_models.py

import cgi
import datetime
import email.message
import json as jsonlib
import typing
import urllib.request
from collections.abc import MutableMapping
from http.cookiejar import Cookie, CookieJar
from urllib.parse import parse_qs, quote, unquote, urlencode

import charset_normalizer
import idna
import rfc3986
import rfc3986.exceptions

from ._content import ByteStream, UnattachedStream, encode_request, encode_response
from ._decoders import (
    SUPPORTED_DECODERS,
    ByteChunker,
    ContentDecoder,
    IdentityDecoder,
    LineDecoder,
    MultiDecoder,
    TextChunker,
    TextDecoder,
)
from ._exceptions import (
    CookieConflict,
    HTTPStatusError,
    InvalidURL,
    RequestNotRead,
    ResponseNotRead,
    StreamClosed,
    StreamConsumed,
    request_context,
)
from ._status_codes import codes
from ._transports.base import AsyncByteStream, SyncByteStream
from ._types import (
    CookieTypes,
    HeaderTypes,
    PrimitiveData,
    QueryParamTypes,
    RawURL,
    RequestContent,
    RequestData,
    RequestFiles,
    ResponseContent,
    URLTypes,
)
from ._utils import (
    guess_json_utf,
    is_known_encoding,
    normalize_header_key,
    normalize_header_value,
    obfuscate_sensitive_headers,
    parse_header_links,
    primitive_value_to_str,
)


class URL:
    """
    url = httpx.URL("HTTPS://jo%40email.com:a%20secret@müller.de:1234/pa%20th?search=ab#anchorlink")

    assert url.scheme == "https"
    assert url.username == "jo@email.com"
    assert url.password == "a secret"
    assert url.userinfo == b"jo%40email.com:a%20secret"
    assert url.host == "müller.de"
    assert url.raw_host == b"xn--mller-kva.de"
    assert url.port == 1234
    assert url.netloc == b"xn--mller-kva.de:1234"
    assert url.path == "/pa th"
    assert url.query == b"?search=ab"
    assert url.raw_path == b"/pa%20th?search=ab"
    assert url.fragment == "anchorlink"

    The components of a URL are broken down like this:

       https://jo%40email.com:a%20secret@müller.de:1234/pa%20th?search=ab#anchorlink
    [scheme]   [  username  ] [password] [ host ][port][ path ] [ query ] [fragment]
               [       userinfo        ] [   netloc   ][    raw_path    ]

    Note that:

    * `url.scheme` is normalized to always be lowercased.

    * `url.host` is normalized to always be lowercased. Internationalized domain
      names are represented in unicode, without IDNA encoding applied. For instance:

      url = httpx.URL("http://中国.icom.museum")
      assert url.host == "中国.icom.museum"
      url = httpx.URL("http://xn--fiqs8s.icom.museum")
      assert url.host == "中国.icom.museum"

    * `url.raw_host` is normalized to always be lowercased, and is IDNA encoded.

      url = httpx.URL("http://中国.icom.museum")
      assert url.raw_host == b"xn--fiqs8s.icom.museum"
      url = httpx.URL("http://xn--fiqs8s.icom.museum")
      assert url.raw_host == b"xn--fiqs8s.icom.museum"

    * `url.port` is either None or an integer. URLs that include the default port for
      "http", "https", "ws", "wss", and "ftp" schemes have their port normalized to `None`.

      assert httpx.URL("http://example.com") == httpx.URL("http://example.com:80")
      assert httpx.URL("http://example.com").port is None
      assert httpx.URL("http://example.com:80").port is None

    * `url.userinfo` is raw bytes, without URL escaping. Usually you'll want to work with
      `url.username` and `url.password` instead, which handle the URL escaping.

    * `url.raw_path` is raw bytes of both the path and query, without URL escaping.
      This portion is used as the target when constructing HTTP requests. Usually you'll
      want to work with `url.path` instead.

    * `url.query` is raw bytes, without URL escaping. A URL query string portion can only
      be properly URL escaped when decoding the parameter names and values themselves.
    """

    def __init__(
        self, url: typing.Union["URL", str, RawURL] = "", **kwargs: typing.Any
    ) -> None:
        if isinstance(url, (str, tuple)):
            if isinstance(url, tuple):
                raw_scheme, raw_host, port, raw_path = url
                scheme = raw_scheme.decode("ascii")
                host = raw_host.decode("ascii")
                if host and ":" in host and host[0] != "[":
                    # it's an IPv6 address, so it should be enclosed in "[" and "]"
                    # ref: https://tools.ietf.org/html/rfc2732#section-2
                    # ref: https://tools.ietf.org/html/rfc3986#section-3.2.2
                    host = f"[{host}]"
                port_str = "" if port is None else f":{port}"
                path = raw_path.decode("ascii")
                url = f"{scheme}://{host}{port_str}{path}"

            try:
                self._uri_reference = rfc3986.iri_reference(url).encode()
            except rfc3986.exceptions.InvalidAuthority as exc:
                raise InvalidURL(message=str(exc)) from None

            if self.is_absolute_url:
                # We don't want to normalize relative URLs, since doing so
                # removes any leading `../` portion.
                self._uri_reference = self._uri_reference.normalize()
        elif isinstance(url, URL):
            self._uri_reference = url._uri_reference
        else:
            raise TypeError(
                f"Invalid type for url.  Expected str or httpx.URL, got {type(url)}: {url!r}"
            )

        # Perform port normalization, following the WHATWG spec for default ports.
        #
        # See:
        # * https://tools.ietf.org/html/rfc3986#section-3.2.3
        # * https://url.spec.whatwg.org/#url-miscellaneous
        # * https://url.spec.whatwg.org/#scheme-state
        default_port = {
            "ftp": ":21",
            "http": ":80",
            "https": ":443",
            "ws": ":80",
            "wss": ":443",
        }.get(self._uri_reference.scheme, "")
        authority = self._uri_reference.authority or ""
        if default_port and authority.endswith(default_port):
            authority = authority[: -len(default_port)]
            self._uri_reference = self._uri_reference.copy_with(authority=authority)

        if kwargs:
            self._uri_reference = self.copy_with(**kwargs)._uri_reference

    @property
    def scheme(self) -> str:
        """
        The URL scheme, such as "http", "https".
        Always normalised to lowercase.
        """
        return self._uri_reference.scheme or ""

    @property
    def raw_scheme(self) -> bytes:
        """
        The raw bytes representation of the URL scheme, such as b"http", b"https".
        Always normalised to lowercase.
        """
        return self.scheme.encode("ascii")

    @property
    def userinfo(self) -> bytes:
        """
        The URL userinfo as a raw bytestring.
        For example: b"jo%40email.com:a%20secret".
        """
        userinfo = self._uri_reference.userinfo or ""
        return userinfo.encode("ascii")

    @property
    def username(self) -> str:
        """
        The URL username as a string, with URL decoding applied.
        For example: "jo@email.com"
        """
        userinfo = self._uri_reference.userinfo or ""
        return unquote(userinfo.partition(":")[0])

    @property
    def password(self) -> str:
        """
        The URL password as a string, with URL decoding applied.
        For example: "a secret"
        """
        userinfo = self._uri_reference.userinfo or ""
        return unquote(userinfo.partition(":")[2])

    @property
    def host(self) -> str:
        """
        The URL host as a string.
        Always normalized to lowercase, with IDNA hosts decoded into unicode.

