Moved models to folder, renamed managers to tools

Tools seems to fit better since the classes were a bit of a mixed bunch
and did not always manage.
Also simplified the structure of the SlugGenerator class.
Also focused EntityContext on shelves and simplified to use session
helper.

app/Entities/Tools/SearchOptions.php

@@ -0,0 +1,141 @@
+<?php namespace BookStack\Entities;
+
+use Illuminate\Http\Request;
+
+class SearchOptions
+{
+
+    /**
+     * @var array
+     */
+    public $searches = [];
+
+    /**
+     * @var array
+     */
+    public $exacts = [];
+
+    /**
+     * @var array
+     */
+    public $tags = [];
+
+    /**
+     * @var array
+     */
+    public $filters = [];
+
+    /**
+     * Create a new instance from a search string.
+     */
+    public static function fromString(string $search): SearchOptions
+    {
+        $decoded = static::decode($search);
+        $instance = new static();
+        foreach ($decoded as $type => $value) {
+            $instance->$type = $value;
+        }
+        return $instance;
+    }
+
+    /**
+     * Create a new instance from a request.
+     * Will look for a classic string term and use that
+     * Otherwise we'll use the details from an advanced search form.
+     */
+    public static function fromRequest(Request $request): SearchOptions
+    {
+        if (!$request->has('search') && !$request->has('term')) {
+            return static::fromString('');
+        }
+
+        if ($request->has('term')) {
+            return static::fromString($request->get('term'));
+        }
+
+        $instance = new static();
+        $inputs = $request->only(['search', 'types', 'filters', 'exact', 'tags']);
+        $instance->searches = explode(' ', $inputs['search'] ?? []);
+        $instance->exacts = array_filter($inputs['exact'] ?? []);
+        $instance->tags = array_filter($inputs['tags'] ?? []);
+        foreach (($inputs['filters'] ?? []) as $filterKey => $filterVal) {
+            if (empty($filterVal)) {
+                continue;
+            }
+            $instance->filters[$filterKey] = $filterVal === 'true' ? '' : $filterVal;
+        }
+        if (isset($inputs['types']) && count($inputs['types']) < 4) {
+            $instance->filters['type'] = implode('|', $inputs['types']);
+        }
+        return $instance;
+    }
+
+    /**
+     * Decode a search string into an array of terms.
+     */
+    protected static function decode(string $searchString): array
+    {
+        $terms = [
+            'searches' => [],
+            'exacts' => [],
+            'tags' => [],
+            'filters' => []
+        ];
+
+        $patterns = [
+            'exacts' => '/"(.*?)"/',
+            'tags' => '/\[(.*?)\]/',
+            'filters' => '/\{(.*?)\}/'
+        ];
+
+        // Parse special terms
+        foreach ($patterns as $termType => $pattern) {
+            $matches = [];
+            preg_match_all($pattern, $searchString, $matches);
+            if (count($matches) > 0) {
+                $terms[$termType] = $matches[1];
+                $searchString = preg_replace($pattern, '', $searchString);
+            }
+        }
+
+        // Parse standard terms
+        foreach (explode(' ', trim($searchString)) as $searchTerm) {
+            if ($searchTerm !== '') {
+                $terms['searches'][] = $searchTerm;
+            }
+        }
+
+        // Split filter values out
+        $splitFilters = [];
+        foreach ($terms['filters'] as $filter) {
+            $explodedFilter = explode(':', $filter, 2);
+            $splitFilters[$explodedFilter[0]] = (count($explodedFilter) > 1) ? $explodedFilter[1] : '';
+        }
+        $terms['filters'] = $splitFilters;
+
+        return $terms;
+    }
+
+    /**
+     * Encode this instance to a search string.
+     */
+    public function toString(): string
+    {
+        $string = implode(' ', $this->searches ?? []);
+
+        foreach ($this->exacts as $term) {
+            $string .= ' "' . $term . '"';
+        }
+
+        foreach ($this->tags as $term) {
+            $string .= " [{$term}]";
+        }
+
+        foreach ($this->filters as $filterName => $filterVal) {
+            $string .= ' {' . $filterName . ($filterVal ? ':' . $filterVal : '') . '}';
+        }
+
+        return $string;
+    }
+
+}