/* 
 * @author Claudio Giampaolo
 * @version 2.1.2
 * 
 * refresh shot script
 */

function updateView(data){

    let {
        src, date, time, place, timeshot, delay
    } = data || {
        delay: 300
    };
    let now = Date.now();

    document.getElementById("cam_shot").src = src + "?r=" + now;
    document.getElementById("cam_date").innerHTML = date;
    document.getElementById("cam_time").innerHTML = time;
    document.getElementById("cam_place").innerHTML = place;

    // timer
    let epoch = parseInt( now/1000 );         // ms -> s
    let tout = delay - (epoch - timeshot);
    if(tout<0)                  // in caso di blocco della webcam -> tout <0 => uso il delay suggerito
        tout = delay;
    
    setTimeout(refreshShot, tout * 1000);
}

function loadManifest(url) {
    let conn = new XMLHttpRequest();
    conn.open("GET", url, true);
    conn.onreadystatechange = (c, ev) => {

        if (conn.readyState == XMLHttpRequest.DONE)
            try{
                let json = JSON.parse(conn.responseText);
                updateView(json);
            } catch(e) {
                console.error('Error on parsing JSON response:', e.message || e);
            }
    };
    conn.send();
}

function refreshShot() {
    let url = "https://storage.googleapis.com/webcam-rol-capture/handler.manifest?r=" + Date.now();        // manifest direct link
    loadManifest(url);
}

refreshShot();