chat.ts

/**
 * Chat
 * Pokemon Showdown - http://pokemonshowdown.com/
 *
 * This handles chat and chat commands sent from users to chatrooms
 * and PMs. The main function you're looking for is Chat.parse
 * (scroll down to its definition for details)
 *
 * Individual commands are put in:
 *   chat-commands/ - "core" commands that shouldn't be modified
 *   chat-plugins/ - other commands that can be safely modified
 *
 * The command API is (mostly) documented in chat-plugins/COMMANDS.md
 *
 * @license MIT
 */

/*

To reload chat commands:

/hotpatch chat

*/

import type {RoomPermission, GlobalPermission} from './user-groups';
import type {Punishment} from './punishments';
import type {PartialModlogEntry} from './modlog';
import {FriendsDatabase, PM} from './friends';
import {SQL, Repl, FS, Utils} from '../lib';
import * as Artemis from './artemis';
import {Dex} from '../sim';
import {resolve} from 'path';
import * as JSX from './chat-jsx';

export type PageHandler = (this: PageContext, query: string[], user: User, connection: Connection)
=> Promise<string | null | void | JSX.VNode> | string | null | void | JSX.VNode;
export interface PageTable {
	[k: string]: PageHandler | PageTable;
}

export type ChatHandler = (
	this: CommandContext,
	target: string,
	room: Room | null,
	user: User,
	connection: Connection,
	cmd: string,
	message: string
) => void;
export type AnnotatedChatHandler = ChatHandler & {
	requiresRoom: boolean | RoomID,
	hasRoomPermissions: boolean,
	broadcastable: boolean,
	cmd: string,
	fullCmd: string,
	isPrivate: boolean,
	disabled: boolean,
	aliases: string[],
	requiredPermission?: GlobalPermission | RoomPermission,
};
export interface ChatCommands {
	[k: string]: ChatHandler | string | string[] | ChatCommands;
}
export interface AnnotatedChatCommands {
	[k: string]: AnnotatedChatHandler | string | string[] | AnnotatedChatCommands;
}

export type HandlerTable = {[key in keyof Handlers]?: Handlers[key]};

interface Handlers {
	onRoomClose: (id: string, user: User, connection: Connection, page: boolean) => any;
	onRenameRoom: (oldId: RoomID, newID: RoomID, room: BasicRoom) => void;
	onBattleStart: (user: User, room: GameRoom) => void;
	onBattleLeave: (user: User, room: GameRoom) => void;
	onRoomJoin: (room: BasicRoom, user: User, connection: Connection) => void;
	onDisconnect: (user: User) => void;
	onRoomDestroy: (roomid: RoomID) => void;
	onBattleEnd: (battle: RoomBattle, winner: ID, players: ID[]) => void;
	onLadderSearch: (user: User, connection: Connection, format: ID) => void;
	onBattleRanked: (
		battle: Rooms.RoomBattle, winner: ID, ratings: (AnyObject | null | undefined)[], players: ID[]
	) => void;
}

export interface ChatPlugin {
	commands?: AnnotatedChatCommands;
	pages?: PageTable;
	destroy?: () => void;
	roomSettings?: SettingsHandler | SettingsHandler[];
	[k: string]: any;
}

export type SettingsHandler = (
	room: Room,
	user: User,
	connection: Connection
) => {
	label: string,
	permission: boolean | RoomPermission,
	// button label, command | disabled
	options: [string, string | true][],
};

export type CRQHandler = (this: CommandContext, target: string, user: User, trustable?: boolean) => any;
export type RoomCloseHandler = (id: string, user: User, connection: Connection, page: boolean) => any;

/**
 * Chat filters can choose to:
 * 1. return false OR null - to not send a user's message
 * 2. return an altered string - to alter a user's message
 * 3. return undefined to send the original message through
 */
export type ChatFilter = ((
	this: CommandContext,
	message: string,
	user: User,
	room: Room | null,
	connection: Connection,
	targetUser: User | null,
	originalMessage: string
) => string | false | null | undefined | void) & {priority?: number};

export type NameFilter = (name: string, user: User) => string;
export type NicknameFilter = (name: string, user: User) => string | false;
export type StatusFilter = (status: string, user: User) => string;
export type PunishmentFilter = (user: User | ID, punishment: Punishment) => void;
export type LoginFilter = (user: User, oldUser: User | null, userType: string) => void;
export type HostFilter = (host: string, user: User, connection: Connection, hostType: string) => void;

export interface Translations {
	name?: string;
	strings: {[english: string]: string};
}

const LINK_WHITELIST = [
	'*.pokemonshowdown.com', 'psim.us', 'smogtours.psim.us',
	'*.smogon.com', '*.pastebin.com', '*.hastebin.com',
];

const MAX_MESSAGE_LENGTH = 300;

const BROADCAST_COOLDOWN = 20 * 1000;
const MESSAGE_COOLDOWN = 5 * 60 * 1000;

const MAX_PARSE_RECURSION = 10;

const VALID_COMMAND_TOKENS = '/!';
const BROADCAST_TOKEN = '!';

const PLUGIN_DATABASE_PATH = './databases/chat-plugins.db';
const MAX_PLUGIN_LOADING_DEPTH = 3;
const VALID_PLUGIN_ENDINGS = ['.jsx', '.tsx', '.js', '.ts'];

import {formatText, linkRegex, stripFormatting} from './chat-formatter';

// @ts-ignore no typedef available
import ProbeModule = require('probe-image-size');
const probe: (url: string) => Promise<{width: number, height: number}> = ProbeModule;

const EMOJI_REGEX = /[\p{Emoji_Modifier_Base}\p{Emoji_Presentation}\uFE0F]/u;
// to account for Sucrase
const TRANSLATION_PATH = __dirname.endsWith('.server-dist') ? `../.translations-dist` : `../translations`;
const TRANSLATION_DIRECTORY = `${__dirname}/${TRANSLATION_PATH}`;

class PatternTester {
	// This class sounds like a RegExp
	// In fact, one could in theory implement it as a RegExp subclass
	// However, ES2016 RegExp subclassing is a can of worms, and it wouldn't allow us
	// to tailor the test method for fast command parsing.
	readonly elements: string[];
	readonly fastElements: Set<string>;
	regexp: RegExp | null;
	constructor() {
		this.elements = [];
		this.fastElements = new Set();
		this.regexp = null;
	}
	fastNormalize(elem: string) {
		return elem.slice(0, -1);
	}
	update() {
		const slowElements = this.elements.filter(elem => !this.fastElements.has(this.fastNormalize(elem)));
		if (slowElements.length) {
			this.regexp = new RegExp('^(' + slowElements.map(elem => '(?:' + elem + ')').join('|') + ')', 'i');
		}
	}
	register(...elems: string[]) {
		for (const elem of elems) {
			this.elements.push(elem);
			if (/^[^ ^$?|()[\]]+ $/.test(elem)) {
				this.fastElements.add(this.fastNormalize(elem));
			}
		}
		this.update();
	}
	testCommand(text: string) {
		const spaceIndex = text.indexOf(' ');
		if (this.fastElements.has(spaceIndex >= 0 ? text.slice(0, spaceIndex) : text)) {
			return true;
		}
		if (!this.regexp) return false;
		return this.regexp.test(text);
	}
	test(text: string) {
		if (!text.includes('\n')) return null;
		if (this.testCommand(text)) return text;
		// The PM matching is a huge mess, and really needs to be replaced with
		// the new multiline command system soon.
		const pmMatches = /^(\/(?:pm|w|whisper|msg) [^,]*, ?)(.*)/i.exec(text);
		if (pmMatches && this.testCommand(pmMatches[2])) {
			if (text.split('\n').every(line => line.startsWith(pmMatches[1]))) {
				return text.replace(/\n\/(?:pm|w|whisper|msg) [^,]*, ?/g, '\n');
			}
			return text;
		}
		return null;
	}
}

/*********************************************************
 * Parser
 *********************************************************/

/**
 * An ErrorMessage will, if used in a command/page context, simply show the user
 * the error, rather than logging a crash. It's used to simplify showing errors.
 *
 * Outside of a command/page context, it would still cause a crash.
 */
export class ErrorMessage extends Error {
	constructor(message: string) {
		super(message);
		this.name = 'ErrorMessage';
		Error.captureStackTrace(this, ErrorMessage);
	}
}

export class Interruption extends Error {
	constructor() {
		super('');
		this.name = 'Interruption';
		Error.captureStackTrace(this, ErrorMessage);
	}
}

// These classes need to be declared here because they aren't hoisted
export abstract class MessageContext {
	readonly user: User;
	language: ID | null;
	recursionDepth: number;
	constructor(user: User, language: ID | null = null) {
		this.user = user;
		this.language = language;
		this.recursionDepth = 0;
	}

	splitOne(target: string) {
		const commaIndex = target.indexOf(',');
		if (commaIndex < 0) {
			return [target.trim(), ''];
		}
		return [target.slice(0, commaIndex).trim(), target.slice(commaIndex + 1).trim()];
	}
	meansYes(text: string) {
		switch (text.toLowerCase().trim()) {
		case 'on': case 'enable': case 'yes': case 'true': case 'allow': case '1':
			return true;
		}
		return false;
	}
	meansNo(text: string) {
		switch (text.toLowerCase().trim()) {
		case 'off': case 'disable': case 'no': case 'false': case 'disallow': case '0':
			return true;
		}
		return false;
	}
	/**
	 * Given an array of strings (or a comma-delimited string), check the
	 * first and last string for a format/mod/gen. If it exists, remove
	 * it from the array.
	 *
	 * @returns `format` (null if no format was found), `dex` (the dex
	 * for the format/mod, or the default dex if none was found), and
	 * `targets` (the rest of the array).
	 */
	splitFormat(target: string | string[], atLeastOneTarget?: boolean) {
		const targets = typeof target === 'string' ? target.split(',') : target;
		if (!targets[0].trim()) targets.pop();

		if (targets.length > (atLeastOneTarget ? 1 : 0)) {
			const {dex, format, isMatch} = this.extractFormat(targets[0].trim());
			if (isMatch) {
				targets.shift();
				return {dex, format, targets};
			}
		}
		if (targets.length > 1) {
			const {dex, format, isMatch} = this.extractFormat(targets[targets.length - 1].trim());
			if (isMatch) {
				targets.pop();
				return {dex, format, targets};
			}
		}

		const room = (this as any as CommandContext).room;
		const {dex, format} = this.extractFormat(room?.settings.defaultFormat || room?.battle?.format);
		return {dex, format, targets};
	}
	extractFormat(formatOrMod?: string): {dex: ModdedDex, format: Format | null, isMatch: boolean} {
		if (!formatOrMod) {
			return {dex: Dex.includeData(), format: null, isMatch: false};
		}

		const format = Dex.formats.get(formatOrMod);
		if (format.exists) {
			return {dex: Dex.forFormat(format), format: format, isMatch: true};
		}

		if (toID(formatOrMod) in Dex.dexes) {
			return {dex: Dex.mod(toID(formatOrMod)).includeData(), format: null, isMatch: true};
		}

		return this.extractFormat();
	}
	splitUser(target: string, {exactName}: {exactName?: boolean} = {}) {
		const [inputUsername, rest] = this.splitOne(target).map(str => str.trim());
		const targetUser = Users.get(inputUsername, exactName);

		return {
			targetUser,
			inputUsername,
			targetUsername: targetUser ? targetUser.name : inputUsername,
			rest,
		};
	}
	requireUser(target: string, options: {allowOffline?: boolean, exactName?: boolean} = {}) {
		const {targetUser, targetUsername, rest} = this.splitUser(target, options);

		if (!targetUser) {
			throw new Chat.ErrorMessage(`The user "${targetUsername}" is offline or misspelled.`);
		}
		if (!options.allowOffline && !targetUser.connected) {
			throw new Chat.ErrorMessage(`The user "${targetUsername}" is offline.`);
		}

		// `inputUsername` and `targetUsername` are never needed because we already handle the "user not found" error messages
		// just use `targetUser.name` where previously necessary
		return {targetUser, rest};
	}
	getUserOrSelf(target: string, {exactName}: {exactName?: boolean} = {}) {
		if (!target.trim()) return this.user;

		return Users.get(target, exactName);
	}
	tr(strings: TemplateStringsArray | string, ...keys: any[]) {
		return Chat.tr(this.language, strings, ...keys);
	}
}

export class PageContext extends MessageContext {
	readonly connection: Connection;
	room: Room | null;
	pageid: string;
	initialized: boolean;
	title: string;
	args: string[];
	constructor(options: {pageid: string, user: User, connection: Connection, language?: ID}) {
		super(options.user, options.language);

		this.connection = options.connection;
		this.room = null;
		this.pageid = options.pageid;
		this.args = this.pageid.split('-');

		this.initialized = false;
		this.title = 'Page';
	}

	checkCan(permission: RoomPermission, target: User | null, room: Room): boolean;
	checkCan(permission: GlobalPermission, target?: User | null): boolean;
	checkCan(permission: string, target: User | null = null, room: Room | null = null) {
		if (!this.user.can(permission as any, target, room as any)) {
			throw new Chat.ErrorMessage(`<h2>Permission denied.</h2>`);
		}
		return true;
	}

	privatelyCheckCan(permission: RoomPermission, target: User | null, room: Room): boolean;
	privatelyCheckCan(permission: GlobalPermission, target?: User | null): boolean;
	privatelyCheckCan(permission: string, target: User | null = null, room: Room | null = null) {
		if (!this.user.can(permission as any, target, room as any)) {
			this.pageDoesNotExist();
		}
		return true;
	}

	pageDoesNotExist(): never {
		throw new Chat.ErrorMessage(`Page "${this.pageid}" not found`);
	}

	requireRoom(pageid?: string) {
		const room = this.extractRoom(pageid);
		if (!room) {
			throw new Chat.ErrorMessage(`Invalid link: This page requires a room ID.`);
		}

		this.room = room;
		return room;
	}
	extractRoom(pageid?: string) {
		if (!pageid) pageid = this.pageid;
		const parts = pageid.split('-');