        Examples:

        url = httpx.URL("http://www.EXAMPLE.org")
        assert url.host == "www.example.org"

        url = httpx.URL("http://中国.icom.museum")
        assert url.host == "中国.icom.museum"

        url = httpx.URL("http://xn--fiqs8s.icom.museum")
        assert url.host == "中国.icom.museum"

        url = httpx.URL("https://[::ffff:192.168.0.1]")
        assert url.host == "::ffff:192.168.0.1"
        """
        host: str = self._uri_reference.host or ""

        if host and ":" in host and host[0] == "[":
            # it's an IPv6 address
            host = host.lstrip("[").rstrip("]")

        if host.startswith("xn--"):
            host = idna.decode(host)

        return host

    @property
    def raw_host(self) -> bytes:
        """
        The raw bytes representation of the URL host.
        Always normalized to lowercase, and IDNA encoded.

        Examples:

        url = httpx.URL("http://www.EXAMPLE.org")
        assert url.raw_host == b"www.example.org"

        url = httpx.URL("http://中国.icom.museum")
        assert url.raw_host == b"xn--fiqs8s.icom.museum"

        url = httpx.URL("http://xn--fiqs8s.icom.museum")
        assert url.raw_host == b"xn--fiqs8s.icom.museum"

        url = httpx.URL("https://[::ffff:192.168.0.1]")
        assert url.raw_host == b"::ffff:192.168.0.1"
        """
        host: str = self._uri_reference.host or ""

        if host and ":" in host and host[0] == "[":
            # it's an IPv6 address
            host = host.lstrip("[").rstrip("]")

        return host.encode("ascii")

    @property
    def port(self) -> typing.Optional[int]:
        """
        The URL port as an integer.

        Note that the URL class performs port normalization as per the WHATWG spec.
        Default ports for "http", "https", "ws", "wss", and "ftp" schemes are always
        treated as `None`.

        For example:

        assert httpx.URL("http://www.example.com") == httpx.URL("http://www.example.com:80")
        assert httpx.URL("http://www.example.com:80").port is None
        """
        port = self._uri_reference.port
        return int(port) if port else None

    @property
    def netloc(self) -> bytes:
        """
        Either `<host>` or `<host>:<port>` as bytes.
        Always normalized to lowercase, and IDNA encoded.

        This property may be used for generating the value of a request
        "Host" header.
        """
        host = self._uri_reference.host or ""
        port = self._uri_reference.port
        netloc = host.encode("ascii")
        if port:
            netloc = netloc + b":" + port.encode("ascii")
        return netloc

    @property
    def path(self) -> str:
        """
        The URL path as a string. Excluding the query string, and URL decoded.

        For example:

        url = httpx.URL("https://example.com/pa%20th")
        assert url.path == "/pa th"
        """
        path = self._uri_reference.path or "/"
        return unquote(path)

    @property
    def query(self) -> bytes:
        """
        The URL query string, as raw bytes, excluding the leading b"?".

        This is neccessarily a bytewise interface, because we cannot
        perform URL decoding of this representation until we've parsed
        the keys and values into a QueryParams instance.

        For example:

        url = httpx.URL("https://example.com/?filter=some%20search%20terms")
        assert url.query == b"filter=some%20search%20terms"
        """
        query = self._uri_reference.query or ""
        return query.encode("ascii")

    @property
    def params(self) -> "QueryParams":
        """
        The URL query parameters, neatly parsed and packaged into an immutable
        multidict representation.
        """
        return QueryParams(self._uri_reference.query)

    @property
    def raw_path(self) -> bytes:
        """
        The complete URL path and query string as raw bytes.
        Used as the target when constructing HTTP requests.

        For example:

        GET /users?search=some%20text HTTP/1.1
        Host: www.example.org
        Connection: close
        """
        path = self._uri_reference.path or "/"
        if self._uri_reference.query is not None:
            path += "?" + self._uri_reference.query
        return path.encode("ascii")

    @property
    def fragment(self) -> str:
        """
        The URL fragments, as used in HTML anchors.
        As a string, without the leading '#'.
        """
        return unquote(self._uri_reference.fragment or "")

    @property
    def raw(self) -> RawURL:
        """
        The URL in the raw representation used by the low level
        transport API. See `BaseTransport.handle_request`.

        Provides the (scheme, host, port, target) for the outgoing request.
        """
        return (
            self.raw_scheme,
            self.raw_host,
            self.port,
            self.raw_path,
        )

    @property
    def is_absolute_url(self) -> bool:
        """
        Return `True` for absolute URLs such as 'http://example.com/path',
        and `False` for relative URLs such as '/path'.
        """
        # We don't use `.is_absolute` from `rfc3986` because it treats
        # URLs with a fragment portion as not absolute.
        # What we actually care about is if the URL provides
        # a scheme and hostname to which connections should be made.
        return bool(self._uri_reference.scheme and self._uri_reference.host)

    @property
    def is_relative_url(self) -> bool:
        """
        Return `False` for absolute URLs such as 'http://example.com/path',
        and `True` for relative URLs such as '/path'.
        """
        return not self.is_absolute_url

    def copy_with(self, **kwargs: typing.Any) -> "URL":
        """
        Copy this URL, returning a new URL with some components altered.
        Accepts the same set of parameters as the components that are made
        available via properties on the `URL` class.

        For example:

        url = httpx.URL("https://www.example.com").copy_with(username="jo@gmail.com", password="a secret")
        assert url == "https://jo%40email.com:a%20secret@www.example.com"
        """
        allowed = {
            "scheme": str,
            "username": str,
            "password": str,
            "userinfo": bytes,
            "host": str,
            "port": int,
            "netloc": bytes,
            "path": str,
            "query": bytes,
            "raw_path": bytes,
            "fragment": str,
            "params": object,
        }

        # Step 1
        # ======
        #
        # Perform type checking for all supported keyword arguments.
        for key, value in kwargs.items():
            if key not in allowed:
                message = f"{key!r} is an invalid keyword argument for copy_with()"
                raise TypeError(message)
            if value is not None and not isinstance(value, allowed[key]):
                expected = allowed[key].__name__
                seen = type(value).__name__
                message = f"Argument {key!r} must be {expected} but got {seen}"
                raise TypeError(message)

