Function InitializeLanguagePacks

src/strings.cpp:2249–2291

* Make a list of the available language packs. Put the data in * #_languages list. */

 * #_languages list.
 */
void InitializeLanguagePacks()
{
	for (Searchpath sp : _valid_searchpaths) {
		FillLanguageList(FioGetDirectory(sp, LANG_DIR));
	}
	if (_languages.empty()) UserError("No available language packs (invalid versions?)");

	/* Acquire the locale of the current system */
	auto str_lang = GetCurrentLocale("LC_MESSAGES");
	std::string_view lang = str_lang.has_value() ? std::string_view{*str_lang} : "en_GB";

	const LanguageMetadata *chosen_language   = nullptr; ///< Matching the language in the configuration file or the current locale
	const LanguageMetadata *language_fallback = nullptr; ///< Using pt_PT for pt_BR locale when pt_BR is not available
	const LanguageMetadata *en_GB_fallback    = _languages.data(); ///< Fallback when no locale-matching language has been found

	/* Find a proper language. */
	for (const LanguageMetadata &lng : _languages) {
		/* We are trying to find a default language. The priority is by
		 * configuration file, local environment and last, if nothing found,
		 * English. */
		if (_config_language_file == FS2OTTD(lng.file.filename().native())) {
			chosen_language = &lng;
			break;
		}

		std::string_view iso_code = lng.isocode;
		if (iso_code == "en_GB") en_GB_fallback = &lng;

		/* Only auto-pick finished translations */
		if (!lng.IsReasonablyFinished()) continue;

		if (iso_code.starts_with(lang.substr(0, 5))) chosen_language = &lng;
		if (iso_code.starts_with(lang.substr(0, 2))) language_fallback = &lng;
	}

	/* We haven't found the language in the config nor the one in the locale.
	 * Now we set it to one of the fallback languages */
	if (chosen_language == nullptr) {
		chosen_language = (language_fallback != nullptr) ? language_fallback : en_GB_fallback;
	}

	if (!ReadLanguagePack(chosen_language)) UserError("Can't read language pack '{}'", FS2OTTD(chosen_language->file.native()));
}

/**
 * Get the ISO language code of the currently loaded language.