const STORAGE_KEY = 'winston_attribution_v1';
const APPROVED_SOURCES = new Set(['instagram', 'facebook']);
const APPROVED_CONTENT = new Set(['bio', 'story', 'feed', 'reel', 'carousel', 'comment']);
const APPROVED_MEDIUM = 'organic_social';
const MAX_CAMPAIGN_LENGTH = 120;

function clean(value, max = 120) {
  return String(value ?? '').trim().slice(0, max);
}

function normalizeAttribution(value) {
  if (!value || typeof value !== 'object' || Array.isArray(value)) return null;
  const source = clean(value.utm_source, 32).toLowerCase();
  const medium = clean(value.utm_medium, 40).toLowerCase();
  const campaign = clean(value.utm_campaign, MAX_CAMPAIGN_LENGTH);
  const content = clean(value.utm_content, 32).toLowerCase();
  if (!APPROVED_SOURCES.has(source)) return null;
  if (medium !== APPROVED_MEDIUM) return null;
  if (!campaign || /[\u0000-\u001f\u007f]/.test(campaign)) return null;
  if (!APPROVED_CONTENT.has(content)) return null;
  return {
    utm_source: source,
    utm_medium: medium,
    utm_campaign: campaign,
    utm_content: content,
  };
}

export function parseApprovedAttribution(search = '') {
  const params = new URLSearchParams(String(search || '').replace(/^\?/, ''));
  return normalizeAttribution({
    utm_source: params.get('utm_source'),
    utm_medium: params.get('utm_medium'),
    utm_campaign: params.get('utm_campaign'),
    utm_content: params.get('utm_content'),
  });
}

export function readStoredAttribution(storage) {
  if (!storage || typeof storage.getItem !== 'function') return null;
  try {
    return normalizeAttribution(JSON.parse(storage.getItem(STORAGE_KEY) || 'null'));
  } catch {
    return null;
  }
}

export function captureAttribution(search, storage, analyticsAllowed) {
  if (analyticsAllowed !== true || !storage || typeof storage.setItem !== 'function') return null;
  const existing = readStoredAttribution(storage);
  if (existing) return existing;
  const incoming = parseApprovedAttribution(search);
  if (!incoming) return null;
  try {
    storage.setItem(STORAGE_KEY, JSON.stringify(incoming));
  } catch {
    return incoming;
  }
  return incoming;
}

export function classifyOutbound(href, currentOrigin) {
  try {
    const base = new URL(String(currentOrigin || 'https://santuariowinston.org'));
    const url = new URL(String(href || ''), base);
    if (!/^https?:$/.test(url.protocol) || url.origin === base.origin) return '';
    const host = url.hostname.toLowerCase().replace(/^www\./, '');
    if (host === 'teaming.net' || host.endsWith('.teaming.net')) return 'teaming';
    if (host === 'wa.me' || host === 'whatsapp.com' || host.endsWith('.whatsapp.com')) return 'whatsapp';
    if (host === 'amazon.es' || host.endsWith('.amazon.es') || host === 'amazon.com' || host.endsWith('.amazon.com') || host === 'amzn.eu') return 'amazon';
    if (host === 'paypal.com' || host.endsWith('.paypal.com')) return 'paypal';
    return 'other';
  } catch {
    return '';
  }
}

function browserStorage() {
  try {
    return window.sessionStorage;
  } catch {
    return null;
  }
}

function analyticsAllowed() {
  try {
    return window.WinstonConsent?.get?.().analytics === true;
  } catch {
    return false;
  }
}

function measurementId() {
  const marker = document.querySelector('[data-winston-ga4-id]');
  const value = clean(marker?.getAttribute('data-winston-ga4-id'), 32).toUpperCase();
  return /^G-[A-Z0-9]+$/.test(value) ? value : '';
}

let pendingAttribution = null;
let gaConfigured = false;
let pageViewSent = false;
const startedForms = new WeakSet();

function currentAttribution() {
  if (!analyticsAllowed()) return null;
  const storage = browserStorage();
  const stored = readStoredAttribution(storage);
  if (stored) return stored;
  const incoming = pendingAttribution || parseApprovedAttribution(window.location.search);
  if (!incoming || !storage) return incoming;
  try {
    storage.setItem(STORAGE_KEY, JSON.stringify(incoming));
  } catch {
    // A browser may block sessionStorage; attribution then remains memory-only.
  }
  return incoming;
}

function ensureGa4() {
  if (!analyticsAllowed()) return false;
  const id = measurementId();
  if (!id) return false;
  window.dataLayer = window.dataLayer || [];
  window.gtag = window.gtag || function gtag() {
    window.dataLayer.push(arguments);
  };
  if (!gaConfigured) {
    window.gtag('js', new Date());
    window.gtag('config', id, { send_page_view: false });
    gaConfigured = true;
  }
  return true;
}

export function trackEvent(name, params = {}) {
  if (!ensureGa4()) return false;
  const attribution = currentAttribution();
  window.gtag('event', name, {
    ...params,
    ...(attribution || {}),
  });
  return true;
}

function sendPageView() {
  if (pageViewSent || !ensureGa4()) return;
  pageViewSent = true;
  trackEvent('page_view', {
    page_location: window.location.href,
    page_path: `${window.location.pathname}${window.location.search}`,
    page_title: document.title,
  });
}

function formName(form) {
  return clean(form.id || form.getAttribute('name') || form.className || 'form', 120);
}

function startForm(form) {
  if (!(form instanceof HTMLFormElement) || startedForms.has(form)) return;
  startedForms.add(form);
  trackEvent('form_start', { form_name: formName(form) });
}

function onInteraction(event) {
  const target = event.target instanceof Element ? event.target : null;
  const form = target?.closest('form');
  if (form instanceof HTMLFormElement) startForm(form);
}

function onSubmit(event) {
  const form = event.target instanceof HTMLFormElement ? event.target : null;
  if (!form) return;
  startForm(form);
  trackEvent('form_submit', { form_name: formName(form) });
}

function onClick(event) {
  const target = event.target instanceof Element ? event.target : null;
  const anchor = target?.closest('a[href]');
  if (!(anchor instanceof HTMLAnchorElement)) return;
  const provider = classifyOutbound(anchor.href, window.location.origin);
  if (!provider) return;
  let domain = '';
  try {
    domain = new URL(anchor.href).hostname;
  } catch {
    domain = '';
  }
  trackEvent('outbound_click', {
    link_url: anchor.href,
    link_domain: domain,
    link_text: clean(anchor.textContent, 160),
    outbound_provider: provider,
  });
}

function handleConsent() {
  if (!analyticsAllowed()) {
    const storage = browserStorage();
    try {
      storage?.removeItem(STORAGE_KEY);
    } catch {
      // Consent remains authoritative even when storage access fails.
    }
    return;
  }
  currentAttribution();
  sendPageView();
}

function initBrowserTracking() {
  pendingAttribution = parseApprovedAttribution(window.location.search);
  document.addEventListener('winston:consent-changed', handleConsent);
  document.addEventListener('focusin', onInteraction, true);
  document.addEventListener('input', onInteraction, true);
  document.addEventListener('submit', onSubmit, true);
  document.addEventListener('click', onClick, true);
  window.WinstonTracking = Object.freeze({
    getAttribution: currentAttribution,
    trackEvent,
  });
  handleConsent();
}

if (typeof window !== 'undefined' && typeof document !== 'undefined') {
  if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', initBrowserTracking, { once: true });
  else initBrowserTracking();
}