/*
 * Lightweight analytics tracker.
 * Usage:
 *   <script defer src="https://analytics.midominio.com/tracker.js"
 *           data-site-id="SITE-001" data-token="PUBLIC_TOKEN"></script>
 *
 * Design goals: never block page load, tolerate the collector being down,
 * and batch requests via sendBeacon so unload doesn't drop data.
 */
(function () {
  "use strict";

  var CURRENT_SCRIPT = document.currentScript;
  if (!CURRENT_SCRIPT) return;

  var SITE_ID = CURRENT_SCRIPT.getAttribute("data-site-id");
  var TOKEN = CURRENT_SCRIPT.getAttribute("data-token");
  if (!SITE_ID || !TOKEN) {
    console.warn("[analytics] missing data-site-id or data-token, tracker not started");
    return;
  }

  var API_BASE =
    CURRENT_SCRIPT.getAttribute("data-api") ||
    new URL(CURRENT_SCRIPT.src).origin;
  var TRACK_URL = API_BASE + "/api/v1/track";

  if (navigator.doNotTrack === "1" || window.doNotTrack === "1") {
    return;
  }

  var SESSION_TIMEOUT_MS = 30 * 60 * 1000;
  var FLUSH_INTERVAL_MS = 5000;
  var MAX_BATCH_SIZE = 10;

  var VISITOR_KEY = "_awa_visitor_id";
  var SESSION_KEY = "_awa_session_id";
  var LAST_ACTIVITY_KEY = "_awa_last_activity";

  function uuid() {
    if (window.crypto && crypto.randomUUID) return crypto.randomUUID();
    return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(/[xy]/g, function (c) {
      var r = (Math.random() * 16) | 0;
      var v = c === "x" ? r : (r & 0x3) | 0x8;
      return v.toString(16);
    });
  }

  function safeGet(storage, key) {
    try {
      return storage.getItem(key);
    } catch (e) {
      return null;
    }
  }
  function safeSet(storage, key, value) {
    try {
      storage.setItem(key, value);
    } catch (e) {
      /* storage unavailable (private mode, quota) — degrade silently */
    }
  }

  function getOrCreateVisitorId() {
    var id = safeGet(localStorage, VISITOR_KEY);
    var isNew = false;
    if (!id) {
      id = uuid();
      isNew = true;
      safeSet(localStorage, VISITOR_KEY, id);
    }
    return { id: id, isNew: isNew };
  }

  function getOrCreateSessionId() {
    var now = Date.now();
    var lastActivity = parseInt(safeGet(localStorage, LAST_ACTIVITY_KEY) || "0", 10);
    var sessionId = safeGet(localStorage, SESSION_KEY);
    var isNew = false;

    if (!sessionId || now - lastActivity > SESSION_TIMEOUT_MS) {
      sessionId = uuid();
      isNew = true;
      safeSet(localStorage, SESSION_KEY, sessionId);
    }
    safeSet(localStorage, LAST_ACTIVITY_KEY, String(now));
    return { id: sessionId, isNew: isNew };
  }

  var visitor = getOrCreateVisitorId();
  var session = getOrCreateSessionId();

  function getUtmParams() {
    var params = new URLSearchParams(window.location.search);
    return {
      utm_source: params.get("utm_source"),
      utm_medium: params.get("utm_medium"),
      utm_campaign: params.get("utm_campaign"),
      utm_term: params.get("utm_term"),
      utm_content: params.get("utm_content"),
    };
  }

  var queue = [];
  var flushTimer = null;

  function scheduleFlush() {
    if (flushTimer) return;
    flushTimer = setTimeout(function () {
      flushTimer = null;
      flush(false);
    }, FLUSH_INTERVAL_MS);
  }

  function buildPayload(items) {
    return JSON.stringify({
      site_id: SITE_ID,
      token: TOKEN,
      visitor_id: visitor.id,
      session_id: session.id,
      is_new_session: session.isNew,
      is_new_visitor: visitor.isNew,
      client: {
        language: navigator.language || null,
        screen_resolution: screen.width + "x" + screen.height,
        viewport: window.innerWidth + "x" + window.innerHeight,
        browser_timezone: Intl.DateTimeFormat().resolvedOptions().timeZone || null,
      },
      items: items,
    });
  }

