feature: support serving from subpath (#33)

Co-authored-by: Karthik T <karthikt.holmes+github@gmail.com>

beszel/site/src/components/router.tsx

@@ -1,16 +1,36 @@
 import { createRouter } from "@nanostores/router"
 
-export const $router = createRouter(
-	{
-		home: "/",
-		server: "/system/:name",
-		settings: "/settings/:name?",
-		forgot_password: "/forgot-password",
-	},
-	{ links: false }
-)
+const routes = {
+	home: "/",
+	system: `/system/:name`,
+	settings: `/settings/:name?`,
+	forgot_password: `/forgot-password`,
+} as const
 
-/** Navigate to url using router */
+/**
+ * The base path of the application.
+ * This is used to prepend the base path to all routes.
+ */
+export const basePath = window.BASE_PATH || ""
+
+/**
+ * Prepends the base path to the given path.
+ * @param path The path to prepend the base path to.
+ * @returns The path with the base path prepended.
+ */
+export const prependBasePath = (path: string) => (basePath + path).replaceAll("//", "/")
+
+// prepend base path to routes
+for (const route in routes) {
+	// @ts-ignore need as const above to get nanostores to parse types properly
+	routes[route] = prependBasePath(routes[route])
+}
+
+export const $router = createRouter(routes, { links: false })
+
+/** Navigate to url using router
+ *  Base path is automatically prepended if serving from subpath
+ */
 export const navigate = (urlString: string) => {
 	$router.open(urlString)
 }