"""The 620 output points as locations on the GNM Head mesh (points_gnm.json)."""

import json
import os

import numpy as np

DEFAULT = os.path.join(os.path.dirname(os.path.abspath(__file__)), "points_gnm.json")


def load_points(path=DEFAULT):
    """Return the point rows in output order: dicts with index, class, region, vertices, weights."""
    with open(path, encoding="utf-8") as fh:
        return json.load(fh)["points"]


def gnm_positions(vertices_xyz, points=None):
    """Return (620, 3) positions of the points on a posed GNM Head mesh from its (V, 3) vertices."""
    points = load_points() if points is None else points
    V = np.asarray(vertices_xyz, np.float64)
    out = np.zeros((len(points), 3), np.float64)
    for p in points:
        out[p["index"]] = np.asarray(p["weights"], np.float64) @ V[p["vertices"]]
    return out