vanadium: use parameterized google search engine

nix/configurations/vanadium/home/firefox.nix

@@ -1,20 +1,44 @@
 {
   pkgs,
   config,
+  lib,
   ...
 }: let
   inherit (pkgs) nur;
+
+  # reference: https://developers.google.com/custom-search/docs/xml_results?hl=zh-tw#advanced-search-query-parameters
+  mkLrFlag = languageRestrictions:
+    "&lr=" + lib.escapeURL (builtins.concatStringsSep "|" languageRestrictions);
+
+  mkGlFlag = preferredCountry:
+    "&gl=" + preferredCountry;
+
+  mkHlFlag = hostLanguage:
+    "&hl=" + hostLanguage;
 in {
   programs.firefox = {
     enable = true;
 
     policies.SearchEngines = {
-      Default = "searxng";
+      Default = "Google Customized";
       Add = [
+        /*
+        searxng doesn't
+        - have good multilingual search support
+        - use google backend on my server for some reason
+        */
         {
           Name = "searxng";
           URLTemplate = "https://sxng.confusedcompiler.org/search?q={searchTerms}";
         }
+        {
+          Name = "Google Customized";
+          URLTemplate =
+            "https://google.com/search?q={searchTerms}"
+            + mkLrFlag ["lang_fr" "lang_en" "lang_zh-TW"]
+            + mkGlFlag "fr"
+            + mkHlFlag "fr";
+        }
       ];
     };