Add notification badges

src/app/notifications.ts

@@ -0,0 +1,51 @@
+import {writable, derived} from "svelte/store"
+import {deriveEvents} from "@welshman/store"
+import {repository, pubkey} from "@welshman/app"
+import {prop, max, sortBy, assoc, lt, now} from "@welshman/lib"
+import type {Filter} from "@welshman/util"
+import {DIRECT_MESSAGE} from "@welshman/util"
+import {MESSAGE, THREAD, COMMENT, deriveEventsForUrl} from "@app/state"
+
+// Checked state
+
+export const checked = writable<Record<string, number>>({})
+
+export const deriveChecked = (key: string) => derived(checked, prop(key))
+
+export const setChecked = (key: string, ts = now()) =>
+  checked.update(state => ({...state, [key]: ts}))
+
+// Filters for various routes
+
+export const CHAT_FILTERS: Filter[] = [{kinds: [DIRECT_MESSAGE]}]
+
+export const SPACE_FILTERS: Filter[] = [{kinds: [THREAD, MESSAGE, COMMENT]}]
+
+export const ROOM_FILTERS: Filter[] = [{kinds: [MESSAGE]}]
+
+export const THREAD_FILTERS: Filter[] = [
+  {kinds: [THREAD]},
+  {kinds: [COMMENT], "#K": [String(THREAD)]},
+]
+
+export const getNotificationFilters = (since: number): Filter[] =>
+  [...CHAT_FILTERS, ...SPACE_FILTERS, ...THREAD_FILTERS].map(assoc("since", since))
+
+export const getRoomFilters = (room: string): Filter[] => ROOM_FILTERS.map(assoc("#~", [room]))
+
+// Notification derivation
+
+export const deriveNotification = (path: string, filters: Filter[], url?: string) => {
+  const events = url ? deriveEventsForUrl(url, filters) : deriveEvents(repository, {filters})
+
+  return derived(
+    [pubkey, deriveChecked("*"), deriveChecked(path), events],
+    ([$pubkey, $allChecked, $checked, $events]) => {
+      const [latestEvent] = sortBy($e => -$e.created_at, $events)
+
+      return (
+        latestEvent?.pubkey !== $pubkey && lt(max([$allChecked, $checked]), latestEvent?.created_at)
+      )
+    },
+  )
+}