        # Step 2
        # ======
        #
        # Consolidate "username", "password", "userinfo", "host", "port" and "netloc"
        # into a single "authority" keyword, for `rfc3986`.
        if "username" in kwargs or "password" in kwargs:
            # Consolidate "username" and "password" into "userinfo".
            username = quote(kwargs.pop("username", self.username) or "")
            password = quote(kwargs.pop("password", self.password) or "")
            userinfo = f"{username}:{password}" if password else username
            kwargs["userinfo"] = userinfo.encode("ascii")

        if "host" in kwargs or "port" in kwargs:
            # Consolidate "host" and "port" into "netloc".
            host = kwargs.pop("host", self.host) or ""
            port = kwargs.pop("port", self.port)

            if host and ":" in host and host[0] != "[":
                # IPv6 addresses need to be escaped within sqaure brackets.
                host = f"[{host}]"

            kwargs["netloc"] = (
                f"{host}:{port}".encode("ascii")
                if port is not None
                else host.encode("ascii")
            )

        if "userinfo" in kwargs or "netloc" in kwargs:
            # Consolidate "userinfo" and "netloc" into authority.
            userinfo = (kwargs.pop("userinfo", self.userinfo) or b"").decode("ascii")
            netloc = (kwargs.pop("netloc", self.netloc) or b"").decode("ascii")
            authority = f"{userinfo}@{netloc}" if userinfo else netloc
            kwargs["authority"] = authority

        # Step 3
        # ======
        #
        # Wrangle any "path", "query", "raw_path" and "params" keywords into
        # "query" and "path" keywords for `rfc3986`.
        if "raw_path" in kwargs:
            # If "raw_path" is included, then split it into "path" and "query" components.
            raw_path = kwargs.pop("raw_path") or b""
            path, has_query, query = raw_path.decode("ascii").partition("?")
            kwargs["path"] = path
            kwargs["query"] = query if has_query else None

        else:
            if kwargs.get("path") is not None:
                # Ensure `kwargs["path"] = <url quoted str>` for `rfc3986`.
                kwargs["path"] = quote(kwargs["path"])

            if kwargs.get("query") is not None:
                # Ensure `kwargs["query"] = <str>` for `rfc3986`.
                #
                # Note that `.copy_with(query=None)` and `.copy_with(query=b"")`
                # are subtly different. The `None` style will not include an empty
                # trailing "?" character.
                kwargs["query"] = kwargs["query"].decode("ascii")

            if "params" in kwargs:
                # Replace any "params" keyword with the raw "query" instead.
                #
                # Ensure that empty params use `kwargs["query"] = None` rather
                # than `kwargs["query"] = ""`, so that generated URLs do not
                # include an empty trailing "?".
                params = kwargs.pop("params")
                kwargs["query"] = None if not params else str(QueryParams(params))

        # Step 4
        # ======
        #
        # Ensure any fragment component is quoted.
        if kwargs.get("fragment") is not None:
            kwargs["fragment"] = quote(kwargs["fragment"])

        # Step 5
        # ======
        #
        # At this point kwargs may include keys for "scheme", "authority", "path",
        # "query" and "fragment". Together these constitute the entire URL.
        #
        # See https://tools.ietf.org/html/rfc3986#section-3
        #
        #  foo://example.com:8042/over/there?name=ferret#nose
        #  \_/   \______________/\_________/ \_________/ \__/
        #   |           |            |            |        |
        # scheme     authority       path        query   fragment
        return URL(self._uri_reference.copy_with(**kwargs).unsplit())

    def copy_set_param(self, key: str, value: typing.Any = None) -> "URL":
        return self.copy_with(params=self.params.set(key, value))

    def copy_add_param(self, key: str, value: typing.Any = None) -> "URL":
        return self.copy_with(params=self.params.add(key, value))

    def copy_remove_param(self, key: str) -> "URL":
        return self.copy_with(params=self.params.remove(key))

    def copy_merge_params(self, params: QueryParamTypes) -> "URL":
        return self.copy_with(params=self.params.merge(params))

    def join(self, url: URLTypes) -> "URL":
        """
        Return an absolute URL, using this URL as the base.

        Eg.

        url = httpx.URL("https://www.example.com/test")
        url = url.join("/new/path")
        assert url == "https://www.example.com/new/path"
        """
        if self.is_relative_url:
            # Workaround to handle relative URLs, which otherwise raise
            # rfc3986.exceptions.ResolutionError when used as an argument
            # in `.resolve_with`.
            return (
                self.copy_with(scheme="http", host="example.com")
                .join(url)
                .copy_with(scheme=None, host=None)
            )

        # We drop any fragment portion, because RFC 3986 strictly
        # treats URLs with a fragment portion as not being absolute URLs.
        base_uri = self._uri_reference.copy_with(fragment=None)
        relative_url = URL(url)
        return URL(relative_url._uri_reference.resolve_with(base_uri).unsplit())

    def __hash__(self) -> int:
        return hash(str(self))

    def __eq__(self, other: typing.Any) -> bool:
        return isinstance(other, (URL, str)) and str(self) == str(URL(other))

    def __str__(self) -> str:
        return self._uri_reference.unsplit()

    def __repr__(self) -> str:
        class_name = self.__class__.__name__
        url_str = str(self)
        if self._uri_reference.userinfo:
            # Mask any password component in the URL representation, to lower the
            # risk of unintended leakage, such as in debug information and logging.
            username = quote(self.username)
            url_str = (
                rfc3986.urlparse(url_str)
                .copy_with(userinfo=f"{username}:[secure]")
                .unsplit()
            )
        return f"{class_name}({url_str!r})"


class QueryParams(typing.Mapping[str, str]):
    """
    URL query parameters, as a multi-dict.
    """

    def __init__(self, *args: QueryParamTypes, **kwargs: typing.Any) -> None:
        assert len(args) < 2, "Too many arguments."
        assert not (args and kwargs), "Cannot mix named and unnamed arguments."

        value = args[0] if args else kwargs

        items: typing.Sequence[typing.Tuple[str, PrimitiveData]]
        if value is None or isinstance(value, (str, bytes)):
            value = value.decode("ascii") if isinstance(value, bytes) else value
            self._dict = parse_qs(value)
        elif isinstance(value, QueryParams):
            self._dict = {k: list(v) for k, v in value._dict.items()}
        else:
            dict_value: typing.Dict[typing.Any, typing.List[typing.Any]] = {}
            if isinstance(value, (list, tuple)):
                # Convert list inputs like:
                #     [("a", "123"), ("a", "456"), ("b", "789")]
                # To a dict representation, like:
                #     {"a": ["123", "456"], "b": ["789"]}
                for item in value:
                    dict_value.setdefault(item[0], []).append(item[1])
            else:
                # Convert dict inputs like:
                #    {"a": "123", "b": ["456", "789"]}
                # To dict inputs where values are always lists, like:
                #    {"a": ["123"], "b": ["456", "789"]}
                dict_value = {
                    k: list(v) if isinstance(v, (list, tuple)) else [v]
                    for k, v in value.items()
                }

            # Ensure that keys and values are neatly coerced to strings.
            # We coerce values `True` and `False` to JSON-like "true" and "false"
            # representations, and coerce `None` values to the empty string.
            self._dict = {
                str(k): [primitive_value_to_str(item) for item in v]
                for k, v in dict_value.items()
            }

    def keys(self) -> typing.KeysView:
        """
        Return all the keys in the query params.

        Usage:

        q = httpx.QueryParams("a=123&a=456&b=789")
        assert list(q.keys()) == ["a", "b"]
        """
        return self._dict.keys()

    def values(self) -> typing.ValuesView:
        """
        Return all the values in the query params. If a key occurs more than once
        only the first item for that key is returned.

