# Stage 6d: self-locating spot melt of remaining flaps in the thigh gap.
# Finds high-roughness verts inside the gap box (an open-slit flap the membrane pulled),
# grows a 2-ring collar, melts. Prints the cluster it found so the fix is auditable.
#   blender --background --python 06d_spot_melt.py -- <in.blend> <out.blend>
import bpy, sys, time
import numpy as np

argv = sys.argv[sys.argv.index("--") + 1:]
BLEND, OUT = argv[0], argv[1]
t0 = time.time()

BOX = lambda co: (np.abs(co[:, 0]) < 0.075) & (co[:, 2] > 0.345) & (co[:, 2] < 0.475)
ROUGH_THR = 0.0012
MELT_ITERS = 80


def log(m):
    print(f"[spot {time.time()-t0:6.1f}s] {m}", flush=True)


bpy.ops.wm.open_mainfile(filepath=BLEND)
ob = max([o for o in bpy.data.objects if o.type == 'MESH'],
         key=lambda o: len(o.data.vertices))
me = ob.data
n_v = len(me.vertices)
co = np.empty(n_v * 3)
me.vertices.foreach_get("co", co)
co = co.reshape(-1, 3)

n_e = len(me.edges)
ev = np.empty(n_e * 2, dtype=np.int32)
me.edges.foreach_get("vertices", ev)
ev = ev.reshape(-1, 2)
order = np.concatenate([ev[:, 0], ev[:, 1]])
nbr = np.concatenate([ev[:, 1], ev[:, 0]])
srt = np.argsort(order, kind="stable")
o_s = order[srt]
n_s = nbr[srt]
ptr = np.searchsorted(o_s, np.arange(n_v + 1))
cnt = np.maximum(ptr[1:] - ptr[:-1], 1)


def smooth_field(Q, iters):
    X = Q.copy()
    for _ in range(iters):
        acc = np.zeros_like(X)
        np.add.at(acc, o_s, X[n_s])
        X = acc / cnt[:, None]
    return X


sm = smooth_field(co, 8)
rough = np.linalg.norm(co - sm, axis=1)
box = BOX(co)
hot = box & (rough > ROUGH_THR)
log(f"box {box.sum()} verts, hot {hot.sum()} (rough>{ROUGH_THR})")
if hot.sum():
    hc = co[hot]
    log(f"hot cluster: x [{hc[:,0].min():+.4f}..{hc[:,0].max():+.4f}] "
        f"y [{hc[:,1].min():+.4f}..{hc[:,1].max():+.4f}] "
        f"z [{hc[:,2].min():+.4f}..{hc[:,2].max():+.4f}]")
    m = hot.copy()
    for _ in range(2):
        h = m[ev[:, 0]] | m[ev[:, 1]]
        m2 = m.copy()
        m2[ev[:, 0]] |= h
        m2[ev[:, 1]] |= h
        m = m2
    sidx = np.nonzero(m)[0]
    Q = co.copy()
    for _ in range(MELT_ITERS):
        acc = np.zeros_like(Q)
        np.add.at(acc, o_s, Q[n_s])
        mean = acc / cnt[:, None]
        Q[sidx] = 0.5 * Q[sidx] + 0.5 * mean[sidx]
    d = np.linalg.norm(Q - co, axis=1)
    log(f"melted {len(sidx)} verts, max move {d.max():.4f}")
    me.vertices.foreach_set("co", Q.reshape(-1))
    me.update()
    if me.has_custom_normals:
        vn = np.empty(n_v * 3, dtype=np.float32)
        me.vertices.foreach_get("normal", vn)
        me.normals_split_custom_set_from_vertices(vn.reshape(-1, 3))
else:
    log("nothing hot — no melt applied")
bpy.context.preferences.filepaths.save_version = 0  # no .blend1 autosave
bpy.ops.wm.save_as_mainfile(filepath=OUT)
log(f"WROTE {OUT}")
print("SPOT_DONE")