(function() {
    var startTs = Date.now();
    var mouseMoved = false;
    var mouseMoveCount = 0;
    var clickCount = 0;
    var keydownCount = 0;
    var scrollCount = 0;
    var copyDetected = false;
    var pasteDetected = false;
    var tabHiddenCount = 0;
    var tabHiddenDuration = 0;
    var tabHiddenStart = null;
    var windowBlurCount = 0;
    var windowBlurDuration = 0;
    var windowBlurStart = null;
    var eventLog = [];

    function serialize() {
        var form = document.getElementById('form');
        if (!form) return;
        var now = Date.now();
        var thd = tabHiddenDuration;
        if (tabHiddenStart !== null) thd += (performance.now() - tabHiddenStart) / 1000;
        var wbd = windowBlurDuration;
        if (windowBlurStart !== null) wbd += (performance.now() - windowBlurStart) / 1000;

        var data = {
            start_ts: startTs,
            end_ts: now,
            time_on_page: Math.round((now - startTs) / 100) / 10,
            mouse_moved: mouseMoved,
            mouse_move_count: mouseMoveCount,
            click_count: clickCount,
            keydown_count: keydownCount,
            scroll_count: scrollCount,
            copy_detected: copyDetected,
            paste_detected: pasteDetected,
            tab_hidden_count: tabHiddenCount,
            tab_hidden_duration: Math.round(thd * 10) / 10,
            window_blur_count: windowBlurCount,
            window_blur_duration: Math.round(wbd * 10) / 10,
            event_log: eventLog
        };

        var input = form.querySelector('input[name="tracking_json"]');
        if (!input) {
            input = document.createElement('input');
            input.type = 'hidden';
            input.name = 'tracking_json';
            form.appendChild(input);
        }
        input.value = JSON.stringify(data);
    }

    // Mouse move (throttled)
    var lastMoveTs = 0;
    document.addEventListener('mousemove', function() {
        mouseMoved = true;
        var now = Date.now();
        if (now - lastMoveTs > 100) {
            mouseMoveCount++;
            lastMoveTs = now;
        }
    });

    document.addEventListener('click', function() {
        clickCount++;
        serialize();
    });

    document.addEventListener('keydown', function() {
        keydownCount++;
    });

    var lastScrollTs = 0;
    document.addEventListener('scroll', function() {
        var now = Date.now();
        if (now - lastScrollTs > 100) {
            scrollCount++;
            lastScrollTs = now;
        }
    });

    document.addEventListener('copy', function() {
        copyDetected = true;
        eventLog.push({event: 'COPY', ts: Date.now()});
        serialize();
    });

    document.addEventListener('paste', function() {
        pasteDetected = true;
        eventLog.push({event: 'PASTE', ts: Date.now()});
        serialize();
    });

    document.addEventListener('visibilitychange', function() {
        if (document.hidden) {
            tabHiddenCount++;
            tabHiddenStart = performance.now();
            eventLog.push({event: 'TAB_HIDDEN', ts: Date.now()});
        } else {
            if (tabHiddenStart !== null) {
                tabHiddenDuration += (performance.now() - tabHiddenStart) / 1000;
                tabHiddenStart = null;
            }
            eventLog.push({event: 'TAB_VISIBLE', ts: Date.now()});
        }
        serialize();
    });

    window.addEventListener('blur', function() {
        windowBlurCount++;
        windowBlurStart = performance.now();
        eventLog.push({event: 'WINDOW_BLUR', ts: Date.now()});
        serialize();
    });

    window.addEventListener('focus', function() {
        if (windowBlurStart !== null) {
            windowBlurDuration += (performance.now() - windowBlurStart) / 1000;
            windowBlurStart = null;
        }
        eventLog.push({event: 'WINDOW_FOCUS', ts: Date.now()});
        serialize();
    });

    // Initialize on load and keep fresh
    serialize();
    setInterval(serialize, 2000);
})();