		// The roomid for the page should be view-pagename-roomid
		const room = Rooms.get(parts[2]) || null;

		this.room = room;
		return room;
	}

	setHTML(html: string) {
		const roomid = this.room ? `[${this.room.roomid}] ` : '';
		let content = `|title|${roomid}${this.title}\n|pagehtml|${html}`;
		if (!this.initialized) {
			content = `|init|html\n${content}`;
			this.initialized = true;
		}
		this.send(content);
	}
	errorReply(message: string) {
		this.setHTML(`<div class="pad"><p class="message-error">${message}</p></div>`);
	}

	send(content: string) {
		this.connection.send(`>${this.pageid}\n${content}`);
	}
	close() {
		this.send('|deinit');
	}

	async resolve(pageid?: string) {
		if (pageid) this.pageid = pageid;

		const parts = this.pageid.split('-');
		parts.shift(); // first part is always `view`

		if (!this.connection.openPages) this.connection.openPages = new Set();
		this.connection.openPages.add(parts.join('-'));

		let handler: PageHandler | PageTable = Chat.pages;
		while (handler) {
			if (typeof handler === 'function') {
				break;
			}
			handler = handler[parts.shift() || 'default'] || handler[''];
		}

		this.args = parts;

		let res;
		try {
			if (typeof handler !== 'function') this.pageDoesNotExist();
			res = await handler.call(this, parts, this.user, this.connection);
		} catch (err: any) {
			if (err.name?.endsWith('ErrorMessage')) {
				if (err.message) this.errorReply(err.message);
				return;
			}
			if (err.name.endsWith('Interruption')) {
				return;
			}
			Monitor.crashlog(err, 'A chat page', {
				user: this.user.name,
				room: this.room && this.room.roomid,
				pageid: this.pageid,
			});
			this.setHTML(
				`<div class="pad"><div class="broadcast-red">` +
				`<strong>Pokemon Showdown crashed!</strong><br />Don't worry, we're working on fixing it.` +
				`</div></div>`
			);
		}
		if (typeof res === 'object' && res) res = JSX.render(res);
		if (typeof res === 'string') {
			this.setHTML(res);
			res = undefined;
		}
		return res;
	}
}

/**
 * This is a message sent in a PM or to a chat/battle room.
 *
 * There are three cases to be aware of:
 * - PM to user: `context.pmTarget` will exist and `context.room` will be `null`
 * - message to room: `context.room` will exist and `context.pmTarget` will be `null`
 * - console command (PM to `~`): `context.pmTarget` and `context.room` will both be `null`
 */
export class CommandContext extends MessageContext {
	message: string;
	pmTarget: User | null;
	room: Room | null;
	connection: Connection;

	cmd: string;
	cmdToken: string;
	target: string;
	fullCmd: string;
	handler: AnnotatedChatHandler | null;

	isQuiet: boolean;
	bypassRoomCheck?: boolean;
	broadcasting: boolean;
	broadcastToRoom: boolean;
	/** Used only by !rebroadcast */
	broadcastPrefix: string;
	broadcastMessage: string;
	constructor(options: {
		message: string, user: User, connection: Connection,
		room?: Room | null, pmTarget?: User | null, cmd?: string, cmdToken?: string, target?: string, fullCmd?: string,
		recursionDepth?: number, isQuiet?: boolean, broadcastPrefix?: string, bypassRoomCheck?: boolean,
	}) {
		super(
			options.user, options.room && options.room.settings.language ?
				options.room.settings.language : options.user.language
		);

		this.message = options.message || ``;
		this.recursionDepth = options.recursionDepth || 0;

		// message context
		this.pmTarget = options.pmTarget || null;
		this.room = options.room || null;
		this.connection = options.connection;

		// command context
		this.cmd = options.cmd || '';
		this.cmdToken = options.cmdToken || '';
		this.target = options.target || ``;
		this.fullCmd = options.fullCmd || '';
		this.handler = null;
		this.isQuiet = options.isQuiet || false;
		this.bypassRoomCheck = options.bypassRoomCheck || false;

		// broadcast context
		this.broadcasting = false;
		this.broadcastToRoom = true;
		this.broadcastPrefix = options.broadcastPrefix || '';
		this.broadcastMessage = '';
	}

	// TODO: return should be void | boolean | Promise<void | boolean>
	parse(
		msg?: string,
		options: Partial<{isQuiet: boolean, broadcastPrefix: string, bypassRoomCheck: boolean}> = {}
	): any {
		if (typeof msg === 'string') {
			// spawn subcontext
			const subcontext = new CommandContext({
				message: msg,
				user: this.user,
				connection: this.connection,
				room: this.room,
				pmTarget: this.pmTarget,
				recursionDepth: this.recursionDepth + 1,
				bypassRoomCheck: this.bypassRoomCheck,
				...options,
			});
			if (subcontext.recursionDepth > MAX_PARSE_RECURSION) {
				throw new Error("Too much command recursion");
			}
			return subcontext.parse();
		}
		let message: string | void | boolean | Promise<string | void | boolean> = this.message;

		const parsedCommand = Chat.parseCommand(message);
		if (parsedCommand) {
			this.cmd = parsedCommand.cmd;
			this.fullCmd = parsedCommand.fullCmd;
			this.cmdToken = parsedCommand.cmdToken;
			this.target = parsedCommand.target;
			this.handler = parsedCommand.handler;
		}

		if (!this.bypassRoomCheck && this.room && !(this.user.id in this.room.users)) {
			return this.popupReply(`You tried to send "${message}" to the room "${this.room.roomid}" but it failed because you were not in that room.`);
		}

		if (this.user.statusType === 'idle' && !['unaway', 'unafk', 'back'].includes(this.cmd)) {
			this.user.setStatusType('online');
		}

		try {
			if (this.handler) {
				if (this.handler.disabled) {
					throw new Chat.ErrorMessage(
						`The command /${this.cmd} is temporarily unavailable due to technical difficulties. Please try again in a few hours.`
					);
				}
				message = this.run(this.handler);
			} else {
				if (this.cmdToken) {
					// To guard against command typos, show an error message
					if (!(this.shouldBroadcast() && !/[a-z0-9]/.test(this.cmd.charAt(0)))) {
						this.commandDoesNotExist();
					}
				} else if (!VALID_COMMAND_TOKENS.includes(message.charAt(0)) &&
						VALID_COMMAND_TOKENS.includes(message.trim().charAt(0))) {
					message = message.trim();
					if (!message.startsWith(BROADCAST_TOKEN)) {
						message = message.charAt(0) + message;
					}
				}

				message = this.checkChat(message);
			}
		} catch (err: any) {
			if (err.name?.endsWith('ErrorMessage')) {
				this.errorReply(err.message);
				this.update();
				return false;
			}
			if (err.name.endsWith('Interruption')) {
				this.update();
				return;
			}
			Monitor.crashlog(err, 'A chat command', {
				user: this.user.name,
				room: this.room?.roomid,
				pmTarget: this.pmTarget?.name,
				message: this.message,
			});
			this.sendReply(`|html|<div class="broadcast-red"><b>Pokemon Showdown crashed!</b><br />Don't worry, we're working on fixing it.</div>`);
			return;
		}

		// Output the message
		if (message && typeof (message as any).then === 'function') {
			this.update();
			return (message as Promise<string | boolean | void>).then(resolvedMessage => {
				if (resolvedMessage && resolvedMessage !== true) {
					this.sendChatMessage(resolvedMessage);
				}
				this.update();
				if (resolvedMessage === false) return false;
			}).catch(err => {
				if (err.name?.endsWith('ErrorMessage')) {
					this.errorReply(err.message);
					this.update();
					return false;
				}
				if (err.name.endsWith('Interruption')) {
					this.update();
					return;
				}
				Monitor.crashlog(err, 'An async chat command', {
					user: this.user.name,
					room: this.room?.roomid,
					pmTarget: this.pmTarget?.name,
					message: this.message,
				});
				this.sendReply(`|html|<div class="broadcast-red"><b>Pokemon Showdown crashed!</b><br />Don't worry, we're working on fixing it.</div>`);
				return false;
			});
		} else if (message && message !== true) {
			this.sendChatMessage(message as string);
			message = true;
		}

		this.update();

		return message;
	}

	sendChatMessage(message: string) {
		if (this.pmTarget) {
			const blockInvites = this.pmTarget.settings.blockInvites;
			if (blockInvites && /^<<.*>>$/.test(message.trim())) {
				if (
					!this.user.can('lock') && blockInvites === true ||
					!Users.globalAuth.atLeast(this.user, blockInvites as GroupSymbol)
				) {
					Chat.maybeNotifyBlocked(`invite`, this.pmTarget, this.user);
					return this.errorReply(`${this.pmTarget.name} is blocking room invites.`);
				}
			}
			Chat.sendPM(message, this.user, this.pmTarget);
		} else if (this.room) {
			this.room.add(`|c|${this.user.getIdentity(this.room)}|${message}`);
			if (this.room.game && this.room.game.onLogMessage) {
				this.room.game.onLogMessage(message, this.user);
			}
		} else {
			this.connection.popup(`Your message could not be sent:\n\n${message}\n\nIt needs to be sent to a user or room.`);
		}
	}
	run(handler: string | AnnotatedChatHandler) {
		if (typeof handler === 'string') handler = Chat.commands[handler] as AnnotatedChatHandler;
		if (!handler.broadcastable && this.cmdToken === '!') {
			this.errorReply(`The command "${this.fullCmd}" can't be broadcast.`);
			this.errorReply(`Use /${this.fullCmd} instead.`);
			return false;
		}
		let result: any = handler.call(this, this.target, this.room, this.user, this.connection, this.cmd, this.message);
		if (result === undefined) result = false;

		return result;
	}

	checkFormat(room: BasicRoom | null | undefined, user: User, message: string) {
		if (!room) return true;
		if (
			!room.settings.filterStretching && !room.settings.filterCaps &&
			!room.settings.filterEmojis && !room.settings.filterLinks
		) {
			return true;
		}
		if (user.can('mute', null, room)) return true;

		if (room.settings.filterStretching && /(.+?)\1{5,}/i.test(user.name)) {
			throw new Chat.ErrorMessage(`Your username contains too much stretching, which this room doesn't allow.`);
		}
		if (room.settings.filterLinks) {
			const bannedLinks = this.checkBannedLinks(message);
			if (bannedLinks.length) {
				throw new Chat.ErrorMessage(
					`You have linked to ${bannedLinks.length > 1 ? 'unrecognized external websites' : 'an unrecognized external website'} ` +
					`(${bannedLinks.join(', ')}), which this room doesn't allow.`
				);
			}
		}
		if (room.settings.filterCaps && /[A-Z\s]{6,}/.test(user.name)) {
			throw new Chat.ErrorMessage(`Your username contains too many capital letters, which this room doesn't allow.`);
		}
		if (room.settings.filterEmojis && EMOJI_REGEX.test(user.name)) {
			throw new Chat.ErrorMessage(`Your username contains emojis, which this room doesn't allow.`);
		}
		// Removes extra spaces and null characters
		message = message.trim().replace(/[ \u0000\u200B-\u200F]+/g, ' ');

		if (room.settings.filterStretching && /(.+?)\1{7,}/i.test(message)) {
			throw new Chat.ErrorMessage(`Your message contains too much stretching, which this room doesn't allow.`);
		}
		if (room.settings.filterCaps && /[A-Z\s]{18,}/.test(message)) {
			throw new Chat.ErrorMessage(`Your message contains too many capital letters, which this room doesn't allow.`);
		}
		if (room.settings.filterEmojis && EMOJI_REGEX.test(message)) {
			throw new Chat.ErrorMessage(`Your message contains emojis, which this room doesn't allow.`);
		}

		return true;
	}

	checkSlowchat(room: Room | null | undefined, user: User) {
		if (!room?.settings.slowchat) return true;
		if (user.can('show', null, room)) return true;
		const lastActiveSeconds = (Date.now() - user.lastMessageTime) / 1000;
		if (lastActiveSeconds < room.settings.slowchat) {
			throw new Chat.ErrorMessage(this.tr`This room has slow-chat enabled. You can only talk once every ${room.settings.slowchat} seconds.`);
		}
		return true;
	}

