# IfcOpenShell - IFC toolkit and geometry engine
# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.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.util.representation
from ifcopenshell import entity_instance


def get_curve(alignment: entity_instance) -> entity_instance:
    """
    Returns the geometric representation curve for an alignment.
    An alignment without layouts will have a curve of type IfcPolyLine or IfcIndexedPolyCurve
    A horizontal only will have a curve of type IfcCompositeCurve
    A horizontal+vertical will have a curve of type IfcGradientCurve
    A horizontal+vertical+cant will have a curve of tyep IfcSegmentedReferenceCurve

    :param alignment: The alignment
    :return: The geometric representation of the alignemnt or None if the alignment does not have a representation

    Example:

    .. code:: python
        alignment = model.by_type("IfcAlignment")[0]
        gradient_curve = ifcopenshell.api.alignment.get_curve(alignment)
    """
    axis = None
    representations = ifcopenshell.util.representation.get_representations_iter(alignment)
    for representation in representations:
        if representation.RepresentationIdentifier == "Axis" and (
            representation.RepresentationType == "Curve2D" or representation.RepresentationType == "Curve3D"
        ):
            axis = representation
            break

    return None if axis == None or len(axis.Items) == 0 else axis.Items[0]