/**
 * api-status.js — Live API health indicator
 * ------------------------------------------
 * Polls the /readyz endpoint and updates any .status-dot + .nav-status
 * elements on the page. Green = reachable, red = unreachable.
 *
 * Usage: <script src="/js/api-status.js" data-api="https://api.modulos.com.au"></script>
 * Falls back to data-api attribute, then window.API_BASE, then a hardcoded default.
 */
(function () {
  'use strict';

  const POLL_INTERVAL_OK   = 30000;  // 30s when healthy
  const POLL_INTERVAL_FAIL = 10000;  // 10s when down (recover faster)
  const TIMEOUT_MS         = 5000;   // 5s request timeout

  // Resolve API base from attribute → global → fallback
  const scriptEl  = document.currentScript;
  const API_BASE  = (scriptEl && scriptEl.dataset.api)
    || (typeof window.API_BASE !== 'undefined' ? window.API_BASE : null)
    || 'https://api.modulos.com.au';

  const READYZ_URL = API_BASE.replace(/\/$/, '') + '/readyz';

  // CSS injected once
  const STYLE = `
    .status-dot {
      display: inline-block;
      width: 7px; height: 7px; border-radius: 50%;
      flex-shrink: 0;
      transition: background 0.4s ease, box-shadow 0.4s ease;
    }
    .status-dot.api-ok {
      background: #2ddc8a;
      box-shadow: 0 0 6px rgba(45,220,138,0.5);
      animation: api-pulse 2.5s ease-in-out infinite;
    }
    .status-dot.api-fail {
      background: #f08080;
      box-shadow: 0 0 6px rgba(240,128,128,0.5);
      animation: api-pulse-fail 1.5s ease-in-out infinite;
    }
    .status-dot.api-checking {
      background: #888;
      box-shadow: none;
      animation: none;
      opacity: 0.5;
    }
    @keyframes api-pulse {
      0%, 100% { opacity: 1; }
      50%       { opacity: 0.4; }
    }
    @keyframes api-pulse-fail {
      0%, 100% { opacity: 1; }
      50%       { opacity: 0.3; }
    }
  `;

  function injectStyles() {
    if (document.getElementById('api-status-style')) return;
    const s = document.createElement('style');
    s.id = 'api-status-style';
    s.textContent = STYLE;
    document.head.appendChild(s);
  }

  function getDots()   { return document.querySelectorAll('.status-dot'); }
  function getLabels() { return document.querySelectorAll('.nav-status-text'); }

  function setState(state) {
    // state: 'ok' | 'fail' | 'checking'
    const dots   = getDots();
    const labels = getLabels();

    dots.forEach(dot => {
      dot.classList.remove('api-ok', 'api-fail', 'api-checking');
      dot.classList.add('api-' + state);
      dot.setAttribute('title', state === 'ok'
        ? 'API reachable'
        : state === 'fail'
          ? 'API unreachable — check connection'
          : 'Checking API…'
      );
    });

    labels.forEach(label => {
      if (state === 'ok') {
        label.textContent = 'API live';
        label.style.color = '';
      } else if (state === 'fail') {
        label.textContent = 'API offline';
        label.style.color = '#f08080';
      } else {
        label.textContent = 'Checking…';
        label.style.color = '';
      }
    });
  }

  let _lastOk = null;
  let _timer  = null;

  async function check() {
    try {
      const controller = new AbortController();
      const tid = setTimeout(() => controller.abort(), TIMEOUT_MS);

      const res = await fetch(READYZ_URL, {
        method: 'GET',
        credentials: 'omit',
        mode: 'cors',
        signal: controller.signal,
        cache: 'no-store'
      });
      clearTimeout(tid);

      const ok = res.ok;
      if (ok !== _lastOk) {
        setState(ok ? 'ok' : 'fail');
        _lastOk = ok;
      }
      schedule(ok ? POLL_INTERVAL_OK : POLL_INTERVAL_FAIL);
    } catch (_) {
      if (_lastOk !== false) {
        setState('fail');
        _lastOk = false;
      }
      schedule(POLL_INTERVAL_FAIL);
    }
  }

  function schedule(ms) {
    clearTimeout(_timer);
    _timer = setTimeout(check, ms);
  }

  function init() {
    injectStyles();

    // Add nav-status-text span inside every .nav-status if not already present
    document.querySelectorAll('.nav-status').forEach(el => {
      if (!el.querySelector('.nav-status-text')) {
        // Wrap any existing text node into a span
        const existing = [...el.childNodes].find(n => n.nodeType === 3 && n.textContent.trim());
        if (existing) {
          const span = document.createElement('span');
          span.className = 'nav-status-text';
          span.textContent = existing.textContent.trim();
          existing.replaceWith(span);
        } else {
          const span = document.createElement('span');
          span.className = 'nav-status-text';
          span.textContent = 'Checking…';
          el.appendChild(span);
        }
      }
    });

    setState('checking');
    check(); // immediate first check
  }

  // Run after DOM is available
  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', init);
  } else {
    init();
  }

  // Re-check immediately when tab becomes visible again after being hidden
  document.addEventListener('visibilitychange', () => {
    if (!document.hidden) {
      clearTimeout(_timer);
      check();
    }
  });

})();