# 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.guid
import ifcopenshell.util.element


def update_group_products(
    file: ifcopenshell.file, group: ifcopenshell.entity_instance, products: list[ifcopenshell.entity_instance]
) -> ifcopenshell.entity_instance:
    """Sets a group products to be an explicit list of products

    Any previous products assigned to that group will have their assignment
    removed.

    :param products: A list of IfcProduct elements to assign to the group
    :param group: The IfcGroup to assign the products to
    :return: The IfcRelAssignsToGroup relationship

    Example:

    .. code:: python

        group = ifcopenshell.api.group.add_group(model, name="Furniture")
        ifcopenshell.api.group.update_group_products(model,
            products=model.by_type("IfcFurniture"), group=group)
    """
    if not group.IsGroupedBy:
        return file.create_entity(
            "IfcRelAssignsToGroup",
            **{
                "GlobalId": ifcopenshell.guid.new(),
                "OwnerHistory": ifcopenshell.api.owner.create_owner_history(file),
                "RelatedObjects": products,
                "RelatingGroup": group,
            }
        )
    else:
        rels = group.IsGroupedBy
        objects = set(products)
        for rel in rels:
            objects.update([g for g in rel.RelatedObjects if g.is_a("IfcGroup")])
        to_purge = rels[1:]

        for rel in to_purge:
            history = rel.OwnerHistory
            file.remove(rel)
            if history:
                ifcopenshell.util.element.remove_deep2(file, history)

        rels[0].RelatedObjects = list(objects)
        return rels[0]
