import { useEffect, useRef, useState } from 'react';
import { useLocation } from 'react-router-dom';

type AnalyticsIdentity = {
  distinctId: string;
  username: string;
  ownerSegment: string;
  planType: string;
  channel: string;
  surface: 'product';
  identityMode: 'raw' | 'pseudonymous';
};

type ProductAnalyticsContext = {
  enabled: boolean;
  websiteId?: string;
  scriptPath?: string;
  hostPath?: string;
  domains?: string;
  identity?: AnalyticsIdentity | null;
};

type PageViewProperties = Record<string, unknown>;
type UmamiTracker = {
  track: (
    value?: string | ((properties: PageViewProperties) => PageViewProperties),
    data?: Record<string, unknown>,
  ) => Promise<unknown> | unknown;
  identify: (id: string, data?: Record<string, unknown>) => Promise<unknown> | unknown;
};

declare global {
  interface Window {
    umami?: UmamiTracker;
  }
}

const SAFE_QUERY_KEYS = new Set(['category', 'utm_source', 'preview']);
let trackerLoad: Promise<void> | null = null;
let lastPageViewKey = '';
let lastIdentityKey = '';

export function normalizeProductRoute(pathname: string, search = '') {
  const params = new URLSearchParams(search);
  const safe = new URLSearchParams();
  for (const key of SAFE_QUERY_KEYS) {
    const value = params.get(key);
    if (value) safe.set(key, value.slice(0, 100));
  }
  const query = safe.toString();
  return `${pathname || '/'}${query ? `?${query}` : ''}`;
}

export function resolveProductRouteName(pathname: string) {
  if (pathname === '/') return 'chat';
  if (pathname === '/space') return 'mindspace_home';
  if (pathname === '/space/achievements') return 'mindspace_achievements';
  if (pathname.startsWith('/space/page/')) return 'mindspace_page';
  if (pathname.startsWith('/feedback/')) return 'feedback_detail';
  if (pathname === '/feedback') return 'feedback';
  return 'other';
}

function safeTargetPath(element: Element) {
  if (!(element instanceof HTMLAnchorElement) || !element.href) return '';
  try {
    const target = new URL(element.href, window.location.href);
    return target.origin === window.location.origin
      ? target.pathname
      : `external:${target.hostname}`;
  } catch {
    return '';
  }
}

function actionName(element: Element) {
  const stableClasses = Array.from(element.classList)
    .filter((name) => /^[a-z][a-z0-9_-]{1,80}$/i.test(name))
    .slice(0, 3)
    .join('.');
  return String(
    element.getAttribute('data-analytics-action') ||
      element.getAttribute('data-umami-event') ||
      element.getAttribute('aria-label') ||
      element.getAttribute('title') ||
      element.id ||
      stableClasses ||
      element.tagName.toLowerCase(),
  ).slice(0, 100);
}

function waitForTracker() {
  if (window.umami) return Promise.resolve();
  return new Promise<void>((resolve, reject) => {
    const startedAt = Date.now();
    const timer = window.setInterval(() => {
      if (window.umami) {
        window.clearInterval(timer);
        resolve();
      } else if (Date.now() - startedAt > 5000) {
        window.clearInterval(timer);
        reject(new Error('Umami tracker did not initialize'));
      }
    }, 25);
  });
}

function loadTracker(context: ProductAnalyticsContext) {
  if (window.umami) return Promise.resolve();
  if (trackerLoad) return trackerLoad;
  trackerLoad = new Promise<void>((resolve, reject) => {
    const existing = document.querySelector<HTMLScriptElement>('#memind-product-analytics');
    if (existing) {
      void waitForTracker().then(resolve, reject);
      return;
    }
    const script = document.createElement('script');
    script.id = 'memind-product-analytics';
    script.defer = true;
    script.src = context.scriptPath || '/analytics/script.js';
    script.dataset.websiteId = context.websiteId || '';
    script.dataset.hostUrl = context.hostPath || '/analytics';
    script.dataset.autoTrack = 'false';
    if (context.domains) script.dataset.domains = context.domains;
    script.addEventListener('load', () => void waitForTracker().then(resolve, reject), { once: true });
    script.addEventListener('error', () => reject(new Error('Unable to load Umami tracker')), {
      once: true,
    });
    document.head.appendChild(script);
  }).catch((error) => {
    trackerLoad = null;
    throw error;
  });
  return trackerLoad;
}

