# This code is part of Qiskit.
#
# (C) Copyright IBM 2017, 2018.
#
# 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.

"""Check if a DAG circuit is already mapped to a coupling map."""

from qiskit.transpiler.basepasses import AnalysisPass
from qiskit.transpiler.target import Target, _FakeTarget
from qiskit._accelerate import check_map


class CheckMap(AnalysisPass):
    """Check if a DAG circuit is already mapped to a coupling map.

    Check if a DAGCircuit is mapped to ``coupling_map`` by checking that all
    2-qubit interactions are laid out to be on adjacent qubits in the global coupling
    map of the device, setting the property set field (either specified with ``property_set_field``
    or the default ``is_swap_mapped``) to ``True`` or ``False`` accordingly. Note this does not
    validate directionality of the connectivity between  qubits. If you need to check gates are
    implemented in a native direction for a target use the :class:`~.CheckGateDirection` pass
    instead.
    """

    def __init__(self, coupling_map, property_set_field=None):
        """CheckMap initializer.

        Args:
            coupling_map (Union[CouplingMap, Target]): Directed graph representing a coupling map.
            property_set_field (str): An optional string to specify the property set field to
                store the result of the check. If not provided the result is stored in
                the property set field ``"is_swap_mapped"``.
        """
        super().__init__()
        if property_set_field is None:
            self.property_set_field = "is_swap_mapped"
        else:
            self.property_set_field = property_set_field
        if isinstance(coupling_map, Target):
            if isinstance(coupling_map, _FakeTarget):
                self._target = Target.from_configuration(
                    ["u", "cx"], coupling_map=coupling_map.build_coupling_map()
                )
            else:
                self._target = coupling_map
        else:
            self._target = Target.from_configuration(["u", "cx"], coupling_map=coupling_map)
        self._qargs = None

    def run(self, dag):
        """Run the CheckMap pass on `dag`.

        If ``dag`` is mapped to the configured :class:`.Target`, the property whose name is
        specified in ``self.property_set_field`` is set to ``True`` (or to ``False`` otherwise).

        Args:
            dag (DAGCircuit): DAG to map.
        """
        if self._target.qargs is None or not any(
            len(x) == 2 for x in self._target.qargs if x is not None
        ):
            self.property_set[self.property_set_field] = True
            return
        res = check_map.check_map(dag, self._target)
        if res is None:
            self.property_set[self.property_set_field] = True
            return
        self.property_set[self.property_set_field] = False
        self.property_set["check_map_msg"] = (
            f"{res[0]}({dag.qubits[res[1][0]]}, {dag.qubits[res[1][1]]}) failed"
        )