        Usage:

        q = httpx.QueryParams("a=123&a=456&b=789")
        assert list(q.values()) == ["123", "789"]
        """
        return {k: v[0] for k, v in self._dict.items()}.values()

    def items(self) -> typing.ItemsView:
        """
        Return all items in the query params. If a key occurs more than once
        only the first item for that key is returned.

        Usage:

        q = httpx.QueryParams("a=123&a=456&b=789")
        assert list(q.items()) == [("a", "123"), ("b", "789")]
        """
        return {k: v[0] for k, v in self._dict.items()}.items()

    def multi_items(self) -> typing.List[typing.Tuple[str, str]]:
        """
        Return all items in the query params. Allow duplicate keys to occur.

        Usage:

        q = httpx.QueryParams("a=123&a=456&b=789")
        assert list(q.multi_items()) == [("a", "123"), ("a", "456"), ("b", "789")]
        """
        multi_items: typing.List[typing.Tuple[str, str]] = []
        for k, v in self._dict.items():
            multi_items.extend([(k, i) for i in v])
        return multi_items

    def get(self, key: typing.Any, default: typing.Any = None) -> typing.Any:
        """
        Get a value from the query param for a given key. If the key occurs
        more than once, then only the first value is returned.

        Usage:

        q = httpx.QueryParams("a=123&a=456&b=789")
        assert q.get("a") == "123"
        """
        if key in self._dict:
            return self._dict[str(key)][0]
        return default

    def get_list(self, key: str) -> typing.List[str]:
        """
        Get all values from the query param for a given key.

        Usage:

        q = httpx.QueryParams("a=123&a=456&b=789")
        assert q.get_list("a") == ["123", "456"]
        """
        return list(self._dict.get(str(key), []))

    def set(self, key: str, value: typing.Any = None) -> "QueryParams":
        """
        Return a new QueryParams instance, setting the value of a key.

        Usage:

        q = httpx.QueryParams("a=123")
        q = q.set("a", "456")
        assert q == httpx.QueryParams("a=456")
        """
        q = QueryParams()
        q._dict = dict(self._dict)
        q._dict[str(key)] = [primitive_value_to_str(value)]
        return q

    def add(self, key: str, value: typing.Any = None) -> "QueryParams":
        """
        Return a new QueryParams instance, setting or appending the value of a key.

        Usage:

        q = httpx.QueryParams("a=123")
        q = q.add("a", "456")
        assert q == httpx.QueryParams("a=123&a=456")
        """
        q = QueryParams()
        q._dict = dict(self._dict)
        q._dict[str(key)] = q.get_list(key) + [primitive_value_to_str(value)]
        return q

    def remove(self, key: str) -> "QueryParams":
        """
        Return a new QueryParams instance, removing the value of a key.

        Usage:

        q = httpx.QueryParams("a=123")
        q = q.remove("a")
        assert q == httpx.QueryParams("")
        """
        q = QueryParams()
        q._dict = dict(self._dict)
        q._dict.pop(str(key), None)
        return q

    def merge(self, params: QueryParamTypes = None) -> "QueryParams":
        """
        Return a new QueryParams instance, updated with.

        Usage:

        q = httpx.QueryParams("a=123")
        q = q.merge({"b": "456"})
        assert q == httpx.QueryParams("a=123&b=456")

        q = httpx.QueryParams("a=123")
        q = q.merge({"a": "456", "b": "789"})
        assert q == httpx.QueryParams("a=456&b=789")
        """
        q = QueryParams(params)
        q._dict = {**self._dict, **q._dict}
        return q

    def __getitem__(self, key: typing.Any) -> str:
        return self._dict[key][0]

    def __contains__(self, key: typing.Any) -> bool:
        return key in self._dict

    def __iter__(self) -> typing.Iterator[typing.Any]:
        return iter(self.keys())

    def __len__(self) -> int:
        return len(self._dict)

    def __bool__(self) -> bool:
        return bool(self._dict)

    def __hash__(self) -> int:
        return hash(str(self))

    def __eq__(self, other: typing.Any) -> bool:
        if not isinstance(other, self.__class__):
            return False
        return sorted(self.multi_items()) == sorted(other.multi_items())

    def __str__(self) -> str:
        return urlencode(self.multi_items())

    def __repr__(self) -> str:
        class_name = self.__class__.__name__
        query_string = str(self)
        return f"{class_name}({query_string!r})"

    def update(self, params: QueryParamTypes = None) -> None:
        raise RuntimeError(
            "QueryParams are immutable since 0.18.0. "
            "Use `q = q.merge(...)` to create an updated copy."
        )

    def __setitem__(self, key: str, value: str) -> None:
        raise RuntimeError(
            "QueryParams are immutable since 0.18.0. "
            "Use `q = q.set(key, value)` to create an updated copy."
        )


class Headers(typing.MutableMapping[str, str]):
    """
    HTTP headers, as a case-insensitive multi-dict.
    """

    def __init__(self, headers: HeaderTypes = None, encoding: str = None) -> None:
        if headers is None:
            self._list = []  # type: typing.List[typing.Tuple[bytes, bytes, bytes]]
        elif isinstance(headers, Headers):
            self._list = list(headers._list)
        elif isinstance(headers, dict):
            self._list = [
                (
                    normalize_header_key(k, lower=False, encoding=encoding),
                    normalize_header_key(k, lower=True, encoding=encoding),
                    normalize_header_value(v, encoding),
                )
                for k, v in headers.items()
            ]
        else:
            self._list = [
                (
                    normalize_header_key(k, lower=False, encoding=encoding),
                    normalize_header_key(k, lower=True, encoding=encoding),
                    normalize_header_value(v, encoding),
                )
                for k, v in headers
            ]

        self._encoding = encoding

    @property
    def encoding(self) -> str:
        """
        Header encoding is mandated as ascii, but we allow fallbacks to utf-8
        or iso-8859-1.
        """
        if self._encoding is None:
            for encoding in ["ascii", "utf-8"]:
                for key, value in self.raw:
                    try:
                        key.decode(encoding)
                        value.decode(encoding)
                    except UnicodeDecodeError:
                        break
                else:
                    # The else block runs if 'break' did not occur, meaning
                    # all values fitted the encoding.
                    self._encoding = encoding
                    break
            else:
                # The ISO-8859-1 encoding covers all 256 code points in a byte,
                # so will never raise decode errors.
                self._encoding = "iso-8859-1"
        return self._encoding

    @encoding.setter
    def encoding(self, value: str) -> None:
        self._encoding = value

