Fix material unassignment greedy purging bug, and auto assign usages of typed layer / profile sets.

src/ifcopenshell-python/ifcopenshell/api/material/assign_material.py

@@ -1,4 +1,5 @@
 import ifcopenshell
+import ifcopenshell.api
 import ifcopenshell.util.element
 
 
@@ -10,6 +11,9 @@ class Usecase:
             self.settings[key] = value
 
     def execute(self):
+        material = ifcopenshell.util.element.get_material(self.settings["product"])
+        if material:
+            ifcopenshell.api.run("material.unassign_material", self.file, product=self.settings["product"])
         if self.settings["type"] == "IfcMaterial":
             self.assign_ifc_material()
         elif self.settings["type"] == "IfcMaterialConstituentSet":

src/ifcopenshell-python/ifcopenshell/api/material/unassign_material.py

@@ -9,6 +9,15 @@ class Usecase:
             self.settings[key] = value
 
     def execute(self):
-        for association in self.settings["product"].HasAssociations:
-            if association.is_a("IfcRelAssociatesMaterial"):
-                self.file.remove(association)
+        for rel in self.settings["product"].HasAssociations:
+            if rel.is_a("IfcRelAssociatesMaterial"):
+                if rel.RelatingMaterial.is_a("IfcMaterialLayerSetUsage") or rel.RelatingMaterial.is_a(
+                    "IfcMaterialProfileSetUsage"
+                ):
+                    self.file.remove(rel.RelatingMaterial)
+                if len(rel.RelatedObjects) == 1:
+                    self.file.remove(rel)
+                    continue
+                related_objects = set(rel.RelatedObjects)
+                related_objects.remove(self.settings["product"])
+                rel.RelatedObjects = list(related_object)