https://t.me/Loskirs/1140

generateLocaleTypings.js

const yaml = require('js-yaml')
const fs = require('fs')
const path = require('path')

function* getDotPaths(data) {
  function* iter(obj, parentPaths) {
    for (const [k, v] of Object.entries(obj)) {
      const p = [...parentPaths, k]
      if (typeof v === 'object' && v !== null) {
        yield* iter(v, p)
      } else {
        yield p.join('.')
      }
    }
  }
  yield* iter(data, [])
}

const data = yaml.load(fs.readFileSync('./locales/ru.yaml'))

const s = [...getDotPaths(data)]

let content = ''
content += `export declare function t(resourceKey: ${s.map((v) => `'${v}'`).join('|')}, templateData?: Record<string, any>): string\n`

// ↓ function overloading

// for (const v of s) {
//   content += `export declare function t(resourceKey: '${v}', templateData?: Record<string, any>): string\n`
// }
// content += `export declare function t(resourceKey: string, templateData?: Record<string, any>): string\n`

const dir = './types/_generated'
if (!fs.existsSync(dir)) {
  fs.mkdirSync(dir)
}
fs.writeFileSync(path.join(dir, 'locales.d.ts'), content)

index.d.ts

import { t } from './_generated/locales'
import { TelegrafContext } from 'telegraf/typings/context'

declare class I18nContext {
  locale(languageCode: string): void
  getTemplate(languageCode: string, resourceKey: string): object
  t: typeof t
}

declare module 'telegraf' {
  export class Context extends TelegrafContext {
    i18n: I18nContext
  }
}

export interface CustomI18n {
  t (languageCode?: string, resourceKey?: Parameters<typeof t>[0], templateData?: object): string;
  t (resourceKey?: Parameters<typeof t>[0], templateData?: object): string;
}