"""

requests.sessions

~~~~~~~~~~~~~~~~~

This module provides a Session object to manage and persist settings across

requests (cookies, auth, proxies).

"""

from __future__ import annotations

import os

import sys

import time

from collections import OrderedDict

from collections.abc import Generator, Mapping, MutableMapping

from datetime import timedelta

from typing import TYPE_CHECKING, Any, cast

from ._internal_utils import to_native_string

from ._types import is_prepared as _is_prepared

from .adapters import HTTPAdapter

from .auth import _basic_auth_str  # type: ignore[reportPrivateUsage]

from .compat import cookielib, urljoin, urlparse

from .cookies import (

    RequestsCookieJar,

    cookiejar_from_dict,

    extract_cookies_to_jar,

    merge_cookies,

)

from .exceptions import (

    ChunkedEncodingError,

    ContentDecodingError,

    InvalidSchema,

    TooManyRedirects,

)

from .hooks import default_hooks, dispatch_hook

# formerly defined here, reexposed here for backward compatibility

from .models import (  # noqa: F401

    DEFAULT_REDIRECT_LIMIT,

    REDIRECT_STATI,  # type: ignore[reportUnusedImport]

    PreparedRequest,

    Request,

    Response,

)

from .status_codes import codes

from .structures import CaseInsensitiveDict

from .utils import (  # noqa: F401

    DEFAULT_PORTS,

    default_headers,

    get_auth_from_url,

    get_environ_proxies,

    get_netrc_auth,

    requote_uri,

    resolve_proxies,

    rewind_body,

    should_bypass_proxies,  # type: ignore[reportUnusedImport]  # re-export for external consumers

    to_key_val_list,

)

if TYPE_CHECKING:

    from http.cookiejar import CookieJar

    from typing_extensions import Self, Unpack

    from . import _types as _t

    from .adapters import BaseAdapter

# Preferred clock, based on which one is more accurate on a given system.

if sys.platform == "win32":

    preferred_clock = time.perf_counter

else:

    preferred_clock = time.time

def merge_setting(

    request_setting: Any, session_setting: Any, dict_class: type = OrderedDict

) -> Any:

    """Determines appropriate setting for a given request, taking into account

    the explicit setting on that request, and the setting in the session. If a

    setting is a dictionary, they will be merged together using `dict_class`

    """

    if session_setting is None:

        return request_setting

    if request_setting is None:

        return session_setting

    # Bypass if not a dictionary (e.g. verify)

    if not (

        isinstance(session_setting, Mapping) and isinstance(request_setting, Mapping)

    ):

        return request_setting

    merged_setting = dict_class(to_key_val_list(session_setting))  # type: ignore[arg-type]  # isinstance narrows Any to Mapping[Unknown]

    merged_setting.update(to_key_val_list(request_setting))  # type: ignore[arg-type]

    # Remove keys that are set to None. Extract keys first to avoid altering

    # the dictionary during iteration.

    none_keys = [k for (k, v) in merged_setting.items() if v is None]

    for key in none_keys:

        del merged_setting[key]

    return merged_setting

def merge_hooks(

    request_hooks: _t.HooksType,

    session_hooks: _t.HooksType,

    dict_class: type = OrderedDict,

) -> _t.HooksType:

    """Properly merges both requests and session hooks.

    This is necessary because when request_hooks == {'response': []}, the

    merge breaks Session hooks entirely.

    """

    if session_hooks is None or session_hooks.get("response") == []:

        return request_hooks

    if request_hooks is None or request_hooks.get("response") == []:

        return session_hooks

    return merge_setting(request_hooks, session_hooks, dict_class)

class SessionRedirectMixin:

    max_redirects: int

    trust_env: bool

    cookies: RequestsCookieJar

    def send(self, request: PreparedRequest, **kwargs: Any) -> Response: ...

