var on_switch_heat = function() {
    var state = true;
    if(document.getElementById("heat_switch").value == "ausschalten") {
        state = false;
    }
    var json_str = JSON.stringify({"id": "1", "heat": state});
    patch_sample(json_str);
}

var on_switch_water = function() {
    var state = true;
    if(document.getElementById("water_switch").value == "ausschalten") {
        state = false;
    }
    var json_str = JSON.stringify({"id": "1", "water": state});
    patch_sample(json_str);
}

var patch_http = new XMLHttpRequest();
var patch_sample = function(sample) {
    patch_http.abort();
    patch_http.open("PATCH", "/sample");
    patch_http.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
    patch_http.send(sample);
}

var get_sample = function (event) {
    var sample = JSON.parse(event)
    output = "einschalten"
    out_state = "aus"
    if(sample.water) {
        output = "ausschalten"
        out_state = "an"
    }
    document.getElementById("temperature_value").innerHTML = sample.temperature + " °C";
    document.getElementById("water_switch").value = output;
    document.getElementById("water_state").innerHTML = out_state;
    if(sample.heat) {
        output = "ausschalten"
        out_state = "an"
    } else {
        output = "einschalten"
        out_state = "aus"
    }
    document.getElementById("heat_switch").value = output;
    document.getElementById("heat_state").innerHTML = out_state;
}

var http = new XMLHttpRequest();
http.onreadystatechange = function () {
    if (http.readyState === 4) {
    var status = http.status;
    if (status === 0 || (status >= 200 && status < 400)) {
        // The request has been completed successfully
        get_sample(http.responseText);
        setTimeout(function () {
            http.open("GET", 'sample');
            http.send();
        }, 500);
        }
    } else {
        // request error
    }
}
http.open("GET", "sample");
http.send();