// Declaring valid date character, minimum year and maximum year
var dtCh= "/";
var minYear=1900;
var maxYear=2100;

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)
		return false;
	if (strMonth.length<1 || month<1 || month>12)
		return false;
	if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month])
		return false;
	if (strYear.length != 4 || year==0 || year<minYear || year>maxYear)
		return false;
	if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false)
		return false;
	return true;
}

function isEmail(str) {
	var at="@";
	var dot=".";
	var lat=str.indexOf(at);
	var lstr=str.length;
	var ldot=str.indexOf(dot);
	if (str.indexOf(at)==-1)
	   return false;
	if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr)
	   return false;
	if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr)
		return false;
	 if (str.indexOf(at,(lat+1))!=-1)
		return false;
	 if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot)
		return false;
	 if (str.indexOf(dot,(lat+2))==-1)
		return false;
	 if (str.indexOf(" ")!=-1)
		return false;
	 return true;				
}

function checkStartDate(dtStr) {
	var now = new Date().getTime();
	var startDt = Date.parse(dtStr);
	var diff = startDt-now;
	days = Math.ceil(diff/(1000*60*60*24));
	if (days<0)
		return false;
	return true;
}

function checkEndDate(dtStr) {
	var now = new Date().getTime();
	var endDt = Date.parse(dtStr);
	var diff = endDt-now;
	days = Math.ceil(diff/(1000*60*60*24));
	if (days>90)
		return false;
	return true;
}

function compareDates(sDt,eDt) {
	var stDt = Date.parse(sDt);
	var endDt = Date.parse(eDt);
	var diff = endDt-stDt;
	days = Math.ceil(diff/(1000*60*60*24));
	//alert(now+', '+startDt+', '+diff+', '+days);
	if (days<1)
		return false; // return date is same as or before departure date
	return true;
}

function ValidForm(the_form){

	okToGo=true;

	if (document.this_form.date_start.value=='' || !isDate(document.this_form.date_start.value)){
		alert("Please enter a valid date of departure. Format should be mm/dd/yyyy.");
		document.this_form.date_start.focus();
		return false;
	}

	if (document.this_form.date_end.value=='' || !isDate(document.this_form.date_end.value)){
		alert("Please enter a valid date of return. Format should be mm/dd/yyyy.");
		document.this_form.date_end.focus();
		return false;
	}

	if (!checkStartDate(document.this_form.date_start.value)) {
		alert("Please enter a valid date of departure. It cannot be in the past.");
		document.this_form.date_start.focus();
		return false;
	}

	if (!checkEndDate(document.this_form.date_end.value)) {
		alert("Please enter a valid date of return. It cannot be more than 90 days from now.");
		document.this_form.date_end.focus();
		return false;
	}

	if (!compareDates(document.this_form.date_start.value,document.this_form.date_end.value)) {
		alert("Please enter a valid date of return. Your return date must be after your depature date.");
		document.this_form.date_end.focus();
		return false;
	}

	if (document.this_form.customername.value==''){
		alert("Please enter your name in the Customer Name area.");
		document.this_form.customername.focus();
		return false;
	}

	if (document.this_form.email.value=='' || !isEmail(document.this_form.email.value)){
		alert("Please enter a valid email address. Coupons are delivered via email.");
		document.this_form.email.focus();
		return false;
	}

	if (okToGo) {
		document.this_form.action="generatepdf.php";
		document.this_form.submit();
	} else {
		alert('Error! Please enter valid information.');
		return false;
	}

}