Add metrics for new Tagged forum posts

src/features/stats.ts

@@ -1,7 +1,9 @@
 import fetch from "node-fetch";
 import queryString from "query-string";
-import { Client } from "discord.js";
+import { ChannelType, Client } from "discord.js";
 import { amplitudeKey } from "../helpers/env";
+import { difference } from "../helpers/sets";
+import { mapAppliedTagsToTagNames } from "../helpers/discord";
 
 type AmplitudeValue = string | number | boolean;
 type EmitEventData = Record<string, AmplitudeValue | AmplitudeValue[]>;
@@ -32,13 +34,16 @@ const emitEvent = (
 };
 
 const message = "message sent";
+const postTagged = "post tagged";
 const threadCreated = "thread created";
 const threadReplyRemoved = "thread reply removed";
 const threadTimeout = "thread timeout";
 const threadResolved = "thread resolved";
 const reacted = "reaction added";
 
 export const threadStats = {
+  postTagged: (tags: string[], channel: string) =>
+    emitEvent(postTagged, { data: { tags, channel } }),
   threadCreated: (channel: string) =>
     emitEvent(threadCreated, { data: { channel } }),
   threadReplyRemoved: (channel: string) =>
@@ -57,6 +62,37 @@ export const threadStats = {
 };
 
 const stats = (client: Client) => {
+  client.on("threadUpdate", async (oldThread, newThread) => {
+    if (oldThread.parent?.type !== ChannelType.GuildForum) {
+      return;
+    }
+    const appliedTags = [
+      ...difference(
+        new Set(newThread.appliedTags),
+        new Set(oldThread.appliedTags),
+      ),
+    ];
+
+    if (appliedTags.length === 0) {
+      return;
+    }
+
+    threadStats.postTagged(
+      mapAppliedTagsToTagNames(appliedTags, oldThread.parent),
+      newThread.parentId ?? "0",
+    );
+  });
+  client.on("threadCreate", async (thread) => {
+    if (
+      thread.parent?.type === ChannelType.GuildForum &&
+      thread.appliedTags.length > 0
+    ) {
+      threadStats.postTagged(
+        mapAppliedTagsToTagNames(thread.appliedTags, thread.parent),
+        thread.parentId ?? "0",
+      );
+    }
+  });
   client.on("messageReactionAdd", async (reaction, user) => {
     const { message, emoji } = reaction;
     const { channel } = message;
@@ -72,6 +108,7 @@ const stats = (client: Client) => {
       data: {
         channel: channelId,
         emoji: emoji.toString() ?? "n/a",
+        target: message.author?.id ?? "0",
       },
       userId: user.id,
     });

src/helpers/discord.ts

@@ -13,6 +13,7 @@ import {
   SlashCommandBuilder,
   APIApplicationCommand,
   APIApplicationCommandOption,
+  ForumChannel,
 } from "discord.js";
 import prettyBytes from "pretty-bytes";
 
@@ -113,6 +114,16 @@ export const quoteAndEscape = (content: string) => {
   return escapeDisruptiveContent(quoteMessageContent(content));
 };
 
+export const mapAppliedTagsToTagNames = (
+  appliedTags: string[],
+  channel: ForumChannel,
+) => {
+  const { availableTags: tags } = channel;
+  const tagLookup = new Map(tags.map((e) => [e.id, e]));
+
+  return appliedTags.map((id) => tagLookup.get(id)?.name ?? "");
+};
+
 //
 // Types and type helpers for command configs
 //

src/helpers/sets.ts

@@ -1,2 +1,5 @@
+/**
+ * Difference returns a list of items that are in A but is not present in B.
+ */
 export const difference = <T>(a: Set<T>, b: Set<T>) =>
   new Set(Array.from(a).filter((x) => !b.has(x)));