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import base64
import logging
import threading
import uuid
try:
    from urlparse import urlparse # type: ignore # pylint: disable=unused-import
except ImportError:
    from urllib.parse import urlparse

from typing import TYPE_CHECKING, TypeVar, Generic
from azure.core.exceptions import AzureError
from azure.core.tracing.decorator import distributed_trace
from azure.core.tracing.common import with_current_context

if TYPE_CHECKING:
    from typing import Any, Callable, Union, List, Optional, Tuple


PollingReturnType = TypeVar("PollingReturnType")

_LOGGER = logging.getLogger(__name__)


class PollingMethod(Generic[PollingReturnType]):
    """ABC class for polling method.
    """
    def initialize(self, client, initial_response, deserialization_callback):
        # type: (Any, Any, Any) -> None
        raise NotImplementedError("This method needs to be implemented")

    def run(self):
        # type: () -> None
        raise NotImplementedError("This method needs to be implemented")

    def status(self):
        # type: () -> str
        raise NotImplementedError("This method needs to be implemented")

    def finished(self):
        # type: () -> bool
        raise NotImplementedError("This method needs to be implemented")

    def resource(self):
        # type: () -> PollingReturnType
        raise NotImplementedError("This method needs to be implemented")

    def get_continuation_token(self):
        # type() -> str
        raise TypeError(
            "Polling method '{}' doesn't support get_continuation_token".format(
                self.__class__.__name__
            )
        )

    @classmethod
    def from_continuation_token(cls, continuation_token, **kwargs):
        # type(str, Any) -> Tuple[Any, Any, Callable]
        raise TypeError(
            "Polling method '{}' doesn't support from_continuation_token".format(
                cls.__name__
            )
        )


class NoPolling(PollingMethod):
    """An empty poller that returns the deserialized initial response.
    """
    def __init__(self):
        self._initial_response = None
        self._deserialization_callback = None

    def initialize(self, _, initial_response, deserialization_callback):
        # type: (Any, Any, Callable) -> None
        self._initial_response = initial_response
        self._deserialization_callback = deserialization_callback

    def run(self):
        # type: () -> None
        """Empty run, no polling.
        """

    def status(self):
        # type: () -> str
        """Return the current status as a string.

        :rtype: str
        """
        return "succeeded"

    def finished(self):
        # type: () -> bool
        """Is this polling finished?

        :rtype: bool
        """
        return True

    def resource(self):
        # type: () -> Any
        return self._deserialization_callback(self._initial_response)

    def get_continuation_token(self):
        # type() -> str
        import pickle
        return base64.b64encode(pickle.dumps(self._initial_response)).decode('ascii')

    @classmethod
    def from_continuation_token(cls, continuation_token, **kwargs):
        # type(str, Any) -> Tuple
        try:
            deserialization_callback = kwargs["deserialization_callback"]
        except KeyError:
            raise ValueError("Need kwarg 'deserialization_callback' to be recreated from continuation_token")
        import pickle
        initial_response = pickle.loads(base64.b64decode(continuation_token))   # nosec
        return None, initial_response, deserialization_callback


class LROPoller(Generic[PollingReturnType]):
    """Poller for long running operations.

    :param client: A pipeline service client
    :type client: ~azure.core.PipelineClient
    :param initial_response: The initial call response
    :type initial_response: ~azure.core.pipeline.PipelineResponse
    :param deserialization_callback: A callback that takes a Response and return a deserialized object.
                                     If a subclass of Model is given, this passes "deserialize" as callback.
    :type deserialization_callback: callable or msrest.serialization.Model
    :param polling_method: The polling strategy to adopt
    :type polling_method: ~azure.core.polling.PollingMethod
    """

    def __init__(self, client, initial_response, deserialization_callback, polling_method):
        # type: (Any, Any, Callable, PollingMethod[PollingReturnType]) -> None
        self._callbacks = []  # type: List[Callable]
        self._polling_method = polling_method

        # This implicit test avoids bringing in an explicit dependency on Model directly
        try:
            deserialization_callback = deserialization_callback.deserialize # type: ignore
        except AttributeError:
            pass

        # Might raise a CloudError
        self._polling_method.initialize(client, initial_response, deserialization_callback)

        # Prepare thread execution
        self._thread = None
        self._done = None
        self._exception = None
        if not self._polling_method.finished():
            self._done = threading.Event()
            self._thread = threading.Thread(
                target=with_current_context(self._start),
                name="LROPoller({})".format(uuid.uuid4()))
            self._thread.daemon = True
            self._thread.start()

    def _start(self):
        """Start the long running operation.
        On completion, runs any callbacks.

