function handleHttpResponseModels() {
	if (httpModels.readyState == 4) {

		if(httpModels.status==200) {
			var results=httpModels.responseText;
			document.getElementById('model_div').innerHTML = "<select name='model' id='model' onchange='requestYears();'>"+results+"</select>";
			document.getElementById('year_div').innerHTML = "<select name='year' id='year' onchange='requestModifications();'></select>";
			document.getElementById('modification_div').innerHTML = "<select name='modification' id='modification'  onchange='requestResult();'></select>";
			document.getElementById('result').innerHTML = "";
		}
	}
}

function requestModels() {
	var mark = document.getElementById("mark").value;
	httpModels.open("GET", "ajax/getModels.php?mark=" + escape(mark), true);
	httpModels.onreadystatechange = handleHttpResponseModels;
	httpModels.send(null);
}

function getHTTPObject() {
	var xmlhttp;

	if(window.XMLHttpRequest){
		xmlhttp = new XMLHttpRequest();
	}
	else if (window.ActiveXObject){
		xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
		
		if (!xmlhttp){
			xmlhttp=new ActiveXObject("Msxml2.XMLHTTP");
		}
	}
  return xmlhttp;
}

var httpModels = getHTTPObject(); // We create the HTTP Object


function handleHttpResponseYears() {
	if (httpYears.readyState == 4) {

		if(httpYears.status==200) {
			var results=httpYears.responseText;
			document.getElementById('year_div').innerHTML = "<select name='year' id='year'  onchange='requestModifications();'>"+results+"</select>";
			document.getElementById('modification_div').innerHTML = "<select name='modification' id='modification'   onchange='requestResult();'></select>";
			document.getElementById('result').innerHTML = "";
		}
	}
}

function requestYears() {
	var mark = document.getElementById("mark").value;
	var model = document.getElementById("model").value;
	httpYears.open("GET", "ajax/getYears.php?mark=" + escape(mark) + "&model=" + escape(model), true);
	httpYears.onreadystatechange = handleHttpResponseYears;
	httpYears.send(null);
}

var httpYears = getHTTPObject(); // We create the HTTP Object



function handleHttpResponseModifications() {
	if (httpModifications.readyState == 4) {

		if(httpModifications.status==200) {
			var results=httpModifications.responseText;
			document.getElementById('modification_div').innerHTML = "<select name='modification' id='modification'   onchange='requestResult();'>"+results+"</select>";
			document.getElementById('result').innerHTML = "";
		}
	}
}

function requestModifications() {
	var mark = document.getElementById("mark").value;
	var model = document.getElementById("model").value;
	var year = document.getElementById("year").value;
	httpModifications.open("GET", "ajax/getModifications.php?mark=" + escape(mark) + "&model=" + escape(model) + "&year=" + escape(year), true);
	httpModifications.onreadystatechange = handleHttpResponseModifications;
	httpModifications.send(null);
}

var httpModifications = getHTTPObject(); // We create the HTTP Object


function handleHttpResponseResult() {
	if (httpResult.readyState == 4) {

		if(httpResult.status==200) {
			var results=httpResult.responseText;
			document.getElementById('result').innerHTML = results;
		}
	}
}

function requestResult() {
	var mark = document.getElementById("mark").value;
	var model = document.getElementById("model").value;
	var year = document.getElementById("year").value;
	var modify = document.getElementById("modification").value;
	httpResult.open("GET", "ajax/getResult.php?mark=" + escape(mark) + "&model=" + escape(model) + "&year=" + escape(year) + "&modify=" + escape(modify), true);
	httpResult.onreadystatechange = handleHttpResponseResult;
	httpResult.send(null);
}

var httpResult = getHTTPObject(); // We create the HTTP Object