# 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_product=None, related_object=None):
        """Associates a product and an object, typically for annotation

        Warning: this is an experimental API.

        When you want to draw attention to a feature or characteristic (such as
        a dimension, material, or name) or of a product (e.g. wall, slab,
        furniture, etc), an annotation object is created. This annotation is
        then associated with the product so that it can reference attributes,
        properties, and relationships.

        For example, an annotation of a line will be associated with a grid
        axis, such that when that grid axis moves, the annotation of that grid
        axis (which is typically truncated to the extents of a drawing) will
        also move.

        Another example might be a label of a furniture product, which might
        have some text of the name of the furniture to be shown on drawings or
        in 3D.

        :param relating_product: The IfcProduct the object is related to
        :type relating_product: ifcopenshell.entity_instance.entity_instance
        :param related_object: The object (typically IfcAnnotation) that the
            product is related to
        :type related_object: ifcopenshell.entity_instance.entity_instance
        :return: The created IfcRelAssignsToProduct relationship
        :rtype: ifcopenshell.entity_instance.entity_instance

        Example:

        .. code:: python

            furniture = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcFurniture")
            annotation = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcAnnotation")
            ifcopenshell.api.run("drawing.assign_product", model,
                relating_product=furniture, related_object=annotation)
        """
        self.file = file
        self.settings = {
            "relating_product": relating_product,
            "related_object": related_object,
        }

    def execute(self):
        is_grid_axis = self.settings["relating_product"].is_a("IfcGridAxis")

        if is_grid_axis:
            if self.settings["related_object"].HasAssignments:
                for rel in self.settings["related_object"].HasAssignments:
                    if rel.is_a("IfcRelAssignsToProduct") and rel.Name == self.settings["relating_product"].AxisTag:
                        return
        elif self.settings["related_object"].HasAssignments:
            for rel in self.settings["related_object"].HasAssignments:
                if rel.is_a("IfcRelAssignsToProduct") and rel.RelatingProduct == self.settings["relating_product"]:
                    return

        referenced_by = None

        if is_grid_axis:
            axis = self.settings["relating_product"]
            grid = None
            for attribute in ("PartOfW", "PartOfV", "PartOfU"):
                if getattr(axis, attribute, None):
                    grid = getattr(axis, attribute)[0]
            self.settings["relating_product"] = grid
            for rel in grid.ReferencedBy:
                if rel.Name == axis.AxisTag:
                    referenced_by = rel
                    break
        elif self.settings["relating_product"].ReferencedBy:
            referenced_by = self.settings["relating_product"].ReferencedBy[0]

        if referenced_by:
            related_objects = list(referenced_by.RelatedObjects)
            related_objects.append(self.settings["related_object"])
            referenced_by.RelatedObjects = related_objects
            ifcopenshell.api.run("owner.update_owner_history", self.file, **{"element": referenced_by})
        else:
            referenced_by = self.file.create_entity(
                "IfcRelAssignsToProduct",
                **{
                    "GlobalId": ifcopenshell.guid.new(),
                    "OwnerHistory": ifcopenshell.api.run("owner.create_owner_history", self.file),
                    "RelatedObjects": [self.settings["related_object"]],
                    "RelatingProduct": self.settings["relating_product"],
                }
            )

        if is_grid_axis:
            referenced_by.Name = axis.AxisTag
        return referenced_by