# This code is part of Qiskit.
#
# (C) Copyright IBM 2021.
#
# 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.

"""A quantum oracle constructed from a logical expression or a string in the DIMACS format."""

from abc import ABCMeta, abstractmethod

from qiskit.circuit import Gate


class ClassicalElement(Gate, metaclass=ABCMeta):
    """The classical element gate."""

    @abstractmethod
    def simulate(self, bitstring: str) -> bool:
        """Evaluate the expression on a bitstring.

        This evaluation is done classically.

        Args:
            bitstring: The bitstring for which to evaluate.

        Returns:
            bool: result of the evaluation.
        """
        pass

    @abstractmethod
    def synth(self, registerless=True, synthesizer=None):
        """Synthesis the logic network into a :class:`~qiskit.circuit.QuantumCircuit`.

        Args:
            registerless (bool): Default ``True``. If ``False`` uses the parameter names
                to create registers with those names. Otherwise, creates a circuit with a flat
                quantum register.
            synthesizer (callable): A callable that takes a Logic Network and returns a Tweedledum
                circuit.
        Returns:
            QuantumCircuit: A circuit implementing the logic network.
        """
        pass

    def _define(self):
        """The definition of the boolean expression is its synthesis"""
        self.definition = self.synth()