# 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.owner
import ifcopenshell.util.element


def unassign_resource(
    file: ifcopenshell.file,
    relating_resource: ifcopenshell.entity_instance,
    related_object: ifcopenshell.entity_instance,
) -> None:
    """Removes the relationship between a resource and object

    :param relating_resource: The IfcResource to assign the object to.
    :param related_object: The IfcProduct or IfcActor to assign to the
        object.
    :return: None

    Example:

    .. code:: python

        # Add our own crew
        crew = ifcopenshell.api.resource.add_resource(model, ifc_class="IfcCrewResource")

        # Add some a tower crane to our crew.
        crane = ifcopenshell.api.resource.add_resource(model,
            parent_resource=crew, ifc_class="IfcConstructionEquipmentResource", name="Tower Crane 01")

        # Our tower crane will be placed via this physical product.
        product = ifcopenshell.api.root.create_entity(model,
            ifc_class="IfcBuildingElementProxy", predefined_type="CRANE")

        # Let's assign our crane to the resource. The crane now represents
        # the resource.
        ifcopenshell.api.resource.assign_resource(model,
            relating_resource=crane, related_object=product)

        # Undo it.
        ifcopenshell.api.resource.unassign_resource(model,
            relating_resource=crane, related_object=product)
    """
    for rel in related_object.HasAssignments or []:
        if not rel.is_a("IfcRelAssignsToResource") or rel.RelatingResource != relating_resource:
            continue
        if len(rel.RelatedObjects) == 1:
            history = rel.OwnerHistory
            file.remove(rel)
            if history:
                ifcopenshell.util.element.remove_deep2(file, history)
            return
        related_objects = list(rel.RelatedObjects)
        related_objects.remove(related_object)
        rel.RelatedObjects = related_objects
        ifcopenshell.api.owner.update_owner_history(file, element=rel)