    def get_redirect_target(self, resp: Response) -> str | None:

        """Receives a Response. Returns a redirect URI or ``None``"""

        # Due to the nature of how requests processes redirects this method will

        # be called at least once upon the original response and at least twice

        # on each subsequent redirect response (if any).

        # If a custom mixin is used to handle this logic, it may be advantageous

        # to cache the redirect location onto the response object as a private

        # attribute.

        if resp.is_redirect:

            location = resp.headers["location"]

            # Currently the underlying http module on py3 decode headers

            # in latin1, but empirical evidence suggests that latin1 is very

            # rarely used with non-ASCII characters in HTTP headers.

            # It is more likely to get UTF8 header rather than latin1.

            # This causes incorrect handling of UTF8 encoded location headers.

            # To solve this, we re-encode the location in latin1.

            location = location.encode("latin1")

            return to_native_string(location, "utf8")

        return None

    def should_strip_auth(self, old_url: str, new_url: str) -> bool:

        """Decide whether Authorization header should be removed when redirecting"""

        old_parsed = urlparse(old_url)

        new_parsed = urlparse(new_url)

        if old_parsed.hostname != new_parsed.hostname:

            return True

        # Special case: allow http -> https redirect when using the standard

        # ports. This isn't specified by RFC 7235, but is kept to avoid

        # breaking backwards compatibility with older versions of requests

        # that allowed any redirects on the same host.

        if (

            old_parsed.scheme == "http"

            and old_parsed.port in (80, None)

            and new_parsed.scheme == "https"

            and new_parsed.port in (443, None)

        ):

            return False

        # Handle default port usage corresponding to scheme.

        changed_port = old_parsed.port != new_parsed.port

        changed_scheme = old_parsed.scheme != new_parsed.scheme

        default_port = (DEFAULT_PORTS.get(old_parsed.scheme, None), None)

        if (

            not changed_scheme

            and old_parsed.port in default_port

            and new_parsed.port in default_port

        ):

            return False

        # Standard case: root URI must match

        return changed_port or changed_scheme

    def resolve_redirects(

        self,

        resp: Response,

        req: PreparedRequest,

        stream: bool = False,

        timeout: _t.TimeoutType = None,

        verify: _t.VerifyType = True,

        cert: _t.CertType = None,

        proxies: dict[str, str] | None = None,

        yield_requests: bool = False,

        **adapter_kwargs: Any,

    ) -> Generator[Response, None, None]:

        """Receives a Response. Returns a generator of Responses or Requests."""

        hist: list[Response] = []  # keep track of history

        url = self.get_redirect_target(resp)

        previous_fragment = urlparse(req.url).fragment

        while url:

            prepared_request = req.copy()

            # Update history and keep track of redirects.

            resp.history = hist[:]

            hist.append(resp)

            try:

                resp.content  # Consume socket so it can be released

            except (ChunkedEncodingError, ContentDecodingError, RuntimeError):

                resp.raw.read(decode_content=False)

            if len(resp.history) >= self.max_redirects:

                raise TooManyRedirects(

                    f"Exceeded {self.max_redirects} redirects.", response=resp

                )

            # Release the connection back into the pool.

            resp.close()

            # Handle redirection without scheme (see: RFC 1808 Section 4)

            if url.startswith("//"):

                parsed_rurl = urlparse(resp.url)

                url = ":".join([to_native_string(parsed_rurl.scheme), url])

            # Normalize url case and attach previous fragment if needed (RFC 7231 7.1.2)

            parsed = urlparse(url)

            if parsed.fragment == "" and previous_fragment:

                parsed = parsed._replace(fragment=previous_fragment)

            elif parsed.fragment:

                previous_fragment = parsed.fragment

            url = parsed.geturl()

            # Facilitate relative 'location' headers, as allowed by RFC 7231.

            # (e.g. '/path/to/resource' instead of 'http://domain.tld/path/to/resource')

            # Compliant with RFC3986, we percent encode the url.

            if not parsed.netloc:

                url = urljoin(resp.url, requote_uri(url))

            else:

                url = requote_uri(url)

            prepared_request.url = to_native_string(url)

            self.rebuild_method(prepared_request, resp)

            # https://github.com/psf/requests/issues/1084

            if resp.status_code not in (

                codes.temporary_redirect,

                codes.permanent_redirect,

            ):

                # https://github.com/psf/requests/issues/3490

                purged_headers = ("Content-Length", "Content-Type", "Transfer-Encoding")

                for header in purged_headers:

                    prepared_request.headers.pop(header, None)

                prepared_request.body = None

            headers = prepared_request.headers

            headers.pop("Cookie", None)

            # Extract any cookies sent on the response to the cookiejar

            # in the new request. Because we've mutated our copied prepared

