import {
  createContext,
  useCallback,
  useContext,
  useEffect,
  useMemo,
  useState,
  type ReactNode,
} from "react";
import { useNavigate, useRouter } from "@tanstack/react-router";
import type { QueryClient } from "@tanstack/react-query";
import type { Session } from "@supabase/supabase-js";

import { supabase } from "@/integrations/supabase/client";

type AuthState = {
  session: Session | null;
  signedIn: boolean;
  loading: boolean;
  email: string | null;
  signOut: () => Promise<void>;
};

const AuthContext = createContext<AuthState>({
  session: null,
  signedIn: false,
  loading: true,
  email: null,
  signOut: async () => {},
});

export function useAuth() {
  return useContext(AuthContext);
}

export function AuthProvider({ children, queryClient }: { children: ReactNode; queryClient: QueryClient }) {
  const router = useRouter();
  const navigate = useNavigate();
  const [session, setSession] = useState<Session | null>(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    let active = true;

    supabase.auth.getSession().then(({ data }) => {
      if (!active) return;
      setSession(data.session);
      setLoading(false);
    });

    // The single session listener for the whole app: identity changes refresh
    // router context and the query cache. TOKEN_REFRESHED / INITIAL_SESSION are
    // ignored on purpose so nothing thrashes.
    const { data: sub } = supabase.auth.onAuthStateChange((event, next) => {
      if (event !== "SIGNED_IN" && event !== "SIGNED_OUT" && event !== "USER_UPDATED") return;
      setSession(event === "SIGNED_OUT" ? null : next);
      void router.invalidate();
      if (event !== "SIGNED_OUT") queryClient.invalidateQueries();
    });

    return () => {
      active = false;
      sub.subscription.unsubscribe();
    };
  }, [router, queryClient]);

  const signOut = useCallback(async () => {
    await queryClient.cancelQueries();
    queryClient.clear();
    await supabase.auth.signOut();
    await navigate({ to: "/auth", replace: true });
  }, [navigate, queryClient]);

  const value = useMemo<AuthState>(
    () => ({
      session,
      signedIn: Boolean(session?.user),
      loading,
      email: session?.user.email ?? null,
      signOut,
    }),
    [session, loading, signOut],
  );

  return <AuthContext.Provider value={value}>{children}</AuthContext.Provider>;
}