    @property
    def raw(self) -> typing.List[typing.Tuple[bytes, bytes]]:
        """
        Returns a list of the raw header items, as byte pairs.
        """
        return [(raw_key, value) for raw_key, _, value in self._list]

    def keys(self) -> typing.KeysView[str]:
        return {key.decode(self.encoding): None for _, key, value in self._list}.keys()

    def values(self) -> typing.ValuesView[str]:
        values_dict: typing.Dict[str, str] = {}
        for _, key, value in self._list:
            str_key = key.decode(self.encoding)
            str_value = value.decode(self.encoding)
            if str_key in values_dict:
                values_dict[str_key] += f", {str_value}"
            else:
                values_dict[str_key] = str_value
        return values_dict.values()

    def items(self) -> typing.ItemsView[str, str]:
        """
        Return `(key, value)` items of headers. Concatenate headers
        into a single comma seperated value when a key occurs multiple times.
        """
        values_dict: typing.Dict[str, str] = {}
        for _, key, value in self._list:
            str_key = key.decode(self.encoding)
            str_value = value.decode(self.encoding)
            if str_key in values_dict:
                values_dict[str_key] += f", {str_value}"
            else:
                values_dict[str_key] = str_value
        return values_dict.items()

    def multi_items(self) -> typing.List[typing.Tuple[str, str]]:
        """
        Return a list of `(key, value)` pairs of headers. Allow multiple
        occurences of the same key without concatenating into a single
        comma seperated value.
        """
        return [
            (key.decode(self.encoding), value.decode(self.encoding))
            for _, key, value in self._list
        ]

    def get(self, key: str, default: typing.Any = None) -> typing.Any:
        """
        Return a header value. If multiple occurences of the header occur
        then concatenate them together with commas.
        """
        try:
            return self[key]
        except KeyError:
            return default

    def get_list(self, key: str, split_commas: bool = False) -> typing.List[str]:
        """
        Return a list of all header values for a given key.
        If `split_commas=True` is passed, then any comma seperated header
        values are split into multiple return strings.
        """
        get_header_key = key.lower().encode(self.encoding)

        values = [
            item_value.decode(self.encoding)
            for _, item_key, item_value in self._list
            if item_key.lower() == get_header_key
        ]

        if not split_commas:
            return values

        split_values = []
        for value in values:
            split_values.extend([item.strip() for item in value.split(",")])
        return split_values

    def update(self, headers: HeaderTypes = None) -> None:  # type: ignore
        headers = Headers(headers)
        for key, value in headers.raw:
            self[key.decode(headers.encoding)] = value.decode(headers.encoding)

    def copy(self) -> "Headers":
        return Headers(self, encoding=self.encoding)

    def __getitem__(self, key: str) -> str:
        """
        Return a single header value.

        If there are multiple headers with the same key, then we concatenate
        them with commas. See: https://tools.ietf.org/html/rfc7230#section-3.2.2
        """
        normalized_key = key.lower().encode(self.encoding)

        items = [
            header_value.decode(self.encoding)
            for _, header_key, header_value in self._list
            if header_key == normalized_key
        ]

        if items:
            return ", ".join(items)

        raise KeyError(key)

    def __setitem__(self, key: str, value: str) -> None:
        """
        Set the header `key` to `value`, removing any duplicate entries.
        Retains insertion order.
        """
        set_key = key.encode(self._encoding or "utf-8")
        set_value = value.encode(self._encoding or "utf-8")
        lookup_key = set_key.lower()

        found_indexes = [
            idx
            for idx, (_, item_key, _) in enumerate(self._list)
            if item_key == lookup_key
        ]

        for idx in reversed(found_indexes[1:]):
            del self._list[idx]

        if found_indexes:
            idx = found_indexes[0]
            self._list[idx] = (set_key, lookup_key, set_value)
        else:
            self._list.append((set_key, lookup_key, set_value))

    def __delitem__(self, key: str) -> None:
        """
        Remove the header `key`.
        """
        del_key = key.lower().encode(self.encoding)

        pop_indexes = [
            idx
            for idx, (_, item_key, _) in enumerate(self._list)
            if item_key.lower() == del_key
        ]

        if not pop_indexes:
            raise KeyError(key)

        for idx in reversed(pop_indexes):
            del self._list[idx]

    def __contains__(self, key: typing.Any) -> bool:
        header_key = key.lower().encode(self.encoding)
        return header_key in [key for _, key, _ in self._list]

    def __iter__(self) -> typing.Iterator[typing.Any]:
        return iter(self.keys())

    def __len__(self) -> int:
        return len(self._list)

    def __eq__(self, other: typing.Any) -> bool:
        try:
            other_headers = Headers(other)
        except ValueError:
            return False

        self_list = [(key, value) for _, key, value in self._list]
        other_list = [(key, value) for _, key, value in other_headers._list]
        return sorted(self_list) == sorted(other_list)

    def __repr__(self) -> str:
        class_name = self.__class__.__name__

        encoding_str = ""
        if self.encoding != "ascii":
            encoding_str = f", encoding={self.encoding!r}"

        as_list = list(obfuscate_sensitive_headers(self.multi_items()))
        as_dict = dict(as_list)

        no_duplicate_keys = len(as_dict) == len(as_list)
        if no_duplicate_keys:
            return f"{class_name}({as_dict!r}{encoding_str})"
        return f"{class_name}({as_list!r}{encoding_str})"


class Request:
    def __init__(
        self,
        method: typing.Union[str, bytes],
        url: typing.Union["URL", str, RawURL],
        *,
        params: QueryParamTypes = None,
        headers: HeaderTypes = None,
        cookies: CookieTypes = None,
        content: RequestContent = None,
        data: RequestData = None,
        files: RequestFiles = None,
        json: typing.Any = None,
        stream: typing.Union[SyncByteStream, AsyncByteStream] = None,
    ):
        if isinstance(method, bytes):
            self.method = method.decode("ascii").upper()
        else:
            self.method = method.upper()
        self.url = URL(url)
        if params is not None:
            self.url = self.url.copy_merge_params(params=params)
        self.headers = Headers(headers)
        if cookies:
            Cookies(cookies).set_cookie_header(self)

        if stream is None:
            headers, stream = encode_request(content, data, files, json)
            self._prepare(headers)
            self.stream = stream
            # Load the request body, except for streaming content.
            if isinstance(stream, ByteStream):
                self.read()
        else:
            # There's an important distinction between `Request(content=...)`,
            # and `Request(stream=...)`.
            #
            # Using `content=...` implies automatically populated `Host` and content
            # headers, of either `Content-Length: ...` or `Transfer-Encoding: chunked`.
            #
            # Using `stream=...` will not automatically include *any* auto-populated headers.
            #
            # As an end-user you don't really need `stream=...`. It's only
            # useful when:
            #
            # * Preserving the request stream when copying requests, eg for redirects.
            # * Creating request instances on the *server-side* of the transport API.
            self.stream = stream

    def _prepare(self, default_headers: typing.Dict[str, str]) -> None:
        for key, value in default_headers.items():
            # Ignore Transfer-Encoding if the Content-Length has been set explicitly.
            if key.lower() == "transfer-encoding" and "Content-Length" in self.headers:
                continue
            self.headers.setdefault(key, value)

        auto_headers: typing.List[typing.Tuple[bytes, bytes]] = []

        has_host = "Host" in self.headers
        has_content_length = (
            "Content-Length" in self.headers or "Transfer-Encoding" in self.headers
        )

        if not has_host and self.url.host:
            auto_headers.append((b"Host", self.url.netloc))
        if not has_content_length and self.method in ("POST", "PUT", "PATCH"):
            auto_headers.append((b"Content-Length", b"0"))

        self.headers = Headers(auto_headers + self.headers.raw)