            # request, use the old one that we haven't yet touched.

            cookie_jar = cast("CookieJar", prepared_request._cookies)  # type: ignore[reportPrivateUsage]

            extract_cookies_to_jar(cookie_jar, req, resp.raw)

            merge_cookies(cookie_jar, self.cookies)

            prepared_request.prepare_cookies(cookie_jar)

            # Rebuild auth and proxy information.

            proxies = self.rebuild_proxies(prepared_request, proxies)

            self.rebuild_auth(prepared_request, resp)

            # A failed tell() sets `_body_position` to `object()`. This non-None

            # value ensures `rewindable` will be True, allowing us to raise an

            # UnrewindableBodyError, instead of hanging the connection.

            rewindable = prepared_request._body_position is not None and (  # type: ignore[reportPrivateUsage]

                "Content-Length" in headers or "Transfer-Encoding" in headers

            )

            # Attempt to rewind consumed file-like object.

            if rewindable:

                rewind_body(prepared_request)

            # Override the original request.

            req = prepared_request

            if yield_requests:

                yield req  # type: ignore[misc]  # Internal use only, returns PreparedRequest

            else:

                resp = self.send(

                    req,

                    stream=stream,

                    timeout=timeout,

                    verify=verify,

                    cert=cert,

                    proxies=proxies,

                    allow_redirects=False,

                    **adapter_kwargs,

                )

                extract_cookies_to_jar(self.cookies, prepared_request, resp.raw)

                # extract redirect url, if any, for the next loop

                url = self.get_redirect_target(resp)

                yield resp

    def rebuild_auth(

        self, prepared_request: PreparedRequest, response: Response

    ) -> None:

        """When being redirected we may want to strip authentication from the

        request to avoid leaking credentials. This method intelligently removes

        and reapplies authentication where possible to avoid credential loss.

        """

        original_request = response.request

        assert _is_prepared(original_request)

        assert _is_prepared(prepared_request)

        headers = prepared_request.headers

        original_url = original_request.url

        url = prepared_request.url

        if "Authorization" in headers and self.should_strip_auth(original_url, url):

            # If we get redirected to a new host, we should strip out any

            # authentication headers.

            del headers["Authorization"]

        # .netrc might have more auth for us on our new host.

        new_auth = get_netrc_auth(url) if self.trust_env else None

        if new_auth is not None:

            prepared_request.prepare_auth(new_auth)

    def rebuild_proxies(

        self,

        prepared_request: PreparedRequest,

        proxies: dict[str, str] | None,

    ) -> dict[str, str]:

        """This method re-evaluates the proxy configuration by considering the

        environment variables. If we are redirected to a URL covered by

        NO_PROXY, we strip the proxy configuration. Otherwise, we set missing

        proxy keys for this URL (in case they were stripped by a previous

        redirect).

        This method also replaces the Proxy-Authorization header where

        necessary.

        :rtype: dict

        """

        assert _is_prepared(prepared_request)

        headers = prepared_request.headers

        scheme = urlparse(prepared_request.url).scheme

        new_proxies = resolve_proxies(prepared_request, proxies, self.trust_env)

        if "Proxy-Authorization" in headers:

            del headers["Proxy-Authorization"]

        try:

            username, password = get_auth_from_url(new_proxies[scheme])

        except KeyError:

            username, password = None, None

        # urllib3 handles proxy authorization for us in the standard adapter.

        # Avoid appending this to TLS tunneled requests where it may be leaked.

        if not scheme.startswith("https") and username and password:

            headers["Proxy-Authorization"] = _basic_auth_str(username, password)

        return new_proxies

    def rebuild_method(

        self, prepared_request: PreparedRequest, response: Response

    ) -> None:

        """When being redirected we may want to change the method of the request

        based on certain specs or browser behavior.

        """

        method = prepared_request.method

        # https://tools.ietf.org/html/rfc7231#section-6.4.4

        if response.status_code == codes.see_other and method != "HEAD":

            method = "GET"

        # Do what the browsers do, despite standards...

        # First, turn 302s into GETs.

        if response.status_code == codes.found and method != "HEAD":

            method = "GET"

        # Second, if a POST is responded to with a 301, turn it into a GET.

        # This bizarre behaviour is explained in Issue 1704.

        if response.status_code == codes.moved and method == "POST":

            method = "GET"

        prepared_request.method = method

class Session(SessionRedirectMixin):

    """A Requests session.