function absoluteRoute(route: string) {
  return new URL(route, window.location.origin).toString();
}

function trackPageView(route: string) {
  return window.umami?.track((properties) => ({
    ...properties,
    url: absoluteRoute(route),
    title: document.title,
  }));
}

function trackProductEvent(
  eventName: string,
  route: string,
  identity: AnalyticsIdentity | null | undefined,
  data: Record<string, unknown> = {},
) {
  return window.umami?.track((properties) => ({
    ...properties,
    name: eventName,
    url: absoluteRoute(route),
    title: document.title,
    data: {
      surface: 'product',
      route,
      route_name: resolveProductRouteName(window.location.pathname),
      channel: identity?.channel || 'h5',
      owner_segment: identity?.ownerSegment || 'anonymous',
      plan_type: identity?.planType || 'anonymous',
      identity_mode: identity?.identityMode || 'anonymous',
      ...data,
    },
  }));
}

export function useProductAnalytics(userId?: string | null) {
  const location = useLocation();
  const [context, setContext] = useState<ProductAnalyticsContext>({ enabled: false });
  const [ready, setReady] = useState(false);
  const contextRef = useRef(context);
  const route = normalizeProductRoute(location.pathname, location.search);
  const routeRef = useRef(route);

  contextRef.current = context;
  routeRef.current = route;

  useEffect(() => {
    let cancelled = false;
    void fetch('/api/analytics/context', { credentials: 'same-origin', cache: 'no-store' })
      .then(async (response) => (response.ok ? ((await response.json()) as ProductAnalyticsContext) : null))
      .then((next) => {
        if (!cancelled && next) setContext(next);
      })
      .catch(() => undefined);
    return () => {
      cancelled = true;
    };
  }, [userId]);

  useEffect(() => {
    if (!context.enabled || !context.websiteId) return;
    let cancelled = false;
    void loadTracker(context)
      .then(() => {
        if (cancelled) return;
        const identity = context.identity;
        if (identity?.distinctId) {
          const identityKey = `${context.websiteId}:${identity.distinctId}`;
          if (lastIdentityKey !== identityKey) {
            lastIdentityKey = identityKey;
            void window.umami?.identify(identity.distinctId, {
              username: identity.username,
              owner_segment: identity.ownerSegment,
              plan_type: identity.planType,
              channel: identity.channel,
              surface: identity.surface,
              identity_mode: identity.identityMode,
            });
          }
        } else if (lastIdentityKey) {
          lastIdentityKey = '';
          void window.umami?.identify('', {
            auth_state: 'anonymous',
            channel: 'h5',
            surface: 'product',
          });
        }
        setReady(true);
      })
      .catch(() => undefined);
    return () => {
      cancelled = true;
    };
  }, [context]);

  useEffect(() => {
    if (!ready || !context.enabled || !context.websiteId) return;
    const pageViewKey = `${context.websiteId}:${route}`;
    if (lastPageViewKey === pageViewKey) return;
    lastPageViewKey = pageViewKey;
    void trackPageView(route);

    const tenSecond = window.setTimeout(() => {
      void trackProductEvent('product_engaged_10s', route, context.identity);
    }, 10_000);
    const thirtySecond = window.setTimeout(() => {
      void trackProductEvent('product_engaged_30s', route, context.identity);
    }, 30_000);
    return () => {
      window.clearTimeout(tenSecond);
      window.clearTimeout(thirtySecond);
    };
  }, [context, ready, route]);

  useEffect(() => {
    if (!ready || !context.enabled) return;
    const handleClick = (event: MouseEvent) => {
      const target = event.target instanceof Element
        ? event.target.closest('a,button,[role="button"],[data-analytics-action],[data-umami-event]')
        : null;
      if (!target) return;
      void trackProductEvent('product_click', routeRef.current, contextRef.current.identity, {
        action: actionName(target),
        element: target.tagName.toLowerCase(),
        element_id: target.id.slice(0, 100),
        element_class: Array.from(target.classList).slice(0, 3).join(' ').slice(0, 200),
        target_path: safeTargetPath(target),
      });
    };
    document.addEventListener('click', handleClick, { capture: true, passive: true });
    return () => document.removeEventListener('click', handleClick, { capture: true });
  }, [context.enabled, ready]);
}