Normalize Slidev subpage routing for standalone decks

setup/main.ts

@@ -1,3 +1,48 @@
 import { defineAppSetup } from "@slidev/types";
 
-export default defineAppSetup(() => {});
+export default defineAppSetup(({ router }) => {
+  if (typeof window === "undefined" || !router) return;
+
+  const routerOptions =
+    "options" in router
+      ? (router.options as
+          | {
+              history?: {
+                base?: string;
+              };
+            }
+          | undefined)
+      : undefined;
+  const base = routerOptions?.history?.base ?? "";
+  const normalizedBase = base.endsWith("/") ? base.slice(0, -1) : base;
+  const baseWithoutLeadingSlash = normalizedBase.replace(/^\//, "");
+
+  if (!normalizedBase) return;
+
+  const hasPathPrefix = (path: string, prefix: string) =>
+    path.startsWith(prefix) &&
+    (path.length === prefix.length || path[prefix.length] === "/");
+
+  const stripBase = (path: string) => {
+    if (hasPathPrefix(path, normalizedBase))
+      return path.slice(normalizedBase.length) || "/";
+    if (baseWithoutLeadingSlash && hasPathPrefix(path, baseWithoutLeadingSlash))
+      return path.slice(baseWithoutLeadingSlash.length) || "/";
+    return path;
+  };
+
+  type NavigationTarget = Parameters<typeof router.push>[0];
+  type NavigationMethod = (to: NavigationTarget) => ReturnType<typeof router.push>;
+
+  const wrapNavigationMethod = (navigate: NavigationMethod): NavigationMethod => {
+    return (to) => {
+      if (typeof to === "string") return navigate(stripBase(to));
+      if (to && typeof to === "object" && "path" in to && typeof to.path === "string")
+        return navigate({ ...to, path: stripBase(to.path) });
+      return navigate(to);
+    };
+  };
+
+  router.push = wrapNavigationMethod(router.push.bind(router) as NavigationMethod);
+  router.replace = wrapNavigationMethod(router.replace.bind(router) as NavigationMethod);
+});