From dae1d6057e61dc5bf5d9d96bf4422e210f0a9acb Mon Sep 17 00:00:00 2001
From: tot92 <tobi-theis@gmx.de>
Date: Sat, 9 Nov 2019 22:07:06 +0100
Subject: [PATCH] fixed i18n language fallback behaviour

---
 .../node_modules/@node-red/util/lib/i18n.js   | 59 +++++++++++++------
 1 file changed, 41 insertions(+), 18 deletions(-)

diff --git a/packages/node_modules/@node-red/util/lib/i18n.js b/packages/node_modules/@node-red/util/lib/i18n.js
index 738212b82..51b488129 100644
--- a/packages/node_modules/@node-red/util/lib/i18n.js
+++ b/packages/node_modules/@node-red/util/lib/i18n.js
@@ -81,35 +81,58 @@ function mergeCatalog(fallback,catalog) {
     }
 }
 
-var MessageFileLoader = {
-    type: "backend",
-    init: function(services, backendOptions, i18nextOptions) {},
-    read: function(lng, ns, callback) {
-        if (resourceMap[ns]) {
-            var file = path.join(resourceMap[ns].basedir,lng,resourceMap[ns].file);
-            //console.log(file);
-            fs.readFile(file,"utf8",function(err,content) {
+
+function readFile(lng, ns) {
+    return new Promise((resolve, reject) => {
+        if (resourceCache[ns] && resourceCache[ns][lng]) {
+            resolve(resourceCache[ns][lng]);
+        } else if (resourceMap[ns]) {
+            var file = path.join(resourceMap[ns].basedir, lng, resourceMap[ns].file);
+            fs.readFile(file, "utf8", function (err, content) {
                 if (err) {
-                    callback(err);
+                    reject(err);
                 } else {
                     try {
-                        resourceCache[ns] = resourceCache[ns]||{};
+                        resourceCache[ns] = resourceCache[ns] || {};
                         resourceCache[ns][lng] = JSON.parse(content.replace(/^\uFEFF/, ''));
-                        //console.log(resourceCache[ns][lng]);
-                        if (lng !== defaultLang) {
-                            mergeCatalog(resourceCache[ns][defaultLang],resourceCache[ns][lng]);
+                        var baseLng = lng.split('-')[0];
+                        if (baseLng !== lng && resourceCache[ns][baseLng]) {
+                            mergeCatalog(resourceCache[ns][baseLng], resourceCache[ns][lng]);
                         }
-                        callback(null, resourceCache[ns][lng]);
-                    } catch(e) {
-                        callback(e);
+                        if (lng !== defaultLang) {
+                            mergeCatalog(resourceCache[ns][defaultLang], resourceCache[ns][lng]);
+                        }
+                        resolve(resourceCache[ns][lng]);
+                    } catch (e) {
+                        reject(e);
                     }
                 }
             });
         } else {
-            callback(new Error("Unrecognised namespace"));
+            reject(new Error("Unrecognised namespace"));
         }
-    }
+    });
+}
 
+var MessageFileLoader = {
+    type: "backend",
+    init: function (services, backendOptions, i18nextOptions) { },
+    read: function (lng, ns, callback) {
+        // there are two languages to consider:
+        // 1) the actual language lng (e. g. 'en-US' or 'de-DE', 'fr-FR',...)
+        // 2) the base language (e. g. 'en', 'de', 'fr',...)
+        var baseLng = lng.split('-')[0];
+        // read base language (e. g. 'de'), then actual language (e. g. 'de-DE') 
+        readFile(baseLng, ns).then(
+            baseData => {
+                // scenario 2: reading base language was successful -> read actual language -> if this fails, return base language data
+                readFile(lng, ns).then(data => callback(null, data), () => callback(null, baseData))
+            },
+            () => {
+                // scenario 2: reading base language failed -> read actual language -> if this fails too, return error
+                readFile(lng, ns).then(data => callback(null, data), err => callback(err))
+            });
+    }
 }
 
 function getCurrentLocale() {