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TypeScript

import type { MetadataRoute } from 'next';
import type { SitemapEntry } from '#web-runtime/types';
import type { PublicPathResolver } from './page-metadata';
/**
* Turns the backend's page listing into sitemap entries.
*
* Pages that share a `groupKey` are the same page in different languages, so each entry links
* to its siblings through `alternates.languages` — the sitemap equivalent of the `hreflang`
* tags on the page itself, and the form Google prefers for multilingual sites.
*
* Kept free of `next/headers` and routing setup so it can be tested directly: the caller
* supplies the path resolver and the absolute origin.
*/
export function buildSitemap(
entries: SitemapEntry[],
origin: URL,
publicPath: PublicPathResolver
): MetadataRoute.Sitemap {
const absolute = (locale: string, path: string) => new URL(publicPath(locale, path), origin).href;
const byGroupKey = new Map<string, SitemapEntry[]>();
for (const entry of entries) {
if (!entry.groupKey) continue;
const group = byGroupKey.get(entry.groupKey);
if (group) group.push(entry);
else byGroupKey.set(entry.groupKey, [entry]);
}
return entries.map((entry) => {
const siblings = byGroupKey.get(entry.groupKey) ?? [];
const lastModified = entry.updatedAt ?? entry.publishedAt;
const item: MetadataRoute.Sitemap[number] = {
url: absolute(entry.locale, entry.path)
};
if (lastModified) {
item.lastModified = new Date(lastModified);
}
// A single-locale group has nothing to point at but itself; omit the noise.
if (siblings.length > 1) {
item.alternates = {
languages: Object.fromEntries(
siblings.map((sibling) => [sibling.locale, absolute(sibling.locale, sibling.path)])
)
};
}
return item;
});
}