Source code for qurry.tools.backend.import_simulator

"""Import Simulator (:mod:`qurry.tools.backend.import_simulator`)

This module provides the default simulator for Qurrium.
For the simulator, the following sources are considered:

- qiskit_aer
- qiskit.providers.aer
- qiskit.providers.basicaer
- qiskit.providers.basic_provider

which are used in different qiskit, qiskit-aer version,
and ordered by priority.
"""

from typing import Literal, Type, Optional, Any
from qiskit.providers import BackendV2, Backend

from ..qiskit_version import QISKIT_VERSION
from .utils import backend_name_getter


# pylint: disable=ungrouped-imports
ImportPointType = Literal[
    "qiskit_aer",
    "qiskit.providers.aer",
    "qiskit.providers.basicaer",
    "qiskit.providers.basic_provider",
]
ImportPointOrder = [
    "qiskit_aer",
    "qiskit.providers.basic_provider",
    "qiskit.providers.basicaer",
    "qiskit.providers.aer",
]
SIMULATOR_SOURCES: dict[ImportPointType, Type[Backend]] = {}
SIM_BACKEND_SOURCES: dict[ImportPointType, Type[Backend]] = {}
SIM_PROVIDER_SOURCES: dict[ImportPointType, Type[Any]] = {}
SIM_VERSION_INFOS: dict[ImportPointType, Optional[str]] = {}
SIM_IMPORT_ERROR_INFOS: dict[ImportPointType, ImportError] = {}

try:
    from qiskit_aer import AerProvider, AerSimulator  # type: ignore
    from qiskit_aer.backends.aerbackend import AerBackend  # type: ignore
    from qiskit_aer.version import get_version_info as get_version_info_aer  # type: ignore

    SIM_VERSION_INFOS["qiskit_aer"] = get_version_info_aer()
    SIMULATOR_SOURCES["qiskit_aer"] = AerSimulator
    SIM_BACKEND_SOURCES["qiskit_aer"] = AerBackend
    SIM_PROVIDER_SOURCES["qiskit_aer"] = AerProvider  # type: ignore
    # wtf, AerProvider is not inherited from Provider for qiskit-aer 0.15.0
except ImportError as err:
    SIM_IMPORT_ERROR_INFOS["qiskit_aer"] = err

try:
    from qiskit.providers.basic_provider import BasicSimulator, BasicProvider  # type: ignore

    SIM_VERSION_INFOS["qiskit.providers.basic_provider"] = QISKIT_VERSION.get("qiskit")
    SIMULATOR_SOURCES["qiskit.providers.basic_provider"] = BasicSimulator
    SIM_BACKEND_SOURCES["qiskit.providers.basic_provider"] = BackendV2
    SIM_PROVIDER_SOURCES["qiskit.providers.basic_provider"] = BasicProvider
except ImportError as err:
    SIM_IMPORT_ERROR_INFOS["qiskit.providers.basic_provider"] = err

try:
    from qiskit.providers.aer import (  # type: ignore
        AerProvider as AerProviderDep,  # type: ignore
        AerSimulator as AerSimulatorDep,  # type: ignore
    )
    from qiskit.providers.aer.backends.aerbackend import (  # type: ignore
        AerBackend as AerBackendDep,
    )  # type: ignore
    from qiskit.providers.aer.version import VERSION  # type: ignore

    SIM_VERSION_INFOS["qiskit.providers.aer"] = VERSION
    SIMULATOR_SOURCES["qiskit.providers.aer"] = AerSimulatorDep
    SIM_BACKEND_SOURCES["qiskit.providers.aer"] = AerBackendDep
    SIM_PROVIDER_SOURCES["qiskit.providers.aer"] = AerProviderDep
except ImportError as err:
    SIM_IMPORT_ERROR_INFOS["qiskit.providers.aer"] = err

try:
    from qiskit.providers.basicaer.basicaerprovider import (  # type: ignore
        BasicAerProvider,
        QasmSimulatorPy,
    )

    SIM_VERSION_INFOS["qiskit.providers.basicaer"] = QISKIT_VERSION.get("qiskit")
    SIMULATOR_SOURCES["qiskit.providers.basicaer"] = QasmSimulatorPy
    SIM_BACKEND_SOURCES["qiskit.providers.basicaer"] = Backend
    SIM_PROVIDER_SOURCES["qiskit.providers.basicaer"] = BasicAerProvider
except ImportError as err:
    SIM_IMPORT_ERROR_INFOS["qiskit.providers.basicaer"] = err




def get_default_sim_source() -> ImportPointType:
    """Get the default source for the simulator.

    Returns:
        ImportPointType: The default source for the simulator.

    Raises:
        ImportError: If no available simulator source is found.
    """

    for source in ImportPointOrder:
        if source in SIMULATOR_SOURCES:
            return source
    raise ImportError("No available simulator source, please check the installation of qiskit.")



SIM_DEFAULT_SOURCE: ImportPointType = get_default_sim_source()


# pylint: disable=too-few-public-methods


class GeneralSimulator(SIMULATOR_SOURCES[SIM_DEFAULT_SOURCE]):
    """Default simulator."""

    def __repr__(self):
        if SIM_DEFAULT_SOURCE == "qiskit.providers.basicaer":
            return f"<QasmSimulatorPy('{backend_name_getter(self)}')>"
        if SIM_DEFAULT_SOURCE == "qiskit.providers.basic_provider":
            return f"<BasicSimulator('{backend_name_getter(self)}')>"
        if SIM_DEFAULT_SOURCE == "qiskit_aer":
            return f"<AerSimulator('{backend_name_getter(self)}')>"
        return f"<UnknownSimulator('{backend_name_getter(self)}')>"





class GeneralBackend(SIM_BACKEND_SOURCES[SIM_DEFAULT_SOURCE]):
    """The abstract class of default simulator."""