        :param callable update_cmd: The API request to check the status of
         the operation.
        """
        try:
            self._polling_method.run()
        except AzureError as error:
            if not error.continuation_token:
                try:
                    error.continuation_token = self.continuation_token()
                except Exception as err:  # pylint: disable=broad-except
                    _LOGGER.warning("Unable to retrieve continuation token: %s", err)
                    error.continuation_token = None

            self._exception = error
        except Exception as error:  # pylint: disable=broad-except
            self._exception = error

        finally:
            self._done.set()

        callbacks, self._callbacks = self._callbacks, []
        while callbacks:
            for call in callbacks:
                call(self._polling_method)
            callbacks, self._callbacks = self._callbacks, []

    def polling_method(self):
        # type: () -> PollingMethod[PollingReturnType]
        """Return the polling method associated to this poller.
        """
        return self._polling_method

    def continuation_token(self):
        # type: () -> str
        """Return a continuation token that allows to restart the poller later.

        :returns: An opaque continuation token
        :rtype: str
        """
        return self._polling_method.get_continuation_token()

    @classmethod
    def from_continuation_token(cls, polling_method, continuation_token, **kwargs):
        # type: (PollingMethod[PollingReturnType], str, Any) -> LROPoller[PollingReturnType]
        client, initial_response, deserialization_callback = polling_method.from_continuation_token(
            continuation_token, **kwargs
        )
        return cls(client, initial_response, deserialization_callback, polling_method)

    def status(self):
        # type: () -> str
        """Returns the current status string.

        :returns: The current status string
        :rtype: str
        """
        return self._polling_method.status()

    def result(self, timeout=None):
        # type: (Optional[int]) -> PollingReturnType
        """Return the result of the long running operation, or
        the result available after the specified timeout.

        :returns: The deserialized resource of the long running operation,
         if one is available.
        :raises ~azure.core.exceptions.HttpResponseError: Server problem with the query.
        """
        self.wait(timeout)
        return self._polling_method.resource()

    @distributed_trace
    def wait(self, timeout=None):
        # type: (Optional[float]) -> None
        """Wait on the long running operation for a specified length
        of time. You can check if this call as ended with timeout with the
        "done()" method.

        :param float timeout: Period of time to wait for the long running
         operation to complete (in seconds).
        :raises ~azure.core.exceptions.HttpResponseError: Server problem with the query.
        """
        if self._thread is None:
            return
        self._thread.join(timeout=timeout)
        try:
            # Let's handle possible None in forgiveness here
            # https://github.com/python/mypy/issues/8165
            raise self._exception # type: ignore
        except TypeError: # Was None
            pass

    def done(self):
        # type: () -> bool
        """Check status of the long running operation.

        :returns: 'True' if the process has completed, else 'False'.
        :rtype: bool
        """
        return self._thread is None or not self._thread.is_alive()

    def add_done_callback(self, func):
        # type: (Callable) -> None
        """Add callback function to be run once the long running operation
        has completed - regardless of the status of the operation.

        :param callable func: Callback function that takes at least one
         argument, a completed LongRunningOperation.
        """
        # Still use "_done" and not "done", since CBs are executed inside the thread.
        if self._done is None or self._done.is_set():
            func(self._polling_method)
        # Let's add them still, for consistency (if you wish to access to it for some reasons)
        self._callbacks.append(func)

    def remove_done_callback(self, func):
        # type: (Callable) -> None
        """Remove a callback from the long running operation.

        :param callable func: The function to be removed from the callbacks.
        :raises ValueError: if the long running operation has already completed.
        """
        if self._done is None or self._done.is_set():
            raise ValueError("Process is complete.")
        self._callbacks = [c for c in self._callbacks if c != func]
