Move rice transplant entries on variety change

backend/apps/plans/services_rice_transplant.py

@@ -0,0 +1,46 @@
+from django.db import transaction
+
+from .models import RiceTransplantEntry, RiceTransplantPlan
+
+
+@transaction.atomic
+def move_rice_transplant_entries_for_variety_change(change):
+    old_variety_id = change.old_variety_id
+    new_variety = change.new_variety
+    if old_variety_id is None or new_variety is None:
+        return 0
+
+    old_plans = (
+        RiceTransplantPlan.objects
+        .filter(
+            year=change.year,
+            variety_id=old_variety_id,
+            entries__field_id=change.field_id,
+        )
+        .distinct()
+        .prefetch_related('entries')
+    )
+
+    moved_count = 0
+    for old_plan in old_plans:
+        entries_to_move = list(
+            old_plan.entries.filter(field_id=change.field_id).order_by('id')
+        )
+        if not entries_to_move:
+            continue
+
+        new_plan = RiceTransplantPlan.objects.create(
+            name=f'{change.year}年度 {new_variety.name} 田植え計画（品種変更移動）',
+            year=change.year,
+            variety=new_variety,
+            default_seed_grams_per_box=old_plan.default_seed_grams_per_box,
+            seedling_boxes_per_tan=old_plan.seedling_boxes_per_tan,
+            notes=old_plan.notes,
+        )
+
+        RiceTransplantEntry.objects.filter(
+            id__in=[entry.id for entry in entries_to_move]
+        ).update(plan=new_plan)
+        moved_count += len(entries_to_move)
+
+    return moved_count