text: import email
  import logging
  import re
  import time
  from itertools import takewhile
  from types import TracebackType
  from typing import (
      TYPE_CHECKING,
      Any,
      ClassVar,
      Collection,
      NamedTuple,
      Optional,
      Tuple,
      Union,
  )
  
  from ..exceptions import (
      ConnectTimeoutError,
      InvalidHeader,
      MaxRetryError,
      ProtocolError,
      ProxyError,
      ReadTimeoutError,
      ResponseError,
  )
  from .util import reraise
  
  if TYPE_CHECKING:
      from ..connectionpool import ConnectionPool
      from ..response import HTTPResponse
  
  log = logging.getLogger(__name__)
  
  
  # Data structure for representing the metadata of requests that result in a retry.
  class RequestHistory(NamedTuple):
      method: Optional[str]
      url: Optional[str]
      error: Optional[Exception]
      status: Optional[int]
      redirect_location: Optional[str]
  
  
  class Retry:
      """Retry configuration.
  
      Each retry attempt will create a new Retry object with updated values, so
      they can be safely reused.
  
      Retries can be defined as a default for a pool:
  
      .. code-block:: python
  
          retries = Retry(connect=5, read=2, redirect=5)
          http = PoolManager(retries=retries)
          response = http.request("GET", "https://example.com/")
  
      Or per-request (which overrides the default for the pool):
  
      .. code-block:: python
  
          response = http.request("GET", "https://example.com/", retries=Retry(10))
  
      Retries can be disabled by passing ``False``:
  
      .. code-block:: python
  
          response = http.request("GET", "https://example.com/", retries=False)
  
      Errors will be wrapped in :class:`~urllib3.exceptions.MaxRetryError` unless
      retries are disabled, in which case the causing exception will be raised.
  
      :param int total:
          Total number of retries to allow. Takes precedence over other counts.
  
          Set to ``None`` to remove this constraint and fall back on other
          counts.
  
          Set to ``0`` to fail on the first retry.
  
          Set to ``False`` to disable and imply ``raise_on_redirect=False``.
  
      :param int connect:
          How many connection-related errors to retry on.
  
          These are errors raised before the request is sent to the remote server,
          which we assume has not triggered the server to process the request.
  
          Set to ``0`` to fail on the first retry of this type.
  
      :param int read:
          How many times to retry on read errors.
  
          These errors are raised after the request was sent to the server, so the
          request may have side-effects.
  
          Set to ``0`` to fail on the first retry of this type.
  
      :param int redirect:
          How many redirects to perform. Limit this to avoid infinite redirect
          loops.
  
          A redirect is a HTTP response with a status code 301, 302, 303, 307 or
          308.
  
          Set to ``0`` to fail on the first retry of this type.
  
          Set to ``False`` to disable and imply ``raise_on_redirect=False``.
  
      :param int status:
          How many times to retry on bad status codes.
  
          These are retries made on responses, where status code matches
          ``status_forcelist``.
  
          Set to ``0`` to fail on the first retry of this type.
  
      :param int other:
          How many times to retry on other errors.
  
          Other errors are errors that are not connect, read, redirect or status errors.
          These errors might be raised after the request was sent to the server, so the
          request might have side-effects.
  
          Set to ``0`` to fail on the first retry of this type.
  
          If ``total`` is not set, it's a good idea to set this to 0 to account
          for unexpected edge cases and avoid infinite retry loops.
  
      :param iterable allowed_methods:
          Set of uppercased HTTP method verbs that we should retry on.
  
          By default, we only retry on methods which are considered to be
          idempotent (multiple requests with the same parameters end with the
          same state). See :attr:`Retry.DEFAULT_ALLOWED_METHODS`.
  
          Set to a ``None`` value to retry on any verb.
  
      :param iterable status_forcelist:
          A set of integer HTTP status codes that we should force a retry on.
          A retry is initiated if the request method is in ``allowed_methods``
          and the response status code is in ``status_forcelist``.
  
          By default, this is disabled with ``None``.
  
