# This code is part of Qiskit.
#
# (C) Copyright IBM 2017, 2024.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.

"""Functions to generate the basic approximations of single qubit gates for Solovay-Kitaev."""

from __future__ import annotations

from qiskit.circuit import Gate
from qiskit.utils.deprecation import deprecate_func
from qiskit._accelerate.synthesis.discrete_basis import GateSequence

from .solovay_kitaev import SolovayKitaevDecomposition


@deprecate_func(
    since="2.1",
    additional_msg=(
        "Use the SolovayKitaevDecomposition class directly, to generate, store, and load the "
        "basic approximations."
    ),
    pending=True,
)
def generate_basic_approximations(
    basis_gates: list[str | Gate], depth: int, filename: str | None = None
) -> list[GateSequence]:
    """Generates a list of :class:`GateSequence`\\ s with the gates in ``basis_gates``.

    Args:
        basis_gates: The gates from which to create the sequences of gates.
        depth: The maximum depth of the approximations.
        filename: If provided, the basic approximations are stored in this file.

    Returns:
        List of :class:`GateSequence`\\ s using the gates in ``basis_gates``.

    Raises:
        ValueError: If ``basis_gates`` contains an invalid gate identifier.
    """
    sk = SolovayKitaevDecomposition(basis_gates=basis_gates, depth=depth)

    if filename is not None:
        sk.save_basic_approximations(filename)

    return sk._sk.get_gate_sequences()