limit audit log reasons for kicks and bans to 512 characters

Author: eritbh

src/bot/commands/moderation/ban.js

@@ -1,7 +1,7 @@
 import createLogger from 'another-logger';
 const log = createLogger({label: 'command:ban'});
 import {Command} from 'yuuko';
-import {parseUser, parseTime, formatDateRelative, awaitReaction} from '../../util/discord';
+import {parseUser, parseTime, formatDateRelative, awaitReaction, truncate} from '../../util/discord';
 import {escape, blockquote} from '../../util/formatting';
 
 const confirmationEmoji = '🔨';
@@ -61,7 +61,7 @@ const command = new Command('ban', async (message, args, context) => {
 	try {
 		// TODO: check if member is already banned before banning again
 		// TODO: service to clear bans after they expire
-		await message.channel.guild.banMember(user.id, 0, reason);
+		await message.channel.guild.banMember(user.id, 0, truncate(512, reason));
 	} catch (error) {
 		log.error(`Error banning user ${user.id} from guild ${message.channel.guild.id}:`, error);
 

src/bot/commands/moderation/kick.js

@@ -1,7 +1,7 @@
 import createLogger from 'another-logger';
 const log = createLogger({label: 'command:kick'});
 import {Command} from 'yuuko';
-import {parseGuildMember, awaitReaction} from '../../util/discord';
+import {parseGuildMember, awaitReaction, truncate} from '../../util/discord';
 import {escape, blockquote} from '../../util/formatting';
 
 const confirmationEmoji = '👢';
@@ -52,7 +52,7 @@ const command = new Command('kick', async (message, args, context) => {
 
 	// Kick the member
 	try {
-		await member.kick(reason);
+		await member.kick(truncate(512, reason));
 	} catch (error) {
 		log.error(`Error kicking user ${member.id} from guild ${message.channel.guild.id}:`, error);
 

src/bot/util/discord.ts

@@ -220,3 +220,18 @@ export const formatDateRelative = (date: Date) => `<t:${Math.round(date.getTime(
 
 /** Size of avatars shown from the avatar and defaultavatar command */
 export const AVATAR_IMAGE_SIZE = 512;
+
+/**
+ * Truncates a string to the given number of characters, adding an ellipsis
+ * at the end if part of the string had to be cut off.
+ * @param n The maximum number of characters for the returned string
+ * @param str The string to be truncated
+ * @see https://discord.com/developers/docs/resources/audit-log#audit-log-entry-object
+ */
+export function truncate (n: number, str: string) {
+	if (str.length <= n) {
+		return str;
+	}
+	// U+2026 is a single-character ellipsis
+	return `${str.slice(0, n - 1)}\u2026`;
+}