      :param float backoff_factor:
          A backoff factor to apply between attempts after the second try
          (most errors are resolved immediately by a second try without a
          delay). urllib3 will sleep for::
  
              {backoff factor} * (2 ** ({number of total retries} - 1))
  
          seconds. If the backoff_factor is 0.1, then :func:`.sleep` will sleep
          for [0.0s, 0.2s, 0.4s, ...] between retries. It will never be longer
          than :attr:`Retry.BACKOFF_MAX`.
  
          By default, backoff is disabled (set to 0).
  
      :param bool raise_on_redirect: Whether, if the number of redirects is
          exhausted, to raise a MaxRetryError, or to return a response with a
          response code in the 3xx range.
  
      :param bool raise_on_status: Similar meaning to ``raise_on_redirect``:
          whether we should raise an exception, or return a response,
          if status falls in ``status_forcelist`` range and retries have
          been exhausted.
  
      :param tuple history: The history of the request encountered during
          each call to :meth:`~Retry.increment`. The list is in the order
          the requests occurred. Each list item is of class :class:`RequestHistory`.
  
      :param bool respect_retry_after_header:
          Whether to respect Retry-After header on status codes defined as
          :attr:`Retry.RETRY_AFTER_STATUS_CODES` or not.
  
      :param iterable remove_headers_on_redirect:
          Sequence of headers to remove from the request when a response
          indicating a redirect is returned before firing off the redirected
          request.
      """
  
      #: Default methods to be used for ``allowed_methods``
      DEFAULT_ALLOWED_METHODS = frozenset(
          ["HEAD", "GET", "PUT", "DELETE", "OPTIONS", "TRACE"]
      )
  
      #: Default status codes to be used for ``status_forcelist``
      RETRY_AFTER_STATUS_CODES = frozenset([413, 429, 503])
  
      #: Default headers to be used for ``remove_headers_on_redirect``
      DEFAULT_REMOVE_HEADERS_ON_REDIRECT = frozenset(["Authorization"])
  
      #: Maximum backoff time.
      BACKOFF_MAX = 120
  
      # Backward compatibility; assigned outside of the class.
      DEFAULT: ClassVar["Retry"]
  
      def __init__(
          self,
          total: Optional[Union[bool, int]] = 10,
          connect: Optional[int] = None,
          read: Optional[int] = None,
          redirect: Optional[Union[bool, int]] = None,
          status: Optional[int] = None,
          other: Optional[int] = None,
          allowed_methods: Optional[Collection[str]] = DEFAULT_ALLOWED_METHODS,
          status_forcelist: Optional[Collection[int]] = None,
          backoff_factor: float = 0,
          raise_on_redirect: bool = True,
          raise_on_status: bool = True,
          history: Optional[Tuple[RequestHistory, ...]] = None,
          respect_retry_after_header: bool = True,
          remove_headers_on_redirect: Collection[
              str
          ] = DEFAULT_REMOVE_HEADERS_ON_REDIRECT,
      ) -> None:
          self.total = total
          self.connect = connect
          self.read = read
          self.status = status
          self.other = other
  
          if redirect is False or total is False:
              redirect = 0
              raise_on_redirect = False
  
          self.redirect = redirect
          self.status_forcelist = status_forcelist or set()
          self.allowed_methods = allowed_methods
          self.backoff_factor = backoff_factor
          self.raise_on_redirect = raise_on_redirect
          self.raise_on_status = raise_on_status
          self.history = history or ()
          self.respect_retry_after_header = respect_retry_after_header
          self.remove_headers_on_redirect = frozenset(
              h.lower() for h in remove_headers_on_redirect
          )
  
      def new(self, **kw: Any) -> "Retry":
          params = dict(
              total=self.total,
              connect=self.connect,
              read=self.read,
              redirect=self.redirect,
              status=self.status,
              other=self.other,
              allowed_methods=self.allowed_methods,
              status_forcelist=self.status_forcelist,
              backoff_factor=self.backoff_factor,
              raise_on_redirect=self.raise_on_redirect,
              raise_on_status=self.raise_on_status,
              history=self.history,
              remove_headers_on_redirect=self.remove_headers_on_redirect,
              respect_retry_after_header=self.respect_retry_after_header,
          )
  
          params.update(kw)
          return type(self)(**params)  # type: ignore[arg-type]
  
