Support oft parent groups

app/Models/Event.php

@@ -5,6 +5,7 @@ namespace App\Models;
 
 use App\Casts\AmountCast;
 use App\Enumerations\EatingHabit;
+use App\Enumerations\ParticipantGroupType;
 use App\Enumerations\ParticipationFeeType;
 use App\RelationModels\EventParticipationFee;
 use App\RelationModels\EventPaymentMethods;
@@ -13,6 +14,7 @@ use DateTime;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\BelongsToMany;
 use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Support\Collection;
 
 /**
  * @property string $tenant
@@ -50,6 +52,7 @@ use Illuminate\Database\Eloquent\Relations\HasMany;
  * @property boolean $short_registration
  * @property boolean $swimming_permission_required
  * @property string|null $invoice_key
+ * @property string $participant_group_type
  */
 class Event extends InstancedModel
 {
@@ -101,6 +104,7 @@ class Event extends InstancedModel
         'swimming_permission_required',
 
         'invoice_key',
+        'participant_group_type',
     ];
 
     protected $casts = [
@@ -186,6 +190,33 @@ class Event extends InstancedModel
         return $this->belongsToMany(Tenant::class, 'event_local_groups', 'event_id', 'local_group_id');
     }
 
+    public function participantGroupType() : ParticipantGroupType {
+        return ParticipantGroupType::fromStored($this->participant_group_type);
+    }
+
+    public function asksForParentGroup() : bool {
+        return $this->participantGroupType() === ParticipantGroupType::ParentGroup;
+    }
+
+    /**
+     * Was bei der Anmeldung zur Auswahl steht: die teilnehmenden Local Groups oder -- fragt die Veranstaltung nach der
+     * Parent Group -- deren Parent Groups, jede nur einmal (alphabetisch, „Ohne Zuordnung" zuletzt).
+     * Einzige Quelle für Anzeige und Prüfung der Auswahl.
+     *
+     * @return Collection<int, Tenant>|Collection<int, ParentGroup>
+     */
+    public function participantGroupOptions() : Collection {
+        $localGroups = $this->localGroups()->with('parentGroup')->get();
+
+        if (!$this->asksForParentGroup()) {
+            return $localGroups;
+        }
+
+        return ParentGroup::sortForDisplay(
+            $localGroups->pluck('parentGroup')->filter()->unique('id')
+        );
+    }
+
     public function eatingHabits()  : BelongsToMany{
         return $this->belongsToMany(EatingHabit::class, 'event_allowed_eating_habits', 'event_id', 'eating_habit_id');
     }