	checkBanwords(room: BasicRoom | null | undefined, message: string): boolean {
		if (!room) return true;
		if (!room.banwordRegex) {
			if (room.settings.banwords && room.settings.banwords.length) {
				room.banwordRegex = new RegExp('(?:\\b|(?!\\w))(?:' + room.settings.banwords.join('|') + ')(?:\\b|\\B(?!\\w))', 'i');
			} else {
				room.banwordRegex = true;
			}
		}
		if (!message) return true;
		if (room.banwordRegex !== true && room.banwordRegex.test(message)) {
			throw new Chat.ErrorMessage(`Your username, status, or message contained a word banned by this room.`);
		}
		return this.checkBanwords(room.parent as ChatRoom, message);
	}
	checkGameFilter() {
		if (!this.room?.game || !this.room.game.onChatMessage) return;
		return this.room.game.onChatMessage(this.message, this.user);
	}
	pmTransform(originalMessage: string, sender?: User, receiver?: User | null | string) {
		if (!sender) {
			if (this.room) throw new Error(`Not a PM`);
			sender = this.user;
			receiver = this.pmTarget;
		}
		const targetIdentity = typeof receiver === 'string' ? ` ${receiver}` : receiver ? receiver.getIdentity() : '~';
		const prefix = `|pm|${sender.getIdentity()}|${targetIdentity}|`;
		return originalMessage.split('\n').map(message => {
			if (message.startsWith('||')) {
				return prefix + `/text ` + message.slice(2);
			} else if (message.startsWith(`|html|`)) {
				return prefix + `/raw ` + message.slice(6);
			} else if (message.startsWith(`|uhtml|`)) {
				const [uhtmlid, html] = Utils.splitFirst(message.slice(7), '|');
				return prefix + `/uhtml ${uhtmlid},${html}`;
			} else if (message.startsWith(`|uhtmlchange|`)) {
				const [uhtmlid, html] = Utils.splitFirst(message.slice(13), '|');
				return prefix + `/uhtmlchange ${uhtmlid},${html}`;
			} else if (message.startsWith(`|modaction|`)) {
				return prefix + `/log ` + message.slice(11);
			} else if (message.startsWith(`|raw|`)) {
				return prefix + `/raw ` + message.slice(5);
			} else if (message.startsWith(`|error|`)) {
				return prefix + `/error ` + message.slice(7);
			} else if (message.startsWith(`|c~|`)) {
				return prefix + message.slice(4);
			} else if (message.startsWith(`|c|~|/`)) {
				return prefix + message.slice(5);
			} else if (message.startsWith(`|c|~|`)) {
				return prefix + `/text ` + message.slice(5);
			}
			return prefix + `/text ` + message;
		}).join(`\n`);
	}
	sendReply(data: string) {
		if (this.isQuiet) return;
		if (this.broadcasting && this.broadcastToRoom) {
			// broadcasting
			this.add(data);
		} else {
			// not broadcasting
			if (!this.room) {
				data = this.pmTransform(data);
				this.connection.send(data);
			} else {
				this.connection.sendTo(this.room, data);
			}
		}
	}
	errorReply(message: string) {
		if (this.bypassRoomCheck) { // if they're not in the room, we still want a good error message for them
			return this.popupReply(
				`|html|<strong class="message-error">${message.replace(/\n/ig, '<br />')}</strong>`
			);
		}
		this.sendReply(`|error|` + message.replace(/\n/g, `\n|error|`));
	}
	addBox(htmlContent: string | JSX.VNode) {
		if (typeof htmlContent !== 'string') htmlContent = JSX.render(htmlContent);
		this.add(`|html|<div class="infobox">${htmlContent}</div>`);
	}
	sendReplyBox(htmlContent: string | JSX.VNode) {
		if (typeof htmlContent !== 'string') htmlContent = JSX.render(htmlContent);
		this.sendReply(`|c|${this.room && this.broadcasting ? this.user.getIdentity() : '~'}|/raw <div class="infobox">${htmlContent}</div>`);
	}
	popupReply(message: string) {
		this.connection.popup(message);
	}
	add(data: string) {
		if (this.room) {
			this.room.add(data);
		} else {
			this.send(data);
		}
	}
	send(data: string) {
		if (this.room) {
			this.room.send(data);
		} else {
			data = this.pmTransform(data);
			this.user.send(data);
			if (this.pmTarget && this.pmTarget !== this.user) {
				this.pmTarget.send(data);
			}
		}
	}

	/** like privateModAction, but also notify Staff room */
	privateGlobalModAction(msg: string) {
		this.privateModAction(msg);
		if (this.room?.roomid !== 'staff') {
			Rooms.get('staff')?.addByUser(this.user, `${this.room ? `<<${this.room.roomid}>>` : `<PM:${this.pmTarget}>`} ${msg}`).update();
		}
	}
	addGlobalModAction(msg: string) {
		this.addModAction(msg);
		if (this.room?.roomid !== 'staff') {
			Rooms.get('staff')?.addByUser(this.user, `${this.room ? `<<${this.room.roomid}>>` : `<PM:${this.pmTarget}>`} ${msg}`).update();
		}
	}

	privateModAction(msg: string) {
		if (this.room) {
			if (this.room.roomid === 'staff') {
				this.room.addByUser(this.user, `(${msg})`);
			} else {
				this.room.sendModsByUser(this.user, `(${msg})`);
				// roomlogging in staff causes a duplicate log message, since we do addByUser
				// and roomlogging in pms has no effect, so we can _just_ call this here
				this.roomlog(`(${msg})`);
			}
		} else {
			const data = this.pmTransform(`|modaction|${msg}`);
			this.user.send(data);
			if (this.pmTarget && this.pmTarget !== this.user && this.pmTarget.isStaff) {
				this.pmTarget.send(data);
			}
		}
	}
	globalModlog(action: string, user: string | User | null = null, note: string | null = null, ip?: string) {
		const entry: PartialModlogEntry = {
			action,
			isGlobal: true,
			loggedBy: this.user.id,
			note: note?.replace(/\n/gm, ' ') || '',
		};
		if (user) {
			if (typeof user === 'string') {
				entry.userid = toID(user);
			} else {
				entry.ip = user.latestIp;
				const userid = user.getLastId();
				entry.userid = userid;
				if (user.autoconfirmed && user.autoconfirmed !== userid) entry.autoconfirmedID = user.autoconfirmed;
				const alts = user.getAltUsers(false, true).slice(1).map(alt => alt.getLastId());
				if (alts.length) entry.alts = alts;
			}
		}
		if (ip) entry.ip = ip;
		if (this.room) {
			this.room.modlog(entry);
		} else {
			Rooms.global.modlog(entry);
		}
	}
	modlog(
		action: string,
		user: string | User | null = null,
		note: string | null = null,
		options: Partial<{noalts: any, noip: any}> = {}
	) {
		const entry: PartialModlogEntry = {
			action,
			loggedBy: this.user.id,
			note: note?.replace(/\n/gm, ' ') || '',
		};
		if (user) {
			if (typeof user === 'string') {
				entry.userid = toID(user);
			} else {
				const userid = user.getLastId();
				entry.userid = userid;
				if (!options.noalts) {
					if (user.autoconfirmed && user.autoconfirmed !== userid) entry.autoconfirmedID = user.autoconfirmed;
					const alts = user.getAltUsers(false, true).slice(1).map(alt => alt.getLastId());
					if (alts.length) entry.alts = alts;
				}
				if (!options.noip) entry.ip = user.latestIp;
			}
		}
		(this.room || Rooms.global).modlog(entry);
	}
	parseSpoiler(reason: string) {
		if (!reason) return {publicReason: "", privateReason: ""};

		let publicReason = reason;
		let privateReason = reason;
		const targetLowercase = reason.toLowerCase();
		if (targetLowercase.includes('spoiler:') || targetLowercase.includes('spoilers:')) {
			const proofIndex = targetLowercase.indexOf(targetLowercase.includes('spoilers:') ? 'spoilers:' : 'spoiler:');
			const proofOffset = (targetLowercase.includes('spoilers:') ? 9 : 8);
			const proof = reason.slice(proofIndex + proofOffset).trim();
			publicReason = reason.slice(0, proofIndex).trim();
			privateReason = `${publicReason}${proof ? ` (PROOF: ${proof})` : ''}`;
		}
		return {publicReason, privateReason};
	}
	roomlog(data: string) {
		if (this.room) this.room.roomlog(data);
	}
	stafflog(data: string) {
		(Rooms.get('staff') || Rooms.lobby || this.room)?.roomlog(data);
	}
	addModAction(msg: string) {
		if (this.room) {
			this.room.addByUser(this.user, msg);
		} else {
			this.send(`|modaction|${msg}`);
		}
	}
	update() {
		if (this.room) this.room.update();
	}
	filter(message: string) {
		return Chat.filter(message, this);
	}
	statusfilter(status: string) {
		return Chat.statusfilter(status, this.user);
	}
	checkCan(permission: RoomPermission, target: User | ID | null, room: Room): undefined;
	checkCan(permission: GlobalPermission, target?: User | ID | null): undefined;
	checkCan(permission: string, target: User | ID | null = null, room: Room | null = null) {
		if (!Users.Auth.hasPermission(this.user, permission, target, room, this.fullCmd)) {
			throw new Chat.ErrorMessage(`${this.cmdToken}${this.fullCmd} - Access denied.`);
		}
	}
	privatelyCheckCan(permission: RoomPermission, target: User | ID | null, room: Room): boolean;
	privatelyCheckCan(permission: GlobalPermission, target?: User | ID | null): boolean;
	privatelyCheckCan(permission: string, target: User | ID | null = null, room: Room | null = null) {
		this.handler!.isPrivate = true;
		if (Users.Auth.hasPermission(this.user, permission, target, room, this.fullCmd)) {
			return true;
		}
		this.commandDoesNotExist();
	}
	canUseConsole() {
		if (!this.user.hasConsoleAccess(this.connection)) {
			throw new Chat.ErrorMessage(
				this.cmdToken + this.fullCmd + " - Requires console access, please set up `Config.consoleips`."
			);
		}
		return true;
	}
	shouldBroadcast() {
		return this.cmdToken === BROADCAST_TOKEN;
	}
	checkBroadcast(overrideCooldown?: boolean | string, suppressMessage?: string | null) {
		if (this.broadcasting || !this.shouldBroadcast()) {
			return true;
		}

		if (this.user.locked && !(this.room?.roomid.startsWith('help-') || this.pmTarget?.can('lock'))) {
			this.errorReply(`You cannot broadcast this command's information while locked.`);
			throw new Chat.ErrorMessage(`To see it for yourself, use: /${this.message.slice(1)}`);
		}

		if (this.room && !this.user.can('show', null, this.room)) {
			this.errorReply(`You need to be voiced to broadcast this command's information.`);
			throw new Chat.ErrorMessage(`To see it for yourself, use: /${this.message.slice(1)}`);
		}

		if (!this.room && !this.pmTarget) {
			this.errorReply(`Broadcasting a command with "!" in a PM or chatroom will show it that user or room.`);
			throw new Chat.ErrorMessage(`To see it for yourself, use: /${this.message.slice(1)}`);
		}

		// broadcast cooldown
		const broadcastMessage = (suppressMessage || this.message).toLowerCase().replace(/[^a-z0-9\s!,]/g, '');
		const cooldownMessage = overrideCooldown === true ? null : (overrideCooldown || broadcastMessage);

		if (
			cooldownMessage && this.room && this.room.lastBroadcast === cooldownMessage &&
			this.room.lastBroadcastTime >= Date.now() - BROADCAST_COOLDOWN
		) {
			throw new Chat.ErrorMessage(`You can't broadcast this because it was just broadcasted. If this was intentional, use !rebroadcast ${this.message}`);
		}

		const message = this.checkChat(suppressMessage || this.message);
		if (!message) {
			throw new Chat.ErrorMessage(`To see it for yourself, use: /${this.message.slice(1)}`);
		}

		// checkChat will only return true with no message
		this.message = message;
		this.broadcastMessage = broadcastMessage;
		return true;
	}
	runBroadcast(overrideCooldown?: boolean | string, suppressMessage: string | null = null) {
		if (this.broadcasting || !this.shouldBroadcast()) {
			// Already being broadcast, or the user doesn't intend to broadcast.
			return true;
		}

		if (!this.broadcastMessage) {
			// Permission hasn't been checked yet. Do it now.
			this.checkBroadcast(overrideCooldown, suppressMessage);
		}

		this.broadcasting = true;

		const message = `${this.broadcastPrefix}${suppressMessage || this.message}`;
		if (this.pmTarget) {
			this.sendReply(`|c~|${message}`);
		} else {
			this.sendReply(`|c|${this.user.getIdentity(this.room)}|${message}`);
		}
		if (this.room) {
			// We don't want broadcasted messages in a room to be translated
			// according to a user's personal language setting.
			this.language = this.room.settings.language || null;
			if (overrideCooldown !== true) {
				this.room.lastBroadcast = overrideCooldown || this.broadcastMessage;
				this.room.lastBroadcastTime = Date.now();
			}
		}

		return true;
	}
	/* The sucrase transformation of optional chaining is too expensive to be used in a hot function like this. */
	/* eslint-disable @typescript-eslint/prefer-optional-chain */
	checkChat(message: string, room?: Room | null, targetUser?: User | null): string;
	checkChat(message?: null, room?: Room | null, targetUser?: User | null): void;
	checkChat(message: string | null = null, room: Room | null = null, targetUser: User | null = null) {
		if (!targetUser && this.pmTarget) {
			targetUser = this.pmTarget;
		}
		if (targetUser) {
			room = null;
		} else if (!room) {
			// @ts-ignore excludes GlobalRoom above
			room = this.room;
		}
		const user = this.user;
		const connection = this.connection;

