/**
 * DHTML date validation script. Courtesy of SmartWebby.com (http://www.smartwebby.com/dhtml/)
 */
// Declaring valid date character, minimum year and maximum year
var dtCh= "/";
var minYear=1850;
var maxYear=4000;

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 bissextile(annee) {
	if (annee%4==0 && annee %100!=0 || annee%400==0) return true; else return false
}

function nb_01_01(date){
	nb_mois=new Array(13);
	nb_mois=[,0,31,59,90,120,151,181,212,243,273,304,334];
	j=eval(date[0]) ; m=eval(date[1]) ; a=eval(date[2]);
	nb=nb_mois[m]+j-1 ;
	if (bissextile(a) && m>2) nb++;
	return nb;
}

function nb_jour_annee(a1,a2){
	n=0;
	if (a1==a2) n=0 ; else
	for (i=a1; i<a2; i++) {n += 365; if (bissextile(i)) n++}
	return n;
}

function isDate(dtStr){
	var daysInMonth = 	DaysArray(12)
	var pos1		=	dtStr.indexOf(dtCh)
	var pos2		=	dtStr.indexOf(dtCh,pos1+1)
	var strDay		=	dtStr.substring(0,pos1)
	var strMonth	=	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)
	var date1 		= 	[day,month,year];

	if (pos1==-1 || pos2==-1){
		alert(dtStr+" : La date doit etre sous forme : jj/mm/aaaa");
		return false;
	}
	if (strMonth.length<1 || month<1 || month>12){
		alert(dtStr+" : Veuillez entrer un mois valide");
		return false;
	}
	if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]){
		alert(dtStr+" : Veuillez entrer un jour valide");
		return false;
	}
	if (strYear.length != 4 || year==0 || year<minYear || year>maxYear){
		alert(dtStr+" : Veuillez entrer une annee sur 4 chiffres entre "+minYear+" et "+maxYear);
		return false;
	}
	if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false){
		alert(dtStr+" : Veuillez entrer une date valide");
		return false;
	}
	
	var now 	= 	new Date();
	var jour 	= 	eval(now.getUTCDate());
	var mois 	= 	eval(now.getMonth());
	var an 		= 	eval(now.getFullYear());
	if (String(an).length < 4 ) an+=1900; 
	mois 		= 	mois+1;
	var date2	=	[jour,mois,an];	
	
	nb=nb_jour_annee(date1[2],date2[2]) - nb_01_01(date1) + nb_01_01(date2);
	
	if(an-year==18 && month==mois){
		if(jour>=strDay){
			return true;
		}else{
			alert ('Vous devez avoir au moins 18 ans pour pouvoir vous inscrire!');
			return false;
		}
	}
	
	if(nb/365 < 18){
		alert ('Vous devez avoir au moins 18 ans pour pouvoir vous inscrire!');
		return false;
	}	

	return true;
}