/**
 * The languages an article can be written in: an ISO 639-1 code with the
 * name of the language in its own script, as the editor's picker lists them.
 */
export const LANGUAGES: ReadonlyArray<{ code: string; name: string }> = [
  { code: 'en', name: 'English' },
  { code: 'fr', name: 'Français' },
  { code: 'de', name: 'Deutsch' },
  { code: 'es', name: 'Español' },
  { code: 'ca', name: 'Català' },
  { code: 'pt', name: 'Português' },
  { code: 'it', name: 'Italiano' },
  { code: 'nl', name: 'Nederlands' },
  { code: 'pl', name: 'Polski' },
  { code: 'ru', name: 'Русский' },
  { code: 'uk', name: 'Українська' },
  { code: 'tr', name: 'Türkçe' },
  { code: 'ar', name: 'العربية' },
  { code: 'fa', name: 'فارسی' },
  { code: 'hi', name: 'हिन्दी' },
  { code: 'zh', name: '中文' },
  { code: 'ja', name: '日本語' },
  { code: 'ko', name: '한국어' },
]

export const DEFAULT_LANGUAGE = 'en'

/** The language an article is written in; articles predating the field are English. */
export function articleLanguage(article: { language?: string }): string {
  return article.language?.trim().toLowerCase() || DEFAULT_LANGUAGE
}

/** Display name for a code — the code itself in upper case if it is unfamiliar. */
export function languageName(code: string): string {
  return LANGUAGES.find((l) => l.code === code)?.name ?? code.toUpperCase()
}

/** The first language no version of an article has been written in yet. */
export function nextFreeLanguage(taken: readonly string[]): string {
  const takenCodes = taken.map((c) => c.trim().toLowerCase())
  return LANGUAGES.find((l) => !takenCodes.includes(l.code))?.code ?? DEFAULT_LANGUAGE
}