feat: add sitemap.xml

closes #359
closes #438

src/app/sitemap.ts

@@ -0,0 +1,37 @@
+import { MetadataRoute } from "next";
+
+import { getAbsoluteUrl, getItems, getQuadrants } from "@/lib/data";
+
+export default function sitemap(): MetadataRoute.Sitemap {
+  const quadrants = getQuadrants().map((quadrant) => ({
+    url: getAbsoluteUrl(`/${quadrant.id}/`),
+    lastModified: new Date(),
+    priority: 0.8,
+  }));
+
+  const items = getItems().map((item) => ({
+    url: getAbsoluteUrl(`/${item.quadrant}/${item.id}/`),
+    lastModified: new Date(),
+    priority: 0.5,
+  }));
+
+  return [
+    {
+      url: getAbsoluteUrl(),
+      lastModified: new Date(),
+      priority: 1,
+    },
+    {
+      url: getAbsoluteUrl("/overview/"),
+      lastModified: new Date(),
+      priority: 0.9,
+    },
+    {
+      url: getAbsoluteUrl("/help-and-about-tech-radar/"),
+      lastModified: new Date(),
+      priority: 0.9,
+    },
+    ...quadrants,
+    ...items,
+  ];
+}

src/lib/data.ts

@@ -80,6 +80,10 @@ export function getImprintUrl() {
   return config.imprint;
 }
 
+export function getAbsoluteUrl(path: string = "/") {
+  return `${config.baseUrl}${path}`;
+}
+
 export function getItem(id: string): Item | undefined {
   return data.items.find((item) => item.id === id) as Item;
 }