import { useEffect, useRef } from "react";
import { useChatStore } from "@/store/chatStore";

/**
 * useStreamingNotification — S-NOTIF
 * Browser Notification when streaming ends and tab is hidden.
 * No server/VAPID needed. Works: Android Chrome, iOS 16.4+ PWA, Desktop.
 */
export function useStreamingNotification(): void {
  const isStreaming = useChatStore(s => s.isStreaming);
  const prevRef = useRef(false);
  useEffect(() => {
    if (prevRef.current && !isStreaming) {
      if (
        typeof Notification !== "undefined" &&
        Notification.permission === "granted" &&
        document.visibilityState !== "visible"
      ) {
        try {
          new Notification("Agente AI · Risposta pronta ✓", {
            body: "Tocca per leggere la risposta dell'agente.",
            icon: "/favicon.svg",
            tag: "agent-done",
            // @ts-expect-error renotify is non-standard but supported
      renotify: true,
          });
        } catch { /* Safari older */ }
      }
    }
    prevRef.current = isStreaming;
  }, [isStreaming]);
}

export async function requestNotificationPermission(): Promise<NotificationPermission> {
  if (typeof Notification === "undefined") return "denied";
  if (Notification.permission !== "default") return Notification.permission;
  return Notification.requestPermission();
}