class PolyMesh(object):
    """
    Class to represent a polygonal mesh with vertices and faces.
    """
    @classmethod
    def from_foam_case(cls, time_folder:str) -> 'PolyMesh':
        poly_mesh_path = Path(time_folder) / "polyMesh"
        if not poly_mesh_path.exists():
            raise FileNotFoundError(f"polyMesh directory not found in {time_folder}")

        # Load points
        points_file = FoamFile(str(poly_mesh_path / "points"))
        points = points_file[None]

        # Load faces
        faces_file = FoamFile(str(poly_mesh_path / "faces"))
        faces = faces_file[None]
        # Check if compactList (binary)
        if isinstance(faces, tuple) and len(faces) == 2:
            # Convert to list of np.ndarrays
            vec1, vec2 = faces
            faces = np.fromiter((vec2[start:stop] for start, stop in zip (vec1[:-1], vec1[1:])), dtype=np.ndarray, count=vec1.size-1)
        
        # Load owners
        owners_file = FoamFile(str(poly_mesh_path / "owner"))
        owners = owners_file[None]

        # Load neighbours
        neighbours_file = FoamFile(str(poly_mesh_path / "neighbour"))
        neighbours = neighbours_file[None]

        # Load boundary
        boundary_file = FoamFile(str(poly_mesh_path / "boundary"))
        boundary = {b:data for b,data in boundary_file[None]}

        return cls(points, faces, owners, neighbours, boundary)

    def __init__(self, points:np.ndarray, faces:np.ndarray[np.ndarray], owners:np.ndarray, neighbours:np.ndarray, boundary:dict[str, dict]) -> None:
        # TODO: Validate inputs
        self.vertices = points.copy()
        self.faces = faces.copy()
        self.owners = owners.copy()
        self.neighbours = neighbours.copy()
        self.boundary = cp.deepcopy(boundary)