		if (!user.named) {
			throw new Chat.ErrorMessage(this.tr`You must choose a name before you can talk.`);
		}
		if (!user.can('bypassall')) {
			const lockType = (user.namelocked ? this.tr`namelocked` : user.locked ? this.tr`locked` : ``);
			const lockExpiration = Punishments.checkLockExpiration(user.namelocked || user.locked);
			if (room) {
				if (lockType && !room.settings.isHelp) {
					this.sendReply(`|html|<a href="view-help-request--appeal" class="button">${this.tr`Get help with this`}</a>`);
					if (user.locked === '#hostfilter') {
						throw new Chat.ErrorMessage(this.tr`You are locked due to your proxy / VPN and can't talk in chat.`);
					} else {
						throw new Chat.ErrorMessage(this.tr`You are ${lockType} and can't talk in chat. ${lockExpiration}`);
					}
				}
				if (!room.persist && !room.roomid.startsWith('help-') && !(user.registered || user.autoconfirmed)) {
					this.sendReply(
						this.tr`|html|<div class="message-error">You must be registered to chat in temporary rooms (like battles).</div>` +
						this.tr`You may register in the <button name="openOptions"><i class="fa fa-cog"></i> Options</button> menu.`
					);
					throw new Chat.Interruption();
				}
				if (room.isMuted(user)) {
					throw new Chat.ErrorMessage(this.tr`You are muted and cannot talk in this room.`);
				}
				if (room.settings.modchat && !room.auth.atLeast(user, room.settings.modchat)) {
					if (room.settings.modchat === 'autoconfirmed') {
						throw new Chat.ErrorMessage(
							this.tr`Because moderated chat is set, your account must be at least one week old and you must have won at least one ladder game to speak in this room.`
						);
					}
					if (room.settings.modchat === 'trusted') {
						throw new Chat.ErrorMessage(
							this.tr`Because moderated chat is set, your account must be staff in a public room or have a global rank to speak in this room.`
						);
					}
					const groupName = Config.groups[room.settings.modchat] && Config.groups[room.settings.modchat].name ||
						room.settings.modchat;
					throw new Chat.ErrorMessage(
						this.tr`Because moderated chat is set, you must be of rank ${groupName} or higher to speak in this room.`
					);
				}
				if (!this.bypassRoomCheck && !(user.id in room.users)) {
					connection.popup(`You can't send a message to this room without being in it.`);
					return null;
				}
			}
			if (targetUser) {
				// this accounts for users who are autoconfirmed on another alt, but not registered
				if (!(user.registered || user.autoconfirmed)) {
					this.sendReply(
						this.tr`|html|<div class="message-error">You must be registered to send private messages.</div>` +
						this.tr`You may register in the <button name="openOptions"><i class="fa fa-cog"></i> Options</button> menu.`
					);
					throw new Chat.Interruption();
				}
				if (targetUser.id !== user.id && !(targetUser.registered || targetUser.autoconfirmed)) {
					throw new Chat.ErrorMessage(this.tr`That user is unregistered and cannot be PMed.`);
				}
				if (lockType && !targetUser.can('lock')) {
					this.sendReply(`|html|<a href="view-help-request--appeal" class="button">${this.tr`Get help with this`}</a>`);
					if (user.locked === '#hostfilter') {
						throw new Chat.ErrorMessage(this.tr`You are locked due to your proxy / VPN and can only private message members of the global moderation team.`);
					} else {
						throw new Chat.ErrorMessage(this.tr`You are ${lockType} and can only private message members of the global moderation team. ${lockExpiration}`);
					}
				}
				if (targetUser.locked && !user.can('lock')) {
					throw new Chat.ErrorMessage(this.tr`The user "${targetUser.name}" is locked and cannot be PMed.`);
				}
				if (Config.pmmodchat && !Users.globalAuth.atLeast(user, Config.pmmodchat) &&
					!Users.Auth.hasPermission(targetUser, 'promote', Config.pmmodchat as GroupSymbol)) {
					const groupName = Config.groups[Config.pmmodchat] && Config.groups[Config.pmmodchat].name || Config.pmmodchat;
					throw new Chat.ErrorMessage(this.tr`On this server, you must be of rank ${groupName} or higher to PM users.`);
				}
				if (!this.checkCanPM(targetUser)) {
					Chat.maybeNotifyBlocked('pm', targetUser, user);
					if (!targetUser.can('lock')) {
						throw new Chat.ErrorMessage(this.tr`This user is blocking private messages right now.`);
					} else {
						this.sendReply(`|html|${this.tr`If you need help, try opening a <a href="view-help-request" class="button">help ticket</a>`}`);
						throw new Chat.ErrorMessage(this.tr`This ${Config.groups[targetUser.tempGroup].name} is too busy to answer private messages right now. Please contact a different staff member.`);
					}
				}
				if (!this.checkCanPM(user, targetUser)) {
					throw new Chat.ErrorMessage(this.tr`You are blocking private messages right now.`);
				}
			}
		}

		if (typeof message !== 'string') return true;

		if (!message) {
			throw new Chat.ErrorMessage(this.tr`Your message can't be blank.`);
		}
		let length = message.length;
		length += 10 * message.replace(/[^\ufdfd]*/g, '').length;
		if (length > MAX_MESSAGE_LENGTH && !user.can('ignorelimits')) {
			throw new Chat.ErrorMessage(this.tr`Your message is too long: ` + message);
		}

		// remove zalgo
		message = message.replace(
			/[\u0300-\u036f\u0483-\u0489\u0610-\u0615\u064B-\u065F\u0670\u06D6-\u06DC\u06DF-\u06ED\u0E31\u0E34-\u0E3A\u0E47-\u0E4E]{3,}/g,
			''
		);
		if (/[\u3164\u115f\u1160\u239b-\u23b9]/.test(message)) {
			throw new Chat.ErrorMessage(this.tr`Your message contains banned characters.`);
		}

		// If the corresponding config option is set, non-AC users cannot send links, except to staff.
		if (Config.restrictLinks && !user.autoconfirmed) {
			if (this.checkBannedLinks(message).length && !(targetUser?.can('lock') || room?.settings.isHelp)) {
				throw new Chat.ErrorMessage("Your account must be autoconfirmed to send links to other users, except for global staff.");
			}
		}

		this.checkFormat(room, user, message);

		this.checkSlowchat(room, user);

		if (!user.can('bypassall')) this.checkBanwords(room, user.name);
		if (user.userMessage && !user.can('bypassall')) this.checkBanwords(room, user.userMessage);
		if (room && !user.can('mute', null, room)) this.checkBanwords(room, message);

		const gameFilter = this.checkGameFilter();
		if (typeof gameFilter === 'string') {
			if (gameFilter === '') throw new Chat.Interruption();
			throw new Chat.ErrorMessage(gameFilter);
		}

		if (room?.settings.highTraffic &&
			toID(message).replace(/[^a-z]+/, '').length < 2 &&
			!user.can('show', null, room)) {
			throw new Chat.ErrorMessage(
				this.tr`Due to this room being a high traffic room, your message must contain at least two letters.`
			);
		}

		if (room) {
			const normalized = message.trim();
			if (
				!user.can('bypassall') && (['help', 'lobby'].includes(room.roomid)) && (normalized === user.lastMessage) &&
				((Date.now() - user.lastMessageTime) < MESSAGE_COOLDOWN) && !Config.nothrottle
			) {
				throw new Chat.ErrorMessage(this.tr`You can't send the same message again so soon.`);
			}
			user.lastMessage = message;
			user.lastMessageTime = Date.now();
		}

		if (Chat.filters.length) {
			return this.filter(message);
		}

		return message;
	}
	checkCanPM(targetUser: User, user?: User) {
		if (!user) user = this.user;
		if (user.id === targetUser.id) return true; // lol.
		const setting = targetUser.settings.blockPMs;
		if (user.can('lock') || !setting) return true;
		if (setting === true && !user.can('lock')) return false; // this is to appease TS
		const friends = targetUser.friends || new Set();
		if (setting === 'friends') return friends.has(user.id);
		return Users.globalAuth.atLeast(user, setting as AuthLevel);
	}
	checkPMHTML(targetUser: User) {
		if (!(this.room && (targetUser.id in this.room.users)) && !this.user.can('addhtml')) {
			throw new Chat.ErrorMessage("You do not have permission to use PM HTML to users who are not in this room.");
		}
		const friends = targetUser.friends || new Set();
		if (targetUser.settings.blockPMs &&
			(targetUser.settings.blockPMs === true ||
			(targetUser.settings.blockPMs === 'friends' && !friends.has(this.user.id)) ||
			!Users.globalAuth.atLeast(this.user, targetUser.settings.blockPMs as AuthLevel)) &&
			!this.user.can('lock')
		) {
			Chat.maybeNotifyBlocked('pm', targetUser, this.user);
			throw new Chat.ErrorMessage("This user is currently blocking PMs.");
		}
		if (targetUser.locked && !this.user.can('lock')) {
			throw new Chat.ErrorMessage("This user is currently locked, so you cannot send them HTML.");
		}
		return true;
	}

	checkBannedLinks(message: string) {
		// RegExp#exec only returns one match, String#match returns all of them
		// eslint-disable-next-line @typescript-eslint/prefer-regexp-exec
		return (message.match(Chat.linkRegex) || []).filter(link => {
			link = link.toLowerCase();
			const domainMatches = /^(?:http:\/\/|https:\/\/)?(?:[^/]*\.)?([^/.]*\.[^/.]*)\.?($|\/|:)/.exec(link);
			const domain = domainMatches?.[1];
			const hostMatches = /^(?:http:\/\/|https:\/\/)?([^/]*[^/.])\.?($|\/|:)/.exec(link);
			let host = hostMatches?.[1];
			if (host?.startsWith('www.')) host = host.slice(4);
			if (!domain || !host) return null;
			return !(LINK_WHITELIST.includes(host) || LINK_WHITELIST.includes(`*.${domain}`));
		});
	}
	/* eslint-enable @typescript-eslint/prefer-optional-chain */
	checkEmbedURI(uri: string) {
		if (uri.startsWith('https://')) return uri;
		if (uri.startsWith('//')) return uri;
		if (uri.startsWith('data:')) {
			return uri;
		} else {
			throw new Chat.ErrorMessage("Image URLs must begin with 'https://' or 'data:'; 'http://' cannot be used.");
		}
	}
	/**
	 * This is a quick and dirty first-pass "is this good HTML" check. The full
	 * sanitization is done on the client by Caja in `src/battle-log.ts`
	 * `BattleLog.sanitizeHTML`.
	 */
	checkHTML(htmlContent: string | null) {
		htmlContent = ('' + (htmlContent || '')).trim();
		if (!htmlContent) return '';
		if (/>here.?</i.test(htmlContent) || /click here/i.test(htmlContent)) {
			throw new Chat.ErrorMessage('Do not use "click here" – See [[Design standard #2 <https://github.com/smogon/pokemon-showdown/blob/master/CONTRIBUTING.md#design-standards>]]');
		}

		// check for mismatched tags
		const tags = htmlContent.match(/<!--.*?-->|<\/?[^<>]*/g);
		if (tags) {
			const ILLEGAL_TAGS = [
				'script', 'head', 'body', 'html', 'canvas', 'base', 'meta', 'link', 'iframe',
			];
			const LEGAL_AUTOCLOSE_TAGS = [
				// void elements (no-close tags)
				'br', 'area', 'embed', 'hr', 'img', 'source', 'track', 'input', 'wbr', 'col',
				// autoclose tags
				'p', 'li', 'dt', 'dd', 'option', 'tr', 'th', 'td', 'thead', 'tbody', 'tfoot', 'colgroup',
				// PS custom element
				'psicon', 'youtube',
			];
			const stack = [];
			for (const tag of tags) {
				const isClosingTag = tag.charAt(1) === '/';
				const contentEndLoc = tag.endsWith('/') ? -1 : undefined;
				const tagContent = tag.slice(isClosingTag ? 2 : 1, contentEndLoc).replace(/\s+/, ' ').trim();
				const tagNameEndIndex = tagContent.indexOf(' ');
				const tagName = tagContent.slice(0, tagNameEndIndex >= 0 ? tagNameEndIndex : undefined).toLowerCase();
				if (tagName === '!--') continue;
				if (isClosingTag) {
					if (LEGAL_AUTOCLOSE_TAGS.includes(tagName)) continue;
					if (!stack.length) {
						throw new Chat.ErrorMessage(`Extraneous </${tagName}> without an opening tag.`);
					}
					const expectedTagName = stack.pop();
					if (tagName !== expectedTagName) {
						throw new Chat.ErrorMessage(`Extraneous </${tagName}> where </${expectedTagName}> was expected.`);
					}
					continue;
				}

				if (ILLEGAL_TAGS.includes(tagName) || !/^[a-z]+[0-9]?$/.test(tagName)) {
					throw new Chat.ErrorMessage(`Illegal tag <${tagName}> can't be used here.`);
				}
				if (!LEGAL_AUTOCLOSE_TAGS.includes(tagName)) {
					stack.push(tagName);
				}