    Provides cookie persistence, connection-pooling, and configuration.

    Basic Usage::

      >>> import requests

      >>> s = requests.Session()

      >>> s.get('https://httpbin.org/get')

      <Response [200]>

    Or as a context manager::

      >>> with requests.Session() as s:

      ...     s.get('https://httpbin.org/get')

      <Response [200]>

    """

    headers: CaseInsensitiveDict[str]

    auth: _t.AuthType

    proxies: dict[str, str]

    hooks: dict[str, list[_t.HookType]]

    params: MutableMapping[str, Any]

    stream: bool

    verify: _t.VerifyType

    cert: _t.CertType

    max_redirects: int

    trust_env: bool

    cookies: RequestsCookieJar

    adapters: MutableMapping[str, BaseAdapter]

    __attrs__: list[str] = [

        "headers",

        "cookies",

        "auth",

        "proxies",

        "hooks",

        "params",

        "verify",

        "cert",

        "adapters",

        "stream",

        "trust_env",

        "max_redirects",

    ]

    def __init__(self) -> None:

        #: A case-insensitive dictionary of headers to be sent on each

        #: :class:`Request <Request>` sent from this

        #: :class:`Session <Session>`.

        self.headers = default_headers()

        #: Default Authentication tuple or object to attach to

        #: :class:`Request <Request>`.

        self.auth = None

        #: Dictionary mapping protocol or protocol and host to the URL of the proxy

        #: (e.g. {'http': 'foo.bar:3128', 'http://host.name': 'foo.bar:4012'}) to

        #: be used on each :class:`Request <Request>`.

        self.proxies = {}

        #: Event-handling hooks.

        self.hooks = default_hooks()

        #: Dictionary of querystring data to attach to each

        #: :class:`Request <Request>`. The dictionary values may be lists for

        #: representing multivalued query parameters.

        self.params = {}

        #: Stream response content default.

        self.stream = False

        #: SSL Verification default.

        #: Defaults to `True`, requiring requests to verify the TLS certificate at the

        #: remote end.

        #: If verify is set to `False`, requests will accept any TLS certificate

        #: presented by the server, and will ignore hostname mismatches and/or

        #: expired certificates, which will make your application vulnerable to

        #: man-in-the-middle (MitM) attacks.

        #: Only set this to `False` for testing.

        #: If verify is set to a string, it must be the path to a CA bundle file

        #: that will be used to verify the TLS certificate.

        self.verify = True

        #: SSL client certificate default, if String, path to ssl client

        #: cert file (.pem). If Tuple, ('cert', 'key') pair.

        self.cert = None

        #: Maximum number of redirects allowed. If the request exceeds this

        #: limit, a :class:`TooManyRedirects` exception is raised.

        #: This defaults to requests.models.DEFAULT_REDIRECT_LIMIT, which is

        #: 30.

        self.max_redirects = DEFAULT_REDIRECT_LIMIT

        #: Trust environment settings for proxy configuration, default

        #: authentication and similar.

        self.trust_env = True

        #: A CookieJar containing all currently outstanding cookies set on this

        #: session. By default it is a

        #: :class:`RequestsCookieJar <requests.cookies.RequestsCookieJar>`, but

        #: may be any other ``cookielib.CookieJar`` compatible object.

        self.cookies = cookiejar_from_dict({})

        # Default connection adapters.

        self.adapters = OrderedDict()

        self.mount("https://", HTTPAdapter())

        self.mount("http://", HTTPAdapter())

    def __enter__(self) -> Self:

        return self

    def __exit__(self, *args: Any) -> None:

        self.close()

    def prepare_request(self, request: Request) -> PreparedRequest:

        """Constructs a :class:`PreparedRequest <PreparedRequest>` for

        transmission and returns it. The :class:`PreparedRequest` has settings

        merged from the :class:`Request <Request>` instance and those of the

        :class:`Session`.

        :param request: :class:`Request` instance to prepare with this

            session's settings.

