# 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.owner
import ifcopenshell.api.material
import ifcopenshell.guid
import ifcopenshell.util.element
import ifcopenshell.util.representation
from typing import Optional, Union


def assign_material(
    file: ifcopenshell.file,
    products: list[ifcopenshell.entity_instance],
    type: ifcopenshell.util.element.MATERIAL_TYPE = "IfcMaterial",
    material: Optional[ifcopenshell.entity_instance] = None,
) -> Union[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance], None]:
    """Assigns a material to the list of products

    Will unassign previously assigned material.

    When a material is assigned to a product, it means that the product is
    made out of that material. In its simplest form, a single material may
    be assigned to a product, meaning that the entire product is made out of
    that one material. Alternatively, a material set may be assigned to a
    product, meaning that the product is made out of a set of materials.
    There are three types of sets, including layered construction, profiled
    materials, and arbitrary material constituents. See
    ifcopenshell.api.material.add_material_set for details.

    Materials are typically assigned to the element types rather than
    individual occurrences of elements. Individual occurrences would then
    inherit the material from the type.

    If the type has a material set, then the geometry of the occurrences
    must comply with the material set. For example, if the type has a
    constituent set, then it is expected that all occurrences also inherit
    the geometry of the type, which is made out of those constituents.
    Alternatively, if the type has a layer set, then all occurrences must
    have geometry that has a thickness equal to the sum of all layers. If a
    type has a profile set, then all occurrences must has the same profile
    extruded along its axis.

    For layers and profiles assigned to types, the occurrences must be
    assigned an IfcMaterialLayerSetUsage or an IfcMaterialProfileSetUsage.
    This allows individual occurrences to override the layered or profiled
    construction offset from a reference line.

    :param products: The list of IfcProducts to assign the material or material set
        to.
    :type products: list[ifcopenshell.entity_instance]
    :param type: Choose from "IfcMaterial", "IfcMaterialConstituentSet",
        "IfcMaterialLayerSet", "IfcMaterialLayerSetUsage",
        "IfcMaterialProfileSet", "IfcMaterialProfileSetUsage", or
        "IfcMaterialList". Note that "Set Usages" may only be assigned to
        occurrences, not types. Defaults to "IfcMaterial".
    :type type: str
    :param material: The IfcMaterial or material set you are assigning here.
        If type is Usage then no need to provide `material`, it will be deduced
        from the element type automatically.
        If IfcMaterial is provided as material and type is not IfcMaterial,
        provided material will be ignored except for IfcMaterialList
        where it will be used as part of the list.
    :type material: ifcopenshell.entity_instance, optional
    :return: IfcRelAssociatesMaterial entity
        or a list of IfcRelAssociatesMaterial entities
        (possible if `type` is Usage
        and `products` require different Usages)
        or `None` if `products` was empty list.
    :rtype: Union[
        ifcopenshell.entity_instance,
        list[ifcopenshell.entity_instance], None]

    Example:

    .. code:: python

        # Let's start with a simple concrete material
        concrete = ifcopenshell.api.material.add_material(model, name="CON01", category="concrete")

        # Let's imagine a concrete bench made out of a single concrete
        # material. Let's assign it to the type.
        bench_type = ifcopenshell.api.root.create_entity(model, ifc_class="IfcFurnitureType")
        ifcopenshell.api.material.assign_material(model,
            products=[bench_type], type="IfcMaterial", material=concrete)

        # Let's imagine there are a two occurrences of this bench.  It's not
        # necessary to assign any material to these benches as they
        # automatically inherit the material from the type.
        bench1 = ifcopenshell.api.root.create_entity(model, ifc_class="IfcFurniture")
        bench2 = ifcopenshell.api.root.create_entity(model, ifc_class="IfcFurniture")
        ifcopenshell.api.type.assign_type(model, related_objects=[bench1], relating_type=bench_type)
        ifcopenshell.api.type.assign_type(model, related_objects=[bench2], relating_type=bench_type)

        # If we have a concrete wall, we should use a layer set. Again,
        # let's start with a wall type, not occurrences.
        wall_type = ifcopenshell.api.root.create_entity(model, ifc_class="IfcWallType", name="WAL01")

        # Even though there is only one layer in our layer set, we still use
        # a layer set because it makes it clear that this is a layered
        # construction. Let's say it's a 200mm thick concrete layer.
        material_set = ifcopenshell.api.material.add_material_set(model,
            name="CON200", set_type="IfcMaterialLayerSet")
        layer = ifcopenshell.api.material.add_layer(model, layer_set=material_set, material=steel)
        ifcopenshell.api.material.edit_layer(model, layer=layer, attributes={"LayerThickness": 200})