				if (tagName === 'img') {
					if (!this.room || (this.room.settings.isPersonal && !this.user.can('lock'))) {
						throw new Chat.ErrorMessage(
							`This tag is not allowed: <${tagContent}>. Images are not allowed outside of chatrooms.`
						);
					}
					if (!/width ?= ?(?:[0-9]+|"[0-9]+")/i.test(tagContent) || !/height ?= ?(?:[0-9]+|"[0-9]+")/i.test(tagContent)) {
						// Width and height are required because most browsers insert the
						// <img> element before width and height are known, and when the
						// image is loaded, this changes the height of the chat area, which
						// messes up autoscrolling.
						this.errorReply(`This image is missing a width/height attribute: <${tagContent}>`);
						throw new Chat.ErrorMessage(`Images without predefined width/height cause problems with scrolling because loading them changes their height.`);
					}
					const srcMatch = / src ?= ?(?:"|')?([^ "']+)(?: ?(?:"|'))?/i.exec(tagContent);
					if (srcMatch) {
						this.checkEmbedURI(srcMatch[1]);
					} else {
						this.errorReply(`This image has a broken src attribute: <${tagContent}>`);
						throw new Chat.ErrorMessage(`The src attribute must exist and have no spaces in the URL`);
					}
				}
				if (tagName === 'button') {
					if ((!this.room || this.room.settings.isPersonal || this.room.settings.isPrivate === true) && !this.user.can('lock')) {
						const buttonName = / name ?= ?"([^"]*)"/i.exec(tagContent)?.[1];
						const buttonValue = / value ?= ?"([^"]*)"/i.exec(tagContent)?.[1];
						const msgCommandRegex = /^\/(?:msg|pm|w|whisper|botmsg) /;
						const botmsgCommandRegex = /^\/msgroom (?:[a-z0-9-]+), ?\/botmsg /;
						if (buttonName === 'send' && buttonValue && msgCommandRegex.test(buttonValue)) {
							const [pmTarget] = buttonValue.replace(msgCommandRegex, '').split(',');
							const auth = this.room ? this.room.auth : Users.globalAuth;
							if (auth.get(toID(pmTarget)) !== '*' && toID(pmTarget) !== this.user.id) {
								this.errorReply(`This button is not allowed: <${tagContent}>`);
								throw new Chat.ErrorMessage(`Your scripted button can't send PMs to ${pmTarget}, because that user is not a Room Bot.`);
							}
						} else if (buttonName === 'send' && buttonValue && botmsgCommandRegex.test(buttonValue)) {
							// no need to validate the bot being an actual bot; `/botmsg` will do it for us and is not abusable
						} else if (buttonName) {
							this.errorReply(`This button is not allowed: <${tagContent}>`);
							this.errorReply(`You do not have permission to use most buttons. Here are the two types you're allowed to use:`);
							this.errorReply(`1. Linking to a room: <a href="/roomid"><button>go to a place</button></a>`);
							throw new Chat.ErrorMessage(`2. Sending a message to a Bot: <button name="send" value="/msgroom BOT_ROOMID, /botmsg BOT_USERNAME, MESSAGE">send the thing</button>`);
						}
					}
				}
			}
			if (stack.length) {
				throw new Chat.ErrorMessage(`Missing </${stack.pop()}>.`);
			}
		}

		return htmlContent;
	}

	/**
	 * This is to be used for commands that replicate other commands
	 * (for example, `/pm username, command` or `/msgroom roomid, command`)
	 * to ensure they do not crash with too many levels of recursion.
	 */
	checkRecursion() {
		if (this.recursionDepth > 5) {
			throw new Chat.ErrorMessage(`/${this.cmd} - Too much command recursion has occurred.`);
		}
	}

	requireRoom(id?: RoomID) {
		if (!this.room) {
			throw new Chat.ErrorMessage(`/${this.cmd} - must be used in a chat room, not a ${this.pmTarget ? "PM" : "console"}`);
		}
		if (id && this.room.roomid !== id) {
			const targetRoom = Rooms.get(id);
			if (!targetRoom) {
				throw new Chat.ErrorMessage(`This command can only be used in the room '${id}', but that room does not exist.`);
			}
			throw new Chat.ErrorMessage(`This command can only be used in the ${targetRoom.title} room.`);
		}
		return this.room;
	}
	// eslint-disable-next-line @typescript-eslint/type-annotation-spacing
	requireGame<T extends RoomGame>(constructor: new (...args: any[]) => T, subGame = false) {
		const room = this.requireRoom();
		if (subGame) {
			if (!room.subGame) {
				throw new Chat.ErrorMessage(`This command requires a sub-game of ${constructor.name} (this room has no sub-game).`);
			}
			const game = room.getGame(constructor, subGame);
			// must be a different game
			if (!game) {
				throw new Chat.ErrorMessage(`This command requires a sub-game of ${constructor.name} (this sub-game is ${room.subGame.title}).`);
			}
			return game;
		}
		if (!room.game) {
			throw new Chat.ErrorMessage(`This command requires a game of ${constructor.name} (this room has no game).`);
		}
		const game = room.getGame(constructor);
		// must be a different game
		if (!game) {
			throw new Chat.ErrorMessage(`This command requires a game of ${constructor.name} (this game is ${room.game.title}).`);
		}
		return game;
	}
	requireMinorActivity<T extends MinorActivity>(constructor: new (...args: any[]) => T) {
		const room = this.requireRoom();
		if (!room.minorActivity) {
			throw new Chat.ErrorMessage(`This command requires a ${constructor.name} (this room has no minor activity).`);
		}
		const game = room.getMinorActivity(constructor);
		// must be a different game
		if (!game) {
			throw new Chat.ErrorMessage(`This command requires a ${constructor.name} (this minor activity is a(n) ${room.minorActivity.name}).`);
		}
		return game;
	}
	commandDoesNotExist(): never {
		if (this.cmdToken === '!') {
			throw new Chat.ErrorMessage(`The command "${this.cmdToken}${this.fullCmd}" does not exist.`);
		}
		throw new Chat.ErrorMessage(
			`The command "${this.cmdToken}${this.fullCmd}" does not exist. To send a message starting with "${this.cmdToken}${this.fullCmd}", type "${this.cmdToken}${this.cmdToken}${this.fullCmd}".`
		);
	}
	refreshPage(pageid: string) {
		if (this.connection.openPages?.has(pageid)) {
			this.parse(`/join view-${pageid}`);
		}
	}
	closePage(pageid: string) {
		for (const connection of this.user.connections) {
			if (connection.openPages?.has(pageid)) {
				connection.send(`>view-${pageid}\n|deinit`);
				connection.openPages.delete(pageid);
				if (!connection.openPages.size) {
					connection.openPages = null;
				}
			}
		}
	}
}

export const Chat = new class {
	constructor() {
		void this.loadTranslations().then(() => {
			Chat.translationsLoaded = true;
		});
	}
	translationsLoaded = false;
	/**
	 * As per the node.js documentation at https://nodejs.org/api/timers.html#timers_settimeout_callback_delay_args,
	 * timers with durations that are too long for a 32-bit signed integer will be invoked after 1 millisecond,
	 * which tends to cause unexpected behavior.
	 */
	readonly MAX_TIMEOUT_DURATION = 2147483647;
	readonly Friends = new FriendsDatabase();
	readonly PM = PM;

	readonly multiLinePattern = new PatternTester();

	/*********************************************************
	 * Load command files
	 *********************************************************/
	baseCommands!: AnnotatedChatCommands;
	commands!: AnnotatedChatCommands;
	basePages!: PageTable;
	pages!: PageTable;
	readonly destroyHandlers: (() => void)[] = [Artemis.destroy];
	readonly crqHandlers: {[k: string]: CRQHandler} = {};
	readonly handlers: {[k: string]: ((...args: any) => any)[]} = Object.create(null);
	/** The key is the name of the plugin. */
	readonly plugins: {[k: string]: ChatPlugin} = {};
	/** Will be empty except during hotpatch */
	oldPlugins: {[k: string]: ChatPlugin} = {};
	roomSettings: SettingsHandler[] = [];

	/*********************************************************
	 * Load chat filters
	 *********************************************************/
	readonly filters: ChatFilter[] = [];
	filter(message: string, context: CommandContext) {
		// Chat filters can choose to:
		// 1. return false OR null - to not send a user's message
		// 2. return an altered string - to alter a user's message
		// 3. return undefined to send the original message through
		const originalMessage = message;
		for (const curFilter of Chat.filters) {
			const output = curFilter.call(
				context,
				message,
				context.user,
				context.room,
				context.connection,
				context.pmTarget,
				originalMessage
			);
			if (output === false) return null;
			if (!output && output !== undefined) return output;
			if (output !== undefined) message = output;
		}

		return message;
	}

	readonly namefilters: NameFilter[] = [];
	namefilter(name: string, user: User) {
		if (!Config.disablebasicnamefilter) {
			// whitelist
			// \u00A1-\u00BF\u00D7\u00F7  Latin punctuation/symbols
			// \u02B9-\u0362              basic combining accents
			// \u2012-\u2027\u2030-\u205E Latin punctuation/symbols extended
			// \u2050-\u205F              fractions extended
			// \u2190-\u23FA\u2500-\u2BD1 misc symbols
			// \u2E80-\u32FF              CJK symbols
			// \u3400-\u9FFF              CJK
			// \uF900-\uFAFF\uFE00-\uFE6F CJK extended
			name = name.replace(
				// eslint-disable-next-line no-misleading-character-class
				/[^a-zA-Z0-9 /\\.~()<>^*%&=+$#_'?!"\u00A1-\u00BF\u00D7\u00F7\u02B9-\u0362\u2012-\u2027\u2030-\u205E\u2050-\u205F\u2190-\u23FA\u2500-\u2BD1\u2E80-\u32FF\u3400-\u9FFF\uF900-\uFAFF\uFE00-\uFE6F-]+/g,
				''
			);

			// blacklist
			// \u00a1 upside-down exclamation mark (i)
			// \u2580-\u2590 black bars
			// \u25A0\u25Ac\u25AE\u25B0 black bars
			// \u534d\u5350 swastika
			// \u2a0d crossed integral (f)
			name = name.replace(/[\u00a1\u2580-\u2590\u25A0\u25Ac\u25AE\u25B0\u2a0d\u534d\u5350]/g, '');

			// e-mail address
			if (name.includes('@') && name.includes('.')) return '';

			// url
			if (/[a-z0-9]\.(com|net|org|us|uk|co|gg|tk|ml|gq|ga|xxx|download|stream)\b/i.test(name)) name = name.replace(/\./g, '');

			// Limit the amount of symbols allowed in usernames to 4 maximum, and
			// disallow (R) and (C) from being used in the middle of names.
			const nameSymbols = name.replace(
				/[^\u00A1-\u00BF\u00D7\u00F7\u02B9-\u0362\u2012-\u2027\u2030-\u205E\u2050-\u205F\u2090-\u23FA\u2500-\u2BD1]+/g,
				''
			);
			// \u00ae\u00a9 (R) (C)
			if (
				nameSymbols.length > 4 ||
				/[^a-z0-9][a-z0-9][^a-z0-9]/.test(name.toLowerCase() + ' ') || /[\u00ae\u00a9].*[a-zA-Z0-9]/.test(name)
			) {
				name = name.replace(
					// eslint-disable-next-line no-misleading-character-class
					/[\u00A1-\u00BF\u00D7\u00F7\u02B9-\u0362\u2012-\u2027\u2030-\u205E\u2050-\u205F\u2190-\u23FA\u2500-\u2BD1\u2E80-\u32FF\u3400-\u9FFF\uF900-\uFAFF\uFE00-\uFE6F]+/g,
					''
				).replace(/[^A-Za-z0-9]{2,}/g, ' ').trim();
			}
		}
		name = name.replace(/^[^A-Za-z0-9]+/, ""); // remove symbols from start
		name = name.replace(/@/g, ""); // Remove @ as this is used to indicate status messages

		// cut name length down to 18 chars
		if (/[A-Za-z0-9]/.test(name.slice(18))) {
			name = name.replace(/[^A-Za-z0-9]+/g, "");
		} else {
			name = name.slice(0, 18);
		}

		name = Dex.getName(name);
		for (const curFilter of Chat.namefilters) {
			name = curFilter(name, user);
			if (!name) return '';
		}
		return name;
	}

	readonly hostfilters: HostFilter[] = [];
	hostfilter(host: string, user: User, connection: Connection, hostType: string) {
		for (const curFilter of Chat.hostfilters) {
			curFilter(host, user, connection, hostType);
		}
	}

	readonly loginfilters: LoginFilter[] = [];
	loginfilter(user: User, oldUser: User | null, usertype: string) {
		for (const curFilter of Chat.loginfilters) {
			curFilter(user, oldUser, usertype);
		}
	}

	readonly punishmentfilters: PunishmentFilter[] = [];
	punishmentfilter(user: User | ID, punishment: Punishment) {
		for (const curFilter of Chat.punishmentfilters) {
			curFilter(user, punishment);
		}
	}

	readonly nicknamefilters: NicknameFilter[] = [];
	nicknamefilter(nickname: string, user: User) {
		for (const curFilter of Chat.nicknamefilters) {
			const filtered = curFilter(nickname, user);
			if (filtered === false) return false;
			if (!filtered) return '';
		}
		return nickname;
	}

	readonly statusfilters: StatusFilter[] = [];
	statusfilter(status: string, user: User) {
		status = status.replace(/\|/g, '');
		for (const curFilter of Chat.statusfilters) {
			status = curFilter(status, user);
			if (!status) return '';
		}
		return status;
	}
	/*********************************************************
	 * Translations
	 *********************************************************/
	/** language id -> language name */
	readonly languages = new Map<ID, string>();
	/** language id -> (english string -> translated string) */
	readonly translations = new Map<ID, Map<string, [string, string[], string[]]>>();

	async loadTranslations() {
		const directories = await FS(TRANSLATION_DIRECTORY).readdir();

		// ensure that english is the first entry when we iterate over Chat.languages
		Chat.languages.set('english' as ID, 'English');
		for (const dirname of directories) {
			// translation dirs shouldn't have caps, but things like sourceMaps and the README will
			if (/[^a-z0-9]/.test(dirname)) continue;
			const dir = FS(`${TRANSLATION_DIRECTORY}/${dirname}`);

