"""Scan GLBs: list finger joints and which animations have live (non-frozen) finger rotation tracks."""
import json, struct, sys, math
from pathlib import Path

FINGER_TOKENS = ("thumb", "index", "middle", "ring", "pinky", "finger")

def read_glb(path):
    data = Path(path).read_bytes()
    magic, ver, length = struct.unpack_from("<III", data, 0)
    assert magic == 0x46546C67, "not glb"
    off = 12
    gltf = None
    bin_chunk = None
    while off < length:
        clen, ctype = struct.unpack_from("<II", data, off)
        off += 8
        chunk = data[off:off+clen]
        if ctype == 0x4E4F534A:
            gltf = json.loads(chunk.decode("utf-8"))
        elif ctype == 0x004E4942:
            bin_chunk = chunk
        off += clen
    return gltf, bin_chunk

def accessor_data(gltf, binc, idx):
    acc = gltf["accessors"][idx]
    bv = gltf["bufferViews"][acc["bufferView"]]
    comp = {5126: ("f", 4)}[acc["componentType"]]
    n = {"SCALAR":1, "VEC3":3, "VEC4":4}[acc["type"]]
    off = bv.get("byteOffset", 0) + acc.get("byteOffset", 0)
    count = acc["count"]
    vals = struct.unpack_from("<%d%s" % (count*n, comp[0]), binc, off)
    return [vals[i*n:(i+1)*n] for i in range(count)]

def scan(path, verbose_joints=False):
    gltf, binc = read_glb(path)
    nodes = gltf.get("nodes", [])
    names = [nd.get("name", f"node{i}") for i, nd in enumerate(nodes)]
    # joints from skins
    joint_set = set()
    for skin in gltf.get("skins", []):
        joint_set.update(skin.get("joints", []))
    fingers = sorted(n for i in joint_set for n in [names[i]] if any(t in n.lower() for t in FINGER_TOKENS))
    print(f"\n== {Path(path).name} ==")
    print(f"joints: {len(joint_set)}, finger joints: {len(fingers)}")
    if verbose_joints:
        for n in sorted(names[i] for i in joint_set):
            print("  ", n)
    elif fingers:
        print("  finger joints:", ", ".join(fingers))
    for anim in gltf.get("animations", []):
        aname = anim.get("name", "?")
        live, frozen = [], []
        for ch in anim.get("channels", []):
            tgt = ch["target"]
            if tgt.get("path") != "rotation":
                continue
            nname = names[tgt["node"]]
            if not any(t in nname.lower() for t in FINGER_TOKENS):
                continue
            samp = anim["samplers"][ch["sampler"]]
            quats = accessor_data(gltf, binc, samp["output"])
            # measure max angular deviation from first frame
            q0 = quats[0]
            maxdot = 1.0
            for q in quats[1:]:
                d = abs(sum(a*b for a, b in zip(q0, q)))
                maxdot = min(maxdot, min(d, 1.0))
            ang = 2*math.degrees(math.acos(maxdot))
            (live if ang > 2.0 else frozen).append((nname, ang))
        total = len(live) + len(frozen)
        if total:
            print(f"  anim '{aname}': {total} finger rot tracks, {len(live)} live (>2deg), {len(frozen)} frozen")
            if live:
                top = sorted(live, key=lambda x: -x[1])[:4]
                print("     top movers:", ", ".join(f"{n} {a:.0f}deg" for n, a in top))
        else:
            print(f"  anim '{aname}': NO finger tracks")

if __name__ == "__main__":
    for p in sys.argv[1:]:
        scan(p, verbose_joints="--joints" in sys.argv)