Create `updateListEvent` helper function

src/controllers/api/accounts.ts

@@ -7,9 +7,10 @@ import { type DittoFilter } from '@/filter.ts';
 import { getAuthor, getFollowedPubkeys, getFollows } from '@/queries.ts';
 import { booleanParamSchema, fileSchema } from '@/schema.ts';
 import { jsonMetaContentSchema } from '@/schemas/nostr.ts';
+import { setTag } from '@/tags.ts';
 import { uploadFile } from '@/upload.ts';
 import { isFollowing, lookupAccount, nostrNow } from '@/utils.ts';
-import { paginated, paginationSchema, parseBody } from '@/utils/web.ts';
+import { paginated, paginationSchema, parseBody, updateListEvent } from '@/utils/web.ts';
 import { createEvent } from '@/utils/web.ts';
 import { renderEventAccounts } from '@/views.ts';
 import { accountFromPubkey, renderAccount } from '@/views/mastodon/accounts.ts';
@@ -219,14 +220,12 @@ const followController: AppController = async (c) => {
   const source = await getFollows(sourcePubkey);
 
   if (!source || !isFollowing(source, targetPubkey)) {
-    await createEvent({
-      kind: 3,
-      content: '',
-      tags: [
-        ...(source?.tags ?? []),
-        ['p', targetPubkey],
-      ],
-    }, c);
+    await updateListEvent(
+      source ?? { kind: 3 },
+      ['p', targetPubkey],
+      setTag,
+      c,
+    );
   }
 
   const relationship = await renderRelationship(sourcePubkey, targetPubkey);

src/tags.ts

@@ -11,6 +11,11 @@ function getTagSet(tags: string[][], tagName: string): Set<string> {
   return set;
 }
 
+/** Check if the tag exists by its name and value. */
+function hasTag(tags: string[][], tag: string[]): boolean {
+  return tags.some(([name, value]) => name === tag[0] && value === tag[1]);
+}
+
 /** Delete all occurences of the tag by its name/value pair. */
 function deleteTag(tags: readonly string[][], tag: string[]): string[][] {
   return tags.filter(([name, value]) => !(name === tag[0] && value === tag[1]));
@@ -26,4 +31,4 @@ function setTag(tags: readonly string[][], tag: string[]): string[][] {
   }
 }
 
-export { deleteTag, getTagSet, setTag };
+export { deleteTag, getTagSet, hasTag, setTag };

src/utils.ts

@@ -1,5 +1,6 @@
 import { type Event, type EventTemplate, getEventHash, nip19, z } from '@/deps.ts';
 import { getAuthor } from '@/queries.ts';
+import { hasTag } from '@/tags.ts';
 import { lookupNip05Cached } from '@/utils/nip05.ts';
 import { nostrIdSchema } from '@/schemas/nostr.ts';
 
@@ -97,9 +98,7 @@ const isRelay = (relay: string): relay is `wss://${string}` => relaySchema.safeP
 
 /** Check whether source is following target. */
 function isFollowing(source: Event<3>, targetPubkey: string): boolean {
-  return Boolean(
-    source.tags.find(([tagName, tagValue]) => tagName === 'p' && tagValue === targetPubkey),
-  );
+  return hasTag(source.tags, ['p', targetPubkey]);
 }
 
 /** Deduplicate events by ID. */

src/utils/web.ts

@@ -1,13 +1,12 @@
+import { type AppContext } from '@/app.ts';
 import { Conf } from '@/config.ts';
 import { type Context, type Event, EventTemplate, HTTPException, parseFormData, type TypeFest, z } from '@/deps.ts';
 import * as pipeline from '@/pipeline.ts';
 import { signAdminEvent, signEvent } from '@/sign.ts';
 import { nostrNow } from '@/utils.ts';
 
-import type { AppContext } from '@/app.ts';
-
 /** EventTemplate with defaults. */
-type EventStub<K extends number = number> = TypeFest.SetOptional<EventTemplate<K>, 'created_at' | 'tags'>;
+type EventStub<K extends number = number> = TypeFest.SetOptional<EventTemplate<K>, 'content' | 'created_at' | 'tags'>;
 
 /** Publish an event through the pipeline. */
 async function createEvent<K extends number>(t: EventStub<K>, c: AppContext): Promise<Event<K>> {
@@ -18,6 +17,7 @@ async function createEvent<K extends number>(t: EventStub<K>, c: AppContext): Pr
   }
 
   const event = await signEvent({
+    content: '',
     created_at: nostrNow(),
     tags: [],
     ...t,
@@ -26,9 +26,24 @@ async function createEvent<K extends number>(t: EventStub<K>, c: AppContext): Pr
   return publishEvent(event, c);
 }
 
+/** Add the tag to the list and then publish the new list, or throw if the tag already exists. */
+function updateListEvent<K extends number, E extends EventStub<K>>(
+  t: E,
+  tag: string[],
+  fn: (tags: string[][], tag: string[]) => string[][],
+  c: AppContext,
+): Promise<Event<K>> {
+  const { kind, content, tags = [] } = t;
+  return createEvent(
+    { kind, content, tags: fn(tags, tag) },
+    c,
+  );
+}
+
 /** Publish an admin event through the pipeline. */
 async function createAdminEvent<K extends number>(t: EventStub<K>, c: AppContext): Promise<Event<K>> {
   const event = await signAdminEvent({
+    content: '',
     created_at: nostrNow(),
     tags: [],
     ...t,
@@ -139,4 +154,5 @@ export {
   type PaginationParams,
   paginationSchema,
   parseBody,
+  updateListEvent,
 };