{# Embedded HTML5 video, with optional force-watch gating and telemetry.

   When `id` is set, three telemetry columns are written to the database:
   {id}_started (epoch seconds when first played, 0 if never), {id}_ended
   (epoch seconds at last observed activity), and {id}_watched (accumulated
   forward play time in seconds, excluding seeks and background-tab playback).

   Args:
       id (str, optional): When set, telemetry is recorded; when omitted,
           the video is purely embedded and produces no database columns.
       src (str): URL of the video file.
       width (int, optional): Pixel width of the video element.
       height (int, optional): Pixel height of the video element.
       autoplay (bool, optional): Start playback as soon as the page loads.
           Defaults to False.
       force_watch (bool, optional): When true, the Continue button is
           disabled until the participant has watched at least
           completion_threshold of the video. Defaults to False.
       completion_threshold (float, optional): Fraction of total duration
           that counts as "watched". Defaults to 0.98.
       minimal_controls (bool, optional): When true, hide native controls
           and show only a custom Play/Pause button. When false, native
           controls are shown; if force_watch is also true, a snap-back
           guard prevents seeking past the supposed playhead position.
           Defaults to False.

   Example:
       {
           "questiontype": "video",
           "id": "new_video",
           "instructions": "",
           "src": "/static/intro.mp4",
           "force_watch": false,
           "completion_threshold": 0.98,
           "minimal_controls": false
       }
#}
{% set fw = question.force_watch|default(false) %}
{% set min_ctrl = question.minimal_controls|default(false) %}
{% set threshold = question.completion_threshold|default(0.98) %}
{% set prior_started = question.prior_started|default(0) %}
{% set prior_ended = question.prior_ended|default(0) %}
{% set prior_watched = question.prior_watched|default(0) %}

<div class="bofs-video-wrapper" style="display: inline-block;">
    <video class="bofs-video"
           {% if question.width %}width="{{ question.width }}"{% endif %}
           {% if question.height %}height="{{ question.height }}"{% endif %}
           {% if question.autoplay %}autoplay{% endif %}
           {% if not min_ctrl %}controls{% endif %}
           preload="auto"
           controlsList="nodownload nofullscreen noremoteplayback"
           disablePictureInPicture
           playsinline>
        <source src="{{ question.src }}">
        Your browser does not support HTML5 video.
    </video>
    {% if min_ctrl %}
    <div class="bofs-video-toggle-row" style="margin-top: 6px;">
        <button type="button" class="bofs-btn bofs-btn-outline-secondary bofs-video-toggle">Play</button>
    </div>
    {% endif %}
    {% if question.id %}
    <input type="hidden" name="{{ question.id }}_started" class="bofs-video-started" value="{{ prior_started }}">
    <input type="hidden" name="{{ question.id }}_ended"   class="bofs-video-ended"   value="{{ prior_ended }}">
    <input type="hidden" name="{{ question.id }}_watched" class="bofs-video-watched" value="{{ prior_watched }}">
    {% endif %}
</div>

<script>
(function() {
    // Shared media gate: btnNext is disabled while any force_watch video or
    // force_listen audio question on the page is still unsatisfied. A single
    // italic notice is rendered next to btnNext, with text that adapts based
    // on which media kinds are still pending.
    if (!window.bofsMediaGate) {
        window.bofsMediaGate = (function() {
            var counts = { video: 0, audio: 0 };
            var deferred = false;
            function btn() { return document.getElementById('btnNext'); }
            function noticeText() {
                if (counts.video > 0 && counts.audio > 0) {
                    return 'Please play all media before continuing.';
                }
                if (counts.video > 0) {
                    return counts.video > 1
                        ? 'Please watch the videos before continuing.'
                        : 'Please watch the video before continuing.';
                }
                return counts.audio > 1
                    ? 'Please listen to the audio clips before continuing.'
                    : 'Please listen to the audio before continuing.';
            }
            function update() {
                // The questionnaire template renders btnNext *after* the
                // questions, so at script-parse time btnNext doesn't exist
                // yet. Defer the DOM work until DOMContentLoaded.
                if (document.readyState === 'loading') {
                    if (!deferred) {
                        deferred = true;
                        document.addEventListener('DOMContentLoaded', function() {
                            deferred = false;
                            update();
                        }, { once: true });
                    }
                    return;
                }
                var b = btn();
                var existing = document.getElementById('bofs-media-gate-msg');
                if (counts.video + counts.audio === 0) {
                    if (existing && existing.parentNode) existing.parentNode.removeChild(existing);
                    if (b) b.disabled = false;
                    return;
                }
                if (b) b.disabled = true;
                if (!existing && b && b.parentNode) {
                    existing = document.createElement('span');
                    existing.id = 'bofs-media-gate-msg';
                    existing.className = 'bofs-media-gate-msg';
                    existing.style.marginRight = '12px';
                    existing.style.fontStyle = 'italic';
                    existing.style.color = '#6c757d';
                    b.parentNode.insertBefore(existing, b);
                }
                if (existing) existing.textContent = noticeText();
            }
            return {
                require: function(kind) { counts[kind]++; update(); },
                satisfy: function(kind) {
                    counts[kind] = Math.max(0, counts[kind] - 1);
                    update();
                }
            };
        })();
    }

