chore: get locale domains working in dev

Caddyfile

···
+# French locale (default)
+http://fr.traefik.me {
+    reverse_proxy 127.0.0.1:4321 {
+        header_up Host fr.traefik.me
+        header_up X-Forwarded-Host fr.traefik.me
+        header_up X-Forwarded-Proto http
+    }
+}
+
+# English locale
+http://en.traefik.me {
+    reverse_proxy 127.0.0.1:4321 {
+        header_up Host en.traefik.me
+        header_up X-Forwarded-Host en.traefik.me
+        header_up X-Forwarded-Proto http
+    }
+}

astro.config.mjs

···
 
 // https://astro.build/config
 export default defineConfig({
-    site: "https://next.colinozanne.fr",
+    site: config.domains[config.defaultLocale],
     output: "server",
     adapter: deno(),
     integrations: [preact(), icon()],
···
             prefixDefaultLocale: false,
         },
         domains: config.domains,
+    },
+    vite: {
+        server: {
+            allowedHosts: Object.values(config.domains).map((host) =>
+                host.replace(/^https?:\/\//, ""),
+            ),
+        },
     },
 });

package.json

···
     "type": "module",
     "version": "0.0.1",
     "scripts": {
-        "dev": "astro dev",
+        "dev": "DENO_ENV=development astro dev",
         "build": "astro build",
         "preview": "deno run --allow-net --allow-read --allow-env ./dist/server/entry.mjs",
         "astro": "astro"

src/config.ts

···
+export const isDev = Deno.env.get("DENO_ENV") === "development";
+
 export const config = {
   defaultLocale: "fr",
   locales: ["fr", "en"],
-  domains: {
-    fr: "https://next.colinozanne.fr",
-    en: "https://next.colinozanne.co.uk",
-  },
+  domains: isDev
+    ? {
+      fr: "http://fr.traefik.me",
+      en: "http://en.traefik.me",
+    }
+    : {
+      fr: "https://next.colinozanne.fr",
+      en: "https://next.colinozanne.co.uk",
+    },
 } as const;

src/middleware.ts

···
+import { defineMiddleware } from "astro:middleware";
+import { config, isDev } from "./config.ts";
+
+export const onRequest = isDev && defineMiddleware((context, next) => {
+  const { url } = context;
+
+  // Get the locale from the domain
+  const host = context.request.headers.get("x-forwarded-host") ||
+    context.request.headers.get("host") ||
+    url.host;
+
+  // Find which locale this domain corresponds to
+  let domainLocale: string | undefined;
+  for (const [locale, domain] of Object.entries(config.domains)) {
+    const domainHost = new URL(domain as string).host;
+    if (host === domainHost) {
+      domainLocale = locale;
+      break;
+    }
+  }
+
+  // If we're on a domain-mapped locale and the path doesn't start with the locale prefix,
+  // internally rewrite to add the prefix
+  if (domainLocale && url.pathname === "/") {
+    // Rewrite / to /{locale}/
+    return context.rewrite(`/${domainLocale}/`);
+  }
+
+  // For other paths without locale prefix, also rewrite
+  if (
+    domainLocale && !url.pathname.startsWith(`/${domainLocale}/`) &&
+    !url.pathname.startsWith(`/${domainLocale}`)
+  ) {
+    // Check if the path starts with any other locale
+    const startsWithOtherLocale = config.locales.some(
+      (l: string) =>
+        l !== domainLocale &&
+        (url.pathname.startsWith(`/${l}/`) || url.pathname === `/${l}`),
+    );
+
+    if (!startsWithOtherLocale) {
+      return context.rewrite(`/${domainLocale}${url.pathname}`);
+    }
+  }
+
+  return next();
+});