add event deletion

packages/nostr/.eslintrc.cjs

@@ -12,5 +12,6 @@ module.exports = {
   rules: {
     "require-await": "error",
     eqeqeq: "error",
+    "object-shorthand": "warn",
   },
 }

packages/nostr/src/event/deletion.ts

@@ -0,0 +1,48 @@
+import { EventId, EventKind, RawEvent, signEvent } from "."
+import { NostrError } from "../common"
+import { HexOrBechPrivateKey } from "../crypto"
+
+/**
+ * A deletion event. Used for marking published events as deleted.
+ *
+ * Related NIPs: NIP-09.
+ */
+export interface Deletion extends RawEvent {
+  kind: EventKind.Deletion
+
+  /**
+   * The IDs of events to delete.
+   */
+  getEvents(): EventId[]
+}
+
+/**
+ * Create a deletion event.
+ */
+export function createDeletion(
+  { events, content }: { events: EventId[]; content?: string },
+  priv?: HexOrBechPrivateKey
+): Promise<Deletion> {
+  return signEvent(
+    {
+      kind: EventKind.Deletion,
+      tags: events.map((id) => ["e", id]),
+      content: content ?? "",
+      getEvents,
+    },
+    priv
+  )
+}
+
+export function getEvents(this: Deletion): EventId[] {
+  return this.tags
+    .filter((tag) => tag[0] === "e")
+    .map((tag) => {
+      if (tag[1] !== undefined) {
+        throw new NostrError(
+          `invalid deletion event tag: ${JSON.stringify(tag)}`
+        )
+      }
+      return tag[1]
+    })
+}

packages/nostr/src/event/index.ts

@@ -21,6 +21,7 @@ import {
   getRecipient,
 } from "./direct-message"
 import { ContactList, getContacts } from "./contact-list"
+import { Deletion, getEvents } from "./deletion"
 
 // TODO Add remaining event types
 
@@ -69,8 +70,9 @@ export interface Unknown extends RawEvent {
     EventKind,
     | EventKind.SetMetadata
     | EventKind.TextNote
-    | EventKind.DirectMessage
     | EventKind.ContactList
+    | EventKind.DirectMessage
+    | EventKind.Deletion
   >
 }
 
@@ -79,6 +81,7 @@ export type Event =
   | TextNote
   | ContactList
   | DirectMessage
+  | Deletion
   | Unknown
 
 /**
@@ -189,6 +192,14 @@ export async function parseEvent(event: RawEvent): Promise<Event> {
     }
   }
 
+  if (event.kind === EventKind.Deletion) {
+    return {
+      ...event,
+      kind: EventKind.Deletion,
+      getEvents,
+    }
+  }
+
   return {
     ...event,
     kind: event.kind,