Add notifications at the top right of the screen.

demo/DemoApp.tsx

@@ -33,6 +33,8 @@ import {DemoModal} from "./DemoModal";
 import {useCallableModal} from "../src/Components/Modals/Modals";
 import {ModalType} from "../src/Components/Modals/ModalsTypes";
 import {Buttons} from "../src/Components/Buttons/Buttons";
+import {useNotify} from "../src/Components/Notifications/Notifications";
+import {Notification, NotificationType} from "../src/Components/Notifications/Notification";
 
 export function DemoApp()
 {
@@ -48,6 +50,8 @@ export function DemoApp()
 	// Easy modal.
 	const easyModal = useCallableModal((type: ModalType = ModalType.NONE) => <DemoModal type={type} />);
 
+	const notify = useNotify();
+
 	const [datetime, setDatetime] = useState(null);
 
 	const [selected, setSelected] = useState(null);
@@ -506,11 +510,11 @@ export function DemoApp()
 			<h2>Notifications</h2>
 
 			<Card>
-				<button>Information notification</button>
-				<button className={"success"}>Success notification</button>
-				<button className={"warning"}>Warning notification</button>
-				<button className={"error"}>Error notification</button>
-				<button className={"flat"}>Generic notification</button>
+				<button onClick={() => { notify(<Notification type={NotificationType.INFO}>Test notification</Notification>); }}>Information notification</button>
+				<button className={"success"} onClick={() => { notify(<Notification type={NotificationType.SUCCESS}>Test notification</Notification>); }}>Success notification</button>
+				<button className={"warning"} onClick={() => { notify(<Notification type={NotificationType.WARNING}>Test notification</Notification>); }}>Warning notification</button>
+				<button className={"error"} onClick={() => { notify(<Notification type={NotificationType.ERROR}>Test notification</Notification>); }}>Error notification</button>
+				<button className={"flat"} onClick={() => { notify(<Notification>Test notification</Notification>); }}>Generic notification</button>
 			</Card>
 
 		</Application>

src/Application/Kernel.tsx

@@ -2,6 +2,7 @@ import { IconContext } from "@phosphor-icons/react";
 import React from "react";
 import {createBrowserRouter, RouterProvider} from "react-router-dom";
 import {Curtains} from "../Components/Curtains/Curtains";
+import {NotificationsProvider} from "../Components/Notifications/Notifications";
 
 /**
  * Main Kernel UI app component which initializes everything.
@@ -17,11 +18,13 @@ export function Kernel({header, footer, router}: {
 			size: 16,
 			weight: "bold",
 		}}>
-			<Curtains>
-				{header}
-				<RouterProvider router={router} />
-				{footer}
-			</Curtains>
+			<NotificationsProvider>
+				<Curtains>
+					{header}
+					<RouterProvider router={router} />
+					{footer}
+				</Curtains>
+			</NotificationsProvider>
 		</IconContext.Provider>
 	);
 }

src/Components/Notifications/Notification.tsx

@@ -0,0 +1,41 @@
+import React, {useCallback, useContext} from "react";
+import {classes} from "../../Utils";
+import {NotificationContext, NotificationsContext} from "./Notifications";
+
+/**
+ * Notifications types enumeration.
+ */
+export enum NotificationType
+{
+	NONE = "none",
+	INFO = "info",
+	SUCCESS = "success",
+	WARNING = "warning",
+	ERROR = "error",
+}
+
+/**
+ * Notification component.
+ */
+export function Notification({type, children}: React.PropsWithChildren<{
+	type?: NotificationType;
+}>)
+{
+	// Default type is NONE.
+	type = type ?? NotificationType.NONE;
+
+	// Get notifications context.
+	const {close} = useContext(NotificationsContext);
+
+	// Get current notification UUID.
+	const {uuid, closed} = useContext(NotificationContext);
+
+	// Initialize close notification function.
+	const closeNotification = useCallback(() => { close(uuid); }, [uuid]);
+
+	return (
+		<li className={classes("notification", type, closed ? "closed" : undefined)} onMouseDown={closeNotification}>
+			{children}
+		</li>
+	);
+}

