const ws_url = new URL('ws', window.location.href);
ws_url.protocol = ws_url.protocol.replace('http', 'ws');
const ws = new WebSocket(ws_url.href);

ws.onmessage = function(event) {
    const msg = JSON.parse(event.data);

    console.log(msg);

    if (msg.hasOwnProperty('currentsession')) {
        document.getElementById('current_session').innerText = msg.currentsession;
    }
    if (msg.hasOwnProperty('username')) {
        document.getElementById('greeting').innerText = "Hello, " + msg.username + "!";
    }

    if (msg.hasOwnProperty('allsessions')) {
        const all_sessions = document.getElementById('all_sessions');

        while (all_sessions.children.length) all_sessions.lastChild.remove();

        for (let session of msg.allsessions) {
            const button = document.createElement('button');
            button.innerText = session;
            button.onclick = async (e) => await fetch('api/join_session', {
                method: 'POST', body: JSON.stringify({sessionid: session})
            });
            all_sessions.appendChild(button);
        }
    }
};