/**
 * 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';

  // Mount prefix: '' at the web root, '/move_detect' when the app shares a www/ with another
  // site. Injected by src/View/layout.php from the server's SCRIPT_NAME. Every URL below must
  // go through it — a bare '/api/...' would address the other site instead.
  var B = window.APP_BASE || '';

  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;

  var csrfToken = null;
  function loadCsrfToken() {
    return fetch(B + '/api/csrf', { headers: { Accept: 'application/json' } })
      .then(function (res) { return res.ok ? res.json() : null; })
      .then(function (data) { if (data && data.token) csrfToken = data.token; })
      .catch(function () { /* ack will fail with 403 and re-enable the button */ });
  }

  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;
  }

  // --- desk audio alert: repeating beep while any unacknowledged critical exists ---
  // No binary asset (air-gapped friendly): a WebAudio oscillator tone. The browser
  // blocks audio until a user gesture, so the context is created on first click.
  var audioCtx = null;
  var alarmTimer = null;
  var beepedCritical = {}; // event_id -> true; each new critical beeps once immediately

  function unlockAudio() {
    if (!audioCtx) {
      var AC = window.AudioContext || window.webkitAudioContext;
      if (AC) audioCtx = new AC();
    }
    document.removeEventListener('click', unlockAudio);
  }

  function beep() {
    if (!audioCtx) return;
    try {
      var osc = audioCtx.createOscillator();
      var gain = audioCtx.createGain();
      osc.type = 'sine';
      osc.frequency.value = 880;
      gain.gain.value = 0.2;
      osc.connect(gain);
      gain.connect(audioCtx.destination);
      osc.start();
      osc.stop(audioCtx.currentTime + 0.4);
    } catch (e) {
      // audio unavailable; the visual list still surfaces the critical event
    }
  }

  function updateAlarm(events) {
    var hasUnackedCritical = false;
    events.forEach(function (ev) {
      var acked = ev.acknowledged_by !== null && ev.acknowledged_by !== undefined && ev.acknowledged_by !== '';
      if (ev.severity === 'critical' && !acked) {
        hasUnackedCritical = true;
        if (!beepedCritical[ev.event_id]) { beepedCritical[ev.event_id] = true; beep(); }
      }
    });
    if (hasUnackedCritical && !alarmTimer) {
      alarmTimer = setInterval(beep, 3000);
    } else if (!hasUnackedCritical && alarmTimer) {
      clearInterval(alarmTimer);
      alarmTimer = null;
    }
  }

  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';
    var typeLink = document.createElement('a');
    typeLink.className = 'event-detail-link';
    typeLink.href = B + '/events/' + encodeURIComponent(ev.event_id) + '/view';
    typeLink.textContent = String(ev.event_type || '');
    type.appendChild(typeLink);
    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(B + '/events/' + encodeURIComponent(eventId) + '/ack', {
      method: 'POST',
      headers: { 'X-Csrf-Token': csrfToken || '' }
    })
      .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
    });

    updateAlarm(sorted); // before any early return, so an emptied list also silences the alarm

    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(B + '/api/events', { headers: { Accept: 'application/json' } })
      .then(function (res) {
        if (res.status === 401) {
          window.location.href = B + '/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(B + '/logout', { method: 'POST' }).then(function () { window.location.href = B + '/login'; });
    });
  }

  document.addEventListener('click', unlockAudio);

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