"""Parametric eight-hole circular flange generated with build123d."""

from math import cos, radians, sin

from build123d import Align, BuildPart, Cylinder, Location, Locations, Mode


OUTER_DIAMETER_MM = 50.0
INNER_DIAMETER_MM = 20.0
THICKNESS_MM = 4.0
BOLT_HOLE_COUNT = 8
M3_CLEARANCE_DIAMETER_MM = 3.4
BOLT_CIRCLE_DIAMETER_MM = 40.0


def polar_point(radius: float, angle_degrees: float) -> tuple[float, float]:
    angle = radians(angle_degrees)
    return radius * cos(angle), radius * sin(angle)


def gen_step():
    """Return one STEP-ready flange solid in millimeters."""
    with BuildPart() as flange:
        Cylinder(
            radius=OUTER_DIAMETER_MM / 2.0,
            height=THICKNESS_MM,
            align=(Align.CENTER, Align.CENTER, Align.MIN),
        )

        with Locations(Location((0.0, 0.0, -1.0))):
            Cylinder(
                radius=INNER_DIAMETER_MM / 2.0,
                height=THICKNESS_MM + 2.0,
                align=(Align.CENTER, Align.CENTER, Align.MIN),
                mode=Mode.SUBTRACT,
            )

        for index in range(BOLT_HOLE_COUNT):
            angle_degrees = 360.0 * index / BOLT_HOLE_COUNT
            x_pos, y_pos = polar_point(BOLT_CIRCLE_DIAMETER_MM / 2.0, angle_degrees)
            with Locations(Location((x_pos, y_pos, -1.0))):
                Cylinder(
                    radius=M3_CLEARANCE_DIAMETER_MM / 2.0,
                    height=THICKNESS_MM + 2.0,
                    align=(Align.CENTER, Align.CENTER, Align.MIN),
                    mode=Mode.SUBTRACT,
                )

    part = flange.part
    part.label = "flange_8x_m3_clearance"
    return part