frontend/src/lib/stores/notifications.js

import { writable, derived } from 'svelte/store';

const TOAST_TIMEOUT = 4000;
let toastId = 0;

function createNotificationStore() {
	const { subscribe, update } = writable([]);

	function add(message, type = 'info', duration = TOAST_TIMEOUT) {
		const id = ++toastId;
		update((toasts) => [...toasts, { id, message, type, duration }]);

		if (duration > 0) {
			setTimeout(() => remove(id), duration);
		}

		return id;
	}

	function remove(id) {
		update((toasts) => toasts.filter((t) => t.id !== id));
	}

	return {
		subscribe,
		success: (msg, dur) => add(msg, 'success', dur),
		error: (msg, dur) => add(msg, 'error', dur ?? 6000),
		warning: (msg, dur) => add(msg, 'warning', dur),
		info: (msg, dur) => add(msg, 'info', dur),
		remove
	};
}

export const toasts = createNotificationStore();