/**
 * Events dashboard: polls GET /api/events every 5s, renders the list with
 * severity text+icon+color (never color alone, per NF9), pins unacknowledged
 * events to the top, and wires the acknowledge button to POST /events/{id}/ack.
 *
 * XSS-safe: all dynamic values are set via textContent, never innerHTML.
 */
(function () {
  'use strict';

  var POLL_INTERVAL_MS = 5000;

  var SEVERITY_LABELS = {
    critical: { icon: '⛔', text: '위급', cls: 'sev-critical' }, // ⛔
    high:     { icon: '⚠', text: '높음', cls: 'sev-high' },     // ⚠
    warning:  { icon: '△', text: '경고', cls: 'sev-warning' },  // △
    info:     { icon: 'ℹ', text: '정보', cls: 'sev-info' }      // ℹ
  };

  var root = document.getElementById('events-root');
  if (!root) return;

  function severityInfo(sev) {
    return SEVERITY_LABELS[sev] || { icon: 'ℹ', text: sev || '알수없음', cls: 'sev-info' };
  }

  function formatTime(occurredAt) {
    if (!occurredAt && occurredAt !== 0) return '';
    var d = new Date(Number(occurredAt) * 1000);
    if (isNaN(d.getTime())) return '';
    return d.toLocaleString('ko-KR');
  }

  function buildBadge(sev) {
    var info = severityInfo(sev);
    var badge = document.createElement('span');
    badge.className = 'severity-badge ' + info.cls;
    var icon = document.createElement('span');
    icon.className = 'icon';
    icon.setAttribute('aria-hidden', 'true');
    icon.textContent = info.icon;
    var label = document.createElement('span');
    label.className = 'label';
    label.textContent = info.text;
    badge.appendChild(icon);
    badge.appendChild(label);
    return badge;
  }

  function buildRow(ev) {
    var isAcked = ev.acknowledged_by !== null && ev.acknowledged_by !== undefined && ev.acknowledged_by !== '';

    var row = document.createElement('div');
    row.className = 'event-row' + (isAcked ? '' : ' is-unacknowledged');

    row.appendChild(buildBadge(ev.severity));

    var meta = document.createElement('div');
    meta.className = 'event-meta';

    var type = document.createElement('div');
    type.className = 'event-type';
    type.textContent = String(ev.event_type || '');
    meta.appendChild(type);

    var sub = document.createElement('div');
    sub.className = 'event-time';
    var cam = ev.camera_id ? String(ev.camera_id) : '';
    var time = formatTime(ev.occurred_at);
    sub.textContent = [cam, time].filter(Boolean).join(' · ');
    meta.appendChild(sub);

    row.appendChild(meta);

    var btn = document.createElement('button');
    btn.type = 'button';
    btn.className = 'ack-btn';
    if (isAcked) {
      btn.textContent = '확인됨 (' + String(ev.acknowledged_by) + ')';
      btn.disabled = true;
    } else {
      btn.textContent = '확인';
      btn.addEventListener('click', function () { acknowledge(ev.event_id, btn); });
    }
    row.appendChild(btn);

    return row;
  }

  function acknowledge(eventId, btn) {
    btn.disabled = true;
    fetch('/events/' + encodeURIComponent(eventId) + '/ack', { method: 'POST' })
      .then(function (res) {
        if (!res.ok) throw new Error('ack_failed:' + res.status);
        return loadEvents();
      })
      .catch(function () {
        btn.disabled = false;
      });
  }

  function render(events) {
    var sorted = events.slice().sort(function (a, b) {
      var aAcked = a.acknowledged_by !== null && a.acknowledged_by !== undefined && a.acknowledged_by !== '';
      var bAcked = b.acknowledged_by !== null && b.acknowledged_by !== undefined && b.acknowledged_by !== '';
      if (aAcked === bAcked) return 0;
      return aAcked ? 1 : -1; // unacknowledged first
    });

    root.textContent = '';
    root.removeAttribute('aria-busy');
    if (sorted.length === 0) {
      root.textContent = '표시할 이벤트가 없습니다.';
      return;
    }
    var frag = document.createDocumentFragment();
    sorted.forEach(function (ev) { frag.appendChild(buildRow(ev)); });
    root.appendChild(frag);
  }

  function loadEvents() {
    return fetch('/api/events', { headers: { Accept: 'application/json' } })
      .then(function (res) {
        if (res.status === 401) {
          window.location.href = '/login';
          return null;
        }
        if (!res.ok) throw new Error('list_failed:' + res.status);
        return res.json();
      })
      .then(function (data) {
        if (data && Array.isArray(data.events)) render(data.events);
      })
      .catch(function () {
        // Leave the last rendered state on transient poll failure.
      });
  }

  var logoutBtn = document.getElementById('logout-btn');
  if (logoutBtn) {
    logoutBtn.addEventListener('click', function () {
      fetch('/logout', { method: 'POST' }).then(function () { window.location.href = '/login'; });
    });
  }

  loadEvents();
  setInterval(loadEvents, POLL_INTERVAL_MS);
})();