async function POST(path, data={}) {
    return new Promise(function (onSuccess, onError) {
        var xhr = new XMLHttpRequest();
        xhr.open('POST', path, true);
        xhr.setRequestHeader('Content-Type', 'application/json');
        xhr.onreadystatechange = function () {
            if (xhr.readyState === 4) {
                if (xhr.status === 200) {
                    onSuccess(xhr);
                } else {
                    onError(xhr);
                }
            }
        };

        xhr.onerror = () => onError(xhr);
        xhr.send(JSON.stringify(data));
    });
}

function assert(condition, message) {
    if (!condition) {
        throw message || "Assertion failed";
    }
}

async function transmit(transmitterID, channel, action, shockerPin, intensity=0, lucalEncoded=false) {
    assert(typeof transmitterID === 'number');
    assert(typeof channel === 'number');
    assert(['shock', 'vibrate', 'beep'].includes(action));
    assert(typeof shockerPin === 'number');
    assert(typeof intensity === 'number');
    assert(typeof lucalEncoded === 'boolean');
    POST('/transmit', {transmitterID: transmitterID, channel: channel, action: action, shockerPin: shockerPin, intensity: intensity, lucalEncoded: lucalEncoded});
}



async function txFromUI(action, intensity=0) {
    let transmitterID = Number(document.getElementById('transmitterIDInput').value);
    let channel = Number(document.getElementById('channelIDInput').value);
    let lucalEncoded = document.getElementById('lucalEncodedInput').checked;
    let shockerPin = Number(document.getElementById('shockerPinInput').value);
    transmit(transmitterID, channel, action, shockerPin, intensity, lucalEncoded);
}

async function shock() {
    let intensity = Number(document.getElementById('shockIntensity').value);
    txFromUI('shock', intensity);
}

async function vibrate() {
    let intensity = Number(document.getElementById('vibrateIntensity').value);
    txFromUI('vibrate', intensity);
}

async function beep() {
    txFromUI('beep');
}