# 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/>.


class Usecase:
    def __init__(self, file, parent=None):
        """Adds a new value or subvalue to a cost item

        A cost item's subtotal can be specified in two ways.

        Option 1 is by simply manually specifying the subtotal value, which
        represents the full cost of that cost item. This option occurs when a
        cost item has no quantities associated with it.

        Option 2 is by specifying a unit cost value of the cost item, which is
        then multiplied by the associated quantity of the cost item, to give us
        the subtotal. This option occurs when a cost item has quantities
        associated with it.

        For either option 1 (full cost value) or option 2 (unit cost value), the
        cost value may be specified as a single number, or as a sum of
        subcomponents or formulas (e.g. multiplication by wastage factor, or
        adding taxes or other adjustments).

        This function lets you add a single top level unit value to a cost item,
        or alternatively price subcomponents by using the "parent" parameter.

        More advanced usage, which involves summing, subcategory-filtered costs,
        and formulas are possible but not yet documented.

        :param parent: A parent IfcCostItem, if specifying a price directly to a
            cost item, or a top-level price component. Alternatively, this can
            be set to a IfcCostValue, if specifying price subcomponents.
        :type parent: ifcopenshell.entity_instance.entity_instance
        :return: The newly created IfcCostValue
        :rtype: ifcopenshell.entity_instance.entity_instance

        Example:

        .. code:: python

            # We always need a schedule first prior to adding any cost items
            schedule = ifcopenshell.api.run("cost.add_cost_schedule", model)

            # Option 1: This cost item will have a full cost of 42.0
            item1 = ifcopenshell.api.run("cost.add_cost_item", model, cost_schedule=schedule)
            value = ifcopenshell.api.run("cost.add_cost_value", model, parent=item1)
            ifcopenshell.api.run("cost.edit_cost_value", model, cost_value=value,
                attributes={"AppliedValue": 42.0})

            # Option 2: This cost item will have a unit cost of 5.0 per unit
            # area, multiplied by the quantity of area specified explicitly as
            # 3.0, giving us a subtotal cost of 15.0.
            item2 = ifcopenshell.api.run("cost.add_cost_item", model, cost_schedule=schedule)
            value = ifcopenshell.api.run("cost.add_cost_value", model, parent=item2)
            ifcopenshell.api.run("cost.edit_cost_value", model, cost_value=value,
                attributes={"AppliedValue": 5.0})
            quantity = ifcopenshell.api.run("cost.add_cost_item_quantity", model,
                cost_item=item2, ifc_class="IfcQuantityVolume")
            ifcopenshell.api.run("cost.edit_cost_item_quantity", model,
                physical_quantity=quantity, "attributes": {"VolumeValue": 3.0})

            # A cost value may also be specified in terms of the sum of its
            # subcomponents. In this case, it's broken down into 2 subvalues.
            item1 = ifcopenshell.api.run("cost.add_cost_item", model, cost_schedule=schedule)
            value = ifcopenshell.api.run("cost.add_cost_value", model, parent=item1)
            subvalue1 = ifcopenshell.api.run("cost.add_cost_value", model, parent=value)
            subvalue2 = ifcopenshell.api.run("cost.add_cost_value", model, parent=value)

            # This specifies that the value is the sum of all subitems
            # regardless of their cost category. The first subvalue is 2.0 and
            # the second is 3.0, giving a total value of 5.0.
            ifcopenshell.api.run("cost.edit_cost_value", model, cost_value=value, attributes={"Category": "*"})
            ifcopenshell.api.run("cost.edit_cost_value", model,
                cost_value=subvalue1, attributes={"AppliedValue": 2.0})
            ifcopenshell.api.run("cost.edit_cost_value", model,
                cost_value=subvalue2, attributes={"AppliedValue": 3.0})
        """
        self.file = file
        self.settings = {"parent": parent}

    def execute(self):
        value = self.file.create_entity("IfcCostValue")
        if self.settings["parent"].is_a("IfcCostItem"):
            values = list(self.settings["parent"].CostValues or [])
            values.append(value)
            self.settings["parent"].CostValues = values
        elif self.settings["parent"].is_a("IfcConstructionResource"):
            values = list(self.settings["parent"].BaseCosts or [])
            values.append(value)
            self.settings["parent"].BaseCosts = values
        elif self.settings["parent"].is_a("IfcCostValue"):
            values = list(self.settings["parent"].Components or [])
            values.append(value)
            self.settings["parent"].Components = values
        return value