malice

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

import { mediaUrl } from './api';

import {

  arrivalIn,

  type Arrival,

  badgeTotal,

  isRoomWatched,

  notifyingCount,

  planNotification,

  roomTag,

  sourceFromSummary,

  sourceFromTimeline,

  type NotificationPlan

} from './notification-model';

import { rooms, selectedRoomId, sessionUser, timelines } from './store';

import type { RoomSummary } from './types';

const SETTLE_MS = 300;

export const OPEN_ROOM_MESSAGE = 'malice-open-room';

export type NotificationPermissionState = NotificationPermission | 'unsupported';

const supported = typeof Notification !== 'undefined';

const preferenceKey = (account: string) => `malice.notifications.${account}`;

export const notificationsEnabled = writable(false);

export const notificationPermission = writable<NotificationPermissionState>(supported ? Notification.permission : 'unsupported');

function readPreference(account: string | null | undefined): boolean {

  if (!account) return false;

  try {

    return localStorage.getItem(preferenceKey(account)) === '1';

  } catch {

    return false;

  }

}

function writePreference(account: string, enabled: boolean): void {

  try {

    localStorage.setItem(preferenceKey(account), enabled ? '1' : '0');

  } catch {}

}

/** Must run inside a user gesture, since browsers refuse the permission prompt otherwise. */

export async function enableNotifications(): Promise<void> {

  const account = get(sessionUser);

  if (!supported || !account) return;

  const result = Notification.permission === 'default' ? await Notification.requestPermission() : Notification.permission;

  notificationPermission.set(result);

  const on = result === 'granted';

  writePreference(account, on);

  notificationsEnabled.set(on);

}

export function disableNotifications(): void {

  const account = get(sessionUser);

  if (account) writePreference(account, false);

  notificationsEnabled.set(false);

}

function active(): boolean {

  return supported && get(notificationsEnabled) && Notification.permission === 'granted';

}

async function registration(): Promise<ServiceWorkerRegistration | null> {

  if (!('serviceWorker' in navigator) || !navigator.serviceWorker.controller) return null;

  try {

    return await navigator.serviceWorker.ready;

  } catch {

    return null;

  }

}

async function show(plan: NotificationPlan, openRoom: (roomId: string) => void): Promise<void> {

  const icon = mediaUrl(plan.iconMxc, 128) ?? undefined;

  const options: NotificationOptions & { renotify?: boolean } = {

    body: plan.body,

    tag: plan.tag,

    icon,

    renotify: plan.renotify,

    data: { roomId: plan.roomId }

  };

  const reg = await registration();

  if (reg) {

    await reg.showNotification(plan.title, options);

    return;

  }

  const note = new Notification(plan.title, options);

  note.onclick = () => {

    window.focus();

    openRoom(plan.roomId);

    note.close();

  };

}

async function closeRoom(roomId: string): Promise<void> {

  const reg = await registration();

  if (!reg) return;

  for (const note of await reg.getNotifications({ tag: roomTag(roomId) })) note.close();

}

function setBadge(total: number): void {

  const nav = navigator as Navigator & { setAppBadge?: (n: number) => Promise<void>; clearAppBadge?: () => Promise<void> };

  if (total > 0) void nav.setAppBadge?.(total).catch(() => undefined);

  else void nav.clearAppBadge?.().catch(() => undefined);

}

/** Watches room summaries for notifying unread increases, shows and clears notifications, and keeps the app badge current. */

export function startNotifications(openRoom: (roomId: string) => void): () => void {

  let previous = new Map<string, RoomSummary>();

  let notified = new Set<string>();

  let badge = -1;

  const unsubscribeSession = sessionUser.subscribe((account) => notificationsEnabled.set(readPreference(account)));

  void registration().then(async (reg) => {

    for (const note of (await reg?.getNotifications()) ?? []) {

      const roomId = (note.data as { roomId?: unknown } | null)?.roomId;

      if (typeof roomId === 'string') notified.add(roomId);

    }

  });

  const watched = (roomId: string) =>

    isRoomWatched(roomId, get(selectedRoomId), document.visibilityState === 'visible', document.hasFocus());

  const clearRead = (list: RoomSummary[]) => {

    for (const room of list) {

      if (notified.has(room.room_id) && (notifyingCount(room) === 0 || watched(room.room_id))) {

        notified.delete(room.room_id);

        void closeRoom(room.room_id);

      }

    }

  };

  const waiting = new Map<string, Arrival & { timer: ReturnType<typeof setTimeout> }>();

  const queue = (roomId: string, mention: boolean) => {

    clearTimeout(waiting.get(roomId)?.timer);

    const timer = setTimeout(() => {

      waiting.delete(roomId);

      const room = get(rooms).find((r) => r.room_id === roomId);

      if (!room || !active() || watched(roomId) || notifyingCount(room) === 0) return;

      const source = sourceFromTimeline(get(timelines)[roomId]) ?? sourceFromSummary(room);

      notified.add(roomId);

      void show(planNotification(room, source, { mention }), openRoom);

    }, SETTLE_MS);

    waiting.set(roomId, { mention, timer });

  };

  const onRooms = (list: RoomSummary[]) => {

    const next = new Map(list.map((room) => [room.room_id, room]));

    const prior = previous;

    previous = next;

    if (!active()) {

      if (badge !== 0) setBadge((badge = 0));

      return;

    }

    const total = badgeTotal(list);

    if (total !== badge) setBadge((badge = total));

    const now = Date.now();

    for (const room of list) {

      const arrival = arrivalIn(prior.get(room.room_id), room, now);

      if (!arrival || watched(room.room_id)) continue;

      queue(room.room_id, arrival.mention || (waiting.get(room.room_id)?.mention ?? false));

    }

    clearRead(list);

  };

  const unsubscribeRooms = rooms.subscribe(onRooms);

  const unsubscribeEnabled = notificationsEnabled.subscribe(() => onRooms(get(rooms)));

  const onAttention = () => clearRead(get(rooms));

  const onMessage = (ev: MessageEvent) => {

    const data = ev.data as { type?: unknown; roomId?: unknown } | null;

    if (data?.type === OPEN_ROOM_MESSAGE && typeof data.roomId === 'string') openRoom(data.roomId);

  };

  window.addEventListener('focus', onAttention);

  document.addEventListener('visibilitychange', onAttention);

  const unsubscribeSelected = selectedRoomId.subscribe(onAttention);

  if ('serviceWorker' in navigator) navigator.serviceWorker.addEventListener('message', onMessage);

  return () => {

    unsubscribeSession();

    unsubscribeRooms();

    unsubscribeEnabled();

    unsubscribeSelected();

    for (const { timer } of waiting.values()) clearTimeout(timer);

    window.removeEventListener('focus', onAttention);

    document.removeEventListener('visibilitychange', onAttention);

    if ('serviceWorker' in navigator) navigator.serviceWorker.removeEventListener('message', onMessage);

  };

}