      @classmethod
      def from_int(
          cls,
          retries: Optional[Union["Retry", bool, int]],
          redirect: Optional[Union[bool, int]] = True,
          default: Optional[Union["Retry", bool, int]] = None,
      ) -> "Retry":
          """Backwards-compatibility for the old retries format."""
          if retries is None:
              retries = default if default is not None else cls.DEFAULT
  
          if isinstance(retries, Retry):
              return retries
  
          redirect = bool(redirect) and None
          new_retries = cls(retries, redirect=redirect)
          log.debug("Converted retries value: %r -> %r", retries, new_retries)
          return new_retries
  
      def get_backoff_time(self) -> float:
          """Formula for computing the current backoff
  
          :rtype: float
          """
          # We want to consider only the last consecutive errors sequence (Ignore redirects).
          consecutive_errors_len = len(
              list(
                  takewhile(lambda x: x.redirect_location is None, reversed(self.history))
              )
          )
          if consecutive_errors_len <= 1:
              return 0
  
          backoff_value = self.backoff_factor * (2 ** (consecutive_errors_len - 1))
          return float(min(self.BACKOFF_MAX, backoff_value))
  
      def parse_retry_after(self, retry_after: str) -> float:
          seconds: float
          # Whitespace: https://tools.ietf.org/html/rfc7230#section-3.2.4
          if re.match(r"^\s*[0-9]+\s*$", retry_after):
              seconds = int(retry_after)
          else:
              retry_date_tuple = email.utils.parsedate_tz(retry_after)
              if retry_date_tuple is None:
                  raise InvalidHeader(f"Invalid Retry-After header: {retry_after}")
  
              retry_date = email.utils.mktime_tz(retry_date_tuple)
              seconds = retry_date - time.time()
  
          seconds = max(seconds, 0)
  
          return seconds
  
      def get_retry_after(self, response: "HTTPResponse") -> Optional[float]:
          """Get the value of Retry-After in seconds."""
  
          retry_after = response.getheader("Retry-After")
  
          if retry_after is None:
              return None
  
          return self.parse_retry_after(retry_after)
  
      def sleep_for_retry(self, response: "HTTPResponse") -> bool:
          retry_after = self.get_retry_after(response)
          if retry_after:
              time.sleep(retry_after)
              return True
  
          return False
  
      def _sleep_backoff(self) -> None:
          backoff = self.get_backoff_time()
          if backoff <= 0:
              return
          time.sleep(backoff)
  
      def sleep(self, response: Optional["HTTPResponse"] = None) -> None:
          """Sleep between retry attempts.
  
          This method will respect a server's ``Retry-After`` response header
          and sleep the duration of the time requested. If that is not present, it
          will use an exponential backoff. By default, the backoff factor is 0 and
          this method will return immediately.
          """
  
          if self.respect_retry_after_header and response:
              slept = self.sleep_for_retry(response)
              if slept:
                  return
  
          self._sleep_backoff()
  
      def _is_connection_error(self, err: Exception) -> bool:
          """Errors when we're fairly sure that the server did not receive the
          request, so it should be safe to retry.
          """
          if isinstance(err, ProxyError):
              err = err.original_error
          return isinstance(err, ConnectTimeoutError)
  
      def _is_read_error(self, err: Exception) -> bool:
          """Errors that occur after the request has been started, so we should
          assume that the server began processing it.
          """
          return isinstance(err, (ReadTimeoutError, ProtocolError))
  
      def _is_method_retryable(self, method: str) -> bool:
          """Checks if a given HTTP method should be retried upon, depending if
          it is included in the allowed_methods
          """
          if self.allowed_methods and method.upper() not in self.allowed_methods:
              return False
          return True
  
