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

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;
+  }
+}