			// For some reason, toID() isn't available as a global when this executes.
			const languageID = Dex.toID(dirname);
			const files = await dir.readdir();
			for (const filename of files) {
				if (!filename.endsWith('.ts')) continue;

				const content: Translations = require(`${TRANSLATION_DIRECTORY}/${dirname}/${filename}`).translations;

				if (!Chat.translations.has(languageID)) {
					Chat.translations.set(languageID, new Map());
				}
				const translationsSoFar = Chat.translations.get(languageID)!;

				if (content.name && !Chat.languages.has(languageID)) {
					Chat.languages.set(languageID, content.name);
				}

				if (content.strings) {
					for (const key in content.strings) {
						const keyLabels: string[] = [];
						const valLabels: string[] = [];
						const newKey = key.replace(/\${.+?}/g, str => {
							keyLabels.push(str);
							return '${}';
						}).replace(/\[TN: ?.+?\]/g, '');
						const val = content.strings[key].replace(/\${.+?}/g, (str: string) => {
							valLabels.push(str);
							return '${}';
						}).replace(/\[TN: ?.+?\]/g, '');
						translationsSoFar.set(newKey, [val, keyLabels, valLabels]);
					}
				}
			}
			if (!Chat.languages.has(languageID)) {
				// Fallback in case no translation files provide the language's name
				Chat.languages.set(languageID, "Unknown Language");
			}
		}
	}
	tr(language: ID | null): (fStrings: TemplateStringsArray | string, ...fKeys: any) => string;
	tr(language: ID | null, strings: TemplateStringsArray | string, ...keys: any[]): string;
	tr(language: ID | null, strings: TemplateStringsArray | string = '', ...keys: any[]) {
		if (!language) language = 'english' as ID;
		// If strings is an array (normally the case), combine before translating.
		const trString = typeof strings === 'string' ? strings : strings.join('${}');

		if (Chat.translationsLoaded && !Chat.translations.has(language)) {
			throw new Error(`Trying to translate to a nonexistent language: ${language}`);
		}
		if (!strings.length) {
			return ((fStrings: TemplateStringsArray | string, ...fKeys: any) => Chat.tr(language, fStrings, ...fKeys));
		}

		const entry = Chat.translations.get(language)?.get(trString);
		let [translated, keyLabels, valLabels] = entry || ["", [], []];
		if (!translated) translated = trString;

		// Replace the gaps in the species string
		if (keys.length) {
			let reconstructed = '';

			const left: (string | null)[] = keyLabels.slice();
			for (const [i, str] of translated.split('${}').entries()) {
				reconstructed += str;
				if (keys[i]) {
					let index = left.indexOf(valLabels[i]);
					if (index < 0) {
						index = left.findIndex(val => !!val);
					}
					if (index < 0) index = i;
					reconstructed += keys[index];
					left[index] = null;
				}
			}

			translated = reconstructed;
		}
		return translated;
	}

	/**
	 * SQL handler
	 *
	 * All chat plugins share one database.
	 * Chat.databaseReadyPromise will be truthy if the database is not yet ready.
	 */
	database = SQL(module, {
		file: ('Config' in global && Config.nofswriting) ? ':memory:' : PLUGIN_DATABASE_PATH,
		processes: global.Config?.chatdbprocesses || 1,
	});
	databaseReadyPromise: Promise<void> | null = null;

	async prepareDatabase() {
		if (!PM.isParentProcess) return; // We don't need a database in a subprocess that requires Chat.
		if (!Config.usesqlite) return;
		// check if we have the db_info table, which will always be present unless the schema needs to be initialized
		const {hasDBInfo} = await this.database.get(
			`SELECT count(*) AS hasDBInfo FROM sqlite_master WHERE type = 'table' AND name = 'db_info'`
		);
		if (!hasDBInfo) await this.database.runFile('./databases/schemas/chat-plugins.sql');

		const result = await this.database.get(
			`SELECT value as curVersion FROM db_info WHERE key = 'version'`
		);
		const curVersion = parseInt(result.curVersion);
		if (!curVersion) throw new Error(`db_info table is present, but schema version could not be parsed`);

		// automatically run migrations of the form "v{number}.sql" in the migrations/chat-plugins folder
		const migrationsFolder = './databases/migrations/chat-plugins';
		const migrationsToRun = [];
		for (const migrationFile of (await FS(migrationsFolder).readdir())) {
			const migrationVersion = parseInt(/v(\d+)\.sql$/.exec(migrationFile)?.[1] || '');
			if (!migrationVersion) continue;
			if (migrationVersion > curVersion) migrationsToRun.push({version: migrationVersion, file: migrationFile});
		}
		Utils.sortBy(migrationsToRun, ({version}) => version);
		for (const {file} of migrationsToRun) {
			await this.database.runFile(resolve(migrationsFolder, file));
		}

		Chat.destroyHandlers.push(() => Chat.database?.destroy());
	}

	readonly MessageContext = MessageContext;
	readonly CommandContext = CommandContext;
	readonly PageContext = PageContext;
	readonly ErrorMessage = ErrorMessage;
	readonly Interruption = Interruption;

	// JSX handling
	readonly JSX = JSX;
	readonly html = JSX.html;
	readonly h = JSX.h;
	readonly Fragment = JSX.Fragment;

	/**
	 * Command parser
	 *
	 * Usage:
	 *   Chat.parse(message, room, user, connection)
	 *
	 * Parses the message. If it's a command, the command is executed, if
	 * not, it's displayed directly in the room.
	 *
	 * Examples:
	 *   Chat.parse("/join lobby", room, user, connection)
	 *     will make the user join the lobby.
	 *
	 *   Chat.parse("Hi, guys!", room, user, connection)
	 *     will return "Hi, guys!" if the user isn't muted, or
	 *     if he's muted, will warn him that he's muted.
	 *
	 * The return value is the return value of the command handler, if any,
	 * or the message, if there wasn't a command. This value could be a success
	 * or failure (few commands report these) or a Promise for when the command
	 * is done executing, if it's not currently done.
	 *
	 * @param message - the message the user is trying to say
	 * @param room - the room the user is trying to say it in
	 * @param user - the user that sent the message
	 * @param connection - the connection the user sent the message from
	 */
	parse(message: string, room: Room | null | undefined, user: User, connection: Connection) {
		Chat.loadPlugins();

		const initialRoomlogLength = room?.log.getLineCount();
		const context = new CommandContext({message, room, user, connection});
		const start = Date.now();
		const result = context.parse();
		if (typeof result?.then === 'function') {
			void result.then(() => {
				this.logSlowMessage(start, context);
			});
		} else {
			this.logSlowMessage(start, context);
		}
		if (room && room.log.getLineCount() !== initialRoomlogLength) {
			room.messagesSent++;
			for (const [handler, numMessages] of room.nthMessageHandlers) {
				if (room.messagesSent % numMessages === 0) handler(room, message);
			}
		}

		return result;
	}
	logSlowMessage(start: number, context: CommandContext) {
		const timeUsed = Date.now() - start;
		if (timeUsed < 1000) return;
		if (context.cmd === 'search' || context.cmd === 'savereplay') return;

		const logMessage = (
			`[slow command] ${timeUsed}ms - ${context.user.name} (${context.connection.ip}): ` +
			`<${context.room ? context.room.roomid : context.pmTarget ? `PM:${context.pmTarget?.name}` : 'CMD'}> ` +
			`${context.message.replace(/\n/ig, ' ')}`
		);

		Monitor.slow(logMessage);
	}
	sendPM(message: string, user: User, pmTarget: User, onlyRecipient: User | null = null) {
		const buf = `|pm|${user.getIdentity()}|${pmTarget.getIdentity()}|${message}`;
		if (onlyRecipient) return onlyRecipient.send(buf);
		user.send(buf);
		if (pmTarget !== user) pmTarget.send(buf);
		pmTarget.lastPM = user.id;
		user.lastPM = pmTarget.id;
	}

	packageData: AnyObject = {};

	loadPluginFile(file: string) {
		if (!VALID_PLUGIN_ENDINGS.some(ext => file.endsWith(ext))) return;
		const filename = file.split('/').pop() || "";
		this.loadPlugin(require(file), filename.slice(0, filename.lastIndexOf('.')) || file);
	}

	loadPluginDirectory(dir: string, depth = 0) {
		for (const file of FS(dir).readdirSync()) {
			const path = resolve(dir, file);
			if (FS(path).isDirectorySync()) {
				depth++;
				if (depth > MAX_PLUGIN_LOADING_DEPTH) continue;
				this.loadPluginDirectory(path, depth);
			} else {
				try {
					this.loadPluginFile(path);
				} catch (e) {
					Monitor.crashlog(e, "A loading chat plugin");
					continue;
				}
			}
		}
	}
	annotateCommands(commandTable: AnyObject, namespace = ''): AnnotatedChatCommands {
		for (const cmd in commandTable) {
			const entry = commandTable[cmd];
			if (typeof entry === 'object') {
				this.annotateCommands(entry, `${namespace}${cmd} `);
			}
			if (typeof entry === 'string') {
				const base = commandTable[entry];
				if (!base) continue;
				if (!base.aliases) base.aliases = [];
				if (!base.aliases.includes(cmd)) base.aliases.push(cmd);
				continue;
			}
			if (typeof entry !== 'function') continue;

			const handlerCode = entry.toString();
			entry.requiresRoom = /requireRoom\((?:'|"|`)(.*?)(?:'|"|`)/.exec(handlerCode)?.[1] as RoomID || /this\.requireRoom\(/.test(handlerCode);
			entry.hasRoomPermissions = /\bthis\.(checkCan|can)\([^,)\n]*, [^,)\n]*,/.test(handlerCode);
			entry.broadcastable = cmd.endsWith('help') || /\bthis\.(?:(check|can|run|should)Broadcast)\(/.test(handlerCode);
			entry.isPrivate = /\bthis\.(?:privately(Check)?Can|commandDoesNotExist)\(/.test(handlerCode);
			entry.requiredPermission = /this\.(?:checkCan|privately(?:Check)?Can)\(['`"]([a-zA-Z0-9]+)['"`](\)|, )/.exec(handlerCode)?.[1];
			if (!entry.aliases) entry.aliases = [];

			// assign properties from the base command if the current command uses CommandContext.run.
			const runsCommand = /this.run\((?:'|"|`)(.*?)(?:'|"|`)\)/.exec(handlerCode);
			if (runsCommand) {
				const [, baseCommand] = runsCommand;
				const baseEntry = commandTable[baseCommand];
				if (baseEntry) {
					if (baseEntry.requiresRoom) entry.requiresRoom = baseEntry.requiresRoom;
					if (baseEntry.hasRoomPermissions) entry.hasRoomPermissions = baseEntry.hasRoomPermissions;
					if (baseEntry.broadcastable) entry.broadcastable = baseEntry.broadcastable;
					if (baseEntry.isPrivate) entry.isPrivate = baseEntry.isPrivate;
				}
			}
			// This is usually the same as `entry.name`, but some weirdness like
			// `commands.a = b` could screw it up. This should make it consistent.
			entry.cmd = cmd;
			entry.fullCmd = `${namespace}${cmd}`;
		}
		return commandTable;
	}
	loadPlugin(plugin: AnyObject, name: string) {
		if (plugin.commands) {
			Object.assign(Chat.commands, this.annotateCommands(plugin.commands));
		}
		if (plugin.pages) {
			Object.assign(Chat.pages, plugin.pages);
		}

		if (plugin.destroy) {
			Chat.destroyHandlers.push(plugin.destroy);
		}
		if (plugin.crqHandlers) {
			Object.assign(Chat.crqHandlers, plugin.crqHandlers);
		}
		if (plugin.roomSettings) {
			if (!Array.isArray(plugin.roomSettings)) plugin.roomSettings = [plugin.roomSettings];
			Chat.roomSettings = Chat.roomSettings.concat(plugin.roomSettings);
		}
		if (plugin.chatfilter) Chat.filters.push(plugin.chatfilter);
		if (plugin.namefilter) Chat.namefilters.push(plugin.namefilter);
		if (plugin.hostfilter) Chat.hostfilters.push(plugin.hostfilter);
		if (plugin.loginfilter) Chat.loginfilters.push(plugin.loginfilter);
		if (plugin.punishmentfilter) Chat.punishmentfilters.push(plugin.punishmentfilter);
		if (plugin.nicknamefilter) Chat.nicknamefilters.push(plugin.nicknamefilter);
		if (plugin.statusfilter) Chat.statusfilters.push(plugin.statusfilter);
		if (plugin.onRenameRoom) {
			if (!Chat.handlers['onRenameRoom']) Chat.handlers['onRenameRoom'] = [];
			Chat.handlers['onRenameRoom'].push(plugin.onRenameRoom);
		}
		if (plugin.onRoomClose) {
			if (!Chat.handlers['onRoomClose']) Chat.handlers['onRoomClose'] = [];
			Chat.handlers['onRoomClose'].push(plugin.onRoomClose);
		}
		if (plugin.handlers) {
			for (const handlerName in plugin.handlers) {
				if (!Chat.handlers[handlerName]) Chat.handlers[handlerName] = [];
				Chat.handlers[handlerName].push(plugin.handlers[handlerName]);
			}
		}
		Chat.plugins[name] = plugin;
	}
	loadPlugins(oldPlugins?: {[k: string]: ChatPlugin}) {
		if (Chat.commands) return;
		if (oldPlugins) Chat.oldPlugins = oldPlugins;

		void FS('package.json').readIfExists().then(data => {
			if (data) Chat.packageData = JSON.parse(data);
		});

