
{
    var i;
    for (i = 0; i < s.length; i++)
    {   
        // Check that current character is number.
        var c = s.charAt(i);
        if (((c < "0") || (c > "9"))) return false;
    }
    // All characters are numbers.
    return true;
}

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++)
    {   
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) 
            returnString += c;
    }

    return returnString;
}

function daysInFebruary (year)
{
    // February has 29 days in any year evenly divisible by four,
    // EXCEPT for centurial years which are not also divisible by 400.
    return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
}

function DaysArray(n) 
{
    for (var i = 1; i <= n; i++) 
    {
        this[i] = 31
        if (i==4 || i==6 || i==9 || i==11) 
            this[i] = 30;
            
        if (i==2) 
            this[i] = 29;
    } 

    return this;
}

function isDate(dtStr)
{
    var daysInMonth = DaysArray(12);
    var pos1 = dtStr.indexOf(dtCh);
    var pos2 = dtStr.indexOf(dtCh, pos1+1);
    var strMonth = dtStr.substring(0, pos1);
    var strDay = dtStr.substring(pos1+1, pos2);
    var strYear = dtStr.substring(pos2+1);
    strYr = strYear;

    if (strDay.charAt(0)=="0" && strDay.length>1) 
        strDay = strDay.substring(1);

    if (strMonth.charAt(0)=="0" && strMonth.length>1) 
        strMonth = strMonth.substring(1);

    for (var i = 1; i <= 3; i++) 
    {
        if (strYr.charAt(0) == "0" && strYr.length > 1) 
            strYr = strYr.substring(1);
    }

    month = parseInt(strMonth);
    day = parseInt(strDay);
    year = parseInt(strYr);

    if (pos1 == -1 || pos2 == -1)
    {
        //alert(DATE_FORMAT);
        setInnerHTML(INNER_HTML, DATE_FORMAT);
        return false;
    }

    if (strMonth.length<1 || month<1 || month>12)
    {
        //alert(MONTH_VALIDATION);
        setInnerHTML(INNER_HTML, MONTH_VALIDATION);
        return false;
    }

    if (strDay.length<1 || day<1 || day>31 || (month==2 && day > daysInFebruary(year)) || day > daysInMonth[month])
    {
        //alert(DAY_VALIDATION);
        setInnerHTML(INNER_HTML, DAY_VALIDATION);
        return false;
    }

    if (strYear.length != 4 || year == 0 || year < MIN_YEAR || year > MAX_YEAR)
    {
        //alert(YEAR_VALIDATION);
        setInnerHTML(INNER_HTML, YEAR_VALIDATION);
        return false;
    }

    if (dtStr.indexOf(dtCh, pos2 + 1) != -1 || isInteger(stripCharsInBag(dtStr, dtCh)) == false)
    {
        //alert(DATE_VALIDATI0N);
        setInnerHTML(INNER_HTML, DATE_VALIDATI0N);
        return false;
    }

    return true;
}