//variables
	var dt;
	var hh;
	var el;
	var co;
	var type;
	var data;
	var summary;
	summary="NULL";

// default options function 
function getopt(){ 

	select = document.getElementById('hh');
	for (var i = 0; i<=24; i++){
    	var opt = document.createElement('option');
    	opt.value = i; opt.innerHTML = i; select.appendChild(opt); }
    	document.getElementById("hh").value=0;

	select = document.getElementById('el');
	for (var i = 0; i<=90; i++){
    	var opt = document.createElement('option');
    	opt.value = i; opt.innerHTML = i; select.appendChild(opt); }
    	document.getElementById("el").value=17;
}

// date input function
$(function init() {

	$('#dtpicker').datetimepicker({
	dayOfWeekStart : 1,
	format:'dMY  H:00',
	lang:'en',
	startDate:currentDate	
	});

    	var currentDate = new Date();
	$('#dtpicker').datetimepicker({value:currentDate,step:60});
});

//read form
function read(form){ 
	dt=form.dt.value;
	hh=form.hh.value;
	el=form.el.value;
	co=form.coord.value;
	co=co.trim(co);
	co=co.replace(/["]+/g, ' ');
	co=co.replace(/[\n]+/g, 'newline');
	co=encodeURIComponent(co);
}

//  calculate and save 
function cal(type) { 

	// generate summary
	if(type == 1) { 
	document.getElementById("table").innerHTML="Please wait...Generating summary(table)...";
	$.get("./star_diff.php?dt="+ dt + "&hh=" + hh + "&el=" + el + "&co=" + co, function(data,status) {document.getElementById("table").innerHTML=data;summary=data;});
	} 

	if(type == 2) { //download summary 
	if(summary == "NULL") {  alert("please calculate before save");exit;} 
	download("summary.txt",summary); 
	} 
}

function download(filename, summary) {
  	var element = document.createElement('a');
        element.setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(summary));
  	element.setAttribute('download', filename);
  	element.style.display = 'none';
  	document.body.appendChild(element);
  	element.click();
  	document.body.removeChild(element);
}