    @property
    def content(self) -> bytes:
        if not hasattr(self, "_content"):
            raise RequestNotRead()
        return self._content

    def read(self) -> bytes:
        """
        Read and return the request content.
        """
        if not hasattr(self, "_content"):
            assert isinstance(self.stream, typing.Iterable)
            self._content = b"".join(self.stream)
            if not isinstance(self.stream, ByteStream):
                # If a streaming request has been read entirely into memory, then
                # we can replace the stream with a raw bytes implementation,
                # to ensure that any non-replayable streams can still be used.
                self.stream = ByteStream(self._content)
        return self._content

    async def aread(self) -> bytes:
        """
        Read and return the request content.
        """
        if not hasattr(self, "_content"):
            assert isinstance(self.stream, typing.AsyncIterable)
            self._content = b"".join([part async for part in self.stream])
            if not isinstance(self.stream, ByteStream):
                # If a streaming request has been read entirely into memory, then
                # we can replace the stream with a raw bytes implementation,
                # to ensure that any non-replayable streams can still be used.
                self.stream = ByteStream(self._content)
        return self._content

    def __repr__(self) -> str:
        class_name = self.__class__.__name__
        url = str(self.url)
        return f"<{class_name}({self.method!r}, {url!r})>"

    def __getstate__(self) -> typing.Dict[str, typing.Any]:
        return {
            name: value
            for name, value in self.__dict__.items()
            if name not in ["stream"]
        }

    def __setstate__(self, state: typing.Dict[str, typing.Any]) -> None:
        for name, value in state.items():
            setattr(self, name, value)
        self.stream = UnattachedStream()


class Response:
    def __init__(
        self,
        status_code: int,
        *,
        headers: HeaderTypes = None,
        content: ResponseContent = None,
        text: str = None,
        html: str = None,
        json: typing.Any = None,
        stream: typing.Union[SyncByteStream, AsyncByteStream] = None,
        request: Request = None,
        extensions: dict = None,
        history: typing.List["Response"] = None,
    ):
        self.status_code = status_code
        self.headers = Headers(headers)

        self._request: typing.Optional[Request] = request

        # When allow_redirects=False and a redirect is received,
        # the client will set `response.next_request`.
        self.next_request: typing.Optional[Request] = None

        self.extensions = {} if extensions is None else extensions
        self.history = [] if history is None else list(history)

        self.is_closed = False
        self.is_stream_consumed = False

        if stream is None:
            headers, stream = encode_response(content, text, html, json)
            self._prepare(headers)
            self.stream = stream
            if isinstance(stream, ByteStream):
                # Load the response body, except for streaming content.
                self.read()
        else:
            # There's an important distinction between `Response(content=...)`,
            # and `Response(stream=...)`.
            #
            # Using `content=...` implies automatically populated content headers,
            # of either `Content-Length: ...` or `Transfer-Encoding: chunked`.
            #
            # Using `stream=...` will not automatically include any content headers.
            #
            # As an end-user you don't really need `stream=...`. It's only
            # useful when creating response instances having received a stream
            # from the transport API.
            self.stream = stream

        self._num_bytes_downloaded = 0

    def _prepare(self, default_headers: typing.Dict[str, str]) -> None:
        for key, value in default_headers.items():
            # Ignore Transfer-Encoding if the Content-Length has been set explicitly.
            if key.lower() == "transfer-encoding" and "content-length" in self.headers:
                continue
            self.headers.setdefault(key, value)

    @property
    def elapsed(self) -> datetime.timedelta:
        """
        Returns the time taken for the complete request/response
        cycle to complete.
        """
        if not hasattr(self, "_elapsed"):
            raise RuntimeError(
                "'.elapsed' may only be accessed after the response "
                "has been read or closed."
            )
        return self._elapsed

    @elapsed.setter
    def elapsed(self, elapsed: datetime.timedelta) -> None:
        self._elapsed = elapsed

    @property
    def request(self) -> Request:
        """
        Returns the request instance associated to the current response.
        """
        if self._request is None:
            raise RuntimeError(
                "The request instance has not been set on this response."
            )
        return self._request

    @request.setter
    def request(self, value: Request) -> None:
        self._request = value

    @property
    def http_version(self) -> str:
        try:
            return self.extensions["http_version"].decode("ascii", errors="ignore")
        except KeyError:
            return "HTTP/1.1"

    @property
    def reason_phrase(self) -> str:
        try:
            return self.extensions["reason_phrase"].decode("ascii", errors="ignore")
        except KeyError:
            return codes.get_reason_phrase(self.status_code)

    @property
    def url(self) -> typing.Optional[URL]:
        """
        Returns the URL for which the request was made.
        """
        return self.request.url

    @property
    def content(self) -> bytes:
        if not hasattr(self, "_content"):
            raise ResponseNotRead()
        return self._content

    @property
    def text(self) -> str:
        if not hasattr(self, "_text"):
            content = self.content
            if not content:
                self._text = ""
            else:
                decoder = TextDecoder(encoding=self.encoding or "utf-8")
                self._text = "".join([decoder.decode(self.content), decoder.flush()])
        return self._text

    @property
    def encoding(self) -> typing.Optional[str]:
        """
        Return an encoding to use for decoding the byte content into text.
        The priority for determining this is given by...

        * `.encoding = <>` has been set explicitly.
        * The encoding as specified by the charset parameter in the Content-Type header.
        * The encoding as determined by `charset_normalizer`.
        * UTF-8.
        """
        if not hasattr(self, "_encoding"):
            encoding = self.charset_encoding
            if encoding is None or not is_known_encoding(encoding):
                encoding = self.apparent_encoding
            self._encoding = encoding
        return self._encoding

    @encoding.setter
    def encoding(self, value: str) -> None:
        self._encoding = value

    @property
    def charset_encoding(self) -> typing.Optional[str]:
        """
        Return the encoding, as specified by the Content-Type header.
        """
        content_type = self.headers.get("Content-Type")
        if content_type is None:
            return None

        _, params = cgi.parse_header(content_type)
        if "charset" not in params:
            return None

        return params["charset"].strip("'\"")

    @property
    def apparent_encoding(self) -> typing.Optional[str]:
        """
        Return the encoding, as detemined by `charset_normalizer`.
        """
        content = getattr(self, "_content", b"")
        if len(content) < 32:
            # charset_normalizer will issue warnings if we run it with
            # fewer bytes than this cutoff.
            return None
        match = charset_normalizer.from_bytes(self.content).best()
        return None if match is None else match.encoding

    def _get_content_decoder(self) -> ContentDecoder:
        """
        Returns a decoder instance which can be used to decode the raw byte
        content, depending on the Content-Encoding used in the response.
        """
        if not hasattr(self, "_decoder"):
            decoders: typing.List[ContentDecoder] = []
            values = self.headers.get_list("content-encoding", split_commas=True)
            for value in values:
                value = value.strip().lower()
                try:
                    decoder_cls = SUPPORTED_DECODERS[value]
                    decoders.append(decoder_cls())
                except KeyError:
                    continue

            if len(decoders) == 1:
                self._decoder = decoders[0]
            elif len(decoders) > 1:
                self._decoder = MultiDecoder(children=decoders)
            else:
                self._decoder = IdentityDecoder()

        return self._decoder

    @property
    def is_error(self) -> bool:
        return codes.is_error(self.status_code)

