fix untagged behaviour in pagination

src/inc/routes/apiv2/index.mjs

@@ -785,8 +785,17 @@ export default router => {
         });
       }
 
+      const effMode = req.query.mode !== undefined ? +req.query.mode : (req.mode ?? 3);
+      const ratingsRaw = req.cookies?.ratings || req.query.ratings;
+      const ratingsArr = (effMode === 3 || effMode === 2) ? null : (ratingsRaw ? (Array.isArray(ratingsRaw) ? ratingsRaw : decodeURIComponent(ratingsRaw).split(/[|,]/)).filter(r => ['sfw','nsfw','nsfl','untagged'].includes(r)) : null);
+
       let guestTagFilter = db``;
       if (!session) {
+        const itemTags = await db`SELECT tag_id FROM tags_assign WHERE item_id = ${+id}`;
+        const isTagged = itemTags.length > 0;
+        if (!isTagged && !cfg.websrv.public_untagged) {
+          return res.json({ success: false, msg: 'no items found' });
+        }
         if (cfg.websrv.public_nsfw) {
           guestTagFilter = cfg.websrv.public_untagged
             ? db`and (id in (select item_id from tags_assign where tag_id in (1, 2)) or not exists (select 1 from tags_assign where item_id = items.id))`
@@ -798,17 +807,30 @@ export default router => {
         }
       }
 
+      let modeCondition = db``;
+      if (effMode === 2) {
+        modeCondition = db`and not exists (select 1 from tags_assign where item_id = items.id)`;
+      } else if (effMode === 0) {
+        modeCondition = db`and id in (select item_id from tags_assign where tag_id = 1)`;
+      } else if (effMode === 1) {
+        modeCondition = db`and id in (select item_id from tags_assign where tag_id = 2)`;
+      } else if (effMode === 4) {
+        modeCondition = db`and id in (select item_id from tags_assign where tag_id = ${parseInt(cfg.nsfl_tag_id, 10) || 3})`;
+      } else if (ratingsArr && ratingsArr.length > 0) {
+        modeCondition = db`and ${db.unsafe(lib.getMultiRatingMode(ratingsArr))}`;
+      }
+
       const next = await db`
         select id
         from "items"
-        where id > ${+id} and active = true and coalesce(visibility, 0) = 0 ${guestTagFilter}
+        where id > ${+id} and active = true and coalesce(visibility, 0) = 0 ${guestTagFilter} ${modeCondition}
         order by id
         limit 1
       `;
       const prev = await db`
         select id
         from "items"
-        where id < ${+id} and active = true and coalesce(visibility, 0) = 0 ${guestTagFilter}
+        where id < ${+id} and active = true and coalesce(visibility, 0) = 0 ${guestTagFilter} ${modeCondition}
         order by id desc
         limit 1
       `;