Fixes (#435)

* Add flight level field to PIREP field closes #401

* Default value for distance 0 closes #400

* Block airline deletion if assets exist #367

* Formatting

* Move some of the base exception classes

* Fix skin references to use settings table

* Set default for theme name if setting is wrong

app/Services/AirlineService.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace App\Services;
+
+use App\Contracts\Service;
+use App\Models\Airline;
+use App\Repositories\AirlineRepository;
+use App\Repositories\FlightRepository;
+use App\Repositories\PirepRepository;
+use App\Repositories\SubfleetRepository;
+
+class AirlineService extends Service
+{
+    private $airlineRepo;
+    private $flightRepo;
+    private $pirepRepo;
+    private $subfleetRepo;
+
+    public function __construct(
+        AirlineRepository $airlineRepo,
+        FlightRepository $flightRepo,
+        PirepRepository $pirepRepo,
+        SubfleetRepository $subfleetRepo
+    ) {
+        $this->airlineRepo = $airlineRepo;
+        $this->flightRepo = $flightRepo;
+        $this->pirepRepo = $pirepRepo;
+        $this->subfleetRepo = $subfleetRepo;
+    }
+
+    /**
+     * Can the airline be deleted? Check if there are flights, etc associated with it
+     *
+     * @param Airline $airline
+     *
+     * @return bool
+     */
+    public function canDeleteAirline(Airline $airline): bool
+    {
+        // Check these asset counts in these repositories
+        $repos = [
+            $this->pirepRepo,
+            $this->flightRepo,
+            $this->subfleetRepo,
+        ];
+
+        $w = ['airline_id' => $airline->id];
+        foreach ($repos as $repo) {
+            if ($repo->count($w) > 0) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}