import cadquery as Cq
import math
import unittest

def hirth_joint(radius=60,
                radius_inner=40,
                radius_centre=30,
                base_height=20,
                n_tooth=16,
                tooth_height=16,
                tooth_height_inner=2):
    """
    Creates a cylindrical Hirth Joint
    """
    # ensures secant doesn't blow up
    assert n_tooth >= 5

    # angle of half of a single tooth
    theta = math.pi / n_tooth

    # Generate a tooth by lofting between two curves

    inner_raise = (tooth_height - tooth_height_inner) / 2
    # Outer tooth triangle spans a curve of length `2 pi r / n_tooth`. This
    # creates the side profile (looking radially inwards) of each of the
    # triangles.
    outer = [
        (radius * math.tan(theta), 0),
        (0, tooth_height),
        (-radius * math.tan(theta), 0),
    ]
    inner = [
        (radius_inner * math.sin(theta), 0),
        (radius_inner * math.sin(theta), inner_raise - tooth_height_inner / 2),
        (0, inner_raise + tooth_height_inner / 2),
        (-radius_inner * math.sin(theta), inner_raise - tooth_height_inner / 2),
        (-radius_inner * math.sin(theta), 0),
    ]
    tooth = (
        Cq.Workplane('YZ')
        .polyline(inner)
        .close()
        .workplane(offset=radius - radius_inner)
        .polyline(outer)
        .close()
        .loft(combine=True)
        .val()
    )
    tooth_centre_radius = radius_inner * math.cos(theta)
    teeth = (
        Cq.Workplane('XY')
        .polarArray(radius=radius_inner, startAngle=0, angle=360, count=n_tooth)
        .eachpoint(lambda loc: tooth.located(loc))
        .intersect(Cq.Solid.makeCylinder(
            height=base_height + tooth_height,
            radius=radius,
        ))
    )
    base = (
        Cq.Workplane('XY')
        .cylinder(
            height=base_height,
            radius=radius,
            centered=(True, True, False))
        .faces(">Z").tag("bore")
        .union(teeth.val().move(Cq.Location((0,0,base_height))))
        .clean()
    )
    #base.workplane(offset=tooth_height/2).circle(radius=radius,forConstruction=True).tag("mate")
    base.polyline([(0, 0, 0), (0, 0, 1)], forConstruction=True).tag("mate")
    return base

def hirth_assembly():
    """
    Example assembly of two Hirth joints
    """
    rotate = 180 / 16
    obj1 = hirth_joint().faces(tag="bore").cboreHole(
        diameter=10,
        cboreDiameter=20,
        cboreDepth=3)
    obj2 = (
        hirth_joint()
        .rotate(
            axisStartPoint=(0,0,0),
            axisEndPoint=(0,0,1),
            angleDegrees=rotate
        )
    )
    result = (
        Cq.Assembly()
        .add(obj1, name="obj1", color=Cq.Color(0.8,0.8,0.5,0.3))
        .add(obj2, name="obj2", color=Cq.Color(0.5,0.5,0.5,0.3), loc=Cq.Location((0,0,80)))
        .constrain("obj1?mate", "obj2?mate", "Axis")
        .solve()
    )
    return result

class TestJoints(unittest.TestCase):

    def test_hirth_assembly(self):
        print(Cq.__version__)
        hirth_assembly()

if __name__ == '__main__':
    unittest.main()