Setup redirection for certain posts to new undefined behaviors blog

next.config.mjs

@@ -5,34 +5,61 @@
  */
 !process.env.SKIP_ENV_VALIDATION && (await import("./src/env/server.mjs"));
 
+/**
+ *
+ * @param {string} text The string to search around with the pattern in.
+ * @param {string} pattern The strict, text only pattern to search for.
+ * @param {number} nth The index of the pattern to find.
+ * @returns
+ */
+function nthIndex(text, pattern, nth) {
+  const L = text.length;
+  let i = -1;
+  while (nth-- && i++ < L) {
+    i = text.indexOf(pattern, i);
+    if (i < 0) break;
+  }
+  return i;
+}
 
 const v2_redirects = [
-    '/2020/12/04/jekyll-github-pages-and-azabani',
-    '/2021/02/25/project-facelift-new-and-old',
-    '/2022/03/29/runnerspace-built-in-under-30-hours',
-    '/2022/07/16/restricted-memory-and-data-framing-tricks',
-    '/drafts/presenting-to-humans',
-    '/photography'
-].map(url => {
+  "/2020/12/04/jekyll-github-pages-and-azabani",
+  "/2021/02/25/project-facelift-new-and-old",
+  "/2022/03/29/runnerspace-built-in-under-30-hours",
+  "/2022/07/16/restricted-memory-and-data-framing-tricks",
+  "/drafts/presenting-to-humans",
+  "/photography",
+].map((url) => {
+  if (url.startsWith("/2"))
     return {
-        source: url, destination: `https://v2.xevion.dev${url}`, permanent: false
-    }
-})
+      source: url,
+      destination: `https://undefined.behavio.rs/posts${url.slice(
+        nthIndex(url, "/", 4)
+      )}`,
+      permanent: false,
+    };
+
+  return {
+    source: url,
+    destination: `https://v2.xevion.dev${url}`,
+    permanent: false,
+  };
+});
 
 /** @type {import("next").NextConfig} */
 const config = {
-    reactStrictMode: true,
-    swcMinify: true,
-    i18n: {
-        locales: ["en"],
-        defaultLocale: "en",
-    },
-    async redirects() {
-        // Source cannot end with / slash
-        return [
-            {source: '/resume', destination: '/resume.pdf', permanent: false},
-            ...v2_redirects
-        ]
-    }
+  reactStrictMode: true,
+  swcMinify: true,
+  i18n: {
+    locales: ["en"],
+    defaultLocale: "en",
+  },
+  async redirects() {
+    // Source cannot end with / slash
+    return [
+      { source: "/resume", destination: "/resume.pdf", permanent: false },
+      ...v2_redirects,
+    ];
+  },
 };
 export default config;