#!/usr/bin/env python3
"""Generate a small synthetic BVH clip (90 frames @ 30fps: hip bob +
arm swing + slight walk-forward) for the smoke test.

Pure Python — no Blender needed. Bone names are Mixamo-style without the
namespace, which exercises the retargeter's fuzzy name matching.

Usage: python3 tests/gen_test_bvh.py out/test_clip.bvh
"""
import math
import sys

# hierarchy: name, parent, offset (BVH Y-up, meters)
JOINTS = [
    ("Hips",          None,          (0, 0.93, 0)),
    ("Spine",         "Hips",        (0, 0.10, 0)),
    ("Spine1",        "Spine",       (0, 0.10, 0)),
    ("Spine2",        "Spine1",      (0, 0.10, 0)),
    ("Neck",          "Spine2",      (0, 0.10, 0)),
    ("Head",          "Neck",        (0, 0.09, 0)),
    ("LeftShoulder",  "Spine2",      (0.06, 0.08, 0)),
    ("LeftArm",       "LeftShoulder", (0.12, 0, 0)),
    ("LeftForeArm",   "LeftArm",     (0.26, 0, 0)),
    ("LeftHand",      "LeftForeArm", (0.24, 0, 0)),
    ("RightShoulder", "Spine2",      (-0.06, 0.08, 0)),
    ("RightArm",      "RightShoulder", (-0.12, 0, 0)),
    ("RightForeArm",  "RightArm",    (-0.26, 0, 0)),
    ("RightHand",     "RightForeArm", (-0.24, 0, 0)),
    ("LeftUpLeg",     "Hips",        (0.09, -0.05, 0)),
    ("LeftLeg",       "LeftUpLeg",   (0, -0.40, 0)),
    ("LeftFoot",      "LeftLeg",     (0, -0.40, 0)),
    ("LeftToeBase",   "LeftFoot",    (0, -0.05, 0.14)),
    ("RightUpLeg",    "Hips",        (-0.09, -0.05, 0)),
    ("RightLeg",      "RightUpLeg",  (0, -0.40, 0)),
    ("RightFoot",     "RightLeg",    (0, -0.40, 0)),
    ("RightToeBase",  "RightFoot",   (0, -0.05, 0.14)),
]

FRAMES = 90
FPS = 30.0


def children_of(name):
    return [j for j in JOINTS if j[1] == name]


def write_joint(f, joint, depth):
    name, parent, off = joint
    ind = "  " * depth
    kw = "ROOT" if parent is None else "JOINT"
    f.write(f"{ind}{kw} {name}\n{ind}{{\n")
    f.write(f"{ind}  OFFSET {off[0]:.4f} {off[1]:.4f} {off[2]:.4f}\n")
    if parent is None:
        f.write(f"{ind}  CHANNELS 6 Xposition Yposition Zposition "
                "Zrotation Xrotation Yrotation\n")
    else:
        f.write(f"{ind}  CHANNELS 3 Zrotation Xrotation Yrotation\n")
    kids = children_of(name)
    if kids:
        for k in kids:
            write_joint(f, k, depth + 1)
    else:
        f.write(f"{ind}  End Site\n{ind}  {{\n")
        f.write(f"{ind}    OFFSET 0 0.05 0\n{ind}  }}\n")
    f.write(f"{ind}}}\n")


def motion_row(frame):
    t = frame / FPS
    phase = 2 * math.pi * t  # 1 Hz cycle
    swing = 35 * math.sin(phase)       # degrees, arm/leg swing
    bob = 0.03 * abs(math.sin(phase))  # hip bob
    fwd = 0.6 * t                      # walk forward (BVH +Z)

    rot = {name: (0.0, 0.0, 0.0) for name, _, _ in JOINTS}  # (Z, X, Y)
    rot["LeftArm"] = (0.0, swing, 0.0)
    rot["RightArm"] = (0.0, -swing, 0.0)
    rot["LeftForeArm"] = (0.0, -10 - 10 * abs(math.sin(phase)), 0.0)
    rot["RightForeArm"] = (0.0, -10 - 10 * abs(math.sin(phase)), 0.0)
    rot["LeftUpLeg"] = (0.0, -swing, 0.0)
    rot["RightUpLeg"] = (0.0, swing, 0.0)
    rot["LeftLeg"] = (0.0, 15 * max(0.0, math.sin(phase)), 0.0)
    rot["RightLeg"] = (0.0, 15 * max(0.0, -math.sin(phase)), 0.0)
    rot["Spine"] = (3 * math.sin(phase), 0.0, 0.0)
    rot["Head"] = (0.0, 5 * math.sin(0.5 * phase), 0.0)

    vals = [0.0, 0.93 + bob, fwd]  # root Xpos Ypos Zpos
    for name, parent, _ in JOINTS:
        z, x, y = rot[name]
        vals.extend([z, x, y])
    return vals


def main(out_path):
    with open(out_path, "w") as f:
        f.write("HIERARCHY\n")
        write_joint(f, JOINTS[0], 0)
        f.write(f"MOTION\nFrames: {FRAMES}\n")
        f.write(f"Frame Time: {1.0 / FPS:.6f}\n")
        for i in range(FRAMES):
            f.write(" ".join(f"{v:.4f}" for v in motion_row(i)) + "\n")
    print(f"[mirpamo] wrote {out_path} ({FRAMES} frames)")


if __name__ == "__main__":
    main(sys.argv[1] if len(sys.argv) > 1 else "out/test_clip.bvh")