        :rtype: requests.PreparedRequest

        """

        url = cast("_t.UriType", request.url)

        method = cast(str, request.method)

        cookies = request.cookies or {}

        # Bootstrap CookieJar.

        if not isinstance(cookies, cookielib.CookieJar):

            cookies = cookiejar_from_dict(cookies)

        # Merge with session cookies

        merged_cookies = merge_cookies(

            merge_cookies(RequestsCookieJar(), self.cookies), cookies

        )

        # Set environment's basic authentication if not explicitly set.

        auth = request.auth

        if self.trust_env and not auth and not self.auth:

            auth = get_netrc_auth(url)

        p = PreparedRequest()

        p.prepare(

            method=method.upper(),

            url=url,

            files=request.files,

            data=request.data,

            json=request.json,

            headers=merge_setting(

                request.headers, self.headers, dict_class=CaseInsensitiveDict

            ),

            params=merge_setting(request.params, self.params),

            auth=merge_setting(auth, self.auth),

            cookies=merged_cookies,

            hooks=merge_hooks(request.hooks, self.hooks),

        )

        return p

    def request(

        self,

        method: str,

        url: _t.UriType,

        params: _t.ParamsType = None,

        data: _t.DataType = None,

        headers: _t.HeadersType = None,

        cookies: RequestsCookieJar | CookieJar | dict[str, str] | None = None,

        files: _t.FilesType = None,

        auth: _t.AuthType = None,

        timeout: _t.TimeoutType = None,

        allow_redirects: bool = True,

        proxies: dict[str, str] | None = None,

        hooks: _t.HooksInputType | None = None,

        stream: bool | None = None,

        verify: _t.VerifyType | None = None,

        cert: _t.CertType = None,

        json: _t.JsonType = None,

    ) -> Response:

        """Constructs a :class:`Request <Request>`, prepares it and sends it.

        Returns :class:`Response <Response>` object.

        :param method: method for the new :class:`Request` object.

        :param url: URL for the new :class:`Request` object.

        :param params: (optional) Dictionary or bytes to be sent in the query

            string for the :class:`Request`.

        :param data: (optional) Dictionary, list of tuples, bytes, or file-like

            object to send in the body of the :class:`Request`.

        :param json: (optional) json to send in the body of the

            :class:`Request`.

        :param headers: (optional) Dictionary of HTTP Headers to send with the

            :class:`Request`.

        :param cookies: (optional) Dict or CookieJar object to send with the

            :class:`Request`.

        :param files: (optional) Dictionary of ``'filename': file-like-objects``

            for multipart encoding upload.

        :param auth: (optional) Auth tuple or callable to enable

            Basic/Digest/Custom HTTP Auth.

        :param timeout: (optional) How many seconds to wait for the server to send

            data before giving up, as a float, or a :ref:`(connect timeout,

            read timeout) <timeouts>` tuple.

        :type timeout: float or tuple

        :param allow_redirects: (optional) Set to True by default.

        :type allow_redirects: bool

        :param proxies: (optional) Dictionary mapping protocol or protocol and

            hostname to the URL of the proxy.

        :param hooks: (optional) Dictionary mapping hook name to one event or

            list of events, event must be callable.

        :param stream: (optional) whether to immediately download the response

            content. Defaults to ``False``.

        :param verify: (optional) Either a boolean, in which case it controls whether we verify

            the server's TLS certificate, or a string, in which case it must be a path

            to a CA bundle to use. Defaults to ``True``. When set to

            ``False``, requests will accept any TLS certificate presented by

            the server, and will ignore hostname mismatches and/or expired

            certificates, which will make your application vulnerable to

            man-in-the-middle (MitM) attacks. Setting verify to ``False``

            may be useful during local development or testing.

        :param cert: (optional) if String, path to ssl client cert file (.pem).

            If Tuple, ('cert', 'key') pair.

        :rtype: requests.Response

        """

        if isinstance(url, bytes):

            url = url.decode("utf-8")

        # Create the Request.

        req = Request(

            method=method.upper(),

            url=url,

            headers=headers,

            files=files,

            data=data or {},

            json=json,

            params=params or {},

            auth=auth,

            cookies=cookies,

            hooks=hooks,

        )

        prep = self.prepare_request(req)

        assert _is_prepared(prep)

        proxies = proxies or {}

        settings = self.merge_environment_settings(

            prep.url, proxies, stream, verify, cert

        )

        # Send the request.

        send_kwargs = {

            "timeout": timeout,

            "allow_redirects": allow_redirects,

        }

        send_kwargs.update(settings)

        resp = self.send(prep, **send_kwargs)

        return resp

    def get(

        self,

        url: _t.UriType,

        params: _t.ParamsType = None,

        **kwargs: Unpack[_t.GetKwargs],

    ) -> Response:

        r"""Sends a GET request. Returns :class:`Response` object.

