"""20 x 20 V-slot aluminium extrusion, any length.

The section, centred on the origin in the XY plane, extruded along +Z by `length`: a 20 x 20 square with 0.5 mm corner
radii and a V-slot in each face. Each slot: a 45 degree V from the face opening down to the lip tips, the lips' flat
undersides, the undercut's straight walls, 45 degree walls down to the core and the core's small V notch; a 4.2 mm
centre bore. All four slots are the same, turned 90 degrees.

Geometry measured from the published FreeCAD-library model "2020x50_V_slot_profile-Part.step" (hasecilu, CC-BY-3.0);
there is no manufacturer drawing. See the README.
"""
import math

from steve import Model

length = 100  # mm Length
finish = "clear"  # Anodising

# mm, measured on the reference model's cross-section at mid-length (OCCT section, edges read exactly; the model's
# own values are given to 0.05 mm, the 45 degree walls' ends to 1e-4 mm). x across the top slot from its centre line,
# y up from the profile's centre.
SECTION = {
    "outer": 20.0,           # outside, square
    "corner_r": 0.5,         # outside corner radius
    "opening": 9.7,          # slot width at the face (x = +-4.85)
    "tip": 6.1,              # between the lip tips (x = +-3.05), 1.8 below the face: the V is 45 degrees
    "lip_y": 8.2,            # lip underside (flat, out to the undercut wall)
    "undercut": 11.0,        # undercut width (walls at x = +-5.5)
    "wall_y": 6.5607,        # where the undercut wall turns into the 45 degree wall
    "floor": 5.6786,         # core face width at y = core_y (x = +-2.8393)
    "core_y": 3.9,           # core face
    "notch": 0.4,            # V notch in the core face, 0.2 deep
    "notch_depth": 0.2,
    "bore": 4.2,             # centre bore
}
FINISHES = {"clear": "#cfd2d6", "black": "#2b2c2e"}

s = SECTION
half = s["outer"] / 2
rc = s["corner_r"]
# one slot, the top one, left to right (the outline runs clockwise: top face, then right face, ...)
slot = [(-s["opening"] / 2, half), (-s["tip"] / 2, s["lip_y"]), (-s["undercut"] / 2, s["lip_y"]),
        (-s["undercut"] / 2, s["wall_y"]), (-s["floor"] / 2, s["core_y"]), (-s["notch"] / 2, s["core_y"]),
        (0.0, s["core_y"] - s["notch_depth"]), (s["notch"] / 2, s["core_y"]), (s["floor"] / 2, s["core_y"]),
        (s["undercut"] / 2, s["wall_y"]), (s["undercut"] / 2, s["lip_y"]), (s["tip"] / 2, s["lip_y"]),
        (s["opening"] / 2, half)]


def turn(points, quarter):
    a = -math.pi / 2 * quarter
    return [(x * math.cos(a) - y * math.sin(a), x * math.sin(a) + y * math.cos(a)) for x, y in points]


model = Model()
with model.sketch("section", on="XY", name="Section") as sk:
    for q in range(4):   # top, right, bottom, left side: the top one turned 90 degrees clockwise each time
        pts = turn([(-half + rc, half)] + slot + [(half - rc, half)], q)
        sk.polyline(f"side_{q}", pts, closed=False)
        cx, cy = turn([(half - rc, half - rc)], q)[0]
        start = 90 - 90 * q - 90
        sk.arc(f"corner_{q}", (cx, cy), rc, start, start + 90)
    sk.circle("bore", (0, 0), s["bore"] / 2)
model.extrude("profile", "section", distance=length, name="Profile")
model.material("aluminum-generic", color=FINISHES[finish])   # 6063-T5 typical (no STEVE entry for 6063)
result = model.result()