# 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.api.root
import ifcopenshell.api.nest
import ifcopenshell.api.owner
import ifcopenshell.guid
from typing import Optional


def add_cost_item(
    file: ifcopenshell.file,
    cost_schedule: Optional[ifcopenshell.entity_instance] = None,
    cost_item: Optional[ifcopenshell.entity_instance] = None,
) -> ifcopenshell.entity_instance:
    """Add a new cost item

    A cost item represents a single line item in a cost schedule. Cost items
    may then be broken down into cost subitems.

    Either `cost_schedule` or `cost_item` must be provided.

    :param cost_schedule: If the cost item is to be added as a root or top
        level cost item to a cost schedule, the IfcCostSchedule may be
        specified. This is mutually exlclusive to the cost_item parameter.
    :type cost_schedule: ifcopenshell.entity_instance, optional.
    :param cost_item: If the cost item is to be added as a subitem to an
        existing cost item, the parent IfcCostItem may be specified. This is
        mutually exclusive to the cost_schedule parameter.
    :type cost_item: ifcopenshell.entity_instance, optional
    :return: The newly created IfcCostItem
    :rtype: ifcopenshell.entity_instance

    Example:

    .. code:: python

        # The very first cost item must be in a cost schedule
        schedule = ifcopenshell.api.cost.add_cost_schedule(model)

        # You may add cost items as top level item in the schedule
        item1 = ifcopenshell.api.cost.add_cost_item(model, cost_schedule=schedule)

        # Alternatively you may add them as subitems
        item2 = ifcopenshell.api.cost.add_cost_item(model, cost_item=item1)
    """
    settings = {"cost_schedule": cost_schedule, "cost_item": cost_item}

    cost_item = ifcopenshell.api.root.create_entity(file, ifc_class="IfcCostItem")

    if settings["cost_schedule"]:
        file.create_entity(
            "IfcRelAssignsToControl",
            **{
                "GlobalId": ifcopenshell.guid.new(),
                "OwnerHistory": ifcopenshell.api.owner.create_owner_history(file),
                "RelatedObjects": [cost_item],
                "RelatingControl": settings["cost_schedule"],
            },
        )
    elif settings["cost_item"]:
        ifcopenshell.api.nest.assign_object(file, related_objects=[cost_item], relating_object=settings["cost_item"])
    return cost_item