function get_cookie(Name) {

    var search = Name + "=";
    var returnvalue = "";
    
    if (document.cookie.length > 0) {
    
        offset = document.cookie.indexOf(search)
        // if cookie exists
        if (offset != -1) { 
            offset += search.length;
            // set index of beginning of value
            end = document.cookie.indexOf(";", offset);
            // set index of end of cookie value
            if (end == -1) end = document.cookie.length;
            returnvalue = unescape(document.cookie.substring(offset, end));
        }
    }
    return returnvalue;
}

function set_map(what) {
    if (what == 'none') {
        document.getElementById('map').style.display = 'none';
        document.getElementById('map_on').style.display = 'block';
        document.getElementById('map_off').style.display = 'none';
    }
    else {
        document.getElementById('map').style.display = 'block';
        document.getElementById('map_on').style.display = 'none';
        document.getElementById('map_off').style.display = 'block';
    }
    document.cookie = "map=" + what;
}

function isDate(dateStr) {
    var datePat = /^(\d{1,2})(\.)(\d{1,2})(\.)(\d{2,4})$/;
    var matchArray = dateStr.match(datePat);
    
    if (matchArray == null) {
        alert("Bitte geben Sie ein Datum im Format tt.mm.jjjj ein.");
        return false;
    }
    
    day = matchArray[1]; // parse date into variables
    month = matchArray[3];
    year = matchArray[5];
    
    if (month < 1 || month > 12) { // check month range
        alert("Der Monat muss zwischen 1 und 12 sein");
        return false;
    }
    
    if (day < 1 || day > 31) {
        alert("Der Tag muss zwischen 1 und 31 sein");
        return false;
    }
    
    if ((month==4 || month==6 || month==9 || month==11) && day==31) {
        alert("Der Monat "+month+" hat keine 31 Tage")
        return false;
    }
    
    if (month == 2) { // check for february 29th
        var isleap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
        if (day > 29 || (day==29 && !isleap)) {
            alert("Der Februar " + year + " hat keine " + day + " Tage");
            return false;
        }
    }
    return true; // date is valid
}