workspace with decoupled nostr package

packages/app/src/Notifications.ts

@@ -0,0 +1,45 @@
+import Nostrich from "nostrich.webp";
+
+import { TaggedRawEvent } from "@snort/nostr";
+import { EventKind } from "@snort/nostr";
+import type { NotificationRequest } from "State/Login";
+import { MetadataCache, UsersDb } from "State/Users";
+import { getDisplayName } from "Element/ProfileImage";
+import { MentionRegex } from "Const";
+
+export async function makeNotification(db: UsersDb, ev: TaggedRawEvent): Promise<NotificationRequest | null> {
+  switch (ev.kind) {
+    case EventKind.TextNote: {
+      const pubkeys = new Set([ev.pubkey, ...ev.tags.filter(a => a[0] === "p").map(a => a[1])]);
+      const users = await db.bulkGet(Array.from(pubkeys));
+      const fromUser = users.find(a => a?.pubkey === ev.pubkey);
+      const name = getDisplayName(fromUser, ev.pubkey);
+      const avatarUrl = fromUser?.picture || Nostrich;
+      return {
+        title: `Reply from ${name}`,
+        body: replaceTagsWithUser(ev, users).substring(0, 50),
+        icon: avatarUrl,
+        timestamp: ev.created_at * 1000,
+      };
+    }
+  }
+  return null;
+}
+
+function replaceTagsWithUser(ev: TaggedRawEvent, users: MetadataCache[]) {
+  return ev.content
+    .split(MentionRegex)
+    .map(match => {
+      const matchTag = match.match(/#\[(\d+)\]/);
+      if (matchTag && matchTag.length === 2) {
+        const idx = parseInt(matchTag[1]);
+        const ref = ev.tags[idx];
+        if (ref && ref[0] === "p" && ref.length > 1) {
+          const u = users.find(a => a.pubkey === ref[1]);
+          return `@${getDisplayName(u, ref[1])}`;
+        }
+      }
+      return match;
+    })
+    .join();
+}