		// Install plug-in commands and chat filters


		Chat.commands = Object.create(null);
		Chat.pages = Object.create(null);
		this.loadPluginDirectory('server/chat-commands');
		Chat.baseCommands = Chat.commands;
		Chat.basePages = Chat.pages;
		Chat.commands = Object.assign(Object.create(null), Chat.baseCommands);
		Chat.pages = Object.assign(Object.create(null), Chat.basePages);

		// Load filters from Config
		this.loadPlugin(Config, 'config');
		this.loadPlugin(Tournaments, 'tournaments');

		this.loadPluginDirectory('server/chat-plugins');
		Chat.oldPlugins = {};
		// lower priority should run later
		Utils.sortBy(Chat.filters, filter => -(filter.priority || 0));
	}

	destroy() {
		for (const handler of Chat.destroyHandlers) {
			handler();
		}
	}

	runHandlers(name: keyof Handlers, ...args: Parameters<Handlers[typeof name]>) {
		const handlers = this.handlers[name];
		if (!handlers) return;
		for (const h of handlers) {
			void h.call(this, ...args);
		}
	}

	handleRoomRename(oldID: RoomID, newID: RoomID, room: Room) {
		Chat.runHandlers('onRenameRoom', oldID, newID, room);
	}

	handleRoomClose(roomid: RoomID, user: User, connection: Connection) {
		Chat.runHandlers('onRoomClose', roomid, user, connection, roomid.startsWith('view-'));
	}

	/**
	 * Takes a chat message and returns data about any command it's
	 * trying to use.
	 *
	 * Returning `null` means the chat message isn't trying to use
	 * a command, and returning `{handler: null}` means it's trying
	 * to use a command that doesn't exist.
	 */
	parseCommand(message: string, recursing = false): {
		cmd: string, fullCmd: string, cmdToken: string, target: string, handler: AnnotatedChatHandler | null,
	} | null {
		if (!message.trim()) return null;

		// hardcoded commands
		if (message.startsWith(`>> `)) {
			message = `/eval ${message.slice(3)}`;
		} else if (message.startsWith(`>>> `)) {
			message = `/evalbattle ${message.slice(4)}`;
		} else if (message.startsWith('>>sql ')) {
			message = `/evalsql ${message.slice(6)}`;
		} else if (message.startsWith(`/me`) && /[^A-Za-z0-9 ]/.test(message.charAt(3))) {
			message = `/mee ${message.slice(3)}`;
		} else if (message.startsWith(`/ME`) && /[^A-Za-z0-9 ]/.test(message.charAt(3))) {
			message = `/MEE ${message.slice(3)}`;
		}

		const cmdToken = message.charAt(0);
		if (!VALID_COMMAND_TOKENS.includes(cmdToken)) return null;
		if (cmdToken === message.charAt(1)) return null;
		if (cmdToken === BROADCAST_TOKEN && /[^A-Za-z0-9]/.test(message.charAt(1))) return null;

		let [cmd, target] = Utils.splitFirst(message.slice(1), ' ');
		cmd = cmd.toLowerCase();

		if (cmd.endsWith(',')) cmd = cmd.slice(0, -1);

		let curCommands: AnnotatedChatCommands = Chat.commands;
		let commandHandler;
		let fullCmd = cmd;
		let prevCmdName = '';

		do {
			if (cmd in curCommands) {
				commandHandler = curCommands[cmd];
			} else {
				commandHandler = undefined;
			}
			if (typeof commandHandler === 'string') {
				// in case someone messed up, don't loop
				commandHandler = curCommands[commandHandler];
			} else if (Array.isArray(commandHandler) && !recursing) {
				return this.parseCommand(cmdToken + 'help ' + fullCmd.slice(0, -4), true);
			}
			if (commandHandler && typeof commandHandler === 'object') {
				[cmd, target] = Utils.splitFirst(target, ' ');
				cmd = cmd.toLowerCase();

				prevCmdName = fullCmd;
				fullCmd += ' ' + cmd;
				curCommands = commandHandler as AnnotatedChatCommands;
			}
		} while (commandHandler && typeof commandHandler === 'object');

		if (!commandHandler && (curCommands.default || curCommands[''])) {
			commandHandler = curCommands.default || curCommands[''];
			fullCmd = prevCmdName;
			target = `${cmd}${target ? ` ${target}` : ''}`;
			cmd = fullCmd.split(' ').shift()!;
			if (typeof commandHandler === 'string') {
				commandHandler = curCommands[commandHandler];
			}
		}

		if (!commandHandler && !recursing) {
			for (const g in Config.groups) {
				const groupid = Config.groups[g].id;
				if (fullCmd === groupid) {
					return this.parseCommand(`/promote ${target}, ${g}`, true);
				} else if (fullCmd === 'global' + groupid) {
					return this.parseCommand(`/globalpromote ${target}, ${g}`, true);
				} else if (fullCmd === 'de' + groupid || fullCmd === 'un' + groupid ||
						fullCmd === 'globalde' + groupid || fullCmd === 'deglobal' + groupid) {
					return this.parseCommand(`/demote ${target}`, true);
				} else if (fullCmd === 'room' + groupid) {
					return this.parseCommand(`/roompromote ${target}, ${g}`, true);
				} else if (fullCmd === 'forceroom' + groupid) {
					return this.parseCommand(`/forceroompromote ${target}, ${g}`, true);
				} else if (fullCmd === 'roomde' + groupid || fullCmd === 'deroom' + groupid || fullCmd === 'roomun' + groupid) {
					return this.parseCommand(`/roomdemote ${target}`, true);
				}
			}
		}

		return {
			cmd: cmd,
			cmdToken: cmdToken,
			target: target,
			fullCmd: fullCmd,
			handler: commandHandler as AnnotatedChatHandler | null,
		};
	}
	allCommands(table: ChatCommands = Chat.commands) {
		const results: AnnotatedChatHandler[] = [];
		for (const cmd in table) {
			const handler = table[cmd];
			if (Array.isArray(handler) || !handler || ['string', 'boolean'].includes(typeof handler)) {
				continue;
			}
			if (typeof handler === 'object') {
				results.push(...this.allCommands(handler));
				continue;
			}
			results.push(handler as AnnotatedChatHandler);
		}
		if (table !== Chat.commands) return results;
		return results.filter((handler, i) => results.indexOf(handler) === i);
	}

	/**
	 * Strips HTML from a string.
	 */
	stripHTML(htmlContent: string) {
		if (!htmlContent) return '';
		return htmlContent.replace(/<[^>]*>/g, '');
	}
	/**
	 * Validates input regex and ensures it won't crash.
	 */
	validateRegex(word: string) {
		word = word.trim();
		if ((word.endsWith('|') && !word.endsWith('\\|')) || word.startsWith('|')) {
			throw new Chat.ErrorMessage(`Your regex was rejected because it included an unterminated |.`);
		}
		try {
			// eslint-disable-next-line no-new
			new RegExp(word);
		} catch (e: any) {
			throw new Chat.ErrorMessage(
				e.message.startsWith('Invalid regular expression: ') ?
					e.message :
					`Invalid regular expression: /${word}/: ${e.message}`
			);
		}
	}

	/**
	 * Returns singular (defaulting to '') if num is 1, or plural
	 * (defaulting to 's') otherwise. Helper function for pluralizing
	 * words.
	 */
	plural(num: any, pluralSuffix = 's', singular = '') {
		if (num && typeof num.length === 'number') {
			num = num.length;
		} else if (num && typeof num.size === 'number') {
			num = num.size;
		} else {
			num = Number(num);
		}
		return (num !== 1 ? pluralSuffix : singular);
	}

	/**
	 * Counts the thing passed.
	 *
	 *     Chat.count(2, "days") === "2 days"
	 *     Chat.count(1, "days") === "1 day"
	 *     Chat.count(["foo"], "things are") === "1 thing is"
	 *
	 */
	count(num: any, pluralSuffix: string, singular = "") {
		if (num && typeof num.length === 'number') {
			num = num.length;
		} else if (num && typeof num.size === 'number') {
			num = num.size;
		} else {
			num = Number(num);
		}
		if (!singular) {
			if (pluralSuffix.endsWith("s")) {
				singular = pluralSuffix.slice(0, -1);
			} else if (pluralSuffix.endsWith("s have")) {
				singular = pluralSuffix.slice(0, -6) + " has";
			} else if (pluralSuffix.endsWith("s were")) {
				singular = pluralSuffix.slice(0, -6) + " was";
			}
		}
		const space = singular.startsWith('<') ? '' : ' ';
		return `${num}${space}${num > 1 ? pluralSuffix : singular}`;
	}

	/**
	 * Returns a timestamp in the form {yyyy}-{MM}-{dd} {hh}:{mm}:{ss}.
	 *
	 * options.human = true will reports hours human-readable
	 */
	toTimestamp(date: Date, options: {human?: boolean} = {}) {
		const human = options.human;
		let parts: any[] = [
			date.getFullYear(),	date.getMonth() + 1, date.getDate(),
			date.getHours(), date.getMinutes(),	date.getSeconds(),
		];
		if (human) {
			parts.push(parts[3] >= 12 ? 'pm' : 'am');
			parts[3] = parts[3] % 12 || 12;
		}
		parts = parts.map(val => val < 10 ? '0' + val : '' + val);
		return parts.slice(0, 3).join("-") + " " + parts.slice(3, human ? 5 : 6).join(":") + (human ? "" + parts[6] : "");
	}

	/**
	 * Takes a number of milliseconds, and reports the duration in English: hours, minutes, etc.
	 *
	 * options.hhmmss = true will instead report the duration in 00:00:00 format
	 *
	 */
	toDurationString(val: number, options: {hhmmss?: boolean, precision?: number} = {}) {
		// TODO: replace by Intl.DurationFormat or equivalent when it becomes available (ECMA-402)
		// https://github.com/tc39/ecma402/issues/47
		const date = new Date(+val);
		if (isNaN(date.getTime())) return 'forever';

		const parts = [
			date.getUTCFullYear() - 1970, date.getUTCMonth(), date.getUTCDate() - 1,
			date.getUTCHours(), date.getUTCMinutes(), date.getUTCSeconds(),
		];
		const roundingBoundaries = [6, 15, 12, 30, 30];
		const unitNames = ["second", "minute", "hour", "day", "month", "year"];
		const positiveIndex = parts.findIndex(elem => elem > 0);
		let precision = (options?.precision ? options.precision : 3);
		if (options?.hhmmss) {
			const str = parts.slice(positiveIndex).map(value => value < 10 ? "0" + value : "" + value).join(":");
			return str.length === 2 ? "00:" + str : str;
		}

		// round least significant displayed unit
		if (positiveIndex + precision < parts.length && precision > 0 && positiveIndex >= 0) {
			if (parts[positiveIndex + precision] >= roundingBoundaries[positiveIndex + precision - 1]) {
				parts[positiveIndex + precision - 1]++;
			}
		}

		// don't display trailing 0's if the number is exact
		let precisionIndex = 5;
		while (precisionIndex > positiveIndex && !parts[precisionIndex]) {
			precisionIndex--;
		}
		precision = Math.min(precision, precisionIndex - positiveIndex + 1);

		return parts
			.slice(positiveIndex)
			.reverse()
			.map((value, index) => `${value} ${unitNames[index]}${value !== 1 ? "s" : ""}`)
			.reverse()
			.slice(0, precision)
			.join(" ")
			.trim();
	}

	/**
	 * Takes an array and turns it into a sentence string by adding commas and the word "and"
	 */
	toListString(arr: string[], conjunction = "and") {
		if (!arr.length) return '';
		if (arr.length === 1) return arr[0];
		if (arr.length === 2) return `${arr[0]} ${conjunction.trim()} ${arr[1]}`;
		return `${arr.slice(0, -1).join(", ")}, ${conjunction.trim()} ${arr.slice(-1)[0]}`;
	}

	/**
	 * Takes an array and turns it into a sentence string by adding commas and the word "or"
	 */
	toOrList(arr: string[]) {
		if (!arr.length) return '';
		if (arr.length === 1) return arr[0];
		if (arr.length === 2) return `${arr[0]} or ${arr[1]}`;
		return `${arr.slice(0, -1).join(", ")}, or ${arr.slice(-1)[0]}`;
	}