        # Our wall type now has the layer set assigned to it
        ifcopenshell.api.material.assign_material(model,
            products=[wall_type], type="IfcMaterialLayerSet", material=material_set)

        # Let's imagine an occurrence of this wall type.
        wall = ifcopenshell.api.root.create_entity(model, ifc_class="IfcWall")
        ifcopenshell.api.type.assign_type(model, related_objects=[wall], relating_type=wall_type)

        # Our wall occurrence needs to have a "set usage" which describes
        # how the layers relate to a reference line (typically a 2D line
        # representing the extents of the wall). Usages are special since
        # they automatically detect the inherited material set from the
        # type. You'd write similar code for a profile set.
        ifcopenshell.api.material.assign_material(model,
            products=[wall], type="IfcMaterialLayerSetUsage")

        # To be complete, let's create the wall's axis and body
        # representation. Notice how the axis guides the walls "reference
        # line" which determines where layers are extruded from, and the
        # body has a thickness of 200mm, same as our total layer set
        # thickness.
        axis = ifcopenshell.api.geometry.add_axis_representation(model,
            context=axis_context, axis=[(0.0, 0.0), (5000.0, 0.0)])
        body = ifcopenshell.api.geometry.add_wall_representation(model,
            context=body_context, length=5000, height=3000, thickness=200)
        ifcopenshell.api.geometry.assign_representation(model, product=wall, representation=axis)
        ifcopenshell.api.geometry.assign_representation(model, product=wall, representation=body)
        ifcopenshell.api.geometry.edit_object_placement(model, product=wall)
    """
    usecase = Usecase()
    usecase.file = file
    usecase.settings = {"products": products, "type": type, "material": material}
    return usecase.execute()


class Usecase:
    def execute(self):
        self.products: set[ifcopenshell.entity_instance] = set(self.settings["products"])
        if not self.products:
            return

        # NOTE: we always reassign material, even if it might be assigned before
        products_to_unassign_material = [p for p in self.products if ifcopenshell.util.element.get_material(p)]
        if products_to_unassign_material:
            ifcopenshell.api.material.unassign_material(self.file, products=products_to_unassign_material)

        if self.settings["type"] == "IfcMaterial" or (
            self.settings["material"] and not self.settings["material"].is_a("IfcMaterial")
        ):
            return self.assign_ifc_material()

        elif self.settings["type"] == "IfcMaterialConstituentSet":
            material_set = self.file.create_entity(self.settings["type"])
            return self.create_material_association(material_set)

        elif self.settings["type"] == "IfcMaterialLayerSet":
            material_set = self.file.create_entity(self.settings["type"])
            return self.create_material_association(material_set)

        elif self.settings["type"] == "IfcMaterialLayerSetUsage":
            # NOTE: might return list of rels
            types_to_products_layers_sets: dict[
                tuple[Union[ifcopenshell.entity_instance, None], str], tuple[ifcopenshell.entity_instance, list]
            ] = dict()

            AXIS3_CLASSES = [
                "IfcSlab",
                "IfcSlabStandardCase",
                "IfcSlabElementedCase",
                "IfcRoof",
                "IfcRamp",
                "IfcPlate",
                "IfcPlateStandardCase",
                "IfcCovering",
                "IfcFurniture",
            ]
            for product in self.products:
                element_type = ifcopenshell.util.element.get_type(product)
                layer_set_direction = "AXIS3" if product.is_a() in AXIS3_CLASSES else "AXIS2"
                material_layer_type = (element_type, layer_set_direction)

                if material_layer_type in types_to_products_layers_sets:
                    types_to_products_layers_sets[material_layer_type][1].append(product)
                    continue

                if element_type:
                    element_type_material = ifcopenshell.util.element.get_material(element_type)
                    if element_type_material and element_type_material.is_a("IfcMaterialLayerSet"):
                        material_set = element_type_material
                    else:
                        material_set = self.file.create_entity("IfcMaterialLayerSet")
                else:
                    material_set = self.file.create_entity("IfcMaterialLayerSet")
                types_to_products_layers_sets[material_layer_type] = (material_set, [product])

            rels = [
                self.create_layer_set_usage(material_set, layer_set_direction, products)
                for (_, layer_set_direction), (material_set, products) in types_to_products_layers_sets.items()
            ]
            return rels[0] if len(rels) == 1 else rels

