# Copyright (c) OpenMMLab. All rights reserved.
import importlib
import logging
from abc import ABCMeta
from typing import Any, Callable, Optional, Sequence


class BaseBackendManager(metaclass=ABCMeta):
    """Abstract interface of backend manager."""

    @classmethod
    def build_wrapper(cls,
                      backend_files: Sequence[str],
                      device: str = 'cpu',
                      input_names: Optional[Sequence[str]] = None,
                      output_names: Optional[Sequence[str]] = None,
                      deploy_cfg: Optional[Any] = None,
                      **kwargs):
        """Build the wrapper for the backend model.

        Args:
            backend_files (Sequence[str]): Backend files.
            device (str, optional): The device info. Defaults to 'cpu'.
            input_names (Optional[Sequence[str]], optional): input names.
                Defaults to None.
            output_names (Optional[Sequence[str]], optional): output names.
                Defaults to None.
            deploy_cfg (Optional[Any], optional): The deploy config. Defaults
                to None.
        """
        raise NotImplementedError(
            f'build_wrapper has not been implemented for "{cls.__name__}"')

    @classmethod
    def is_available(cls, with_custom_ops: bool = False) -> bool:
        """Check whether backend is installed.

        Args:
            with_custom_ops (bool): check custom ops exists.

        Returns:
            bool: True if backend package is installed.
        """
        raise NotImplementedError(
            f'is_available has not been implemented for "{cls.__name__}"')

    @classmethod
    def get_version(cls) -> str:
        """Get the version of the backend."""
        raise NotImplementedError(
            f'get_version has not been implemented for "{cls.__name__}"')

    @classmethod
    def check_env(cls, log_callback: Callable = lambda _: _) -> str:
        """Check current environment.

        Returns:
            str: Info about the environment.
        """
        try:
            available = cls.is_available()
            if available:
                try:
                    backend_version = cls.get_version()
                except NotImplementedError:
                    backend_version = 'Unknown'
            else:
                backend_version = 'None'

            info = f'{cls.backend_name}:\t{backend_version}'
        except Exception:
            info = f'{cls.backend_name}:\tCheckFailed'

        log_callback(info)
        return info

    @classmethod
    def to_backend(cls,
                   ir_files: Sequence[str],
                   work_dir: str,
                   deploy_cfg: Any,
                   log_level: int = logging.INFO,
                   device: str = 'cpu',
                   **kwargs) -> Sequence[str]:
        """Convert intermediate representation to given backend.

        Args:
            ir_files (Sequence[str]): The intermediate representation files.
            work_dir (str): The work directory, backend files and logs should
                be save in this directory.
            deploy_cfg (Any): The deploy config.
            log_level (int, optional): The log level. Defaults to logging.INFO.
            device (str, optional): The device type. Defaults to 'cpu'.

        Returns:
            Seqeuence[str]: Backend files.
        """
        raise NotImplementedError(
            f'to_backend has not been implemented for `{cls.__name__}`')


class BackendManagerRegistry:
    """backend manager registry."""

    def __init__(self):
        self._module_dict = {}

    def register(self, name: str, enum_name: Optional[str] = None):
        """register backend manager.

        Args:
            name (str): name of the backend
            enum_name (Optional[str], optional): enum name of the backend.
                if not given, the upper case of name would be used.
        """
        from mmdeploy.utils import get_root_logger
        logger = get_root_logger()

        if enum_name is None:
            enum_name = name.upper()

        def wrap_manager(cls):

            from mmdeploy.utils import Backend

            if not hasattr(Backend, enum_name):
                from aenum import extend_enum
                extend_enum(Backend, enum_name, name)
                logger.info(f'Registry new backend: {enum_name} = {name}.')

            if name in self._module_dict:
                logger.info(
                    f'Backend manager of `{name}` has already been registered.'
                )

            self._module_dict[name] = cls

            cls.backend_name = name

            return cls

        return wrap_manager

    def find(self, name: str) -> BaseBackendManager:
        """Find the backend manager with name.

        Args:
            name (str): backend name.

        Returns:
            BaseBackendManager: backend manager of the given backend.
        """
        # try import backend if backend is in `mmdeploy.backend`
        try:
            importlib.import_module('mmdeploy.backend.' + name)
        except Exception:
            pass
        return self._module_dict.get(name, None)


BACKEND_MANAGERS = BackendManagerRegistry()


def get_backend_manager(name: str) -> BaseBackendManager:
    """Get backend manager.

    Args:
        name (str): name of the backend.

    Returns:
        BaseBackendManager: The backend manager of given name
    """
    from enum import Enum
    if isinstance(name, Enum):
        name = name.value
    return BACKEND_MANAGERS.find(name)
