feat: enhance FastRequest functionality with shift scheduling and improve payment callback handling

app/Services/Shift/ShiftScheduleService.php

@@ -60,12 +60,17 @@ class ShiftScheduleService
             ->get();
     }
 
+    public function isOnShift(User $doctor, Carbon $moment): bool
+    {
+        return $this->shiftsCoveringMoment($moment)->contains('user_id', $doctor->id);
+    }
+
     public function autoSelectDoctor(Carbon $moment): ?User
     {
         $doctorIds = $this->shiftsCoveringMoment($moment)->pluck('user_id')->filter()->unique();
 
         if ($doctorIds->isEmpty()) {
-            return null;
+            return $this->doctorWithNearestShift($moment);
         }
 
         return User::where('level', UserEnum::Doctor->value)
@@ -81,6 +86,20 @@ class ShiftScheduleService
             ->first();
     }
 
+    // fallback when nobody is on shift: the doctor whose next shift starts soonest
+    public function doctorWithNearestShift(Carbon $from): ?User
+    {
+        $doctorIds = Shift::active()->whereNotNull('user_id')->distinct()->pluck('user_id');
+
+        return User::where('level', UserEnum::Doctor->value)
+            ->whereIn('id', $doctorIds)
+            ->get()
+            ->map(fn (User $doctor) => ['doctor' => $doctor, 'start' => $this->nextShiftStart($doctor, $from)])
+            ->filter(fn (array $item) => $item['start'] !== null)
+            ->sortBy('start')
+            ->first()['doctor'] ?? null;
+    }
+
     public function nextShiftStart(User $doctor, Carbon $from): ?Carbon
     {
         $shifts = Shift::active()->where('user_id', $doctor->id)->get();