/**
 * Kanbante — dynamic board (issue #15).
 *
 * The board reflects reality without a manual refresh: any change
 * (another session, Gitea via webhook/labels, capture) is pushed
 * over SSE; the client then fetches server-rendered card fragments
 * from /api/board/<repo> and swaps only the columns that changed,
 * animating surviving cards to their new place (FLIP). A discreet
 * 45 s poll covers installs without Gitea webhooks. Local drags are
 * never interrupted: a refresh arriving mid-drag waits for its end.
 * Filters, scroll, the detail drawer and Sortable all survive,
 * because only column contents are replaced — never the page.
 */
(function () {
    var match = window.location.pathname.match(/^\/board\/(.+)$/);
    if (!match) return;
    var repoPath = match[1].replace(/\/$/, '');
    var milestone = new URLSearchParams(window.location.search).get('milestone') || '';
    var apiUrl = '/api/board/' + repoPath + (milestone ? '?milestone=' + encodeURIComponent(milestone) : '');
    var repoFullName = repoPath.split('/').map(decodeURIComponent).join('/');

    var lastEventAt = Date.now();
    var inFlight = false;
    var queued = false;
    var debounce = null;
    var failedOnce = false;

    function signature(html) {
        var h = 0;
        for (var i = 0; i < html.length; i++) {
            h = ((h << 5) - h + html.charCodeAt(i)) | 0;
        }
        return html.length + ':' + h;
    }

    function captureRects() {
        var rects = {};
        document.querySelectorAll('.kanban-card').forEach(function (card) {
            rects[card.getAttribute('data-issue')] = card.getBoundingClientRect();
        });
        return rects;
    }

    function playFlip(before) {
        if (window.matchMedia('(prefers-reduced-motion: reduce)').matches) return;
        document.querySelectorAll('.kanban-card').forEach(function (card) {
            var key = card.getAttribute('data-issue');
            var old = before[key];
            if (!old) {
                card.animate(
                    [{ opacity: 0, transform: 'scale(0.96)' }, { opacity: 1, transform: 'none' }],
                    { duration: 220, easing: 'ease-out' }
                );
                return;
            }
            var now = card.getBoundingClientRect();
            var dx = old.left - now.left;
            var dy = old.top - now.top;
            if (dx || dy) {
                card.animate(
                    [{ transform: 'translate(' + dx + 'px,' + dy + 'px)' }, { transform: 'none' }],
                    { duration: 280, easing: 'ease-in-out' }
                );
            }
        });
    }

    function showFallbackPill() {
        if (document.getElementById('live-pill')) return;
        var pill = document.createElement('button');
        pill.id = 'live-pill';
        pill.type = 'button';
        pill.textContent = '🔄 Actualisation automatique en échec — cliquer pour recharger';
        pill.addEventListener('click', function () { window.location.reload(); });
        document.body.appendChild(pill);
    }

    function applyData(data) {
        var before = captureRects();
        var changed = false;
        Object.keys(data.columns).forEach(function (col) {
            var container = document.querySelector('.column-cards[data-column="' + col + '"]');
            if (!container) return;
            var payload = data.columns[col];
            var sig = signature(payload.html);
            if (container.getAttribute('data-sig') === sig) return;
            container.innerHTML = payload.html;
            container.setAttribute('data-sig', sig);
            changed = true;
        });
        if (!changed) return;
        playFlip(before);
        if (window.kanbanteUpdateCounts) window.kanbanteUpdateCounts();
        if (window.kanbanteRefreshHints) window.kanbanteRefreshHints();
        if (window.kanbanteApplyFilters) window.kanbanteApplyFilters();
    }

    function refresh() {
        if (window.__kanbanteDragging) {
            setTimeout(refresh, 700);  // retry once the local drag ends
            return;
        }
        if (inFlight) { queued = true; return; }
        inFlight = true;
        fetch(apiUrl, { headers: { 'Accept': 'application/json' } })
            .then(function (r) { if (!r.ok) throw new Error('HTTP ' + r.status); return r.json(); })
            .then(function (data) { failedOnce = false; applyData(data); })
            .catch(function () { if (!failedOnce) { failedOnce = true; showFallbackPill(); } })
            .finally(function () {
                inFlight = false;
                if (queued) { queued = false; refresh(); }
            });
    }

    function scheduleRefresh() {
        clearTimeout(debounce);
        debounce = setTimeout(refresh, 400);
    }

    // 1. Push: SSE events about this repo (internal moves broadcast
    //    {"type": "board-changed"}; webhooks broadcast their payload).
    if (window.EventSource) {
        var source = new EventSource('/api/stream');
        source.addEventListener('gitea', function (e) {
            try {
                var payload = JSON.parse(e.data);
                if (payload.repo && payload.repo !== repoFullName) return;
            } catch (err) { /* unparseable -> refresh anyway */ }
            lastEventAt = Date.now();
            scheduleRefresh();
        });
        source.addEventListener('error', function () { /* EventSource retries itself */ });
    }

    // 2. Fallback poll (no webhooks configured, or SSE missed
    //    something): only when visible and quiet for a full cycle.
    setInterval(function () {
        if (document.visibilityState === 'visible' && Date.now() - lastEventAt >= 45000) {
            lastEventAt = Date.now();
            refresh();
        }
    }, 5000);

    // 3. Coming back to the tab: catch up immediately.
    document.addEventListener('visibilitychange', function () {
        if (document.visibilityState === 'visible') refresh();
    });
})();