/**
 * Cluster Dashboard — admin surface showing registered cluster nodes.
 *
 * Polls GET /api/v1/admin/cluster every 10s. Renders one card per node
 * with runtime stats from the JSONB stats column. New keys added to
 * stats are rendered automatically — no code change required.
 */
(function () {
    'use strict';

    var mount = document.getElementById('extension-mount');
    if (!mount) return;

    var REFRESH_MS = 10000;
    var timer = null;

    mount.innerHTML =
        '<div class="cluster-dashboard">' +
            '<div class="cluster-header">' +
                '<h1>Cluster</h1>' +
                '<span class="cluster-status" id="clusterStatus">loading...</span>' +
            '</div>' +
            '<div class="cluster-grid" id="clusterGrid"></div>' +
        '</div>';

    load();
    timer = setInterval(load, REFRESH_MS);

    // Cleanup on navigation (SPA)
    window.addEventListener('beforeunload', function () {
        if (timer) clearInterval(timer);
    });

    function load() {
        var api = (window.sw && window.sw.api) || (typeof API !== 'undefined' && API);
        if (!api) return;
        var get = api._get || api.get;
        if (!get) return;
        get.call(api, '/api/v1/admin/cluster').then(render).catch(function () {
            // 404 = SQLite (no cluster route registered), or other fetch error
            render({ data: [] });
        });
    }

    function render(resp) {
        var nodes = (resp && resp.data) || [];
        var status = document.getElementById('clusterStatus');
        var grid = document.getElementById('clusterGrid');

        status.textContent = nodes.length + ' node' + (nodes.length !== 1 ? 's' : '') + ' registered';

        if (nodes.length === 0) {
            grid.innerHTML = '<p class="cluster-empty">No nodes registered. The cluster registry requires PostgreSQL — SQLite runs single-node only.</p>';
            return;
        }

        grid.innerHTML = nodes.map(nodeCard).join('');
    }

    function nodeCard(node) {
        var stats = {};
        try { stats = typeof node.stats === 'string' ? JSON.parse(node.stats) : (node.stats || {}); } catch (e) { /* ignore */ }

        var uptimeSec = stats.uptime_sec || 0;
        var uptime = formatDuration(uptimeSec);
        var heap = formatBytes(stats.heap_alloc || 0);
        var gcPause = ((stats.gc_pause_ns || 0) / 1e6).toFixed(1) + ' ms';
        var wsClients = stats.ws_clients != null ? stats.ws_clients : '-';
        var goroutines = stats.goroutines != null ? stats.goroutines : '-';
        var gcCycles = stats.gc_cycles != null ? stats.gc_cycles : '-';
        var heartbeatAge = timeSince(node.heartbeat);

        return (
            '<div class="cluster-card">' +
                '<div class="card-header">' +
                    '<span class="node-id">' + esc(node.node_id) + '</span>' +
                    '<span class="heartbeat-badge" title="Last heartbeat">' + heartbeatAge + '</span>' +
                '</div>' +
                (node.endpoint ? '<div class="node-endpoint">' + esc(node.endpoint) + '</div>' : '') +
                '<div class="card-stats">' +
                    stat('Uptime', uptime) +
                    stat('WS Clients', wsClients) +
                    stat('Goroutines', goroutines) +
                    stat('Heap', heap) +
                    stat('GC Pause', gcPause) +
                    stat('GC Cycles', gcCycles) +
                '</div>' +
            '</div>'
        );
    }

    function stat(label, value) {
        return '<div class="stat"><span class="stat-label">' + label + '</span><span class="stat-value">' + value + '</span></div>';
    }

    function formatBytes(b) {
        if (b < 1024) return b + ' B';
        if (b < 1024 * 1024) return (b / 1024).toFixed(1) + ' KB';
        return (b / (1024 * 1024)).toFixed(1) + ' MB';
    }

    function formatDuration(sec) {
        if (sec < 60) return Math.floor(sec) + 's';
        if (sec < 3600) return Math.floor(sec / 60) + 'm ' + Math.floor(sec % 60) + 's';
        var h = Math.floor(sec / 3600);
        var m = Math.floor((sec % 3600) / 60);
        return h + 'h ' + m + 'm';
    }

    function timeSince(iso) {
        if (!iso) return '-';
        var ms = Date.now() - new Date(iso).getTime();
        if (ms < 0) ms = 0;
        var sec = Math.floor(ms / 1000);
        if (sec < 60) return sec + 's ago';
        return Math.floor(sec / 60) + 'm ago';
    }

    function esc(s) {
        var d = document.createElement('div');
        d.appendChild(document.createTextNode(s || ''));
        return d.innerHTML;
    }
})();