Fix alias mapping in Express

backend/langs.js

@@ -9,6 +9,9 @@ import { log } from "./util.js";
 // populated at runtime and updated asynchronously.
 export let langs = {};
 
+// Map from language aliases and IDs to canonical language IDs.
+export let aliases = {};
+
 // Read languages from JSON files in /opt/riju/langs, and update the
 // global langs variable in this module. Never throw an error. If
 // there is a problem then just leave the languages as they previously
@@ -16,6 +19,7 @@ export let langs = {};
 async function readLangsFromDisk() {
   try {
     const newLangs = {};
+    const newAliases = {};
     for (const filename of await fs.readdir("/opt/riju/langs")) {
       if (path.parse(filename).ext !== ".json") {
         continue;
@@ -31,6 +35,10 @@ async function readLangsFromDisk() {
         continue;
       }
       newLangs[id] = langConfig;
+      newAliases[id] = id;
+      for (const alias of langConfig.aliases || []) {
+        newAliases[alias] = id;
+      }
     }
     log.info(
       `Loaded ${
@@ -38,6 +46,7 @@ async function readLangsFromDisk() {
       } language configuration(s) from disk`
     );
     langs = newLangs;
+    aliases = newAliases;
   } catch (err) {
     log.error("Failed to read languages from disk:", err);
   }

backend/server.js

@@ -7,7 +7,7 @@ import ws from "express-ws";
 import _ from "lodash";
 
 import * as api from "./api.js";
-import { langs } from "./langs.js";
+import { aliases, langs } from "./langs.js";
 import { log } from "./util.js";
 
 const host = process.env.HOST || "localhost";
@@ -28,10 +28,7 @@ app.get("/", (_, res) => {
       analyticsEnabled,
     });
   } else {
-    res.send(
-      503,
-      "Still loading languages, or encountered error while doing so\n"
-    );
+    res.send(503, "Encountered unexpected error while loading languages\n");
   }
 });
 for (const [lang, { aliases }] of Object.entries(langs)) {
@@ -48,14 +45,19 @@ app.get("/:lang", (req, res) => {
   const lowered = lang.toLowerCase();
   if (lowered !== lang) {
     res.redirect(301, `/${lowered}`);
-  } else if (langs[lang]) {
-    res.render(path.resolve("frontend/pages/app"), {
-      config: { id: lang, ...langs[lang] },
-      analyticsEnabled,
-    });
-  } else {
-    res.send(404, `No such language: ${lang}\n`);
+    return;
   }
+  const canonical = aliases[lang];
+  if (!canonical) {
+    res.send(404, `No such language: ${lang}\n`);
+  } else if (canonical !== lang) {
+    res.redirect(301, `/${canonical}`);
+    return;
+  }
+  res.render(path.resolve("frontend/pages/app"), {
+    config: langs[lang],
+    analyticsEnabled,
+  });
 });
 app.use("/css", express.static("frontend/styles"));
 app.use("/js", express.static("frontend/out"));