Current state with latest updates

app/Services/Sitemaps/SitemapIndexService.php

@@ -4,6 +4,9 @@ declare(strict_types=1);
 
 namespace App\Services\Sitemaps;
 
+use DateTimeImmutable;
+use DateTimeInterface;
+
 final class SitemapIndexService
 {
     public function __construct(
@@ -18,8 +21,25 @@ final class SitemapIndexService
     public function items(?array $families = null): array
     {
         $items = [];
+        $selectedFamilies = $families ?? (array) config('sitemaps.enabled', []);
+        $groupedFamilies = [];
+
+        foreach ($this->activeGroupIndexes($selectedFamilies) as $groupName => $groupFamilies) {
+            $items[] = new SitemapIndexItem(
+                url('/sitemaps/' . $groupName . '.xml'),
+                $this->lastModifiedForFamilies($groupFamilies),
+            );
+
+            foreach ($groupFamilies as $family) {
+                $groupedFamilies[$family] = true;
+            }
+        }
+
+        foreach ($selectedFamilies as $name) {
+            if (isset($groupedFamilies[(string) $name])) {
+                continue;
+            }
 
-        foreach ($families ?? (array) config('sitemaps.enabled', []) as $name) {
             $builder = $this->registry->get((string) $name);
 
             if ($builder === null) {
@@ -35,6 +55,30 @@ final class SitemapIndexService
         return $items;
     }
 
+    /**
+     * @param  list<string>  $families
+     * @return list<SitemapIndexItem>
+     */
+    public function itemsForFamilies(array $families): array
+    {
+        $items = [];
+
+        foreach ($families as $family) {
+            $builder = $this->registry->get($family);
+
+            if ($builder === null) {
+                continue;
+            }
+
+            $items[] = new SitemapIndexItem(
+                url('/sitemaps/' . $this->shards->rootEntryName($builder) . '.xml'),
+                $builder->lastModified(),
+            );
+        }
+
+        return $items;
+    }
+
     /**
      * @return list<SitemapIndexItem>
      */
@@ -58,4 +102,69 @@ final class SitemapIndexService
             $builder->lastModified(),
         )];
     }
-}
+
+    /**
+     * @param  list<string>  $selectedFamilies
+     * @return array<string, list<string>>
+     */
+    public function activeGroupIndexes(array $selectedFamilies): array
+    {
+        $selectedLookup = array_fill_keys($selectedFamilies, true);
+        $groups = [];
+
+        foreach ((array) config('sitemaps.group_indexes', []) as $groupName => $groupFamilies) {
+            if (! is_string($groupName) || $groupName === '') {
+                continue;
+            }
+
+            $validFamilies = array_values(array_filter(
+                (array) $groupFamilies,
+                fn (mixed $family): bool => is_string($family) && $family !== '' && $this->registry->get($family) !== null,
+            ));
+
+            if ($validFamilies === []) {
+                continue;
+            }
+
+            foreach ($validFamilies as $family) {
+                if (! isset($selectedLookup[$family])) {
+                    continue 2;
+                }
+            }
+
+            $groups[$groupName] = $validFamilies;
+        }
+
+        return $groups;
+    }
+
+    /**
+     * @param  list<string>  $families
+     */
+    private function lastModifiedForFamilies(array $families): ?DateTimeInterface
+    {
+        $latest = null;
+
+        foreach ($families as $family) {
+            $builder = $this->registry->get($family);
+
+            if ($builder === null) {
+                continue;
+            }
+
+            $lastModified = $builder->lastModified();
+
+            if ($lastModified !== null) {
+                $candidate = $lastModified instanceof DateTimeInterface
+                    ? $lastModified
+                    : new DateTimeImmutable((string) $lastModified);
+
+                if ($latest === null || $candidate->getTimestamp() > $latest->getTimestamp()) {
+                    $latest = $candidate;
+                }
+            }
+        }
+
+        return $latest;
+    }
+}