        :param url: URL for the new :class:`Request` object.

        :param params: (optional) Dictionary, list of tuples or bytes to send

            in the query string for the :class:`Request`.

        :param \*\*kwargs: Optional arguments that ``request`` takes.

        :rtype: requests.Response

        """

        kwargs.setdefault("allow_redirects", True)

        return self.request("GET", url, params=params, **kwargs)

    def options(self, url: _t.UriType, **kwargs: Unpack[_t.RequestKwargs]) -> Response:

        r"""Sends a OPTIONS request. Returns :class:`Response` object.

        :param url: URL for the new :class:`Request` object.

        :param \*\*kwargs: Optional arguments that ``request`` takes.

        :rtype: requests.Response

        """

        kwargs.setdefault("allow_redirects", True)

        return self.request("OPTIONS", url, **kwargs)

    def head(self, url: _t.UriType, **kwargs: Unpack[_t.RequestKwargs]) -> Response:

        r"""Sends a HEAD request. Returns :class:`Response` object.

        :param url: URL for the new :class:`Request` object.

        :param \*\*kwargs: Optional arguments that ``request`` takes.

        :rtype: requests.Response

        """

        kwargs.setdefault("allow_redirects", False)

        return self.request("HEAD", url, **kwargs)

    def post(

        self,

        url: _t.UriType,

        data: _t.DataType = None,

        json: _t.JsonType = None,

        **kwargs: Unpack[_t.PostKwargs],

    ) -> Response:

        r"""Sends a POST request. Returns :class:`Response` object.

        :param url: URL for the new :class:`Request` object.

        :param data: (optional) Dictionary, list of tuples, bytes, or file-like

            object to send in the body of the :class:`Request`.

        :param json: (optional) json to send in the body of the :class:`Request`.

        :param \*\*kwargs: Optional arguments that ``request`` takes.

        :rtype: requests.Response

        """

        return self.request("POST", url, data=data, json=json, **kwargs)

    def put(

        self, url: _t.UriType, data: _t.DataType = None, **kwargs: Unpack[_t.DataKwargs]

    ) -> Response:

        r"""Sends a PUT request. Returns :class:`Response` object.

        :param url: URL for the new :class:`Request` object.

        :param data: (optional) Dictionary, list of tuples, bytes, or file-like

            object to send in the body of the :class:`Request`.

        :param \*\*kwargs: Optional arguments that ``request`` takes.

        :rtype: requests.Response

        """

        return self.request("PUT", url, data=data, **kwargs)

    def patch(

        self, url: _t.UriType, data: _t.DataType = None, **kwargs: Unpack[_t.DataKwargs]

    ) -> Response:

        r"""Sends a PATCH request. Returns :class:`Response` object.

        :param url: URL for the new :class:`Request` object.

        :param data: (optional) Dictionary, list of tuples, bytes, or file-like

            object to send in the body of the :class:`Request`.

        :param \*\*kwargs: Optional arguments that ``request`` takes.

        :rtype: requests.Response

        """

        return self.request("PATCH", url, data=data, **kwargs)

    def delete(self, url: _t.UriType, **kwargs: Unpack[_t.RequestKwargs]) -> Response:

        r"""Sends a DELETE request. Returns :class:`Response` object.

        :param url: URL for the new :class:`Request` object.

        :param \*\*kwargs: Optional arguments that ``request`` takes.

        :rtype: requests.Response

        """

        return self.request("DELETE", url, **kwargs)

    def send(self, request: PreparedRequest, **kwargs: Any) -> Response:

        """Send a given PreparedRequest.

        :rtype: requests.Response

        """

        # Set defaults that the hooks can utilize to ensure they always have

        # the correct parameters to reproduce the previous request.

        kwargs.setdefault("stream", self.stream)

        kwargs.setdefault("verify", self.verify)

        kwargs.setdefault("cert", self.cert)

        if "proxies" not in kwargs:

            kwargs["proxies"] = resolve_proxies(request, self.proxies, self.trust_env)

        # It's possible that users might accidentally send a Request object.

        # Guard against that specific failure case.

        if isinstance(request, Request):

            raise ValueError("You can only send PreparedRequests.")

