function $(id) {
    return document.getElementById( id );
}

function langalert(lang) {
	if ( lang == 'en') {
		alert('This website is under construction!\nPlease visit later!');
	}
	if ( lang == 'de') {
		alert('An dieser Website wird gerade gebaut.\nBitte schauen Sie später noch einmal vorbei.');
	}
}

var old_table_image = '';
var is_opened_image  = 'none';

function toggle_image( image ) {

    table_obj = document.getElementById(image);
    is_opened_image = table_obj.style.display;

	if (image != 'i01' && document.getElementById('i01') != null)
	{
		document.getElementById('i01').style.display = 'none';
	}

    if (old_table_image != '' && is_opened_image == 'none') {
        old_table_obj = document.getElementById(old_table_image);
        old_table_obj.style.display = 'none';
    }

    if (old_table_image != image || is_opened_image == 'none') {

        table_obj.style.display = 'block';
    }

    old_table_image = image;
}


var old_link = '';

function toggle( block ) {
	
	for ( i=0; i<2; i++ )
	{
		if ( document.getElementById('a0'+i) !== null ) { 
			document.getElementById('a0'+i).style.display = 'none';
		}

		document.getElementById(block).style.display = 'block';
	}

}

var old_table = '';
var is_opened  = 'none';


function show( image, def_image ) {

	if ( def_image )	{
		image = 'a01';
	}

    table_obj = document.getElementById(image);
    is_opened = table_obj.style.display;

	if (image != 'a01')
	{
		document.getElementById('a01').style.display = 'none';
	}

    if (old_table != '' && is_opened == 'none') {
        old_table_obj = document.getElementById(old_table);
        old_table_obj.style.display = 'none';
    }

    if (old_table != image || is_opened == 'none') {

        table_obj.style.display = 'block';
    }

    old_table = image;
}

function generateDate( id ) {
    var year = $( id + '_year' ).value;
    var month = $( id + '_month' ).value-1;
    var day = $( id + '_day' ).value;

    var date = new Date(year, month, day, 1, 1, 1);
    return date;
}

function getDayDiff() {
    var date1 = generateDate('arrive');
    var date2 = generateDate('departure');

    var diff = date2-date1;

    var dayDiff = Math.floor(diff/1000/60/60/24);

    return dayDiff;
}

function getWeekDay( id ) {
    var date = generateDate( id );

    return date.getDay();
}