"""
Flat limb strip cutout — the 316L sheet blank before any bending.
A tapered hexagon, widest at center, symmetric taper to tips.
3 bolt holes at center. Thickness from sheet stock (3.5mm at center
tapering to 1.4mm at tips — but this is a flat cutout so we use
a single sheet thickness and show the WIDTH taper only).

Run in Blender: Scripting workspace > Open > Run Script
"""

import bpy
import bmesh
import math

def clear_scene():
    bpy.ops.object.select_all(action='SELECT')
    bpy.ops.object.delete()

def make_material(name, color, metallic=0.0, roughness=0.5):
    mat = bpy.data.materials.new(name)
    mat.use_nodes = True
    bsdf = mat.node_tree.nodes["Principled BSDF"]
    bsdf.inputs["Base Color"].default_value = (*color, 1.0)
    bsdf.inputs["Metallic"].default_value = metallic
    bsdf.inputs["Roughness"].default_value = roughness
    return mat

def main():
    clear_scene()

    steel = make_material("316L_FullHard", (0.08, 0.08, 0.08), metallic=0.8, roughness=0.4)

    # Taper profile from doc (distance from center in mm, half-width in mm)
    # Symmetric — we define one side and mirror.
    #   Center:  44mm wide  (half = 22)
    #   140mm:   40mm wide  (half = 20)
    #   250mm:   32mm wide  (half = 16)
    #   350mm:   24mm wide  (half = 12)
    #   500mm:   20mm wide  (half = 10)
    #
    # Thickness taper (for the Z extrusion at each section):
    #   Center:  3.5mm
    #   140mm:   3.0mm
    #   250mm:   2.2mm
    #   350mm:   1.8mm
    #   500mm:   1.4mm

    # Profile points: (y_mm, half_width_mm, thickness_mm)
    profile = [
        (0,   22.0, 3.5),
        (50,  21.5, 3.35),
        (100, 20.8, 3.15),
        (140, 20.0, 3.0),
        (180, 18.4, 2.7),
        (220, 17.2, 2.4),
        (250, 16.0, 2.2),
        (280, 14.6, 2.05),
        (310, 13.2, 1.9),
        (350, 12.0, 1.8),
        (380, 11.2, 1.7),
        (420, 10.6, 1.55),
        (460, 10.2, 1.45),
        (500, 10.0, 1.4),
    ]

    # Build mesh: for each Y station, create a rectangular cross-section
    # (width varies, thickness varies). Full strip is symmetric about Y=0.
    bm = bmesh.new()

    # Build both halves: negative Y then positive Y
    all_stations = []
    for y_mm, hw_mm, th_mm in reversed(profile):
        if y_mm > 0:
            all_stations.append((-y_mm, hw_mm, th_mm))
    for y_mm, hw_mm, th_mm in profile:
        all_stations.append((y_mm, hw_mm, th_mm))

    # Scale to meters
    for y_mm, hw_mm, th_mm in all_stations:
        y = y_mm / 1000.0
        hw = hw_mm / 1000.0
        th = th_mm / 1000.0

        # Four corners of cross-section at this Y station
        bm.verts.new((-hw, y, 0))
        bm.verts.new(( hw, y, 0))
        bm.verts.new(( hw, y, th))
        bm.verts.new((-hw, y, th))

    bm.verts.ensure_lookup_table()
    n = len(all_stations)

    # Side faces
    for i in range(n - 1):
        base = i * 4
        for j in range(4):
            v0 = bm.verts[base + j]
            v1 = bm.verts[base + (j + 1) % 4]
            v2 = bm.verts[base + 4 + (j + 1) % 4]
            v3 = bm.verts[base + 4 + j]
            bm.faces.new([v0, v1, v2, v3])

    # Cap ends
    bm.faces.new([bm.verts[0], bm.verts[1], bm.verts[2], bm.verts[3]])
    last = (n - 1) * 4
    bm.faces.new([bm.verts[last+3], bm.verts[last+2], bm.verts[last+1], bm.verts[last]])

    mesh = bpy.data.meshes.new("Limb_Strip_Flat")
    bm.to_mesh(mesh)
    bm.free()

    obj = bpy.data.objects.new("Limb_Strip_Flat", mesh)
    bpy.context.scene.collection.objects.link(obj)
    obj.data.materials.append(steel)

    # Smooth shading
    for f in obj.data.polygons:
        f.use_smooth = True

    # Subdivision for smoothness
    mod = obj.modifiers.new("Subsurf", 'SUBSURF')
    mod.levels = 2
    mod.render_levels = 3

    # --- Bolt holes (3x M6, 30mm spacing at center) ---
    for offset_mm in [-30, 0, 30]:
        bpy.ops.mesh.primitive_cylinder_add(
            radius=0.00325,  # 6.5mm clearance hole / 2
            depth=0.006,     # through the thickness
            location=(0, offset_mm / 1000.0, 0.00175))
        hole = bpy.context.active_object
        hole.name = f"BoltHole_{offset_mm}"

        # Boolean difference
        mod = obj.modifiers.new(f"Hole_{offset_mm}", 'BOOLEAN')
        mod.operation = 'DIFFERENCE'
        mod.object = hole
        bpy.context.view_layer.objects.active = obj
        bpy.ops.object.modifier_apply(modifier=f"Hole_{offset_mm}")
        bpy.data.objects.remove(hole)

    bpy.ops.object.select_all(action='DESELECT')
    obj.select_set(True)
    bpy.context.view_layer.objects.active = obj

    print("Flat limb strip cutout created.")
    print("1000mm total length, tapered width (44mm center -> 20mm tips),")
    print("tapered thickness (3.5mm center -> 1.4mm tips), 3x M6 bolt holes.")
    print("This is the blank before press-brake recurve forming.")

if __name__ == "__main__":
    main()