# IfcOpenShell - IFC toolkit and geometry engine
# Copyright (C) 2021, 2022 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.guid
import ifcopenshell.util.schema
import ifcopenshell.util.date
from typing import Union


def add_classification(
    file: ifcopenshell.file, classification: Union[str, ifcopenshell.entity_instance]
) -> ifcopenshell.entity_instance:
    """Adds a new classification system to the project

    External classification systems such as Uniclass or Omniclass are
    ways of categorising elements in the AEC industry, typically
    standardised or nominated by governments or companies. A system
    typically contains a series of hierarchical reference codes and labels
    like Pr_12_23_34.

    Classifications may be applied to many things, not just physical
    elements, such as doors and windows, spatial elements, tasks, cost
    items, or even resources.

    Prior to assigning classificaion references, you need to add the name
    and metadata of the classification system that you will use in your
    project. Classification systems may be revised over time, so this
    metadata includes the edition date.

    Common classification systems are provided as an IFC library which may
    be downloaded from https://github.com/Moult/IfcClassification for your
    convenience. It is advised to use these to ensure that the
    classification metadata is standardised.

    Adding a classification system will not add the entire hierarchy of
    references available in the classification. References need to be added
    separately. Typically, you'd only add the references that you use in
    your project, see ifcopenshell.api.classification.add_reference for more
    information.

    :param classification: If a string is provided, it is assumed to be the
        name of your classification system. This is necessary if you are
        creating your own custom classification system. Alternatively, you
        may provide an entity_instance of an IfcClassification from an IFC
        classification library. The latter approach is preferred if you are
        using a commonly known system such as Uniclass, as this will ensure
        all metadata is added correctly.
    :type classification: str,ifcopenshell.entity_instance
    :return: The added IfcClassification element
    :rtype: ifcopenshell.entity_instance

    Example:

    .. code:: python

        # Option 1: adding a custom clasification from scratch
        ifcopenshell.api.classification.add_classification(model,
            classification="MyCustomClassification")

        # Option 2: adding a popular classification from a library
        library = ifcopenshell.open("/path/to/Uniclass.ifc")
        classification = library.by_type("IfcClassification")[0]
        ifcopenshell.api.classification.add_classification(model,
            classification=classification)
    """
    usecase = Usecase()
    usecase.file = file
    usecase.settings = {
        "classification": classification,
    }
    return usecase.execute()


class Usecase:
    def execute(self):
        if isinstance(self.settings["classification"], str):
            classification = self.file.createIfcClassification(Name=self.settings["classification"])
            self.relate_to_project(classification)
            return classification
        return self.add_from_library()

    def add_from_library(self):
        edition_date = None
        if self.settings["classification"].EditionDate:
            edition_date = ifcopenshell.util.date.ifc2datetime(self.settings["classification"].EditionDate)
            self.settings["classification"].EditionDate = None

        migrator = ifcopenshell.util.schema.Migrator()
        result = migrator.migrate(self.settings["classification"], self.file)

        # TODO: should auto date migration be part of the migrator?
        if self.file.schema == "IFC2X3" and edition_date:
            result.EditionDate = self.file.create_entity(
                "IfcCalendarDate", **ifcopenshell.util.date.datetime2ifc(edition_date, "IfcCalendarDate")
            )
        else:
            if edition_date:
                edition_date = ifcopenshell.util.date.datetime2ifc(edition_date, "IfcDate")
            result.EditionDate = edition_date

        self.relate_to_project(result)

        return result

    def relate_to_project(self, classification):
        self.file.create_entity(
            "IfcRelAssociatesClassification",
            GlobalId=ifcopenshell.guid.new(),
            RelatedObjects=[self.file.by_type("IfcProject")[0]],
            RelatingClassification=classification,
        )