Convert i18n package to TypeScript

.eslintrc

@@ -319,13 +319,29 @@
         ]
       },
       "rules": {
-        "no-duplicate-imports": "off",
         "@typescript-eslint/no-duplicate-imports": "error",
+        "@typescript-eslint/no-shadow": "error",
+        "jsdoc/check-param-names": "off",
+        "jsdoc/require-param": "off",
         "jsdoc/require-param-type": "off",
+        "jsdoc/require-returns": "off",
+        "jsdoc/require-returns-check": "off",
         "jsdoc/require-returns-type": "off",
+        "jsdoc/no-types": "error",
+        "no-duplicate-imports": "off",
         "no-unused-vars": "off",
         "no-shadow": "off",
-        "@typescript-eslint/no-shadow": "error"
+        "no-restricted-imports": [
+          "error",
+          {
+            "paths": [
+              {
+                "name": "prop-types",
+                "message": "Use TypeScript instead."
+              }
+            ]
+          }
+        ]
       }
     },
     {

packages/i18n/package.json

@@ -28,12 +28,13 @@
   },
   "customExports": {
     ".": {
-      "default": "./src/index.js"
+      "default": "./src/index.ts"
     }
   },
   "main": "dist/index.js",
   "module": "dist-module/index.js",
-  "source": "src/index.js",
+  "types": "dist-types/index.d.ts",
+  "source": "src/index.ts",
   "publishConfig": {
     "access": "public"
   },

packages/i18n/src/i18n.ts

@@ -0,0 +1,118 @@
+/*
+ * Copyright 2021 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * External dependencies
+ */
+import Tannin from 'tannin';
+import type { TanninLocaleDomain } from 'tannin';
+
+interface LocaleData {
+  locale_data: {
+    [key: string]: TanninLocaleDomain;
+  };
+}
+
+const TEXT_DOMAIN = 'web-stories';
+
+const tannin = new Tannin({
+  [TEXT_DOMAIN]: {
+    '': {
+      plural_forms(n: number) {
+        return n === 1 ? 0 : 1;
+      },
+    },
+  },
+});
+
+/**
+ * Merge locale data into the Tannin instance.
+ *
+ * @param data Locale data.
+ */
+export function setLocaleData(data: LocaleData) {
+  const translations =
+    data.locale_data['web-stories'] || data.locale_data.messages;
+
+  tannin.data[TEXT_DOMAIN] = {
+    ...tannin.data[TEXT_DOMAIN],
+    ...translations,
+    '': {
+      ...tannin.data[TEXT_DOMAIN][''],
+    },
+  };
+}
+
+/**
+ * Retrieve the translation of the given text.
+ *
+ * @param text Text to translate.
+ * @param [domain] Text domain. Unique identifier for retrieving translated strings.
+ * @return Translated text.
+ */
+export function __(text: string, domain = TEXT_DOMAIN) {
+  return tannin.dcnpgettext(domain, undefined, text);
+}
+
+/**
+ * Retrieve the translation of the given text with gettext context..
+ *
+ * @param text Text to translate.
+ * @param context Context information for the translators.
+ * @param [domain] Text domain. Unique identifier for retrieving translated strings.
+ * @return Translated text.
+ */
+export function _x(text: string, context: string, domain = TEXT_DOMAIN) {
+  return tannin.dcnpgettext(domain, context, text);
+}
+
+/**
+ * Retrieve the translation of the given text with gettext context..
+ *
+ * @param singular The text to be used if the number is singular.
+ * @param plural The text to be used if the number is plural.
+ * @param number The number to compare against to use either the singular or plural form.
+ * @param [domain] Text domain. Unique identifier for retrieving translated strings.
+ * @return Translated text.
+ */
+export function _n(
+  singular: string,
+  plural: string,
+  number: number,
+  domain = TEXT_DOMAIN
+) {
+  return tannin.dcnpgettext(domain, undefined, singular, plural, number);
+}
+
+/**
+ * Retrieve the translation of the given text with gettext context..
+ *
+ * @param singular The text to be used if the number is singular.
+ * @param plural The text to be used if the number is plural.
+ * @param number The number to compare against to use either the singular or plural form.
+ * @param context Context information for the translators.
+ * @param [domain] Text domain. Unique identifier for retrieving translated strings.
+ * @return Translated text.
+ */
+export function _nx(
+  singular: string,
+  plural: string,
+  number: number,
+  context: string,
+  domain = TEXT_DOMAIN
+) {
+  return tannin.dcnpgettext(domain, context, singular, plural, number);
+}

packages/i18n/src/translateToExclusiveList.js → packages/i18n/src/translateToExclusiveList.ts

@@ -24,10 +24,10 @@ import { __ } from './i18n';
  * Join all options in a list and translate. These will be joined with
  * the conjunction `or`.
  *
- * @param {Array.<string>} options The options that will be joined with the `or` conjunction.
- * @return {string} Localized list items.
+ * @param options The options that will be joined with the `or` conjunction.
+ * @return Localized list items.
  */
-function translateToExclusiveList(options) {
+function translateToExclusiveList(options: string[]) {
   switch (options.length) {
     case 0:
       return '';

packages/i18n/src/translateToInclusiveList.js → packages/i18n/src/translateToInclusiveList.ts

@@ -24,10 +24,10 @@ import { __ } from './i18n';
  * Join all options in a list and translate. These will be joined with
  * the conjunction `and`.
  *
- * @param {Array.<string>} options The options that will be joined with the `and` conjunction.
- * @return {string} Localized list items.
+ * @param options The options that will be joined with the `and` conjunction.
+ * @return Localized list items.
  */
-function translateToInclusiveList(options) {
+function translateToInclusiveList(options: string[]) {
   switch (options.length) {
     case 0:
       return '';