import asyncio
import datetime
import io
import re
import socket
import string
import tempfile
import types
import warnings
from email.utils import parsedate
from http.cookies import SimpleCookie
from types import MappingProxyType
from typing import (  # noqa
    TYPE_CHECKING,
    Any,
    Dict,
    Iterator,
    Mapping,
    MutableMapping,
    Optional,
    Tuple,
    Union,
    cast,
)
from urllib.parse import parse_qsl

import attr
from multidict import CIMultiDict, CIMultiDictProxy, MultiDict, MultiDictProxy
from yarl import URL

from . import hdrs
from .abc import AbstractStreamWriter
from .helpers import DEBUG, ChainMapProxy, HeadersMixin, reify, sentinel
from .http_parser import RawRequestMessage
from .multipart import MultipartReader
from .streams import EmptyStreamReader, StreamReader
from .typedefs import (
    DEFAULT_JSON_DECODER,
    JSONDecoder,
    LooseHeaders,
    RawHeaders,
    StrOrURL,
)
from .web_exceptions import HTTPRequestEntityTooLarge
from .web_response import StreamResponse

__all__ = ('BaseRequest', 'FileField', 'Request')


if TYPE_CHECKING:  # pragma: no cover
    from .web_app import Application  # noqa
    from .web_urldispatcher import UrlMappingMatchInfo  # noqa
    from .web_protocol import RequestHandler  # noqa


@attr.s(frozen=True, slots=True)
class FileField:
    name = attr.ib(type=str)
    filename = attr.ib(type=str)
    file = attr.ib(type=io.BufferedReader)
    content_type = attr.ib(type=str)
    headers = attr.ib(type=CIMultiDictProxy)  # type: CIMultiDictProxy[str]


_TCHAR = string.digits + string.ascii_letters + r"!#$%&'*+.^_`|~-"
# '-' at the end to prevent interpretation as range in a char class

_TOKEN = r'[{tchar}]+'.format(tchar=_TCHAR)

_QDTEXT = r'[{}]'.format(
    r''.join(chr(c) for c in (0x09, 0x20, 0x21) + tuple(range(0x23, 0x7F))))
# qdtext includes 0x5C to escape 0x5D ('\]')
# qdtext excludes obs-text (because obsoleted, and encoding not specified)

_QUOTED_PAIR = r'\\[\t !-~]'

_QUOTED_STRING = r'"(?:{quoted_pair}|{qdtext})*"'.format(
    qdtext=_QDTEXT, quoted_pair=_QUOTED_PAIR)

_FORWARDED_PAIR = (
    r'({token})=({token}|{quoted_string})(:\d{{1,4}})?'.format(
        token=_TOKEN,
        quoted_string=_QUOTED_STRING))

_QUOTED_PAIR_REPLACE_RE = re.compile(r'\\([\t !-~])')
# same pattern as _QUOTED_PAIR but contains a capture group

_FORWARDED_PAIR_RE = re.compile(_FORWARDED_PAIR)

############################################################
# HTTP Request
############################################################


class BaseRequest(MutableMapping[str, Any], HeadersMixin):

    POST_METHODS = {hdrs.METH_PATCH, hdrs.METH_POST, hdrs.METH_PUT,
                    hdrs.METH_TRACE, hdrs.METH_DELETE}

    ATTRS = HeadersMixin.ATTRS | frozenset([
        '_message', '_protocol', '_payload_writer', '_payload', '_headers',
        '_method', '_version', '_rel_url', '_post', '_read_bytes',
        '_state', '_cache', '_task', '_client_max_size', '_loop',
        '_transport_sslcontext', '_transport_peername'])

    def __init__(self, message: RawRequestMessage,
                 payload: StreamReader, protocol: 'RequestHandler',
                 payload_writer: AbstractStreamWriter,
                 task: 'asyncio.Task[None]',
                 loop: asyncio.AbstractEventLoop,
                 *, client_max_size: int=1024**2,
                 state: Optional[Dict[str, Any]]=None,
                 scheme: Optional[str]=None,
                 host: Optional[str]=None,
                 remote: Optional[str]=None) -> None:
        if state is None:
            state = {}
        self._message = message
        self._protocol = protocol
        self._payload_writer = payload_writer

        self._payload = payload
        self._headers = message.headers
        self._method = message.method
        self._version = message.version
        self._rel_url = message.url
        self._post = None  # type: Optional[MultiDictProxy[Union[str, bytes, FileField]]]  # noqa
        self._read_bytes = None  # type: Optional[bytes]

        self._state = state
        self._cache = {}  # type: Dict[str, Any]
        self._task = task
        self._client_max_size = client_max_size
        self._loop = loop

        transport = self._protocol.transport
        assert transport is not None
        self._transport_sslcontext = transport.get_extra_info('sslcontext')
        self._transport_peername = transport.get_extra_info('peername')

        if scheme is not None:
            self._cache['scheme'] = scheme
        if host is not None:
            self._cache['host'] = host
        if remote is not None:
            self._cache['remote'] = remote

    def clone(self, *, method: str=sentinel, rel_url: StrOrURL=sentinel,
              headers: LooseHeaders=sentinel, scheme: str=sentinel,
              host: str=sentinel,
              remote: str=sentinel) -> 'BaseRequest':
        """Clone itself with replacement some attributes.

        Creates and returns a new instance of Request object. If no parameters
        are given, an exact copy is returned. If a parameter is not passed, it
        will reuse the one from the current request object.

