From a3802c25c0cf01cb1ced9d4770a08a343c011dcd Mon Sep 17 00:00:00 2001
From: "Sigma Dimensions (Yass)" <79010126+myoualid@users.noreply.github.com>
Date: Wed, 20 Sep 2023 01:05:19 +0100
Subject: [PATCH] fix cascading schedule when parent tasks have sequence
 relationships #3772

---
 .../api/sequence/cascade_schedule.py          | 10 +++++++++-
 .../ifcopenshell/util/sequence.py             | 20 +++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py
index d8fc4f4384..b541a81670 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py
@@ -135,7 +135,9 @@ class Usecase:
         finishes = []
         starts = []
 
-        for rel in task.IsSuccessorFrom:
+        for rel in ifcopenshell.util.sequence.get_sequence_assignment(
+            task, "predecessor"
+        ):
             predecessor = rel.RelatingProcess
             predecessor_duration = (
                 ifcopenshell.util.date.ifc2datetime(
@@ -314,6 +316,12 @@ class Usecase:
         for rel in task.IsPredecessorTo:
             self.cascade_task(rel.RelatedProcess, task_sequence=task_sequence + [task])
 
+        for rel in task.IsNestedBy:
+            [
+                self.cascade_task(nested_task, task_sequence=task_sequence + [task])
+                for nested_task in rel.RelatedObjects or []
+            ]
+
     def get_lag_time_days(self, lag_time):
         return ifcopenshell.util.date.ifc2datetime(lag_time.LagValue.wrappedValue).days
 
diff --git a/src/ifcopenshell-python/ifcopenshell/util/sequence.py b/src/ifcopenshell-python/ifcopenshell/util/sequence.py
index 02ec945a63..9389320120 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/sequence.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/sequence.py
@@ -426,3 +426,23 @@ def get_tasks_for_product(product, schedule=None):
         ]
 
     return inputs, outputs
+
+
+def get_sequence_assignment(task, sequence="successor"):
+    if sequence == "successor":
+        relationship_attr = "IsPredecessorTo"
+    elif sequence == "predecessor":
+        relationship_attr = "IsSuccessorFrom"
+    else:
+        return []
+
+    relationship = getattr(task, relationship_attr, None)
+    if relationship:
+        return relationship
+
+    for rel in task.Nests or []:
+        result = get_sequence_assignment(rel.RelatingObject, sequence)
+        if result:
+            return result
+
+    return []