# 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


class Usecase:
    def __init__(self, file, relating_control=None, related_object=None):
        """Assigns a planning control or constraint to an object

        IFC can describe concepts that control other objects. For example, a
        planning calendar controls the availability of working days for
        construction planning. As another example, a cost item might constrain
        or limit the ability to procure and build a product.

        This usecase lets you assign controls following the rules of the IFC
        specification. This is an advanced topic and assumes knowledge of the
        IFC concepts to determine what is allowed to control what. In the
        future, this API will likely be deprecated in favour of multiple usecase
        specific APIs.

        :param relating_control: The IfcControl entity that is creating the
            control or constraint
        :type relating_control: ifcopenshell.entity_instance.entity_instance
        :param related_object: The IfcObjectDefinition that is being controlled
        :type related_object: ifcopenshell.entity_instance.entity_instance
        :return: The newly created IfcRelAssignsToControl. If relationship already
            existed before and wasn't changed then returns None.
        :rtype: ifcopenshell.entity_instance.entity_instance, None

        Example:

        .. code:: python

            # One common usecase is to assign a calendar to a task
            calendar = ifcopenshell.api.run("sequence.add_work_calendar", model)
            schedule = ifcopenshell.api.run("sequence.add_work_schedule", model)
            task = ifcopenshell.api.run("sequence.add_task", model,
                work_schedule=schedule)

            # All subtasks will inherit this calendar, so assigning a single
            # calendar to the root task effectively defines a "default" calendar
            ifcopenshell.api.run("control.assign_control", model,
                relating_control=calendar, related_object=task)

            # Another common example might be relating a cost item and a product
            wall = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcWall")
            schedule = ifcopenshell.api.run("cost.add_cost_schedule", model)
            cost_item = ifcopenshell.api.run("cost.add_cost_item", model,
                cost_schedule=schedule)
            ifcopenshell.api.run("control.assign_control", model,
                relating_control=cost_item, related_object=wall)
        """
        self.file = file
        self.settings = {
            "relating_control": relating_control,
            "related_object": related_object,
        }

    def execute(self):
        if self.settings["related_object"].HasAssignments:
            for assignment in self.settings["related_object"].HasAssignments:
                if (
                    assignment.is_a("IfcRelAssignsToControl")
                    and assignment.RelatingControl == self.settings["relating_control"]
                ):
                    return

        controls = None
        if self.settings["relating_control"].Controls:
            controls = self.settings["relating_control"].Controls[0]

        if controls:
            if self.settings["related_object"] in controls.RelatedObjects:
                return
            related_objects = set(controls.RelatedObjects)
            related_objects.add(self.settings["related_object"])
            controls.RelatedObjects = list(related_objects)
            ifcopenshell.api.run("owner.update_owner_history", self.file, **{"element": controls})
        else:
            controls = self.file.create_entity(
                "IfcRelAssignsToControl",
                **{
                    "GlobalId": ifcopenshell.guid.new(),
                    "OwnerHistory": ifcopenshell.api.run("owner.create_owner_history", self.file),
                    "RelatedObjects": [self.settings["related_object"]],
                    "RelatingControl": self.settings["relating_control"],
                },
            )
        return controls