out-of-your-element/d2m/converters/user-to-mxid.js

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// @ts-check
const assert = require("assert")
const passthrough = require("../../passthrough")
const { sync, db } = passthrough
/**
* Downcased and stripped username. Can only include a basic set of characters.
* https://spec.matrix.org/v1.6/appendices/#user-identifiers
* @param {import("discord-api-types/v10").APIUser} user
* @returns {string} localpart
*/
function downcaseUsername(user) {
// First, try to convert the username to the set of allowed characters
let downcased = user.username.toLowerCase()
// spaces to underscores...
.replace(/ /g, "_")
// remove disallowed characters...
.replace(/[^a-z0-9._=/-]*/g, "")
// remove leading and trailing dashes and underscores...
.replace(/(?:^[_-]*|[_-]*$)/g, "")
// The new length must be at least 2 characters (in other words, it should have some content)
if (downcased.length < 2) {
downcased = user.id
}
return downcased
}
/** @param {string[]} preferences */
function* generateLocalpartAlternatives(preferences) {
const best = preferences[0]
assert.ok(best)
// First, suggest the preferences...
for (const localpart of preferences) {
yield localpart
}
// ...then fall back to generating number suffixes...
let i = 2
while (true) {
yield best + (i++)
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/* c8 ignore next */
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}
}
/**
* Whole process for checking the database and generating the right sim name.
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* It is very important this is not an async function: once the name has been chosen, the calling function should be able to immediately claim that name into the database in the same event loop tick.
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* @param {import("discord-api-types/v10").APIUser} user
* @returns {string}
*/
function userToSimName(user) {
assert.notEqual(user.discriminator, "0000", "cannot create user for a webhook")
// 1. Is sim user already registered?
const existing = db.prepare("SELECT sim_name FROM sim WHERE discord_id = ?").pluck().get(user.id)
if (existing) return existing
// 2. Register based on username (could be new or old format)
const downcased = downcaseUsername(user)
const preferences = [downcased]
if (user.discriminator.length === 4) { // Old style tag? If user.username is unavailable, try the full tag next
preferences.push(downcased + user.discriminator)
}
// Check for conflicts with already registered sims
/** @type {string[]} */
const matches = db.prepare("SELECT sim_name FROM sim WHERE sim_name LIKE ? ESCAPE '@'").pluck().all(downcased + "%")
// Keep generating until we get a suggestion that doesn't conflict
for (const suggestion of generateLocalpartAlternatives(preferences)) {
if (!matches.includes(suggestion)) return suggestion
}
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/* c8 ignore next */
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throw new Error(`Ran out of suggestions when generating sim name. downcased: "${downcased}"`)
}
module.exports.userToSimName = userToSimName