Focused base Entity class cleanup

Removed some common functions from other entities.
Aligned implementation of getUrl()
Cleaned phpdocs and added typehinting.
Also extracted sibling search logic out of controller.

app/Entities/Tools/SearchIndex.php

@@ -31,7 +31,7 @@ class SearchIndex
     {
         $this->deleteEntityTerms($entity);
         $nameTerms = $this->generateTermArrayFromText($entity->name, 5 * $entity->searchFactor);
-        $bodyTerms = $this->generateTermArrayFromText($entity->getText() ?? '', 1 * $entity->searchFactor);
+        $bodyTerms = $this->generateTermArrayFromText($entity->getText(), 1 * $entity->searchFactor);
         $terms = array_merge($nameTerms, $bodyTerms);
         foreach ($terms as $index => $term) {
             $terms[$index]['entity_type'] = $entity->getMorphClass();

app/Entities/Tools/SiblingFetcher.php

@@ -0,0 +1,47 @@
+<?php namespace BookStack\Entities\Tools;
+
+use BookStack\Entities\EntityProvider;
+use BookStack\Entities\Models\Book;
+use BookStack\Entities\Models\Bookshelf;
+use Illuminate\Support\Collection;
+
+class SiblingFetcher
+{
+
+    /**
+     * Search among the siblings of the entity of given type and id.
+     */
+    public function fetch(string $entityType, int $entityId): Collection
+    {
+        $entity = (new EntityProvider)->get($entityType)->visible()->findOrFail($entityId);
+        $entities = [];
+
+        // Page in chapter
+        if ($entity->isA('page') && $entity->chapter) {
+            $entities = $entity->chapter->getVisiblePages();
+        }
+
+        // Page in book or chapter
+        if (($entity->isA('page') && !$entity->chapter) || $entity->isA('chapter')) {
+            $entities = $entity->book->getDirectChildren();
+        }
+
+        // Book
+        // Gets just the books in a shelf if shelf is in context
+        if ($entity->isA('book')) {
+            $contextShelf = (new ShelfContext)->getContextualShelfForBook($entity);
+            if ($contextShelf) {
+                $entities = $contextShelf->visibleBooks()->get();
+            } else {
+                $entities = Book::visible()->get();
+            }
+        }
+
+        // Shelve
+        if ($entity->isA('bookshelf')) {
+            $entities = Bookshelf::visible()->get();
+        }
+
+        return $entities;
+    }
+}

app/Entities/Tools/TrashCan.php

@@ -168,11 +168,10 @@ class TrashCan
      */
     public function getTrashedCounts(): array
     {
-        $provider = app(EntityProvider::class);
         $counts = [];
 
         /** @var Entity $instance */
-        foreach ($provider->all() as $key => $instance) {
+        foreach ((new EntityProvider)->all() as $key => $instance) {
             $counts[$key] = $instance->newQuery()->onlyTrashed()->count();
         }