RocketChat/Rocket.Chat

import type { IUser } from '@rocket.chat/core-typings';
import { Users } from '@rocket.chat/models';
import limax from 'limax';

import { settings } from '../../../settings/server';

function slug(text: string): string {
    return limax(text, { replacement: '.' }).replace(/[^0-9a-z-_.]/g, '');
}

async function usernameIsAvailable(username: string): Promise<boolean> {
    if (username.length === 0) {
        return false;
    }

    if (username === 'all') {
        return false;
    }

    return !(await Users.findOneByUsernameIgnoringCase(username, {}));
}

const name = (username: string): string => (settings.get('UTF8_Names_Slugify') ? slug(username) : username);

export async function generateUsernameSuggestion(user: Pick<IUser, 'name' | 'emails' | 'services'>): Promise<string | undefined> {
    let usernames = [];

    if (user.name) {
        usernames.push(name(user.name));

        const nameParts = user.name.split(' ');

        if (nameParts.length > 1) {
            const [first] = nameParts;
            const last = nameParts[nameParts.length - 1];
            usernames.push(name(first[0] + last));
            usernames.push(name(first + last[0]));
        }
    }

    if (user?.name) {
        usernames.push(name(user.name));
    }

    if (Array.isArray(user.services)) {
        const services = [
            ...new Set(user.services.flatMap(({ name, username, firstName, lastName }) => [name, username, firstName, lastName])),
        ];
        usernames.push(...services.map(name));
    }

    if (user.emails && user.emails.length > 0) {
        for (const email of user.emails) {
            if (email.address && email.verified === true) {
                usernames.push(slug(email.address.replace(/@.+$/, '')));
                usernames.push(slug(email.address.replace(/(.+)@(\w+).+/, '$1.$2')));
            }
        }
    }

    usernames = usernames.filter((e) => e);

    for await (const item of usernames) {
        if (await usernameIsAvailable(item)) {
            return item;
        }
    }

    usernames.push(settings.get('Accounts_DefaultUsernamePrefixSuggestion'));

    let index = await Users.col.countDocuments({ username: new RegExp(`^${usernames[0]}-[0-9]+`) });
    const username = '';
    while (!username) {
        // eslint-disable-next-line no-await-in-loop
        if (await usernameIsAvailable(`${usernames[0]}-${index}`)) {
            return `${usernames[0]}-${index}`;
        }
        index++;
    }
}