    @property
    def is_redirect(self) -> bool:
        return codes.is_redirect(self.status_code) and "location" in self.headers

    def raise_for_status(self) -> None:
        """
        Raise the `HTTPStatusError` if one occurred.
        """
        message = (
            "{0.status_code} {error_type}: {0.reason_phrase} for url: {0.url}\n"
            "For more information check: https://httpstatuses.com/{0.status_code}"
        )

        request = self._request
        if request is None:
            raise RuntimeError(
                "Cannot call `raise_for_status` as the request "
                "instance has not been set on this response."
            )

        if codes.is_client_error(self.status_code):
            message = message.format(self, error_type="Client Error")
            raise HTTPStatusError(message, request=request, response=self)
        elif codes.is_server_error(self.status_code):
            message = message.format(self, error_type="Server Error")
            raise HTTPStatusError(message, request=request, response=self)

    def json(self, **kwargs: typing.Any) -> typing.Any:
        if self.charset_encoding is None and self.content and len(self.content) > 3:
            encoding = guess_json_utf(self.content)
            if encoding is not None:
                return jsonlib.loads(self.content.decode(encoding), **kwargs)
        return jsonlib.loads(self.text, **kwargs)

    @property
    def cookies(self) -> "Cookies":
        if not hasattr(self, "_cookies"):
            self._cookies = Cookies()
            self._cookies.extract_cookies(self)
        return self._cookies

    @property
    def links(self) -> typing.Dict[typing.Optional[str], typing.Dict[str, str]]:
        """
        Returns the parsed header links of the response, if any
        """
        header = self.headers.get("link")
        ldict = {}
        if header:
            links = parse_header_links(header)
            for link in links:
                key = link.get("rel") or link.get("url")
                ldict[key] = link
        return ldict

    @property
    def num_bytes_downloaded(self) -> int:
        return self._num_bytes_downloaded

    def __repr__(self) -> str:
        return f"<Response [{self.status_code} {self.reason_phrase}]>"

    def __getstate__(self) -> typing.Dict[str, typing.Any]:
        return {
            name: value
            for name, value in self.__dict__.items()
            if name not in ["stream", "is_closed", "_decoder"]
        }

    def __setstate__(self, state: typing.Dict[str, typing.Any]) -> None:
        for name, value in state.items():
            setattr(self, name, value)
        self.is_closed = True
        self.stream = UnattachedStream()

    def read(self) -> bytes:
        """
        Read and return the response content.
        """
        if not hasattr(self, "_content"):
            self._content = b"".join(self.iter_bytes())
        return self._content

    def iter_bytes(self, chunk_size: int = None) -> typing.Iterator[bytes]:
        """
        A byte-iterator over the decoded response content.
        This allows us to handle gzip, deflate, and brotli encoded responses.
        """
        if hasattr(self, "_content"):
            chunk_size = len(self._content) if chunk_size is None else chunk_size
            for i in range(0, len(self._content), max(chunk_size, 1)):
                yield self._content[i : i + chunk_size]
        else:
            decoder = self._get_content_decoder()
            chunker = ByteChunker(chunk_size=chunk_size)
            with request_context(request=self._request):
                for raw_bytes in self.iter_raw():
                    decoded = decoder.decode(raw_bytes)
                    for chunk in chunker.decode(decoded):
                        yield chunk
                decoded = decoder.flush()
                for chunk in chunker.decode(decoded):
                    yield chunk
                for chunk in chunker.flush():
                    yield chunk

    def iter_text(self, chunk_size: int = None) -> typing.Iterator[str]:
        """
        A str-iterator over the decoded response content
        that handles both gzip, deflate, etc but also detects the content's
        string encoding.
        """
        decoder = TextDecoder(encoding=self.encoding or "utf-8")
        chunker = TextChunker(chunk_size=chunk_size)
        with request_context(request=self._request):
            for byte_content in self.iter_bytes():
                text_content = decoder.decode(byte_content)
                for chunk in chunker.decode(text_content):
                    yield chunk
            text_content = decoder.flush()
            for chunk in chunker.decode(text_content):
                yield chunk
            for chunk in chunker.flush():
                yield chunk

    def iter_lines(self) -> typing.Iterator[str]:
        decoder = LineDecoder()
        with request_context(request=self._request):
            for text in self.iter_text():
                for line in decoder.decode(text):
                    yield line
            for line in decoder.flush():
                yield line

    def iter_raw(self, chunk_size: int = None) -> typing.Iterator[bytes]:
        """
        A byte-iterator over the raw response content.
        """
        if self.is_stream_consumed:
            raise StreamConsumed()
        if self.is_closed:
            raise StreamClosed()
        if not isinstance(self.stream, SyncByteStream):
            raise RuntimeError("Attempted to call a sync iterator on an async stream.")

        self.is_stream_consumed = True
        self._num_bytes_downloaded = 0
        chunker = ByteChunker(chunk_size=chunk_size)

        with request_context(request=self._request):
            for raw_stream_bytes in self.stream:
                self._num_bytes_downloaded += len(raw_stream_bytes)
                for chunk in chunker.decode(raw_stream_bytes):
                    yield chunk

        for chunk in chunker.flush():
            yield chunk

        self.close()

    def close(self) -> None:
        """
        Close the response and release the connection.
        Automatically called if the response body is read to completion.
        """
        if not isinstance(self.stream, SyncByteStream):
            raise RuntimeError("Attempted to call an sync close on an async stream.")

        if not self.is_closed:
            self.is_closed = True
            with request_context(request=self._request):
                self.stream.close()

    async def aread(self) -> bytes:
        """
        Read and return the response content.
        """
        if not hasattr(self, "_content"):
            self._content = b"".join([part async for part in self.aiter_bytes()])
        return self._content

    async def aiter_bytes(self, chunk_size: int = None) -> typing.AsyncIterator[bytes]:
        """
        A byte-iterator over the decoded response content.
        This allows us to handle gzip, deflate, and brotli encoded responses.
        """
        if hasattr(self, "_content"):
            chunk_size = len(self._content) if chunk_size is None else chunk_size
            for i in range(0, len(self._content), max(chunk_size, 1)):
                yield self._content[i : i + chunk_size]
        else:
            decoder = self._get_content_decoder()
            chunker = ByteChunker(chunk_size=chunk_size)
            with request_context(request=self._request):
                async for raw_bytes in self.aiter_raw():
                    decoded = decoder.decode(raw_bytes)
                    for chunk in chunker.decode(decoded):
                        yield chunk
                decoded = decoder.flush()
                for chunk in chunker.decode(decoded):
                    yield chunk
                for chunk in chunker.flush():
                    yield chunk

    async def aiter_text(self, chunk_size: int = None) -> typing.AsyncIterator[str]:
        """
        A str-iterator over the decoded response content
        that handles both gzip, deflate, etc but also detects the content's
        string encoding.
        """
        decoder = TextDecoder(encoding=self.encoding or "utf-8")
        chunker = TextChunker(chunk_size=chunk_size)
        with request_context(request=self._request):
            async for byte_content in self.aiter_bytes():
                text_content = decoder.decode(byte_content)
                for chunk in chunker.decode(text_content):
                    yield chunk
            text_content = decoder.flush()
            for chunk in chunker.decode(text_content):
                yield chunk
            for chunk in chunker.flush():
                yield chunk

    async def aiter_lines(self) -> typing.AsyncIterator[str]:
        decoder = LineDecoder()
        with request_context(request=self._request):
            async for text in self.aiter_text():
                for line in decoder.decode(text):
                    yield line
            for line in decoder.flush():
                yield line

    async def aiter_raw(self, chunk_size: int = None) -> typing.AsyncIterator[bytes]:
        """
        A byte-iterator over the raw response content.
        """
        if self.is_stream_consumed:
            raise StreamConsumed()
        if self.is_closed:
            raise StreamClosed()
        if not isinstance(self.stream, AsyncByteStream):
            raise RuntimeError("Attempted to call an async iterator on an sync stream.")

