feat: add add-missing command to translations cli

common/translations-cli/addMissing.js

@@ -0,0 +1,43 @@
+//@ts-check
+const { getDefaultTranslations, getLanguageTranslations } = require('./helpers');
+
+/**
+ * @param {string} language
+ */
+function getMissingTranslations(language) {
+  const source = getDefaultTranslations();
+  /** @type {Record<string, string>} */
+  let target;
+
+  try {
+    target = getLanguageTranslations(language);
+  } catch {
+    console.log(`Language ${language} not found, creating a new one`);
+    target = {};
+  }
+
+  let added = 0;
+  let removed = 0;
+
+  for (const key in source) {
+    if (!target[key]) {
+      target[key] = `*** ${source[key]}`;
+      added++;
+    }
+  }
+
+  for (const key in target) {
+    if (!source[key]) {
+      delete target[key];
+      removed++;
+    }
+  }
+
+  const newLength = Object.keys(target).length;
+
+  return { result: target, stats: { added, removed, newLength } };
+}
+
+module.exports = {
+  getMissingTranslations,
+};