	/**
	 * Convert multiline HTML into a single line without losing whitespace (so
	 * <pre> blocks still render correctly). Linebreaks inside <> are replaced
	 * with ` `, and linebreaks outside <> are replaced with `&#10;`.
	 *
	 * PS's protocol often requires sending a block of HTML in a single line,
	 * so this ensures any block of HTML ends up as a single line.
	 */
	collapseLineBreaksHTML(htmlContent: string) {
		htmlContent = htmlContent.replace(/<[^>]*>/g, tag => tag.replace(/\n/g, ' '));
		htmlContent = htmlContent.replace(/\n/g, '&#10;');
		return htmlContent;
	}
	/**
	 * Takes a string of text and transforms it into a block of html using the details tag.
	 * If it has a newline, will make the 3 lines the preview, and fill the rest in.
	 * @param str string to block
	 */
	getReadmoreBlock(str: string, isCode?: boolean, cutoff = 3) {
		const params = str.slice(+str.startsWith('\n')).split('\n');
		const output: string[] = [];
		for (const [i, param] of params.entries()) {
			if (output.length < cutoff && param.length > 80 && cutoff > 2) cutoff--;
			if (param.length > cutoff * 160 && i < cutoff) cutoff = i;
			output.push(Utils[isCode ? 'escapeHTMLForceWrap' : 'escapeHTML'](param));
		}

		if (output.length > cutoff) {
			return `<details class="readmore${isCode ? ` code" style="white-space: pre-wrap; display: table; tab-size: 3` : ``}"><summary>${
				output.slice(0, cutoff).join('<br />')
			}</summary>${
				output.slice(cutoff).join('<br />')
			}</details>`;
		} else {
			const tag = isCode ? `code` : `div`;
			return `<${tag} style="white-space: pre-wrap; display: table; tab-size: 3">${
				output.join('<br />')
			}</${tag}>`;
		}
	}

	getReadmoreCodeBlock(str: string, cutoff?: number) {
		return Chat.getReadmoreBlock(str, true, cutoff);
	}

	getDataPokemonHTML(species: Species, gen = 8, tier = '') {
		let buf = '<li class="result">';
		buf += '<span class="col numcol">' + (tier || species.tier) + '</span> ';
		buf += `<span class="col iconcol"><psicon pokemon="${species.id}"/></span> `;
		buf += `<span class="col pokemonnamecol" style="white-space:nowrap"><a href="https://${Config.routes.dex}/pokemon/${species.id}" target="_blank">${species.name}</a></span> `;
		buf += '<span class="col typecol">';
		if (species.types) {
			for (const type of species.types) {
				buf += `<img src="https://${Config.routes.client}/sprites/types/${type}.png" alt="${type}" height="14" width="32">`;
			}
		}
		buf += '</span> ';
		if (gen >= 3) {
			buf += '<span style="float:left;min-height:26px">';
			if (species.abilities['1'] && (gen >= 4 || Dex.abilities.get(species.abilities['1']).gen === 3)) {
				buf += '<span class="col twoabilitycol">' + species.abilities['0'] + '<br />' + species.abilities['1'] + '</span>';
			} else {
				buf += '<span class="col abilitycol">' + species.abilities['0'] + '</span>';
			}
			if (species.abilities['H'] && species.abilities['S']) {
				buf += '<span class="col twoabilitycol' + (species.unreleasedHidden ? ' unreleasedhacol' : '') + '"><em>' + species.abilities['H'] + '<br />(' + species.abilities['S'] + ')</em></span>';
			} else if (species.abilities['H']) {
				buf += '<span class="col abilitycol' + (species.unreleasedHidden ? ' unreleasedhacol' : '') + '"><em>' + species.abilities['H'] + '</em></span>';
			} else if (species.abilities['S']) {
				// special case for Zygarde
				buf += '<span class="col abilitycol"><em>(' + species.abilities['S'] + ')</em></span>';
			} else {
				buf += '<span class="col abilitycol"></span>';
			}
			buf += '</span>';
		}
		buf += '<span style="float:left;min-height:26px">';
		buf += '<span class="col statcol"><em>HP</em><br />' + species.baseStats.hp + '</span> ';
		buf += '<span class="col statcol"><em>Atk</em><br />' + species.baseStats.atk + '</span> ';
		buf += '<span class="col statcol"><em>Def</em><br />' + species.baseStats.def + '</span> ';
		if (gen <= 1) {
			buf += '<span class="col statcol"><em>Spc</em><br />' + species.baseStats.spa + '</span> ';
		} else {
			buf += '<span class="col statcol"><em>SpA</em><br />' + species.baseStats.spa + '</span> ';
			buf += '<span class="col statcol"><em>SpD</em><br />' + species.baseStats.spd + '</span> ';
		}
		buf += '<span class="col statcol"><em>Spe</em><br />' + species.baseStats.spe + '</span> ';
		buf += '<span class="col bstcol"><em>BST<br />' + species.bst + '</em></span> ';
		buf += '</span>';
		buf += '</li>';
		return `<div class="message"><ul class="utilichart">${buf}<li style="clear:both"></li></ul></div>`;
	}
	getDataMoveHTML(move: Move) {
		let buf = `<ul class="utilichart"><li class="result">`;
		buf += `<span class="col movenamecol"><a href="https://${Config.routes.dex}/moves/${move.id}">${move.name}</a></span> `;
		// encoding is important for the ??? type icon
		const encodedMoveType = encodeURIComponent(move.type);
		buf += `<span class="col typecol"><img src="//${Config.routes.client}/sprites/types/${encodedMoveType}.png" alt="${move.type}" width="32" height="14">`;
		buf += `<img src="//${Config.routes.client}/sprites/categories/${move.category}.png" alt="${move.category}" width="32" height="14"></span> `;
		if (move.basePower) {
			buf += `<span class="col labelcol"><em>Power</em><br>${typeof move.basePower === 'number' ? move.basePower : '—'}</span> `;
		}
		buf += `<span class="col widelabelcol"><em>Accuracy</em><br>${typeof move.accuracy === 'number' ? (move.accuracy + '%') : '—'}</span> `;
		const basePP = move.pp || 1;
		const pp = Math.floor(move.noPPBoosts ? basePP : basePP * 8 / 5);
		buf += `<span class="col pplabelcol"><em>PP</em><br>${pp}</span> `;
		buf += `<span class="col movedesccol">${move.shortDesc || move.desc}</span> `;
		buf += `</li><li style="clear:both"></li></ul>`;
		return buf;
	}
	getDataAbilityHTML(ability: Ability) {
		let buf = `<ul class="utilichart"><li class="result">`;
		buf += `<span class="col namecol"><a href="https://${Config.routes.dex}/abilities/${ability.id}">${ability.name}</a></span> `;
		buf += `<span class="col abilitydesccol">${ability.shortDesc || ability.desc}</span> `;
		buf += `</li><li style="clear:both"></li></ul>`;
		return buf;
	}
	getDataItemHTML(item: Item) {
		let buf = `<ul class="utilichart"><li class="result">`;
		buf += `<span class="col itemiconcol"><psicon item="${item.id}"></span> <span class="col namecol"><a href="https://${Config.routes.dex}/items/${item.id}">${item.name}</a></span> `;
		buf += `<span class="col itemdesccol">${item.shortDesc || item.desc}</span> `;
		buf += `</li><li style="clear:both"></li></ul>`;
		return buf;
	}

	/**
	 * Gets the dimension of the image at url. Returns 0x0 if the image isn't found, as well as the relevant error.
	 */
	getImageDimensions(url: string): Promise<{height: number, width: number}> {
		return probe(url);
	}

	parseArguments(str: string, delim = ',', paramDelim = '=', useIDs = true) {
		const result: Record<string, string[]> = {};
		for (const part of str.split(delim)) {
			let [key, val] = Utils.splitFirst(part, paramDelim).map(f => f.trim());
			if (useIDs) key = toID(key);
			if (!toID(key) || !toID(val)) {
				throw new Chat.ErrorMessage(`Invalid option ${part}. Must be in [key]${paramDelim}[value] format.`);
			}
			if (!result[key]) result[key] = [];
			result[key].push(val);
		}
		return result;
	}

	/**
	 * Normalize a message for the purposes of applying chat filters.
	 *
	 * Not used by PS itself, but feel free to use it in your own chat filters.
	 */
	normalize(message: string) {
		message = message.replace(/'/g, '').replace(/[^A-Za-z0-9]+/g, ' ').trim();
		if (!/[A-Za-z][A-Za-z]/.test(message)) {
			message = message.replace(/ */g, '');
		} else if (!message.includes(' ')) {
			message = message.replace(/([A-Z])/g, ' $1').trim();
		}
		return ' ' + message.toLowerCase() + ' ';
	}

	/**
	 * Generates dimensions to fit an image at url into a maximum size of maxWidth x maxHeight,
	 * preserving aspect ratio.
	 *
	 * @return [width, height, resized]
	 */
	async fitImage(url: string, maxHeight = 300, maxWidth = 300): Promise<[number, number, boolean]> {
		const {height, width} = await Chat.getImageDimensions(url);

		if (width <= maxWidth && height <= maxHeight) return [width, height, false];

		const ratio = Math.min(maxHeight / height, maxWidth / width);

		return [Math.round(width * ratio), Math.round(height * ratio), true];
	}

	refreshPageFor(
		pageid: string,
		roomid: Room | RoomID,
		checkPrefix = false,
		ignoreUsers: ID[] | null = null
	) {
		const room = Rooms.get(roomid);
		if (!room) return false;
		for (const id in room.users) {
			if (ignoreUsers?.includes(id as ID)) continue;
			const u = room.users[id];
			for (const conn of u.connections) {
				if (conn.openPages) {
					for (const page of conn.openPages) {
						if ((checkPrefix ? page.startsWith(pageid) : page === pageid)) {
							void this.parse(`/j view-${page}`, room, u, conn);
						}
					}
				}
			}
		}
	}

	/**
	 * Notifies a targetUser that a user was blocked from reaching them due to a setting they have enabled.
	 */
	maybeNotifyBlocked(blocked: 'pm' | 'challenge' | 'invite', targetUser: User, user: User) {
		const prefix = `|pm|&|${targetUser.getIdentity()}|/nonotify `;
		const options = 'or change it in the <button name="openOptions" class="subtle">Options</button> menu in the upper right.';
		if (blocked === 'pm') {
			if (!targetUser.notified.blockPMs) {
				targetUser.send(`${prefix}The user '${Utils.escapeHTML(user.name)}' attempted to PM you but was blocked. To enable PMs, use /unblockpms ${options}`);
				targetUser.notified.blockPMs = true;
			}
		} else if (blocked === 'challenge') {
			if (!targetUser.notified.blockChallenges) {
				targetUser.send(`${prefix}The user '${Utils.escapeHTML(user.name)}' attempted to challenge you to a battle but was blocked. To enable challenges, use /unblockchallenges ${options}`);
				targetUser.notified.blockChallenges = true;
			}
		} else if (blocked === 'invite') {
			if (!targetUser.notified.blockInvites) {
				targetUser.send(`${prefix}The user '${Utils.escapeHTML(user.name)}' attempted to invite you to a room but was blocked. To enable invites, use /unblockinvites.`);
				targetUser.notified.blockInvites = true;
			}
		}
	}
	readonly formatText = formatText;
	readonly linkRegex = linkRegex;
	readonly stripFormatting = stripFormatting;

	readonly filterWords: {[k: string]: FilterWord[]} = {};
	readonly monitors: {[k: string]: Monitor} = {};

	registerMonitor(id: string, entry: Monitor) {
		if (!Chat.filterWords[id]) Chat.filterWords[id] = [];
		Chat.monitors[id] = entry;
	}

	resolvePage(pageid: string, user: User, connection: Connection) {
		return (new PageContext({pageid, user, connection, language: user.language!})).resolve();
	}
};

// backwards compatibility; don't actually use these
// they're just there so forks have time to slowly transition
(Chat as any).escapeHTML = Utils.escapeHTML;
(Chat as any).splitFirst = Utils.splitFirst;
(CommandContext.prototype as any).can = CommandContext.prototype.checkCan;
(CommandContext.prototype as any).canTalk = CommandContext.prototype.checkChat;
(CommandContext.prototype as any).canBroadcast = CommandContext.prototype.checkBroadcast;
(CommandContext.prototype as any).canHTML = CommandContext.prototype.checkHTML;
(CommandContext.prototype as any).canEmbedURI = CommandContext.prototype.checkEmbedURI;
(CommandContext.prototype as any).privatelyCan = CommandContext.prototype.privatelyCheckCan;
(CommandContext.prototype as any).requiresRoom = CommandContext.prototype.requireRoom;
(CommandContext.prototype as any).targetUserOrSelf = function (this: any, target: string, exactName: boolean) {
	const user = this.getUserOrSelf(target, exactName);
	this.targetUser = user;
	this.inputUsername = target;
	this.targetUsername = user?.name || target;
	return user;
};
(CommandContext.prototype as any).splitTarget = function (this: any, target: string, exactName: boolean) {
	const {targetUser, inputUsername, targetUsername, rest} = this.splitUser(target, exactName);
	this.targetUser = targetUser;
	this.inputUsername = inputUsername;
	this.targetUsername = targetUsername;
	return rest;
};

/**
 * Used by ChatMonitor.
 */
export interface FilterWord {
	regex: RegExp;
	word: string;
	hits: number;
	reason?: string;
	publicReason?: string;
	replacement?: string;
}

export type MonitorHandler = (
	this: CommandContext,
	line: FilterWord,
	room: Room | null,
	user: User,
	message: string,
	lcMessage: string,
	isStaff: boolean
) => string | false | undefined;
export interface Monitor {
	location: string;
	punishment: string;
	label: string;
	condition?: string;
	monitor?: MonitorHandler;
}

// explicitly check this so it doesn't happen in other child processes
if (!process.send) {
	Chat.database.spawn(Config.chatdbprocesses || 1);
	Chat.databaseReadyPromise = Chat.prepareDatabase();
	// we need to make sure it is explicitly JUST the child of the original parent db process
	// no other child processes
} else if (process.mainModule === module) {
	global.Monitor = {
		crashlog(error: Error, source = 'A chat child process', details: AnyObject | null = null) {
			const repr = JSON.stringify([error.name, error.message, source, details]);
			process.send!(`THROW\n@!!@${repr}\n${error.stack}`);
		},
	};
	process.on('uncaughtException', err => {
		Monitor.crashlog(err, 'A chat database process');
	});
	process.on('unhandledRejection', err => {
		Monitor.crashlog(err as Error, 'A chat database process');
	});
	global.Config = require('./config-loader').Config;
	// eslint-disable-next-line no-eval
	Repl.start('chat-db', cmd => eval(cmd));
}