// JavaScript Document
function selectTides(month,year) {
	loadTidesData(month,year);
}

function selectTidesNext() {
	var currentMonth = document.getElementById('tidesmonthselector').selectedIndex + 1;
	var currentYear = parseInt(document.getElementById('tidesyearselector').value);
	var selectMonth;
	var selectYear;
	if(currentMonth == 12)
		{
			selectMonth = 1;
			selectYear = parseInt(currentYear) + 1;
		}
		else
		{
			selectMonth = currentMonth + 1;
			selectYear = currentYear;
		}
	loadTidesData(selectMonth,selectYear);
}

function selectTidesPrevious() {
	var currentMonth = document.getElementById('tidesmonthselector').selectedIndex + 1;
	var currentYear = parseInt(document.getElementById('tidesyearselector').value);
	var selectMonth;
	var selectYear;
	if(currentMonth == 1)
		{
			selectMonth = 12;
			selectYear = parseInt(currentYear) - 1;
		}
		else
		{
			selectMonth = currentMonth - 1;
			selectYear = currentYear;
		}
	loadTidesData(selectMonth,selectYear);
}

function selectorChanged() {
var selectedMonth = document.getElementById('tidesmonthselector').selectedIndex + 1;
var selectedYear = parseInt(document.getElementById('tidesyearselector').value);	

	loadTidesData(selectedMonth,selectedYear);
}

function loadTidesData(month,year) {

var url = '/service/php/getij.php?month='+month+'&year='+year+'';
       if (window.XMLHttpRequest) { // Mozilla, Safari, ...
            httpRequest = new XMLHttpRequest();
            if (httpRequest.overrideMimeType) {
                httpRequest.overrideMimeType('text/html');
                // See note below about this line
            }
        } 
        else if (window.ActiveXObject) { // IE
            try {
                httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
                } 
                catch (e) {
                           try {
                                httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
                               } 
                             catch (e) {}
                          }
                }


        if (!httpRequest) {
            alert('Giving up :( Cannot create an XMLHTTP instance');
            return false;
        }


		httpRequest.onreadystatechange = function() 
			{
				if(httpRequest.readyState <= 3)
					{
						//document.getElementById('header-status').innerHTML = "maak een selectie (laden...)";	
					}
				if(httpRequest.readyState == 4)
					{
						if(httpRequest.status == 200)
							{
								document.getElementById('tides-container').innerHTML = httpRequest.responseText;
							}
							else
							{
								alert('There was a problem with the request.');	
							}
					}
			}

	httpRequest.open('GET', url, true);
    httpRequest.send(null);
	return httpRequest.responseText;
}