from cqparts.constraint import Mate, Coincident

from .base import Fastener
from ..screws import Screw
from ..utils import VectorEvaluator, Selector, Applicator


class ScrewFastener(Fastener):
    """
    Screw fastener assembly.

    Example usage can be found here: :ref:`cqparts_fasteners.built-in.screw`
    """
    Evaluator = VectorEvaluator

    class Selector(Selector):
        ratio = 0.8
        def get_components(self):
            end_effect = self.evaluator.eval[-1]
            end_point = end_effect.start_point + (end_effect.end_point - end_effect.start_point) * self.ratio

            return {'screw': Screw(
                head=('countersunk', {
                    'diameter': 9.5,
                    'height': 3.5,
                }),
                neck_length=abs(self.evaluator.eval[-1].start_point - self.evaluator.eval[0].start_point),
                # only the length after the neck is threaded
                length=abs(end_point - self.evaluator.eval[0].start_point),
                #length=abs(self.evaluator.eval[-1].end_point - self.evaluator.eval[0].start_point),
            )}

        def get_constraints(self):
            # bind fastener relative to its anchor; the part holding it in.
            anchor_part = self.evaluator.eval[-1].part  # last effected part

            return [Coincident(
                self.components['screw'].mate_origin,
                Mate(anchor_part, self.evaluator.eval[0].start_coordsys - anchor_part.world_coords)
            )]

    class Applicator(Applicator):

        def apply_alterations(self):
            screw = self.selector.components['screw']
            cutter = screw.make_cutter()  # cutter in local coords

            for effect in self.evaluator.eval:
                relative_coordsys = screw.world_coords - effect.part.world_coords
                local_cutter = relative_coordsys + cutter
                effect.part.local_obj = effect.part.local_obj.cut(local_cutter)