      def is_retry(
          self, method: str, status_code: int, has_retry_after: bool = False
      ) -> bool:
          """Is this method/status code retryable? (Based on allowlists and control
          variables such as the number of total retries to allow, whether to
          respect the Retry-After header, whether this header is present, and
          whether the returned status code is on the list of status codes to
          be retried upon on the presence of the aforementioned header)
          """
          if not self._is_method_retryable(method):
              return False
  
          if self.status_forcelist and status_code in self.status_forcelist:
              return True
  
          return bool(
              self.total
              and self.respect_retry_after_header
              and has_retry_after
              and (status_code in self.RETRY_AFTER_STATUS_CODES)
          )
  
      def is_exhausted(self) -> bool:
          """Are we out of retries?"""
          retry_counts = [
              x
              for x in (
                  self.total,
                  self.connect,
                  self.read,
                  self.redirect,
                  self.status,
                  self.other,
              )
              if x
          ]
          if not retry_counts:
              return False
  
          return min(retry_counts) < 0
  
      def increment(
          self,
          method: Optional[str] = None,
          url: Optional[str] = None,
          response: Optional["HTTPResponse"] = None,
          error: Optional[Exception] = None,
          _pool: Optional["ConnectionPool"] = None,
          _stacktrace: Optional[TracebackType] = None,
      ) -> "Retry":
          """Return a new Retry object with incremented retry counters.
  
          :param response: A response object, or None, if the server did not
              return a response.
          :type response: :class:`~urllib3.response.HTTPResponse`
          :param Exception error: An error encountered during the request, or
              None if the response was received successfully.
  
          :return: A new ``Retry`` object.
          """
          if self.total is False and error:
              # Disabled, indicate to re-raise the error.
              raise reraise(type(error), error, _stacktrace)
  
          total = self.total
          if total is not None:
              total -= 1
  
          connect = self.connect
          read = self.read
          redirect = self.redirect
          status_count = self.status
          other = self.other
          cause = "unknown"
          status = None
          redirect_location = None
  
          if error and self._is_connection_error(error):
              # Connect retry?
              if connect is False:
                  raise reraise(type(error), error, _stacktrace)
              elif connect is not None:
                  connect -= 1
  
          elif error and self._is_read_error(error):
              # Read retry?
              if read is False or method is None or not self._is_method_retryable(method):
                  raise reraise(type(error), error, _stacktrace)
              elif read is not None:
                  read -= 1
  
          elif error:
              # Other retry?
              if other is not None:
                  other -= 1
  
          elif response and response.get_redirect_location():
              # Redirect retry?
              if redirect is not None:
                  redirect -= 1
              cause = "too many redirects"
              response_redirect_location = response.get_redirect_location()
              if response_redirect_location:
                  redirect_location = response_redirect_location
              status = response.status
  
          else:
              # Incrementing because of a server error like a 500 in
              # status_forcelist and the given method is in the allowed_methods
              cause = ResponseError.GENERIC_ERROR
              if response and response.status:
                  if status_count is not None:
                      status_count -= 1
                  cause = ResponseError.SPECIFIC_ERROR.format(status_code=response.status)
                  status = response.status
  
          history = self.history + (
              RequestHistory(method, url, error, status, redirect_location),
          )
  
          new_retry = self.new(
              total=total,
              connect=connect,
              read=read,
              redirect=redirect,
              status=status_count,
              other=other,
              history=history,
          )
  
          if new_retry.is_exhausted():
              reason = error or ResponseError(cause)
              raise MaxRetryError(_pool, url, reason) from reason  # type: ignore[arg-type]
  
          log.debug("Incremented Retry for (url='%s'): %r", url, new_retry)
  
          return new_retry
  
      def __repr__(self) -> str:
          return (
              f"{type(self).__name__}(total={self.total}, connect={self.connect}, "
              f"read={self.read}, redirect={self.redirect}, status={self.status})"
          )
  
  
  # For backwards compatibility (equivalent to pre-v1.9):
  Retry.DEFAULT = Retry(3)
  