fix(theme): Fix side menu being stuck open and obscuring most of the …

book.toml

@@ -23,7 +23,7 @@ site-url = "/patterns/"
 git-repository-url = "https://github.com/rust-unofficial/patterns"
 git-repository-icon = "fa-github"
 edit-url-template = "https://github.com/rust-unofficial/patterns/edit/main/{path}"
-additional-css = ["./language-picker.css"]
+additional-css = ["theme/css/language-picker.css"]
 
 [output.html.fold]
 enable = true
@@ -33,3 +33,8 @@ level = 1
 editable = false
 
 # [output.linkcheck]  # enable the "mdbook-linkcheck" renderer, disabled due to gh-actions
+
+[output.html.redirect]
+# Redirects in the form of "old-path" = "new-path", where the new path
+# is relative to the old path.
+"functional/lenses.html" = "optics.html"

language-picker.css → theme/css/language-picker.css

@@ -3,6 +3,11 @@
   right: 10px;
 }
 
+[dir="rtl"] #language-list {
+  left: 10px;
+  right: auto;
+}
+
 #language-list a {
   color: inherit;
 }

theme/head.hbs

@@ -0,0 +1,26 @@
+{{! Move to template code after fixing this issue:
+https://github.com/google/mdbook-i18n-helpers/issues/70 }}
+<script>
+    (function () {
+        // See these pages for details:
+        // https://developers.google.com/search/docs/crawling-indexing/consolidate-duplicate-urls
+        // https://developers.google.com/search/docs/crawling-indexing/javascript/javascript-seo-basics
+        let base = "https://rust-unofficial.github.io/patterns";
+        {{#if(eq language "en")}}
+        let canonical_href = `${base}/{{ path }}`;
+        {{else}}
+        let canonical_href = `${base}/{{ language }}/{{ path }}`;
+        {{/if}}
+
+                // mdbook gives us a string ending in ".md", we replace it with ".html":
+                canonical_href = canonical_href.slice(0, -"md".length) + "html";
+                if (canonical_href.endsWith("/index.html")) {
+                    canonical_href = canonical_href.slice(0, -"index.html".length);
+                }
+
+                let link = document.createElement("link");
+                link.rel = "canonical";
+                link.href = canonical_href;
+                document.head.appendChild(link);
+            }) ()
+</script>