        assert _is_prepared(request)

        # Set up variables needed for resolve_redirects and dispatching of hooks

        allow_redirects = kwargs.pop("allow_redirects", True)

        stream = kwargs.get("stream")

        hooks = request.hooks

        # Get the appropriate adapter to use

        adapter = self.get_adapter(url=request.url)

        # Start time (approximately) of the request

        start = preferred_clock()

        # Send the request

        r = adapter.send(request, **kwargs)

        # Total elapsed time of the request (approximately)

        elapsed = preferred_clock() - start

        r.elapsed = timedelta(seconds=elapsed)

        # Response manipulation hooks

        r = dispatch_hook("response", hooks, r, **kwargs)

        # Persist cookies

        if r.history:

            # If the hooks create history then we want those cookies too

            for resp in r.history:

                extract_cookies_to_jar(self.cookies, resp.request, resp.raw)

        extract_cookies_to_jar(self.cookies, request, r.raw)

        # Resolve redirects if allowed.

        if allow_redirects:

            # Redirect resolving generator.

            gen = self.resolve_redirects(r, request, **kwargs)

            history = [resp for resp in gen]

        else:

            history = []

        # Shuffle things around if there's history.

        if history:

            # Insert the first (original) request at the start

            history.insert(0, r)

            # Get the last request made

            r = history.pop()

            r.history = history

        # If redirects aren't being followed, store the response on the Request for Response.next().

        if not allow_redirects:

            try:

                r._next = next(  # type: ignore[assignment]  # yield_requests=True returns PreparedRequest

                    self.resolve_redirects(r, request, yield_requests=True, **kwargs)

                )

            except StopIteration:

                pass

        if not stream:

            r.content

        return r

    def merge_environment_settings(

        self,

        url: str,

        proxies: dict[str, str] | None,

        stream: bool | None,

        verify: _t.VerifyType | None,

        cert: _t.CertType,

    ) -> dict[str, Any]:

        """

        Check the environment and merge it with some settings.

        :rtype: dict

        """

        # Gather clues from the surrounding environment.

        if self.trust_env:

            # Set environment's proxies.

            no_proxy = proxies.get("no_proxy") if proxies is not None else None

            env_proxies = get_environ_proxies(url, no_proxy=no_proxy)

            if proxies is not None:

                for k, v in env_proxies.items():

                    proxies.setdefault(k, v)

            # Look for requests environment configuration

            # and be compatible with cURL.

                verify = (

                    os.environ.get("REQUESTS_CA_BUNDLE")

                    or os.environ.get("CURL_CA_BUNDLE")

                    or verify

                )

        # Merge all the kwargs.

        proxies = merge_setting(proxies, self.proxies)

        stream = merge_setting(stream, self.stream)

        verify = merge_setting(verify, self.verify)

        cert = merge_setting(cert, self.cert)

        return {"proxies": proxies, "stream": stream, "verify": verify, "cert": cert}

    def get_adapter(self, url: str) -> BaseAdapter:

        """

        Returns the appropriate connection adapter for the given URL.

        :rtype: requests.adapters.BaseAdapter

        """

        for prefix, adapter in self.adapters.items():

            if url.lower().startswith(prefix.lower()):

                return adapter

        # Nothing matches :-/

        raise InvalidSchema(f"No connection adapters were found for {url!r}")

    def close(self) -> None:

        """Closes all adapters and as such the session"""

        for v in self.adapters.values():

            v.close()

    def mount(self, prefix: str, adapter: BaseAdapter) -> None:

        """Registers a connection adapter to a prefix.

        Adapters are sorted in descending order by prefix length.

        """

        self.adapters[prefix] = adapter

        keys_to_move = [k for k in self.adapters if len(k) < len(prefix)]

        for key in keys_to_move:

            self.adapters[key] = self.adapters.pop(key)

    def __getstate__(self) -> dict[str, Any]:

        state = {attr: getattr(self, attr, None) for attr in self.__attrs__}

        return state

    def __setstate__(self, state: dict[str, Any]) -> None:

        for attr, value in state.items():

            setattr(self, attr, value)

def session() -> Session:

    """

    Returns a :class:`Session` for context-management.

    .. deprecated:: 1.0.0

        This method has been deprecated since version 1.0.0 and is only kept for

        backwards compatibility. New code should use :class:`~requests.sessions.Session`

        to create a session. This may be removed at a future date.

    :rtype: Session

    """

    return Session()