feat(on_message): audit messages

src/events/on_message/_advise.ts

@@ -0,0 +1,56 @@
+import urlRegex from 'url-regex';
+import {
+	type Message,
+	ChannelType,
+	hideLinkEmbed,
+	codeBlock,
+} from 'discord.js';
+
+export default async function mutate_content(message: Message) {
+	if (message.channel.type != ChannelType.GuildText) return;
+
+	const links = message.content
+		.match(urlRegex())
+		?.filter((link) => link.startsWith('https://x.com'))
+		.map((link) =>
+			link.replace(/^https:\/\/x\.com/, 'https://xcancel.com'),
+		);
+
+	if (!links || links.length === 0) {
+		return;
+	}
+
+	const updated_phrase: string =
+		links.length > 1
+			? 'Here are the updated links:'
+			: 'Here is the updated link:';
+
+	const updated_link_list = links
+		.map((link) => `- ${hideLinkEmbed(link)}`)
+		.join('\n');
+
+	const updated_content = message.content.replace(urlRegex(), (match) => {
+		return match.startsWith('https://x.com')
+			? match.replace(/^https:\/\/x\.com/, 'https://xcancel.com')
+			: match;
+	});
+
+	try {
+		await message.author.send(
+			`Re: ${message.url}\n\nI see you've provided a link to \`x.com\`. Please consider posting a new message having \`x.com\` replaced with \`xcancel.com\`, that way server members may view the message and thread without requiring an account.\n\n${updated_phrase}\n${updated_link_list}\n\nHere is your entire message with adjusted links:\n${codeBlock(updated_content)}`,
+		);
+
+		return; // mission complete
+	} catch {
+		// assume user disabled DMs upon error
+	}
+
+	// Plan B: inline reply
+	try {
+		await message.reply(
+			`I converted your \`x.com\` links to use \`xcancel.com\` so that server members won't require an account to view content and threads:\n${updated_link_list}`,
+		);
+	} catch {
+		// don't handle failures
+	}
+}

src/events/on_message/on_message.ts

@@ -2,6 +2,7 @@ import check_links from './_check_links.js';
 import spam_filter from './_spam_filter.js';
 import autothread from './_autothread.js';
 import slow_mode from './_slow_mode.js';
+import advise from './_advise.js';
 import { event } from 'jellycommands';
 import { STOP } from './_common.js';
 
@@ -16,6 +17,7 @@ export default event({
 			check_links,
 			autothread,
 			slow_mode,
+			advise,
 		]) {
 			try {
 				await handler(message);