function airSearchSubmit(){
	var airSearchForm = document.getElementById("flightForm");
	var flightways = airSearchForm.flightway;
	var depart = airSearchForm.depart.value;
	var arr = airSearchForm.arr.value;
	var deptime = airSearchForm.deptime.value;
	var backtime = airSearchForm.backtime.value;
	//往返标志
	var isDouble = true;
	
	if (isNullValue(depart)){
		alert("请选择出发城市！");
		return false;
	}
	
	if (isNullValue(arr)){
		alert("请选择目的城市！");
		return false;
	}
	
	if (depart == arr){
		alert("出发城市与目的城市不能相同！");
		return false;
	}
	
	if (isNullValue(deptime)){
		alert("您必须指定出发日期！");
		return false;
	}
	
	if (isNullValue(backtime)){
		isDouble = false;
		switchFlightway('single');
		setFlightway(flightways, 'single');
	} else {
		setFlightway(flightways, 'double');
	}
	
	if (isDouble){
		var differNum = dateCompare(backtime, deptime);
		
		if (differNum < 0){
			alert("您的返回日期必须在出发日期之后，请检查！");
			return false;
		}
	}
	
	return true;
}

function setFlightway(flightways, way){
	for (var i = 0 ; i < flightways.length; i ++){
		if (flightways[i].value == way){
			flightways[i].checked = true;
		} else {
			flightways[i].checked = false;
		}
	}
}

function switchFlightway(way){
	var backtime = document.getElementById("backTimeDiv");
	if (way == "double"){
		backtime.style.display = "";
	} else {
		document.getElementById("BackDate").value = "";
		backtime.style.display = "none";
	}
}

/**
 * 日期比较
 * 返回两个日期相差天数
 * 
 * @param bigDate
 * @param smallDate
 * 
 * @return int
 */
function dateCompare(bigDate, smallDate) {
	bigDate = bigDate.replace(/-/g, "/");
	smallDate = smallDate.replace(/-/g, "/");
	bigDate = new Date(bigDate);
	smallDate = new Date(smallDate);

	var days= bigDate.getTime() - smallDate.getTime();
	var time = parseInt(days / (1000 * 60 * 60 * 24));
	
	return time;
}


function isNullValue(value){
	if (value == "" || value == null){
		return true;
	}
	
	return false;
}