from __future__ import annotations

from pathlib import Path
from typing import Dict, Sequence

import numpy as np

from libs.utils.io_pdb import load_structure


def _residue_centroid(residue) -> np.ndarray | None:
    coords = [atom.coord for atom in residue.get_atoms()]
    if not coords:
        return None
    return np.mean(np.asarray(coords, dtype=float), axis=0)


def compute_structure_features(structure_path: str | Path, pocket_residues: Sequence[str] | None = None) -> Dict[str, float]:
    """Compute structure-derived summary features from PDB/mmCIF."""
    structure = load_structure(structure_path)
    residues = [r for r in structure.get_residues() if r.id[0] == " "]
    atoms = list(structure.get_atoms())

    centroids = []
    for residue in residues:
        c = _residue_centroid(residue)
        if c is not None:
            centroids.append(c)
    if centroids:
        xyz = np.vstack(centroids)
        extent = xyz.max(axis=0) - xyz.min(axis=0)
        mean_extent = float(np.mean(extent))
    else:
        mean_extent = 0.0

    pocket_count = 0.0
    pocket_residue_set = set(pocket_residues or [])
    if pocket_residue_set:
        for residue in residues:
            chain = residue.get_parent().id
            idx = residue.id[1]
            key = f"{chain}:{idx}"
            if key in pocket_residue_set:
                pocket_count += 1.0

    return {
        "residue_count": float(len(residues)),
        "atom_count": float(len(atoms)),
        "mean_spatial_extent": mean_extent,
        "pocket_residue_count": pocket_count,
    }