feat: ease usage of a another matrix username

[pierreozoux]

relates to: #5

then I have a file like this:

src/helpers/ih.ts

/*àçéèêëîïñô*/
let latin_map = new Map<string, string>([
  ["à", "a"],
  ["ç", "c"],
  ["é", "e"],
  ["è", "e"],
  ["ë", "e"],
  ["ê", "e"],
  ["î", "i"],
  ["ï", "i"],
  ["ñ", "n"],
  ["ô", "o"],
]);

function latinise(s: string): string{
  return s.replace(/[^A-Za-z0-9\[\] ]/g,function(char){return latin_map.get(char)||char})
};

export function customConvertion(u: string): string{
  return latinise(u.replace(/é/,'_')).replace(/@toot|@bob|@rr|@toto/,'_').replace(/\.io|\.org|\.fr|\.com|\.net|@.*|[^\.a-z0-9_-]/g,'');
};

and then in users.ts, I do (liiibre is the name of my sso):

...
import { axios } from '../helpers/synapse'
import { customConvertion } from '../helpers/ih'

export type RcUser = {
  _id: string
  username: string
  name: string
  services: {
    liiibre: {
      preferred_username: string
    }
  }
  roles: string[]
  __rooms: string[]
}

export type MatrixUser = {
  user_id: string
  username: string
  displayname: string
  password: string
  admin: boolean
  nonce?: string
  mac?: string
  access_token?: string
}

export type AccessToken = {
  access_token: string
  device_id: string
  home_server: string
  user_id: string
}

export function mapUser(rcUser: RcUser): MatrixUser {
  if (!rcUser.services.liiibre.preferred_username) {
    log.debug(`${rcUser.name}  ${rcUser.username} ${rcUser.services.liiibre.preferred_username} has empty username`)
  }

  return {
    user_id: '',
    username: customConvertion(rcUser.services.liiibre.preferred_username),
    displayname: rcUser.name,
...

The rest, I don't know how to PR it, but the part of the PR can hopefully helps!
(Sorry, I'm no ts expert :/ )

[HerHde]

Have you considered using a library to latinise the strings? https://github.com/sindresorhus/slugify looks good for that purpose, it has the same results as latin_map, only é translates to e, but it also has custom replacements. May I ask for the reason behind the custom conversions?

[pierreozoux]

For my specific use case, I needed an implementation in js, ts and sql, so it was easier to implement it myself