Add canonical tags

Author: embedding-shapes

website.nix

@@ -4,6 +4,14 @@ let
   h = niccup.lib;
   isLinux = pkgs.stdenv.isLinux;
 
+  defaultSiteUrl = "https://emsh.cat/niccup";
+  siteUrl =
+    let
+      raw = builtins.getEnv "NICCUP_SITE_URL";
+    in pkgs.lib.removeSuffix "/" (if raw != "" then raw else defaultSiteUrl);
+
+  canonicalUrl = path: "${siteUrl}${path}";
+
   # Discover and build examples
   exampleDirs = builtins.attrNames (
     pkgs.lib.filterAttrs (_: type: type == "directory") (builtins.readDir ./examples)
@@ -73,6 +81,7 @@ let
         [ "head"
           [ "meta" { charset = "utf-8"; } ]
           [ "title" "${name} - niccup example" ]
+          [ "link" { rel = "canonical"; href = canonicalUrl "/examples/${name}/"; } ]
           [ "style" (h.raw showcaseStyles) ]
         ]
         [ "body"
@@ -119,6 +128,7 @@ let
       [ "meta" { charset = "utf-8"; } ]
       [ "meta" { name = "viewport"; content = "width=device-width, initial-scale=1"; } ]
       [ "title" "niccup - Hiccup-style HTML generation for Nix" ]
+      [ "link" { rel = "canonical"; href = canonicalUrl "/"; } ]
       [ "style" (h.raw homeStyles) ]
     ]
     [ "body"