        self.is_stream_consumed = True
        self._num_bytes_downloaded = 0
        chunker = ByteChunker(chunk_size=chunk_size)

        with request_context(request=self._request):
            async for raw_stream_bytes in self.stream:
                self._num_bytes_downloaded += len(raw_stream_bytes)
                for chunk in chunker.decode(raw_stream_bytes):
                    yield chunk

        for chunk in chunker.flush():
            yield chunk

        await self.aclose()

    async def aclose(self) -> None:
        """
        Close the response and release the connection.
        Automatically called if the response body is read to completion.
        """
        if not isinstance(self.stream, AsyncByteStream):
            raise RuntimeError("Attempted to call an async close on an sync stream.")

        if not self.is_closed:
            self.is_closed = True
            with request_context(request=self._request):
                await self.stream.aclose()


class Cookies(MutableMapping):
    """
    HTTP Cookies, as a mutable mapping.
    """

    def __init__(self, cookies: CookieTypes = None) -> None:
        if cookies is None or isinstance(cookies, dict):
            self.jar = CookieJar()
            if isinstance(cookies, dict):
                for key, value in cookies.items():
                    self.set(key, value)
        elif isinstance(cookies, list):
            self.jar = CookieJar()
            for key, value in cookies:
                self.set(key, value)
        elif isinstance(cookies, Cookies):
            self.jar = CookieJar()
            for cookie in cookies.jar:
                self.jar.set_cookie(cookie)
        else:
            self.jar = cookies

    def extract_cookies(self, response: Response) -> None:
        """
        Loads any cookies based on the response `Set-Cookie` headers.
        """
        urllib_response = self._CookieCompatResponse(response)
        urllib_request = self._CookieCompatRequest(response.request)

        self.jar.extract_cookies(urllib_response, urllib_request)  # type: ignore

    def set_cookie_header(self, request: Request) -> None:
        """
        Sets an appropriate 'Cookie:' HTTP header on the `Request`.
        """
        urllib_request = self._CookieCompatRequest(request)
        self.jar.add_cookie_header(urllib_request)

    def set(self, name: str, value: str, domain: str = "", path: str = "/") -> None:
        """
        Set a cookie value by name. May optionally include domain and path.
        """
        kwargs = {
            "version": 0,
            "name": name,
            "value": value,
            "port": None,
            "port_specified": False,
            "domain": domain,
            "domain_specified": bool(domain),
            "domain_initial_dot": domain.startswith("."),
            "path": path,
            "path_specified": bool(path),
            "secure": False,
            "expires": None,
            "discard": True,
            "comment": None,
            "comment_url": None,
            "rest": {"HttpOnly": None},
            "rfc2109": False,
        }
        cookie = Cookie(**kwargs)  # type: ignore
        self.jar.set_cookie(cookie)

    def get(  # type: ignore
        self, name: str, default: str = None, domain: str = None, path: str = None
    ) -> typing.Optional[str]:
        """
        Get a cookie by name. May optionally include domain and path
        in order to specify exactly which cookie to retrieve.
        """
        value = None
        for cookie in self.jar:
            if cookie.name == name:
                if domain is None or cookie.domain == domain:
                    if path is None or cookie.path == path:
                        if value is not None:
                            message = f"Multiple cookies exist with name={name}"
                            raise CookieConflict(message)
                        value = cookie.value

        if value is None:
            return default
        return value

    def delete(self, name: str, domain: str = None, path: str = None) -> None:
        """
        Delete a cookie by name. May optionally include domain and path
        in order to specify exactly which cookie to delete.
        """
        if domain is not None and path is not None:
            return self.jar.clear(domain, path, name)

        remove = [
            cookie
            for cookie in self.jar
            if cookie.name == name
            and (domain is None or cookie.domain == domain)
            and (path is None or cookie.path == path)
        ]

        for cookie in remove:
            self.jar.clear(cookie.domain, cookie.path, cookie.name)

    def clear(self, domain: str = None, path: str = None) -> None:
        """
        Delete all cookies. Optionally include a domain and path in
        order to only delete a subset of all the cookies.
        """
        args = []
        if domain is not None:
            args.append(domain)
        if path is not None:
            assert domain is not None
            args.append(path)
        self.jar.clear(*args)

    def update(self, cookies: CookieTypes = None) -> None:  # type: ignore
        cookies = Cookies(cookies)
        for cookie in cookies.jar:
            self.jar.set_cookie(cookie)

    def __setitem__(self, name: str, value: str) -> None:
        return self.set(name, value)

    def __getitem__(self, name: str) -> str:
        value = self.get(name)
        if value is None:
            raise KeyError(name)
        return value

    def __delitem__(self, name: str) -> None:
        return self.delete(name)

    def __len__(self) -> int:
        return len(self.jar)

    def __iter__(self) -> typing.Iterator[str]:
        return (cookie.name for cookie in self.jar)

    def __bool__(self) -> bool:
        for _ in self.jar:
            return True
        return False

    def __repr__(self) -> str:
        cookies_repr = ", ".join(
            [
                f"<Cookie {cookie.name}={cookie.value} for {cookie.domain} />"
                for cookie in self.jar
            ]
        )

        return f"<Cookies[{cookies_repr}]>"

    class _CookieCompatRequest(urllib.request.Request):
        """
        Wraps a `Request` instance up in a compatibility interface suitable
        for use with `CookieJar` operations.
        """

        def __init__(self, request: Request) -> None:
            super().__init__(
                url=str(request.url),
                headers=dict(request.headers),
                method=request.method,
            )
            self.request = request

        def add_unredirected_header(self, key: str, value: str) -> None:
            super().add_unredirected_header(key, value)
            self.request.headers[key] = value

    class _CookieCompatResponse:
        """
        Wraps a `Request` instance up in a compatibility interface suitable
        for use with `CookieJar` operations.
        """

        def __init__(self, response: Response):
            self.response = response

        def info(self) -> email.message.Message:
            info = email.message.Message()
            for key, value in self.response.headers.multi_items():
                # Note that setting `info[key]` here is an "append" operation,
                # not a "replace" operation.
                # https://docs.python.org/3/library/email.compat32-message.html#email.message.Message.__setitem__
                info[key] = value
            return info