Centralize DM logic, don't attempt DMs for an hour after a 20026 error

backend/src/data/DefaultLogMessages.json

@@ -47,6 +47,7 @@
   "CLEAN": "🚿 {userMention(mod)} cleaned **{count}** message(s) in {channelMention(channel)}\n{archiveUrl}",
 
   "CASE_CREATE": "✏ {userMention(mod)} manually created new **{caseType}** case (#{caseNum})",
+  "CASE_DELETE": "✂️ **Case #{case.case_number}** was deleted by {userMention(mod)}",
 
   "MASSBAN": "⚒ {userMention(mod)} massbanned {count} users",
   "MASSMUTE": "📢🚫 {userMention(mod)} massmuted {count} users",
@@ -63,10 +64,9 @@
   "POSTED_SCHEDULED_MESSAGE": "\uD83D\uDCE8 Posted scheduled message (`{messageId}`) to {channelMention(channel)} as scheduled by {userMention(author)}",
 
   "BOT_ALERT": "⚠ **BOT ALERT:** {tmplEval(body)}",
+  "DM_FAILED": "\uD83D\uDEA7 Failed to send DM ({source}) to {userMention(user)}",
+
   "AUTOMOD_ACTION": "\uD83E\uDD16 Automod rule **{rule}** triggered by {userMention(users)}\n{matchSummary}\nActions taken: **{actionsTaken}**",
-
   "SET_ANTIRAID_USER": "⚔ {userMention(user)} set anti-raid to **{level}**",
-  "SET_ANTIRAID_AUTO": "⚔ Anti-raid automatically set to **{level}**",
-
-  "CASE_DELETE": "✂️ **Case #{case.case_number}** was deleted by {userMention(mod)}"
+  "SET_ANTIRAID_AUTO": "⚔ Anti-raid automatically set to **{level}**"
 }

backend/src/data/LogType.ts

@@ -77,4 +77,6 @@ export enum LogType {
   MEMBER_NOTE,
 
   CASE_DELETE,
+
+  DM_FAILED,
 }

backend/src/plugins/WelcomeMessage/events/SendWelcomeMessageEvt.ts

@@ -3,6 +3,7 @@ import { renderTemplate } from "src/templateFormatter";
 import { createChunkedMessage, stripObjectToScalars } from "src/utils";
 import { LogType } from "src/data/LogType";
 import { TextChannel } from "eris";
+import { sendDM } from "../../../utils/sendDM";
 
 export const SendWelcomeMessageEvt = welcomeEvent({
   event: "guildMemberAdd",
@@ -21,14 +22,11 @@ export const SendWelcomeMessageEvt = welcomeEvent({
 
     if (config.send_dm) {
       try {
-        console.log(`Sending welcome message to ${member.id}`);
-        const dmChannel = await member.user.getDMChannel();
-        if (!dmChannel) return;
-        await createChunkedMessage(dmChannel, formatted);
+        await sendDM(member.user, formatted, "welcome message");
       } catch (e) {
-        pluginData.state.logs.log(LogType.BOT_ALERT, {
-          body: `Failed send a welcome DM to {userMention(member)}`,
-          member: stripObjectToScalars(member, ["user"]),
+        pluginData.state.logs.log(LogType.DM_FAILED, {
+          source: "welcome message",
+          user: stripObjectToScalars(member.user),
         });
       }
     }

backend/src/utils.ts

@@ -38,6 +38,8 @@ import moment from "moment-timezone";
 import { SimpleCache } from "./SimpleCache";
 import { logger } from "./logger";
 import { unsafeCoerce } from "fp-ts/lib/function";
+import { sendDM } from "./utils/sendDM";
+import { LogType } from "./data/LogType";
 
 const fsp = fs.promises;
 
@@ -878,9 +880,7 @@ export async function notifyUser(
   for (const method of methods) {
     if (method.type === "dm") {
       try {
-        console.log(`Notifying user ${user.id} via DM`);
-        const dmChannel = await user.getDMChannel();
-        await dmChannel.createMessage(body);
+        await sendDM(user, body, "mod action notification");
         return {
           method,
           success: true,
@@ -1069,8 +1069,6 @@ export async function resolveMember(bot: Client, guild: Guild, value: string): P
     return null;
   }
 
-  logger.debug(`Fetching unknown member (${userId} in ${guild.name} (${guild.id})) from the API`);
-
   const freshMember = await bot.getRESTGuildMember(guild.id, userId).catch(noop);
   if (freshMember) {
     freshMember.id = userId;

backend/src/utils/sendDM.ts

@@ -0,0 +1,46 @@
+import { MessageContent, MessageFile, User } from "eris";
+import { createChunkedMessage, HOURS, isDiscordRESTError } from "../utils";
+import { logger } from "../logger";
+
+let dmsDisabled = false;
+let dmsDisabledTimeout = null;
+
+function disableDMs(duration) {
+  dmsDisabled = true;
+  clearTimeout(dmsDisabledTimeout);
+  dmsDisabledTimeout = setTimeout(() => (dmsDisabled = false), duration);
+}
+
+export class DMError extends Error {}
+
+const error20026 = "The bot cannot currently send DMs";
+
+export async function sendDM(user: User, content: MessageContent, source: string) {
+  if (dmsDisabled) {
+    throw new DMError(error20026);
+  }
+
+  logger.debug(`Sending ${source} DM to ${user.id}`);
+
+  try {
+    const dmChannel = await user.getDMChannel();
+    if (!dmChannel) {
+      throw new DMError("Unable to open DM channel");
+    }
+
+    if (typeof content === "string") {
+      await createChunkedMessage(dmChannel, content);
+    } else {
+      await dmChannel.createMessage(content);
+    }
+  } catch (e) {
+    if (isDiscordRESTError(e) && e.code === 20026) {
+      logger.warn(`Received error code 20026: ${e.message}`);
+      logger.warn("Disabling attempts to send DMs for 1 hour");
+      disableDMs(1 * HOURS);
+      throw new DMError(error20026);
+    }
+
+    throw e;
+  }
+}