        elif self.settings["type"] == "IfcMaterialProfileSet":
            material_set = self.file.create_entity(self.settings["type"])
            return self.create_material_association(material_set)

        elif self.settings["type"] == "IfcMaterialProfileSetUsage":
            # NOTE: might return list of rels
            types_to_products_profile_sets: dict[
                Union[ifcopenshell.entity_instance, None], tuple[ifcopenshell.entity_instance, list]
            ] = dict()
            for product in self.products:
                element_type = ifcopenshell.util.element.get_type(product)
                if element_type in types_to_products_profile_sets:
                    types_to_products_profile_sets[element_type][1].append(product)
                    continue
                if element_type:
                    element_type_material = ifcopenshell.util.element.get_material(element_type)
                    if element_type_material and element_type_material.is_a("IfcMaterialProfileSet"):
                        material_set = element_type_material
                    else:
                        material_set = self.file.create_entity("IfcMaterialProfileSet")
                else:
                    material_set = self.file.create_entity("IfcMaterialProfileSet")
                types_to_products_profile_sets[element_type] = (material_set, [product])

            rels = []
            for _, (material_set, products) in types_to_products_profile_sets.items():
                self.update_representation_profile(material_set, products)
                material_set_usage = self.create_profile_set_usage(material_set)
                rels.append(self.create_material_association(material_set_usage, products))
            return rels[0] if len(rels) == 1 else rels

        elif self.settings["type"] == "IfcMaterialList":
            material_set = self.file.create_entity(self.settings["type"])
            material_set.Materials = [self.settings["material"]]
            return self.create_material_association(material_set)

    def update_representation_profile(
        self, material_set: ifcopenshell.entity_instance, products: list[ifcopenshell.entity_instance]
    ) -> None:
        profile = material_set.CompositeProfile
        if not profile and material_set.MaterialProfiles:
            profile = material_set.MaterialProfiles[0].Profile
        if not profile:
            return
        for product in products:
            representation = ifcopenshell.util.representation.get_representation(product, "Model", "Body", "MODEL_VIEW")
            if not representation:
                return
            for subelement in self.file.traverse(representation):
                if subelement.is_a("IfcSweptAreaSolid"):
                    subelement.SweptArea = profile

    def create_layer_set_usage(
        self,
        material_set: ifcopenshell.entity_instance,
        layer_set_direction: str,
        products: list[ifcopenshell.entity_instance],
    ) -> ifcopenshell.entity_instance:
        usage = self.file.create_entity(
            "IfcMaterialLayerSetUsage",
            **{
                "ForLayerSet": material_set,
                "LayerSetDirection": layer_set_direction,
                "DirectionSense": "POSITIVE",
                "OffsetFromReferenceLine": 0,
            }
        )
        return self.create_material_association(usage, products)

    def create_profile_set_usage(self, material_set: ifcopenshell.entity_instance) -> ifcopenshell.entity_instance:
        return self.file.create_entity("IfcMaterialProfileSetUsage", **{"ForProfileSet": material_set})

    def assign_ifc_material(self) -> ifcopenshell.entity_instance:
        material = self.settings["material"] or self.file.create_entity("IfcMaterial")
        rel = self.get_rel_associates_material(material)
        if not rel:
            return self.create_material_association(material)
        previous_related_objects = set(rel.RelatedObjects)
        rel.RelatedObjects = list(previous_related_objects | self.products)
        ifcopenshell.api.owner.update_owner_history(self.file, **{"element": rel})
        return rel

    def create_material_association(
        self,
        relating_material: ifcopenshell.entity_instance,
        products: Optional[list[ifcopenshell.entity_instance]] = None,
    ) -> ifcopenshell.entity_instance:
        if products is None:
            products = list(self.products)
        return self.file.create_entity(
            "IfcRelAssociatesMaterial",
            **{
                "GlobalId": ifcopenshell.guid.new(),
                "OwnerHistory": ifcopenshell.api.owner.create_owner_history(self.file),
                "RelatedObjects": products,
                "RelatingMaterial": relating_material,
            }
        )

    def get_rel_associates_material(
        self, material: ifcopenshell.entity_instance
    ) -> Union[ifcopenshell.entity_instance, None]:
        if self.file.schema == "IFC2X3" or material.is_a("IfcMaterialList"):
            return next(
                (
                    r
                    for r in self.file.by_type("IfcRelAssociatesMaterial")
                    if r.RelatingMaterial == self.settings["material"]
                ),
                None,
            )
        return next(iter(material.AssociatedTo), None)
