From e2b88d57d965b17dcf24d1e203ef67de7955a76e Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Tue, 5 Sep 2023 21:24:59 -0500
Subject: [PATCH] pipeline: process kind 5 deletion events

---
 src/pipeline.ts | 16 ++++++++++++++++
 src/tags.ts     | 14 ++++++++++++++
 2 files changed, 30 insertions(+)
 create mode 100644 src/tags.ts

diff --git a/src/pipeline.ts b/src/pipeline.ts
index 4bdec81..dddc0f6 100644
--- a/src/pipeline.ts
+++ b/src/pipeline.ts
@@ -7,6 +7,7 @@ import { isEphemeralKind } from '@/kinds.ts';
 import * as mixer from '@/mixer.ts';
 import { isLocallyFollowed } from '@/queries.ts';
 import { Sub } from '@/subs.ts';
+import { getTagSet } from '@/tags.ts';
 import { trends } from '@/trends.ts';
 import { eventAge, isRelay, nostrDate, Time } from '@/utils.ts';
 
@@ -22,6 +23,7 @@ async function handleEvent(event: Event): Promise<void> {
 
   await Promise.all([
     storeEvent(event, data),
+    processDeletions(event),
     trackRelays(event),
     trackHashtags(event),
     streamOut(event, data),
@@ -67,6 +69,20 @@ async function storeEvent(event: Event, data: EventData): Promise<void> {
   }
 }
 
+/** Query to-be-deleted events, ensure their pubkey matches, then delete them from the database. */
+async function processDeletions(event: Event): Promise<void> {
+  if (event.kind === 5) {
+    const ids = getTagSet(event.tags, 'e');
+    const events = await eventsDB.getFilters([{ ids: [...ids] }]);
+
+    const deleteIds = events
+      .filter(({ pubkey, id }) => pubkey === event.pubkey && ids.has(id))
+      .map((event) => event.id);
+
+    await eventsDB.deleteFilters([{ ids: deleteIds }]);
+  }
+}
+
 /** Track whenever a hashtag is used, for processing trending tags. */
 function trackHashtags(event: Event): void {
   const date = nostrDate(event.created_at);
diff --git a/src/tags.ts b/src/tags.ts
new file mode 100644
index 0000000..98efc7d
--- /dev/null
+++ b/src/tags.ts
@@ -0,0 +1,14 @@
+/** Get the values for a tag in a `Set`. */
+function getTagSet(tags: string[][], tagName: string): Set<string> {
+  const set = new Set<string>();
+
+  tags.forEach((tag) => {
+    if (tag[0] === tagName) {
+      set.add(tag[1]);
+    }
+  });
+
+  return set;
+}
+
+export { getTagSet };