import abc
import os
from pathlib import Path
from tempfile import TemporaryDirectory
from typing import Generic, Callable, Iterable, Optional, TypeVar, Union

from .cloudpath import CloudImplementation, CloudPath, implementation_registry

BoundedCloudPath = TypeVar("BoundedCloudPath", bound=CloudPath)


def register_client_class(key: str) -> Callable:
    def decorator(cls: type) -> type:
        if not issubclass(cls, Client):
            raise TypeError("Only subclasses of Client can be registered.")
        implementation_registry[key]._client_class = cls
        implementation_registry[key].name = key
        cls._cloud_meta = implementation_registry[key]
        return cls

    return decorator


class Client(abc.ABC, Generic[BoundedCloudPath]):
    _cloud_meta: CloudImplementation
    _default_client = None

    def __init__(self, local_cache_dir: Optional[Union[str, os.PathLike]] = None):
        self._cloud_meta.validate_completeness()
        # setup caching and local versions of file and track if it is a tmp dir
        self._cache_tmp_dir = None
        if local_cache_dir is None:
            self._cache_tmp_dir = TemporaryDirectory()
            local_cache_dir = self._cache_tmp_dir.name

        self._local_cache_dir = Path(local_cache_dir)

    def __del__(self) -> None:
        # make sure temp is cleaned up if we created it
        if self._cache_tmp_dir is not None:
            self._cache_tmp_dir.cleanup()

    @classmethod
    def get_default_client(cls) -> "Client":
        """Get the default client, which the one that is used when instantiating a cloud path
        instance for this cloud without a client specified.
        """
        if cls._default_client is None:
            cls._default_client = cls()
        return cls._default_client

    def set_as_default_client(self) -> None:
        """Set this client instance as the default one used when instantiating cloud path
        instances for this cloud without a client specified."""
        self.__class__._default_client = self

    def CloudPath(self, cloud_path: Union[str, BoundedCloudPath]) -> BoundedCloudPath:
        return self._cloud_meta.path_class(cloud_path=cloud_path, client=self)

    @abc.abstractmethod
    def _download_file(
        self, cloud_path: BoundedCloudPath, local_path: Union[str, os.PathLike]
    ) -> Path:
        pass

    @abc.abstractmethod
    def _exists(self, cloud_path: BoundedCloudPath) -> bool:
        pass

    @abc.abstractmethod
    def _list_dir(
        self, cloud_path: BoundedCloudPath, recursive: bool
    ) -> Iterable[BoundedCloudPath]:
        """List all the files and folders in a directory.

        Parameters
        ----------
        cloud_path : CloudPath
            The folder to start from.
        recursive : bool
            Whether or not to list recursively.
        """
        pass

    @abc.abstractmethod
    def _move_file(
        self, src: BoundedCloudPath, dst: BoundedCloudPath, remove_src: bool = True
    ) -> BoundedCloudPath:
        pass

    @abc.abstractmethod
    def _remove(self, path: BoundedCloudPath) -> None:
        """Remove a file or folder from the server.

        Parameters
        ----------
        path : CloudPath
            The file or folder to remove.
        """
        pass

    @abc.abstractmethod
    def _upload_file(
        self, local_path: Union[str, os.PathLike], cloud_path: BoundedCloudPath
    ) -> BoundedCloudPath:
        pass
