"use client";

import { useEffect, useState } from "react";
import { collection, onSnapshot, FirestoreError } from "firebase/firestore";
import { onAuthStateChanged } from "firebase/auth";
import { db, auth } from "@/lib/firebase";
import type { SystemRecord } from "@/lib/types";

export function useSystems() {
  const [systems, setSystems] = useState<SystemRecord[]>([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    let unsubFirestore: (() => void) | undefined;

    const unsubAuth = onAuthStateChanged(auth, (user) => {
      if (unsubFirestore) { unsubFirestore(); unsubFirestore = undefined; }

      if (!user) {
        setSystems([]);
        setLoading(false);
        return;
      }

      unsubFirestore = onSnapshot(collection(db, "systems"), (snap) => {
        setSystems(snap.docs.map((d) => d.data() as SystemRecord));
        setLoading(false);
      }, (err: FirestoreError) => { console.error("useSystems:", err); setError(err.message); setLoading(false); });
    });

    return () => {
      unsubAuth();
      if (unsubFirestore) unsubFirestore();
    };
  }, []);

  return { systems, loading, error };
}