RSS Feed includes one <item> per photo (#4500)

Author: cdzombak

app/Actions/RSS/Generate.php

@@ -15,45 +15,57 @@
 use App\Models\Extensions\UTCBasedTimes;
 use App\Models\Photo;
 use App\Policies\AlbumPolicy;
+use App\Policies\AlbumQueryPolicy;
 use App\Policies\PhotoQueryPolicy;
 use App\Repositories\ConfigManager;
 use App\Services\UrlGenerator;
 use Carbon\Exceptions\InvalidFormatException;
 use Carbon\Exceptions\UnitException;
 use GrahamCampbell\Markdown\Facades\Markdown;
 use Illuminate\Contracts\Container\BindingResolutionException;
+use Illuminate\Database\Query\Builder as BaseBuilder;
 use Illuminate\Support\Carbon;
 use Illuminate\Support\Collection;
 use Illuminate\Support\Facades\Auth;
 use Illuminate\Support\Facades\DB;
+use function Safe\parse_url;
 use Spatie\Feed\FeedItem;
 
 /**
- * @template T of object{id:string,title:string,description:?string,type:string,created_at:string,updated_at:string,album_id:string,album_title:string,short_path:string,filesize:int,storage_disk:string,size_variant_type:string,username:string}
+ * @template T of object{id:string,title:string,description:?string,type:string,created_at:string,updated_at:string,short_path:string,filesize:int,storage_disk:string,size_variant_type:string,username:string}
  */
 class Generate
 {
 	use UTCBasedTimes;
 
 	public function __construct(
 		protected PhotoQueryPolicy $photo_query_policy,
+		protected AlbumQueryPolicy $album_query_policy,
 		protected readonly ConfigManager $config_manager,
 		protected readonly UrlGenerator $url_generator,
 	) {
 	}
 
 	/**
-	 * @param T $data
+	 * @param T        $data       the row supplying the item's photo/user fields
+	 * @param string   $album_id   the album whose view of the photo the item links to
+	 * @param string[] $categories album titles to list on the item as `<category>`
 	 *
 	 * @return FeedItem
 	 *
 	 * @throws BindingResolutionException
 	 */
-	private function toFeedItem(object $data): FeedItem
+	private function toFeedItem(object $data, string $album_id, array $categories): FeedItem
 	{
-		$page_link = route('gallery', ['albumId' => $data->album_id, 'photoId' => $data->id]);
+		$page_link = route('gallery', ['albumId' => $album_id, 'photoId' => $data->id]);
+		// A tag: URI (RFC 4151) is an opaque, album-independent identity for the
+		// photo. Unlike $page_link (which points at the newest album and moves if
+		// that album changes), it depends only on the host and the photo's
+		// immutable id/created_at, so a photo keeps the same <guid> for life.
+		$host = parse_url((string) config('app.url'), PHP_URL_HOST) ?? 'lychee';
+		$guid = sprintf('tag:%s,%s:photo/%s', $host, Carbon::parse($data->created_at)->format('Y-m-d'), $data->id);
 		$feed_item = [
-			'id' => $page_link,
+			'id' => $guid,
 			'title' => $data->title,
 			'summary' => Markdown::convert($data->description ?? '')->getContent(),
 			'updated' => $this->asDateTime($data->updated_at),
@@ -64,7 +76,7 @@ private function toFeedItem(object $data): FeedItem
 			'authorName' => ($data->display_name !== null && $data->display_name !== '')
 				? $data->display_name
 				: $data->username,
-			'category' => [$data->album_title],
+			'category' => $categories,
 		];
 
 		return FeedItem::create($feed_item);
@@ -97,34 +109,112 @@ public function do(): Collection
 				origin: null,
 				include_nsfw: !$this->config_manager->getValueAsBool('hide_nsfw_in_rss')
 			)
-			->joinSub(DB::table(PA::PHOTO_ALBUM), 'outer_' . PA::PHOTO_ALBUM, 'photos.id', '=', 'outer_' . PA::PHOTO_ID)
-			->join('base_albums', 'base_albums.id', '=', 'outer_' . PA::ALBUM_ID)
 			->join('size_variants', 'size_variants.photo_id', '=', 'photos.id')
 			->join('users', 'users.id', '=', 'photos.owner_id')
 			->where('size_variants.type', '=', SizeVariantType::ORIGINAL->value)
+			// Require at least one album (needed for the item's link) without
+			// re-introducing the per-album fan-out a join would add. The
+			// base_albums join mirrors the categories query below, so every
+			// selected photo is guaranteed a row there.
+			->whereExists(fn (BaseBuilder $q) => $q
+				->from(PA::PHOTO_ALBUM)
+				->join('base_albums', 'base_albums.id', '=', PA::ALBUM_ID)
+				->whereColumn(PA::PHOTO_ID, 'photos.id'))
 			->select([
 				'photos.id',
 				'photos.title',
 				'photos.description',
 				'photos.type',
 				'photos.created_at',
 				'photos.updated_at',
-				'outer_' . PA::ALBUM_ID,
-				'base_albums.title as album_title',
 				'size_variants.short_path',
 				'size_variants.filesize',
 				'size_variants.storage_disk',
 				'users.username',
 				'users.display_name',
 			]
 			)
+			// distinct() collapses the photo_album fan-out that
+			// applySearchabilityFilter's internal left-join introduces, so each
+			// photo yields a single row (and the LIMIT counts photos).
 			->distinct()
 			->where('photos.created_at', '>=', $now_minus)
 			->limit($rss_max)
 			->orderBy('photos.created_at', 'desc')
 			->toBase() // We use toBase() to avoid the use of the Eloquent casts etc.
 			->get();
 