src/Components/Notifications/Notifications.tsx

@@ -0,0 +1,217 @@
+import React, {startTransition, useCallback, useContext, useEffect, useMemo, useRef, useState} from "react";
+import ReactDOM from "react-dom";
+import {v4 as uuidv4} from "uuid";
+
+/**
+ * Notification UUID type.
+ */
+export type NotificationUuid = string;
+
+/**
+ * Notification data.
+ */
+export interface NotificationData
+{
+	/**
+	 * The notification content.
+	 */
+	content: React.ReactNode;
+}
+
+/**
+ * Type of notification emitter function.
+ */
+export type EmitNotificationFunction = (content: React.ReactNode) => void;
+
+/**
+ * Type of notification close function.
+ */
+export type RemoveNotificationFunction = (uuid: NotificationUuid) => void;
+
+/**
+ * Type of notification close function.
+ */
+export type CloseNotificationFunction = (uuid: NotificationUuid) => void;
+
+/**
+ * Type of notification closed state function.
+ */
+export type IsNotificationClosedFunction = (uuid: NotificationUuid) => boolean;
+
+
+/**
+ * Interface of notifications state.
+ */
+export interface NotificationsContextState
+{
+	/**
+	 * Notification function.
+	 * @param content Notification content.
+	 */
+	notify: EmitNotificationFunction;
+
+	/**
+	 * Close notification function.
+	 * @param uuid UUID of notification to close.
+	 */
+	close: CloseNotificationFunction;
+
+	/**
+	 * Is given notification closed?
+	 * @param uuid UUID of notification to get closed state.
+	 */
+	isClosed: IsNotificationClosedFunction;
+}
+
+export const NotificationsContext = React.createContext<NotificationsContextState>({
+	notify() {},
+	close() {},
+	isClosed() { return false; },
+});
+
+/**
+ * Hook to emit a notification.
+ */
+export function useNotify(): EmitNotificationFunction
+{
+	return useContext(NotificationsContext).notify;
+}
+
+
+
+/**
+ * Notifications provider.
+ */
+export function NotificationsProvider({children}: React.PropsWithChildren<{}>)
+{
+	// Notifications.
+	const [notifications, setNotifications] = useState<Record<NotificationUuid, NotificationData>>({});
+	// Keeping track of closed notifications that are still on (while transitioning out).
+	const [closedNotifications, setClosedNotifications] = useState<Record<NotificationUuid, boolean>>()
+
+	// Initialize remove notification function.
+	const remove = useRef<RemoveNotificationFunction>();
+	remove.current = useCallback((uuid) => {
+		// Copy the notifications list.
+		const newNotifications = {...notifications};
+		const newClosedNotifications = {...closedNotifications};
+		// Remove the given notification from the list.
+		delete newNotifications[uuid];
+		delete newClosedNotifications[uuid];
+		// Set the new notifications list.
+		setNotifications(newNotifications);
+		setClosedNotifications(newClosedNotifications);
+	}, [notifications, setNotifications, closedNotifications, setClosedNotifications]);
+
+	// Initialize close notification function with animation.
+	const close = useRef<CloseNotificationFunction>();
+	close.current = useCallback((uuid) => {
+		// Add the given curtain UUID to the list of closed curtains.
+		setClosedNotifications({
+			...closedNotifications,
+			[uuid]: true,
+		});
+
+		// Remove the notification 300ms later.
+		window.setTimeout(() => {
+			// Remove the curtain.
+			remove.current(uuid);
+		}, 300);
+	}, [remove, closedNotifications, setClosedNotifications]);
+
+	// Initialize isClosed notification function.
+	const isClosed = useRef<IsNotificationClosedFunction>();
+	isClosed.current = useCallback((uuid) => (!!closedNotifications?.[uuid]), [closedNotifications]);
+
+	// Initialize notify function.
+	const notify = useRef<EmitNotificationFunction>();
+	notify.current = useCallback((content: React.ReactNode) => {
+		// Generate a new notification UUID for the new notification.
+		const notificationUuid = uuidv4();
+
+		// Add the notification to the list of notifications, with the generated UUID.
+		setNotifications({
+			...notifications,
+			[notificationUuid]: {
+				content: content,
+			},
+		});
+
+		// Close notification 10s later.
+		setTimeout(() => {
+			close.current(notificationUuid);
+		}, 10000);
+	}, [notifications, setNotifications]);
+
+	// Initialize context state from action functions.
+	const contextState = useMemo(() => ({
+		notify: (content: React.ReactNode) => notify.current(content),
+		close: (uuid: NotificationUuid) => close.current(uuid),
+		isClosed: (uuid: NotificationUuid) => isClosed.current(uuid),
+	}), [notify, isClosed]);
+
+	return (
+		<NotificationsContext.Provider value={contextState}>
+			{children}
+			<NotificationsPortal notifications={notifications} />
+		</NotificationsContext.Provider>
+	);
+}
+
+/**
+ * Curtains portal manager.
+ */
+function NotificationsPortal({notifications}: {
+	notifications: Record<NotificationUuid, NotificationData>;
+})
+{
+	return ReactDOM.createPortal((
+		<ul className={"notifications"}>
+			{ // Show notifications list.
+				Object.entries(notifications).map(([uuid, notificationData]) => (
+					<NotificationInstance key={uuid} uuid={uuid}>
+						{notificationData.content}
+					</NotificationInstance>
+				))
+			}
+		</ul>
+	), document.body);
+}
+
+/**
+ * A notification context.
+ */
+export const NotificationContext = React.createContext<{
+	/**
+	 * Notification UUID.
+	 */
+	uuid: NotificationUuid;
+
+	/**
+	 * Notification closed state.
+	 */
+	closed: boolean;
+}>(undefined);
+
+/**
+ * Notification component.
+ */
+function NotificationInstance({uuid, children}: React.PropsWithChildren<{
+	/**
+	 * Notification UUID.
+	 */
+	uuid: NotificationUuid;
+}>)
+{
+	// Get notifications context.
+	const {isClosed} = useContext(NotificationsContext);
+
+	return (
+		<NotificationContext.Provider value={{
+			uuid: uuid,
+			closed: isClosed(uuid),
+		}}>
+			{children}
+		</NotificationContext.Provider>
+	);
+}

