Add fallback for gettext calls with woocommerce text domain to `wc-…

…calypso-bridge`

src/i18n-loader.js

@@ -2,10 +2,85 @@
  * External dependencies
  */
 import md5 from 'crypto-js/md5';
-import { setLocaleData } from '@wordpress/i18n';
+import {
+	setLocaleData,
+	hasTranslation,
+	__,
+	_n,
+	_nx,
+	_x,
+} from '@wordpress/i18n';
+import { addFilter, applyFilters } from '@wordpress/hooks';
 
 const defaultLocale = 'en_US';
 
+/**
+ * Some gettext calls in this package use the `woocommerce` text domain
+ * and expect that the translation data is already loaded from WooCommerce.
+ * If a translation is missing, these filters will attempt to transate the string
+ * using the `wc-calypso-bridge` text domain as a fallback.
+ */
+addFilter(
+	'i18n.gettext_woocommerce',
+	'wc-calypso-bridge',
+	( translation, text, domain ) => {
+		if (
+			text === translation &&
+			! hasTranslation( text, undefined, domain )
+		) {
+			// eslint-disable-next-line @wordpress/i18n-no-variables
+			return __( text, 'wc-calypso-bridge' );
+		}
+
+		return translation;
+	}
+);
+addFilter(
+	'i18n.ngettext_woocommerce',
+	'wc-calypso-bridge',
+	( translation, single, plural, number, domain ) => {
+		if (
+			( single === translation || plural === translation ) &&
+			! hasTranslation( single, undefined, domain )
+		) {
+			// eslint-disable-next-line @wordpress/i18n-no-variables
+			return _n( single, plural, number, 'wc-calypso-bridge' );
+		}
+
+		return translation;
+	}
+);
+addFilter(
+	'i18n.gettext_with_context_woocommerce',
+	'wc-calypso-bridge',
+	( translation, text, context, domain ) => {
+		if (
+			text === translation &&
+			! hasTranslation( text, context, domain )
+		) {
+			// eslint-disable-next-line @wordpress/i18n-no-variables
+			return _x( text, context, 'wc-calypso-bridge' );
+		}
+
+		return translation;
+	}
+);
+addFilter(
+	'i18n.ngettext_with_context_woocommerce',
+	'wc-calypso-bridge',
+	( translation, single, plural, number, context, domain ) => {
+		if (
+			( single === translation || plural === translation ) &&
+			! hasTranslation( single, context, domain )
+		) {
+			// eslint-disable-next-line @wordpress/i18n-no-variables
+			return _nx( single, plural, number, context, 'wc-calypso-bridge' );
+		}
+
+		return translation;
+	}
+);
+
 /**
  * Load lazy loaded modules translation data.
  *