Fix language redirection with a non-empty base URL

Author: Kobzol

src/main.rs

@@ -68,7 +68,13 @@ fn setup_handlebars() -> anyhow::Result<Handlebars<'static>> {
 }
 
 fn main() -> anyhow::Result<()> {
+    // It is possible to set a base URL for the web.
+    // This should set to the path under which the web is hosted.
+    // For example, if the web is hosted at https://foo.bar/rust-web/, then BASE_URL should be set
+    // to "/rust-web".
+    // This is mainly useful to host the website e.g. on GitHub pages without a custom CNAME.
     let base_url = std::env::var("BASE_URL").unwrap_or_else(|_| "".to_string());
+    assert!(base_url.is_empty() || base_url.starts_with("/"));
     let base_url = BaseUrl::new(&base_url);
 
     let rust_version = fetch_rust_version()?;

static/scripts/languages.js

@@ -12,13 +12,26 @@ function langChange() {
     } else {
         lang = `/${lang}`;
     }
+
+    // Base URL of the web, without a leading slash.
+    // For example "" or "/foo/bar".
+    let base_url = window.RUST_BASE_URL;
+
+    // If we have a path like /foo/bar/<lang>/<page>/<subpage>, we want to extract only
+    // /<page>/<subpage>
     let path = window.location.pathname;
+    // Remove /foo/bar
+    if (path.startsWith(base_url)) {
+        path = path.slice(base_url.length);
+    }
+    // Remove /<lang>
     if (current_lang != "en-US") {
-        path = `/${window.location.pathname.split('/').slice(2).join('/')}`;
+        path = path.slice(current_lang.length + 1); // +1 for leading /
     }
-    window.location = `${lang}${path}`;
+
+    // Now reconstruct back /foo/bar
+    window.location = `${base_url}${lang}${path}`;
 }
 
 nav_dropdown.onchange = langChange;
 footer_dropdown.onchange = langChange;
-// TODO: language redirect

templates/components/layout.html.hbs

@@ -52,6 +52,11 @@
         <link rel="alternate" href="https://www.rust-lang.org/" hreflang="x-default">
     {{/if}}
 
+    <script type="text/javascript">
+      {{!-- Pass the (untranslated) base URL path to languages.js --}}
+      window.RUST_BASE_URL = "{{baseurl_assets}}";
+    </script>
+
     <!-- Custom Highlight pack with: Rust, Markdown, TOML, Bash, JSON, YAML,
          and plaintext. -->
     <script src="{{baseurl_assets}}/static/scripts/highlight.pack.js" defer></script>