Feat: Implement overridable effective pickup date

src/Entity/Assignment.php

@@ -172,13 +172,32 @@ class Assignment implements BlameableEntityInterface, TimestampableEntityInterfa
         return $this;
     }
 
-    public function getTotalPeriod(): CarbonPeriod
+    public function getTotalPeriod(): ?CarbonPeriod
     {
-        $destination = $this->getDestination();
-        $dateFrom = $this->getDateFrom() ?? $destination->getDateFrom();
-        $dateTo = $this->getDateTo() ?? $destination->getDateTo();
+        if (null !== $destination = $this->getDestination()) {
+            $dateFrom = $this->getDateFrom() ?? $destination->getDateFrom();
+            $dateTo = $this->getDateTo() ?? $destination->getDateTo();
 
-        return new CarbonPeriod($dateFrom, $dateTo);
+            return new CarbonPeriod($dateFrom, $dateTo);
+        }
+
+        return null;
+    }
+
+    public function getEffectivePickupDate(): ?\DateTimeImmutable
+    {
+        if (null !== $this->pickupDate) {
+            return $this->pickupDate;
+        }
+
+        if (0 !== (int) $this->pickup && null !== $destination = $this->getDestination()) {
+            return $destination
+                ->getDateFrom()
+                ->modify('-1 day')
+            ;
+        }
+
+        return null;
     }
 
     public function getPickupDate(): ?\DateTimeImmutable