-		return $photos->map(fn (object $p) => $this->toFeedItem($p));
+		// All album memberships of the selected photos, newest-first so first()
+		// is the album each item links to: the most recently created album that
+		// holds the photo (album_id breaks created_at ties for a stable choice).
+		//
+		// The same accessibility/NSFW constraints the photo query applies must
+		// also be applied here: a photo can be shared into a locked or sensitive
+		// album, and that album must not surface as the item's link or as a
+		// <category> to a viewer who cannot reach it.
+		$albums_query = DB::table(PA::PHOTO_ALBUM)
+			->join('base_albums', 'base_albums.id', '=', PA::ALBUM_ID)
+			->whereIn(PA::PHOTO_ID, $photos->pluck('id')->all());
+
+		// Accessibility: keep only albums the current user (or a guest, when
+		// $user is null) may access, honouring password locks. Admins may reach
+		// every album, so — like the album policies themselves — they skip this.
+		if ($user?->may_administrate !== true) {
+			$this->album_query_policy->joinSubComputedAccessPermissions(
+				query: $albums_query,
+				second: PA::ALBUM_ID,
+				type: 'left',
+				user: $user,
+			);
+			$albums_query->where(fn (BaseBuilder $q) => $this->album_query_policy
+				->appendAccessibilityConditions($q, $user, $unlocked_album_ids));
+		}
+
+		// NSFW: when the feed is configured to hide sensitive content, drop
+		// albums that are marked sensitive or sit under a sensitive ancestor.
+		// This mirrors the include_nsfw filter applied to the photo query above
+		// (which is applied to admins too), so it is applied unconditionally.
+		if ($this->config_manager->getValueAsBool('hide_nsfw_in_rss')) {
+			$albums_query
+				->join('albums', 'albums.id', '=', PA::ALBUM_ID)
+				->whereNotExists(fn (BaseBuilder $q) => $this->album_query_policy
+					->appendRecursiveSensitiveAlbumsCondition($q, null, null));
+		}
+
+		$albums_by_photo = $albums_query
+			->orderBy('base_albums.created_at', 'desc')
+			->orderBy(PA::ALBUM_ID)
+			->get([
+				PA::PHOTO_ID . ' as photo_id',
+				PA::ALBUM_ID . ' as album_id',
+				'base_albums.title as album_title',
+			])
+			->groupBy('photo_id');
+
+		return $photos
+			->map(function (object $photo) use ($albums_by_photo): ?FeedItem {
+				/** @var Collection<int,object{album_id:string,album_title:string}>|null $albums */
+				$albums = $albums_by_photo->get($photo->id);
+				// The two queries are not a single snapshot: a concurrent request
+				// can detach the photo from its last album between them, leaving
+				// no album to link to. Drop the photo rather than fatal on null.
+				if ($albums === null) {
+					return null;
+				}
+
+				// The computed-access-permissions join can return an album more
+				// than once (e.g. shared to several of the user's groups), so
+				// collapse to one row per album before listing categories. first()
+				// still yields the newest album for the link (order is preserved).
+				$albums = $albums->unique('album_id');
+
+				return $this->toFeedItem(
+					$photo,
+					$albums->first()->album_id,
+					$albums->pluck('album_title')->all(),
+				);
+			})
+			->filter()
+			->values();
 	}
-}
+}

resources/views/vendor/feed/rss.blade.php

@@ -23,7 +23,7 @@
                 <link>{{ url($item->link) }}</link>
                 <description><![CDATA[@if($item->__isset('enclosure'))<img src="{{ url($item->enclosure) }}" /><br/><br/>@endif{!! $item->summary !!}]]></description>
                 <author><![CDATA[{{ $item->authorName }}@if(!empty($item->authorEmail)) <{{ $item->authorEmail }}>@endif]]></author>
-                <guid>{{ url($item->id) }}</guid>
+                <guid isPermaLink="false">{{ $item->id }}</guid>
                 <pubDate>{{ $item->timestamp() }}</pubDate>
                 @foreach($item->category as $category)
                     <category>{{ $category }}</category>