import { useMemo, useRef, useState } from "react";

export default function useNotifications() {
  const [toasts, setToasts] = useState([]);
  const toastTimers = useRef(new Map());
  const [notifications, setNotifications] = useState([]);
  const [notificationFilter, setNotificationFilter] = useState("all");

  const showNotification = (text, tone = "info") => {
    if (!text) return;
    const key = `${tone}|${text}`;
    const now = Date.now();
    setNotifications((prev) => {
      const existingIndex = prev.findIndex((item) => item.key === key);
      if (existingIndex >= 0) {
        const updated = { ...prev[existingIndex], count: (prev[existingIndex].count || 1) + 1, lastAt: now };
        const next = [updated, ...prev.filter((_, index) => index !== existingIndex)];
        return next.slice(0, 20);
      }
      const entry = { text, tone, id: `${now}-${Math.random().toString(36).slice(2)}`, key, count: 1, lastAt: now };
      return [entry, ...prev].slice(0, 20);
    });
    setToasts((prev) => {
      const existingIndex = prev.findIndex((item) => item.key === key);
      if (existingIndex >= 0) {
        const updated = { ...prev[existingIndex], count: (prev[existingIndex].count || 1) + 1, lastAt: now };
        const next = [updated, ...prev.filter((_, index) => index !== existingIndex)];
        return next.slice(0, 4);
      }
      const entry = { text, tone, id: `${now}-${Math.random().toString(36).slice(2)}`, key, count: 1, lastAt: now };
      return [entry, ...prev].slice(0, 4);
    });
    if (toastTimers.current.has(key)) {
      clearTimeout(toastTimers.current.get(key));
    }
    const timeoutId = setTimeout(() => {
      setToasts((prev) => prev.filter((item) => item.key !== key));
      toastTimers.current.delete(key);
    }, 6000);
    toastTimers.current.set(key, timeoutId);
  };

  const dismissToast = (toast) => {
    setToasts((prev) => prev.filter((item) => item.id !== toast.id));
    if (toast.key && toastTimers.current.has(toast.key)) {
      clearTimeout(toastTimers.current.get(toast.key));
      toastTimers.current.delete(toast.key);
    }
  };

  const filteredNotifications = useMemo(() => {
    if (notificationFilter === "all") return notifications;
    return notifications.filter((item) => item.tone === notificationFilter);
  }, [notifications, notificationFilter]);

  return {
    toasts,
    notifications,
    setNotifications,
    notificationFilter,
    setNotificationFilter,
    filteredNotifications,
    showNotification,
    dismissToast
  };
}