function getWeek(year,month,day) {
    var when = new Date(year,month,day);
    var newYear = new Date(year,0,1);
    var offset = 7 + 1 - newYear.getDay();
    if (offset == 8) offset = 1;
    var daynum = ((Date.UTC(year,when.getMonth(),when.getDate(  ),0,0,0) - Date.UTC(year,0,1,0,0,0)) /1000/60/60/24) + 1;
    var weeknum = Math.floor((daynum-offset+7)/7);
    if (weeknum == 0) {
        year--;
        var prevNewYear = new Date(year,0,1);
        var prevOffset = 7 + 1 - prevNewYear.getDay();
        if (prevOffset == 2 || prevOffset == 8) weeknum = 53; else weeknum = 52;
    }
    return weeknum;
}

function checkDatum(pageNR) {
	
	var formulier = document.forms['formulier'];
	if (pageNR == 2) {
		var chosenHour = document.getElementById("form_tijd_uur_id2").options[document.getElementById("form_tijd_uur_id2").selectedIndex].value;
		var chosenMinute = document.getElementById("form_tijd_minuten_id2").options[document.getElementById("form_tijd_minuten_id2").selectedIndex].value;
		var day = formulier.date_date2.value;
		var month = formulier.date_month2.value;
		var year = formulier.date_year2.value;
	} else {
		var chosenHour = document.getElementById("form_tijd_uur_id").options[document.getElementById("form_tijd_uur_id").selectedIndex].value;
		var chosenMinute = document.getElementById("form_tijd_minuten_id").options[document.getElementById("form_tijd_minuten_id").selectedIndex].value;
		var day = formulier.date_date.value;
		var month = formulier.date_month.value;
		var year = formulier.date_year.value;
	}
																					
	var chosenTime = parseInt(chosenHour.toString() + chosenMinute.toString());

	var currentTime = new Date()
	var currentWeekNR = getWeek(currentTime.getYear(),currentTime.getMonth(),currentTime.getDate());
	
	var nDay = currentTime.getDay();
	var hourC = currentTime.getHours() + 2
	if (hourC < 10) {
		hourC = '0'+hourC;
	}
	var minutesC = currentTime.getMinutes()
	if (minutesC < 10) {
		minutesC = '0'+minutesC;
	}
	var monthC = currentTime.getMonth() + 1
	if (monthC < 10) {
		monthC = '0'+monthC;
	}
	var monthC = monthC.toString()
	var dayC = currentTime.getDate()
	if (dayC < 10) {
		dayC = '0'+dayC;
	}
	var dayC = dayC.toString()
	var yearC = currentTime.getFullYear()
	var yearC = yearC.toString()
	
	var currentDay = dayC + monthC + yearC;
	var currentTimeOfDay = parseInt(hourC.toString() + minutesC.toString())
	
	var chosenDay = day + month + year;

	var chosen = new Date();
	var chosenWeekNR = getWeek(chosen.getYear(),chosen.getMonth(),chosen.getDate());
	chosen.setDate(day);
	chosen.setMonth(month);
	chosen.setYear(year);
	
	if (currentDay == chosenDay) {
		if (currentTimeOfDay >= chosenTime) {
			alert('U kunt via dit formulier geen reservering maken indien u binnen nu en de komende twee uur een taxi nodig heeft. Bel ons in deze gevallen.');
			return false;
		}		
	}
	
	if ((chosen.getDay() == 0 && chosenWeekNR == currentWeekNR+1) || (chosen.getDay() == 6 && chosenWeekNR == currentWeekNR)) {
		alert('U kunt geen reserveringen maken voor het komende weekend');
		return false;
	}
}