  function flush(useBeacon) {
    if (queue.length === 0) return;
    var items = queue.splice(0, queue.length);
    var body = buildPayload(items);

    if (useBeacon && navigator.sendBeacon) {
      var blob = new Blob([body], { type: "application/json" });
      var ok = navigator.sendBeacon(TRACK_URL, blob);
      if (ok) return;
      // fall through to fetch as a best-effort fallback
    }

    fetch(TRACK_URL, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: body,
      keepalive: true,
    }).catch(function () {
      /* collector unreachable — drop silently, never break the host page */
    });
  }

  function enqueue(item) {
    queue.push(item);
    if (queue.length >= MAX_BATCH_SIZE) {
      flush(false);
    } else {
      scheduleFlush();
    }
  }

  // ---- Pageview + active-time + scroll-depth tracking ----

  var activeMs = 0;
  var lastVisibleAt = document.visibilityState === "visible" ? Date.now() : null;
  var maxScrollPct = 0;

  function updateActiveTime() {
    if (lastVisibleAt !== null) {
      activeMs += Date.now() - lastVisibleAt;
      lastVisibleAt = null;
    }
  }

  document.addEventListener("visibilitychange", function () {
    if (document.visibilityState === "visible") {
      lastVisibleAt = Date.now();
    } else {
      updateActiveTime();
    }
  });

  function trackScroll() {
    var doc = document.documentElement;
    var scrollableHeight = doc.scrollHeight - doc.clientHeight;
    if (scrollableHeight <= 0) {
      maxScrollPct = 100;
      return;
    }
    var pct = Math.min(100, Math.round((window.scrollY / scrollableHeight) * 100));
    if (pct > maxScrollPct) maxScrollPct = pct;
  }
  window.addEventListener("scroll", trackScroll, { passive: true });

  var CURRENT_PATH = window.location.pathname;

  function pageviewItem() {
    var utm = getUtmParams();
    return {
      type: "pageview",
      url: window.location.href,
      path: CURRENT_PATH,
      title: document.title,
      referrer: document.referrer || null,
      timestamp: new Date().toISOString(),
      utm_source: utm.utm_source,
      utm_medium: utm.utm_medium,
      utm_campaign: utm.utm_campaign,
      utm_term: utm.utm_term,
      utm_content: utm.utm_content,
      time_active_seconds: 0,
      scroll_depth_pct: 0,
    };
  }

  // Send the pageview immediately so real-time views and page counts show up
  // without waiting for the visitor to leave the page.
  enqueue(pageviewItem());
  flush(false);

  var engagementSent = false;

  function sendEngagement() {
    if (engagementSent) return;
    updateActiveTime();
    // Engagement (active time + scroll depth) is reported as an event rather
    // than a second pageview row, so a single page visit never counts twice
    // in page_views — the tradeoff is that it shows up under Events, not
    // merged back into the original page_views row.
    engagementSent = true;
    enqueue({
      type: "event",
      name: "page_engagement",
      properties: {
        path: CURRENT_PATH,
        time_active_seconds: Math.round(activeMs / 1000),
        scroll_depth_pct: maxScrollPct,
      },
      page_url: window.location.href,
      timestamp: new Date().toISOString(),
    });
    flush(true);
  }

  document.addEventListener("visibilitychange", function () {
    if (document.visibilityState === "hidden") sendEngagement();
  });
  window.addEventListener("pagehide", sendEngagement);

  // ---- Public API for custom events ----
  window.analytics = window.analytics || {};
  window.analytics.track = function (name, properties) {
    if (!name) return;
    enqueue({
      type: "event",
      name: String(name),
      properties: properties || {},
      page_url: window.location.href,
      timestamp: new Date().toISOString(),
    });
  };
})();