# vr_pose.py - the references' wide stance without the bow: feet apart, arms relaxed at the
# sides, hands half closed (a hand-at-the-chest pose needed a twist that turns the shoulder
# block into the chest, so it was dropped). Posed by aiming bones at world directions, parent first.
import bpy, math
from mathutils import Vector as V, Matrix

AIM = [  # bone, world direction (faces -Y, character's left = +X)
    ("thigh_l", (0.07, 0.0, -1)), ("calf_l", (0.06, 0.04, -1)),      # wide hips: legs barely splay
    ("thigh_r", (-0.07, 0.0, -1)), ("calf_r", (-0.06, 0.04, -1)),
]
# arms by hinge: upper arm aimed, twisted about itself, elbow bent about its own axis (Z).
# Elbow flex is +Z on the right side, -Z on the left (mirrored bone axes).
ARMS = {"_r": {"aim": (-0.30, -0.06, -1), "flex": 35, "target": None, "twist": 20},   # relaxed stance, clear of the hip blocks
        "_l": {"aim": (0.30, -0.06, -1), "flex": 35, "target": None, "twist": -20}}
CURL = {"_01": -0.5, "_02": -0.7, "_03": -0.5}       # radians about each finger bone's X (toward the palm)


def _aim(rig, name, d):
    pb = rig.pose.bones[name]
    M = pb.matrix.copy()
    y = V((M[0][1], M[1][1], M[2][1])).normalized()
    q = y.rotation_difference(V(d).normalized())
    R = q.to_matrix().to_4x4()
    t = M.translation.copy()
    N = R @ M; N.translation = t
    pb.matrix = N
    bpy.context.view_layer.update()


def rest(rig=None):
    rig = rig or bpy.data.objects["VR_Rig"]
    for pb in rig.pose.bones:
        pb.matrix_basis = Matrix()
    bpy.context.view_layer.update()


def pose_ref(rig=None):
    rig = rig or bpy.data.objects["VR_Rig"]
    rest(rig)
    feet = {s: rig.pose.bones["foot" + s].matrix.copy() for s in ("_l", "_r")}
    for name, d in AIM:
        _aim(rig, name, d)
    for s_ in ("_l", "_r"):                         # feet stay flat, as in rest
        _aim(rig, "foot" + s_, V((feet[s_][0][1], feet[s_][1][1], feet[s_][2][1])))
    for s_, a in ARMS.items():
        sign = 1 if s_ == "_r" else -1
        def put(tw):
            _aim(rig, "upperarm" + s_, a["aim"])
            ub = rig.pose.bones["upperarm" + s_]
            ub.matrix = ub.matrix @ Matrix.Rotation(math.radians(tw), 4, 'Y')
            lb = rig.pose.bones["lowerarm" + s_]; lb.rotation_mode = 'XYZ'
            lb.rotation_euler = (0, 0, sign * math.radians(a["flex"]))
            bpy.context.view_layer.update()
            return rig.matrix_world @ rig.pose.bones["hand" + s_].head
        if a["target"]:
            best = min(range(-120, 121, 5), key=lambda tw: (put(tw) - V(a["target"])).length)
        else:
            best = a.get("twist", 0)
        put(best); a["used_twist"] = best
    for pb in rig.pose.bones:
        if any(pb.name.startswith(f) for f in ("index", "middle", "ring", "pinky", "thumb")):
            pb.rotation_mode = 'XYZ'
            k = CURL[pb.name[-5:-2]] * (0.6 if pb.name.startswith("thumb") else 1.0)
            pb.rotation_euler = (k, 0, 0)
    head = rig.pose.bones["head"]; head.rotation_mode = 'XYZ'; head.rotation_euler = (math.radians(6), 0, 0)
    bpy.context.view_layer.update()
    # drop the body until the lower foot touches the floor
    dg = bpy.context.evaluated_depsgraph_get()
    zmin = min((o.evaluated_get(dg).matrix_world @ v.co).z
               for o in bpy.data.objects if o.name.startswith(("VR_Foot", "VR_Toe"))
               for v in o.evaluated_get(dg).to_mesh().vertices)
    root = rig.pose.bones["root"]
    root.location = (0, 0, 0)
    bpy.context.view_layer.update()
    rb = rig.pose.bones["root"]
    # root bone's local Y is world +Y, local Z is world +Z (rest), so shift along its local Z axis
    zr = rb.bone.matrix_local.to_3x3().inverted() @ V((0, 0, -zmin))
    rb.location = zr
    bpy.context.view_layer.update()
    return {"dropped": round(zmin, 4)}