        """

        if self._read_bytes:
            raise RuntimeError("Cannot clone request "
                               "after reading its content")

        dct = {}  # type: Dict[str, Any]
        if method is not sentinel:
            dct['method'] = method
        if rel_url is not sentinel:
            new_url = URL(rel_url)
            dct['url'] = new_url
            dct['path'] = str(new_url)
        if headers is not sentinel:
            # a copy semantic
            dct['headers'] = CIMultiDictProxy(CIMultiDict(headers))
            dct['raw_headers'] = tuple((k.encode('utf-8'), v.encode('utf-8'))
                                       for k, v in headers.items())

        message = self._message._replace(**dct)

        kwargs = {}
        if scheme is not sentinel:
            kwargs['scheme'] = scheme
        if host is not sentinel:
            kwargs['host'] = host
        if remote is not sentinel:
            kwargs['remote'] = remote

        return self.__class__(
            message,
            self._payload,
            self._protocol,
            self._payload_writer,
            self._task,
            self._loop,
            client_max_size=self._client_max_size,
            state=self._state.copy(),
            **kwargs)

    @property
    def task(self) -> 'asyncio.Task[None]':
        return self._task

    @property
    def protocol(self) -> 'RequestHandler':
        return self._protocol

    @property
    def transport(self) -> Optional[asyncio.Transport]:
        if self._protocol is None:
            return None
        return self._protocol.transport

    @property
    def writer(self) -> AbstractStreamWriter:
        return self._payload_writer

    @reify
    def message(self) -> RawRequestMessage:
        warnings.warn("Request.message is deprecated",
                      DeprecationWarning,
                      stacklevel=3)
        return self._message

    @reify
    def rel_url(self) -> URL:
        return self._rel_url

    @reify
    def loop(self) -> asyncio.AbstractEventLoop:
        warnings.warn("request.loop property is deprecated",
                      DeprecationWarning,
                      stacklevel=2)
        return self._loop

    # MutableMapping API

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

    def __setitem__(self, key: str, value: Any) -> None:
        self._state[key] = value

    def __delitem__(self, key: str) -> None:
        del self._state[key]

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

    def __iter__(self) -> Iterator[str]:
        return iter(self._state)

    ########

    @reify
    def secure(self) -> bool:
        """A bool indicating if the request is handled with SSL."""
        return self.scheme == 'https'

    @reify
    def forwarded(self) -> Tuple[Mapping[str, str], ...]:
        """A tuple containing all parsed Forwarded header(s).

        Makes an effort to parse Forwarded headers as specified by RFC 7239:

        - It adds one (immutable) dictionary per Forwarded 'field-value', ie
          per proxy. The element corresponds to the data in the Forwarded
          field-value added by the first proxy encountered by the client. Each
          subsequent item corresponds to those added by later proxies.
        - It checks that every value has valid syntax in general as specified
          in section 4: either a 'token' or a 'quoted-string'.
        - It un-escapes found escape sequences.
        - It does NOT validate 'by' and 'for' contents as specified in section
          6.
        - It does NOT validate 'host' contents (Host ABNF).
        - It does NOT validate 'proto' contents for valid URI scheme names.

        Returns a tuple containing one or more immutable dicts
        """
        elems = []
        for field_value in self._message.headers.getall(hdrs.FORWARDED, ()):
            length = len(field_value)
            pos = 0
            need_separator = False
            elem = {}  # type: Dict[str, str]
            elems.append(types.MappingProxyType(elem))
            while 0 <= pos < length:
                match = _FORWARDED_PAIR_RE.match(field_value, pos)
                if match is not None:           # got a valid forwarded-pair
                    if need_separator:
                        # bad syntax here, skip to next comma
                        pos = field_value.find(',', pos)
                    else:
                        name, value, port = match.groups()
                        if value[0] == '"':
                            # quoted string: remove quotes and unescape
                            value = _QUOTED_PAIR_REPLACE_RE.sub(r'\1',
                                                                value[1:-1])
                        if port:
                            value += port
                        elem[name.lower()] = value
                        pos += len(match.group(0))
                        need_separator = True
                elif field_value[pos] == ',':      # next forwarded-element
                    need_separator = False
                    elem = {}
                    elems.append(types.MappingProxyType(elem))
                    pos += 1
                elif field_value[pos] == ';':      # next forwarded-pair
                    need_separator = False
                    pos += 1
                elif field_value[pos] in ' \t':
                    # Allow whitespace even between forwarded-pairs, though
                    # RFC 7239 doesn't. This simplifies code and is in line
                    # with Postel's law.
                    pos += 1
                else:
                    # bad syntax here, skip to next comma
                    pos = field_value.find(',', pos)
        return tuple(elems)

    @reify
    def scheme(self) -> str:
        """A string representing the scheme of the request.

        Hostname is resolved in this order:

        - overridden value by .clone(scheme=new_scheme) call.
        - type of connection to peer: HTTPS if socket is SSL, HTTP otherwise.

        'http' or 'https'.
        """
        if self._transport_sslcontext:
            return 'https'
        else:
            return 'http'

    @reify
    def method(self) -> str:
        """Read only property for getting HTTP method.

        The value is upper-cased str like 'GET', 'POST', 'PUT' etc.
        """
        return self._method

    @reify
    def version(self) -> Tuple[int, int]: