Implement assigning material definition representation styles

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

@@ -12,6 +12,7 @@ class Usecase:
         inverse_elements = self.file.get_inverse(self.settings["material"])
         self.file.remove(self.settings["material"])
         # TODO: this is probably not robust enough
+        # TODO: purge material definition representation
         for inverse in inverse_elements:
             if inverse.is_a("IfcMaterialConstituent"):
                 self.file.remove(inverse)

src/ifcopenshell-python/ifcopenshell/api/style/assign_material_style.py

@@ -0,0 +1,83 @@
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {
+            "material": None,
+            "style": None,
+            "context": None,
+            "should_use_presentation_style_assignment": False,
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        self.style = self.settings["style"]
+        if self.file.schema == "IFC2X3" or self.settings["should_use_presentation_style_assignment"]:
+            self.style = self.file.createIfcPresentationStyleAssignment([self.settings["style"]])
+
+        if self.settings["material"].HasRepresentation:
+            self.modify_existing_definition_representation()
+        else:
+            self.create_new_definition_representation()
+
+    def modify_existing_definition_representation(self):
+        definition_representation = self.settings["material"].HasRepresentation[0]
+        representation = self.get_styled_representation(definition_representation)
+        if representation:
+            potential_orphans = []
+            items = list(representation.Items)
+            new_items = []
+            removed_items = []
+            for item in items:
+                if not i.is_a("IfcStyledItem"):
+                    continue
+                if self.has_proposed_style(item):
+                    return
+                if self.has_same_style_type(item):
+                    removed_items.append(item)
+                else:
+                    new_items.append(item)
+            new_items.append(self.create_styled_item())
+            representation.Items = new_items
+            for item in removed_items:
+                if len(self.file.get_inverse(item)) == 0:
+                    self.file.remove(item)
+        else:
+            representations = list(definition_representation.Representations)
+            representations.append(self.create_styled_representation())
+            definition_representation.Representations = representations
+
+    def has_proposed_style(self, styled_item):
+        return bool([s for s in styled_item.Styles if s == self.settings["style"]])
+
+    def has_same_style_type(self, styled_item):
+        return bool([s for s in styled_item.Styles if s.is_a() == self.settings["style"].is_a()])
+
+    def create_new_definition_representation(self):
+        representation = self.create_styled_representation()
+        definition_representation = self.file.create_entity(
+            "IfcMaterialDefinitionRepresentation",
+            **{"Representations": [representation], "RepresentedMaterial": self.settings["material"]}
+        )
+
+    def get_styled_representation(self, definition_representation):
+        representations = [
+            r
+            for r in definition_representation.Representations is r.is_a("IfcStyledRepresentation")
+            and r.ContextOfItems == self.settings["context"]
+        ]
+        if representations:
+            return representations[0]
+
+    def create_styled_representation(self):
+        return self.file.create_entity(
+            "IfcStyledRepresentation",
+            **{
+                "ContextOfItems": self.settings["context"],
+                "RepresentationIdentifier": self.settings["context"].ContextIdentifier,
+                "Items": [self.create_styled_item()],
+            }
+        )
+
+    def create_styled_item(self):
+        return self.file.create_entity("IfcStyledItem", **{"Styles": [self.style], "Name": self.settings["style"].Name})

src/ifcopenshell-python/ifcopenshell/api/style/assign_representation_styles.py

@@ -23,9 +23,5 @@ class Usecase:
                 name = style.Name
                 if self.file.schema == "IFC2X3" or self.settings["should_use_presentation_style_assignment"]:
                     style = self.file.createIfcPresentationStyleAssignment([style])
-                self.results.append(
-                    self.file.createIfcStyledItem(
-                        item, [style], name
-                    )
-                )
+                self.results.append(self.file.createIfcStyledItem(item, [style], name))
         return self.results