src/styles/_components.less

@@ -12,6 +12,7 @@
 @import "components/_loaders";
 @import "components/_menus";
 @import "components/_modal";
+@import "components/_notifications";
 @import "components/_pagination";
 @import "components/_select";
 @import "components/_steps";

src/styles/components/_curtains.less

@@ -31,7 +31,7 @@ body.dimmed
 { // Disable scroll and blur the content when the body is dimmed.
 	overflow: hidden;
 
-	> *:not(.curtain)
+	> *:not(.curtain):not(.notifications)
 	{
 		transition: filter 0.4s ease-in;
 

src/styles/components/_notifications.less

@@ -0,0 +1,86 @@
+body > ul.notifications
+{ // Notifications list.
+	position: fixed;
+	top: 0;
+	right: 0;
+
+	margin: 0 1em 1em;
+	padding: 0;
+	width: 20em;
+	max-width: 66%;
+
+	list-style: none;
+
+	z-index: 2000;
+
+	> li.notification
+	{ // A single notification.
+		margin: 1em auto;
+		padding: 1em;
+
+		border-radius: 0.25em;
+
+		box-shadow: 0 0 0.5em 0 var(--foreground-shadow);
+		background: var(--background);
+
+		// Show an animation when entering screen.
+		animation: notification-in 0.3s ease-in;
+		transform-origin: center;
+
+		&.closed
+		{ // Added when the notification is closing and will soon be removed from DOM.
+			transition: transform 0.3s ease-out, filter 0.3s ease-out, opacity 0.3s ease-out;
+
+			transform: scale(1.15);
+			filter: blur(0.25em);
+			opacity: 0;
+
+			pointer-events: none;
+		}
+
+		&.info
+		{
+			border: solid var(--primary-darker) thin;
+			background: var(--primary);
+			color: var(--background);
+		}
+
+		&.success
+		{
+			border: solid var(--green-darker) thin;
+			background: var(--green);
+			color: var(--background);
+		}
+
+		&.warning
+		{
+			border: solid var(--orange-darker) thin;
+			background: var(--orange);
+			color: var(--background);
+		}
+
+		&.error
+		{
+			border: solid var(--red-darker) thin;
+			background: var(--red);
+			color: var(--background);
+		}
+	}
+}
+
+@keyframes notification-in
+{ // Screen enter animation.
+	from
+	{
+		transform: scale(1.15);
+		filter: blur(0.25em);
+		opacity: 0;
+	}
+
+	to
+	{
+		transform: scale(1);
+		filter: blur(0);
+		opacity: 1;
+	}
+}