frontend/src/hooks/useSessionSync.ts

import { useEffect } from "react";
import { useHistoryStore, type HistoryItem } from "../store/useAppStore";
import { API_BASE } from "../api/client";

export async function saveSessionToBackend(
  userId: string,
  item: HistoryItem,
): Promise<void> {
  try {
    await fetch(`${API_BASE}/api/sessions/${userId}`, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify(item),
    });
  } catch {
    // fallback silencioso — localStorage es la fuente de verdad local
  }
}

export async function deleteSessionFromBackend(
  userId: string,
  filename: string,
): Promise<void> {
  try {
    await fetch(
      `${API_BASE}/api/sessions/${userId}/${encodeURIComponent(filename)}`,
      { method: "DELETE" },
    );
  } catch {
    // fallback silencioso
  }
}

export function useLoadSessionHistory(): void {
  const userId = useHistoryStore((s) => s.userId);
  const localHistory = useHistoryStore((s) => s.sessionHistory);
  const setSessionHistory = useHistoryStore((s) => s.setSessionHistory);

  useEffect(() => {
    async function load() {
      try {
        const res = await fetch(`${API_BASE}/api/sessions/${userId}`);
        if (!res.ok) return;
        const data = await res.json();
        const remote: HistoryItem[] = data.items ?? [];
        if (remote.length === 0) return;

        // Merge remoto + local: dedupe por filename, más reciente gana
        const merged = [...remote, ...localHistory];
        const seen = new Set<string>();
        const deduped = merged.filter((item) => {
          if (seen.has(item.filename)) return false;
          seen.add(item.filename);
          return true;
        });
        deduped.sort((a, b) => b.uploadedAt - a.uploadedAt);
        setSessionHistory(deduped.slice(0, 10));
      } catch {
        // red no disponible — se mantiene historial local
      }
    }
    load();
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [userId]);
}