[WordPress] Check whether the active locale is formal and whether a formal WooCommerce translation has been downloaded.

woocommerce-check-formal-locale.php

<?php
/**
 * Check whether formal language files exist for WooCommerce.
 *
 * - Admin locales are found in:
 *   - WP_LANG_DIR/woocommerce/woocommerce-admin-LOCALE.mo
 *   - WP_LANG_DIR/plugins/woocommerce-admin-LOCALE.mo
 *
 * - Front-end/global locales found in:
 *   - WP_LANG_DIR/woocommerce/woocommerce-LOCALE.mo
 *   - woocommerce/i18n/languages/woocommerce-LOCALE.mo (which if not found falls back to:)
 *   - WP_LANG_DIR/plugins/woocommerce-LOCALE.mo
 *
 * See: https://github.com/woothemes/woocommerce/blob/2.4.8/woocommerce.php#L306-L330
 *
 * @return bool Whether or not formal MO files are provided by WooCommerce for current locale
 */
function wc_maybe_formal_l10n_exists() {

	$locale = get_locale();

	// MO file names for admin and front-end.
	$wc_mo = array(
		'admin' => sprintf( 'woocommerce-admin-%s.mo', $locale ),
		'front' => sprintf( 'woocommerce-%s.mo', $locale ),
	);

	// Possible file paths for front-end/global.
	$wc_mo_paths  = array(
		file_exists( WP_LANG_DIR   . '/woocommerce/' . $wc_mo[ 'front' ] ),
		file_exists( WP_PLUGIN_DIR . 'woocommerce/i18n/languages/' . $wc_mo[ 'front' ] ),
		file_exists( WP_LANG_DIR   . '/plugins/' . $wc_mo[ 'front' ] ),
	);

	// Possible file paths for admin.
	$wc_admin_mo_paths  = array(
		file_exists( WP_LANG_DIR . '/woocommerce/' . $wc_mo[ 'admin' ] ),
		file_exists( WP_LANG_DIR . '/plugins/' . $wc_mo[ 'admin' ] ),
	);

	// Files must exist for admin AND front-end in order to return true here.
	return ( in_array( true, $wc_mo_paths ) && in_array( true, $wc_admin_mo_paths ) ) ? true : false;
}

// Visualize via admin notice.
add_action( 'admin_notices', function() {

	$wp_maybe_formal             = (bool) strpos( get_locale(), '_formal' );
	$wc_maybe_formal_l10n_exists = wc_maybe_formal_l10n_exists();

	if ( ! $wp_maybe_formal ) {
		printf( '<div class="notice notice-info"><p>WordPress’ current locale (%s) is not formal.</p></div>', get_locale() );
	} elseif ( $wc_maybe_formal_l10n_exists ) {
		printf( '<div class="notice notice-success"><p>A formal WooCommerce translation has been downloaded for this locale (%s).</p></div>', get_locale() );
	} else {
		printf( '<div class="notice notice-error"><p>No formal WooCommerce translation has been downloaded for this locale (%s).</p></div>', get_locale() );
	}
} );