    var wrapper = document.currentScript.previousElementSibling;
    var vid = wrapper.querySelector('video');
    var toggle = wrapper.querySelector('.bofs-video-toggle');
    var startedField = wrapper.querySelector('.bofs-video-started');
    var endedField   = wrapper.querySelector('.bofs-video-ended');
    var watchedField = wrapper.querySelector('.bofs-video-watched');
    var forceWatch = {{ 'true' if fw else 'false' }};
    var minimalControls = {{ 'true' if min_ctrl else 'false' }};
    var threshold = {{ threshold }};

    var startedAt = parseFloat(startedField ? startedField.value : 0) || 0;
    var watchedSeconds = parseFloat(watchedField ? watchedField.value : 0) || 0;
    var lastTime = 0;
    var supposedTime = 0;
    var completed = false;
    var gateRegistered = false;

    function now() { return Date.now() / 1000; }

    function setEnded() {
        if (endedField) endedField.value = now();
    }
    function persistWatched() {
        if (watchedField) watchedField.value = watchedSeconds;
    }

    function checkCompletion() {
        if (completed || !vid.duration || isNaN(vid.duration)) return;
        if (watchedSeconds / vid.duration >= threshold) {
            completed = true;
            if (gateRegistered) {
                window.bofsMediaGate.satisfy('video');
                gateRegistered = false;
            }
        }
    }

    if (forceWatch) {
        // Already watched enough on a prior visit? Don't re-gate.
        var initialDuration = vid.duration;
        if (initialDuration && watchedSeconds / initialDuration >= threshold) {
            completed = true;
        } else {
            window.bofsMediaGate.require('video');
            gateRegistered = true;
        }
    }

    // Pin playback rate so users can't speed through.
    vid.addEventListener('ratechange', function() {
        if (vid.playbackRate !== 1) vid.playbackRate = 1;
    });

    // Snap-back guard: relevant only when native controls are exposed and
    // we're enforcing watch. The accumulator is the real gate; this just
    // prevents the visual confusion of "I scrubbed but Next is still off".
    if (forceWatch && !minimalControls) {
        vid.addEventListener('seeking', function() {
            if (Math.abs(vid.currentTime - supposedTime) > 0.5) {
                vid.currentTime = supposedTime;
            }
        });
    }

    // Accumulate forward play-time only. Forward seeks (large positive deltas)
    // and backward seeks (negative deltas) don't count toward the threshold.
    vid.addEventListener('timeupdate', function() {
        if (vid.seeking || vid.paused) {
            lastTime = vid.currentTime;
            return;
        }
        var delta = vid.currentTime - lastTime;
        if (delta > 0 && delta < 1.0 && document.visibilityState === 'visible') {
            watchedSeconds += delta;
            supposedTime = vid.currentTime;
            persistWatched();
            setEnded();
        }
        lastTime = vid.currentTime;
        if (forceWatch) checkCompletion();
    });

    vid.addEventListener('play', function() {
        lastTime = vid.currentTime;
        if (startedAt === 0) {
            startedAt = now();
            if (startedField) startedField.value = startedAt;
        }
        setEnded();
        if (toggle) toggle.textContent = 'Pause';
    });
    vid.addEventListener('pause', function() {
        setEnded();
        if (toggle) toggle.textContent = 'Play';
    });
    vid.addEventListener('ended', function() {
        setEnded();
        if (forceWatch) checkCompletion();
    });

    // Pause when the tab is hidden or window loses focus, so the video can't
    // play in the background while watchedSeconds is gated by visibility.
    document.addEventListener('visibilitychange', function() {
        if (document.visibilityState !== 'visible' && !vid.paused) vid.pause();
    });
    window.addEventListener('blur', function() { if (!vid.paused) vid.pause(); });

    if (toggle) {
        toggle.addEventListener('click', function() {
            if (vid.paused) vid.play(); else vid.pause();
        });
    }
})();
</script>