IfcOpenShell/src/ifcopenshell-python/ifcopenshell/api/library/assign_reference.py

# IfcOpenShell - IFC toolkit and geometry engine
# Copyright (C) 2021 Dion Moult <dion@thinkmoult.com>
#
# This file is part of IfcOpenShell.
#
# IfcOpenShell is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# IfcOpenShell is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.

import ifcopenshell
import ifcopenshell.api
import ifcopenshell.util.element
from typing import Union


class Usecase:
    def __init__(
        self, file: ifcopenshell.file, products: ifcopenshell.entity_instance, reference: ifcopenshell.entity_instance
    ):
        """Associates a list products with a library reference

        A product may be associated with zero, one, or many references across
        multiple libraries. See ifcopenshell.api.library.add_reference for more
        detail about how references work.

        :param products: The list of IfcProducts you want to associate with the reference
        :type products: list[ifcopenshell.entity_instance.entity_instance]
        :param reference: The IfcLibraryReference you want the product to be
            associated with.
        :type reference: ifcopenshell.entity_instance.entity_instance
        :return: The IfcRelAssociatesLibrary relationship entity
            or `None` if `products` was an empty list or all products were
            already assigned to the `reference`.
        :rtype: Union[ifcopenshell.entity_instance.entity_instance, None]

        Example:

        .. code:: python

            library = ifcopenshell.api.run("library.add_library", model, name="Brickschema")

            # Let's create a reference to a single AHU in our Brickschema dataset
            reference = ifcopenshell.api.run("library.add_reference", model, library=library)
            ifcopenshell.api.run("library.edit_reference", model,
                reference=reference, attributes={"Identification": "http://example.org/digitaltwin#AHU01"})

            # Let's assume we have an AHU in our model.
            ahu = ifcopenshell.api.run("root.create_entity", model,
                ifc_class="IfcUnitaryEquipment", predefined_type="AIRHANDLER")

            # And now assign the IFC model's AHU with its Brickschema counterpart
            ifcopenshell.api.run("library.assign_reference", model, reference=reference, products=[ahu])
        """
        self.file = file
        self.settings = {
            "products": products,
            "reference": reference,
        }

    def execute(self) -> Union[ifcopenshell.entity_instance, None]:
        # TODO: do we need to support non-ifcroot elements like we do in classification.add_reference?

        referenced_elements = ifcopenshell.util.element.get_referenced_elements(self.settings["reference"])
        products: set[ifcopenshell.entity_instance] = set(self.settings["products"])
        products = products - referenced_elements

        if not products:
            return

        if self.file.schema == "IFC2X3":
            rel = next(
                (
                    r
                    for r in self.file.by_type("IfcRelAssociatesLibrary")
                    if r.RelatingLibrary == self.settings["reference"]
                ),
                None,
            )
        else:
            rel = next(iter(self.settings["reference"].LibraryRefForObjects), None)

        if not rel:
            return self.file.create_entity(
                "IfcRelAssociatesLibrary",
                GlobalId=ifcopenshell.guid.new(),
                OwnerHistory=ifcopenshell.api.run("owner.create_owner_history", self.file),
                RelatedObjects=list(products),
                RelatingLibrary=self.settings["reference"],
            )

        related_objects = set(rel.RelatedObjects) | products
        rel.RelatedObjects = list(related_objects)
        ifcopenshell.api.run("owner.update_owner_history", self.file, element=rel)
        return rel