import asyncio  # noqa
import collections.abc  # noqa
import datetime
import enum
import json
import math
import time
import warnings
import zlib
from concurrent.futures import Executor
from email.utils import parsedate
from http.cookies import SimpleCookie
from typing import (  # noqa
    TYPE_CHECKING,
    Any,
    Dict,
    Iterator,
    Mapping,
    MutableMapping,
    Optional,
    Tuple,
    Union,
    cast,
)

from multidict import CIMultiDict, istr

from . import hdrs, payload
from .abc import AbstractStreamWriter
from .helpers import HeadersMixin, rfc822_formatted_time, sentinel
from .http import RESPONSES, SERVER_SOFTWARE, HttpVersion10, HttpVersion11
from .payload import Payload
from .typedefs import JSONEncoder, LooseHeaders

__all__ = ('ContentCoding', 'StreamResponse', 'Response', 'json_response')


if TYPE_CHECKING:  # pragma: no cover
    from .web_request import BaseRequest  # noqa
    BaseClass = MutableMapping[str, Any]
else:
    BaseClass = collections.abc.MutableMapping


class ContentCoding(enum.Enum):
    # The content codings that we have support for.
    #
    # Additional registered codings are listed at:
    # https://www.iana.org/assignments/http-parameters/http-parameters.xhtml#content-coding
    deflate = 'deflate'
    gzip = 'gzip'
    identity = 'identity'


############################################################
# HTTP Response classes
############################################################


class StreamResponse(BaseClass, HeadersMixin):

    _length_check = True

    def __init__(self, *,
                 status: int=200,
                 reason: Optional[str]=None,
                 headers: Optional[LooseHeaders]=None) -> None:
        self._body = None
        self._keep_alive = None  # type: Optional[bool]
        self._chunked = False
        self._compression = False
        self._compression_force = None  # type: Optional[ContentCoding]
        self._cookies = SimpleCookie()

        self._req = None  # type: Optional[BaseRequest]
        self._payload_writer = None  # type: Optional[AbstractStreamWriter]
        self._eof_sent = False
        self._body_length = 0
        self._state = {}  # type: Dict[str, Any]

        if headers is not None:
            self._headers = CIMultiDict(headers)  # type: CIMultiDict[str]
        else:
            self._headers = CIMultiDict()  # type: CIMultiDict[str]

        self.set_status(status, reason)

    @property
    def prepared(self) -> bool:
        return self._payload_writer is not None

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

    @property
    def status(self) -> int:
        return self._status

    @property
    def chunked(self) -> bool:
        return self._chunked

    @property
    def compression(self) -> bool:
        return self._compression

    @property
    def reason(self) -> str:
        return self._reason

    def set_status(self, status: int,
                   reason: Optional[str]=None,
                   _RESPONSES: Mapping[int,
                                       Tuple[str, str]]=RESPONSES) -> None:
        assert not self.prepared, \
            'Cannot change the response status code after ' \
            'the headers have been sent'
        self._status = int(status)
        if reason is None:
            try:
                reason = _RESPONSES[self._status][0]
            except Exception:
                reason = ''
        self._reason = reason

    @property
    def keep_alive(self) -> Optional[bool]:
        return self._keep_alive

    def force_close(self) -> None:
        self._keep_alive = False

    @property
    def body_length(self) -> int:
        return self._body_length

    @property
    def output_length(self) -> int:
        warnings.warn('output_length is deprecated', DeprecationWarning)
        assert self._payload_writer
        return self._payload_writer.buffer_size

    def enable_chunked_encoding(self, chunk_size: Optional[int]=None) -> None:
        """Enables automatic chunked transfer encoding."""
        self._chunked = True

        if hdrs.CONTENT_LENGTH in self._headers:
            raise RuntimeError("You can't enable chunked encoding when "
                               "a content length is set")
        if chunk_size is not None:
            warnings.warn('Chunk size is deprecated #1615', DeprecationWarning)

    def enable_compression(self,
                           force: Optional[Union[bool, ContentCoding]]=None
                           ) -> None:
        """Enables response compression encoding."""
        # Backwards compatibility for when force was a bool <0.17.
        if type(force) == bool:
            force = ContentCoding.deflate if force else ContentCoding.identity
            warnings.warn("Using boolean for force is deprecated #3318",
                          DeprecationWarning)
        elif force is not None:
            assert isinstance(force, ContentCoding), ("force should one of "
                                                      "None, bool or "
                                                      "ContentEncoding")

        self._compression = True
        self._compression_force = force

    @property
    def headers(self) -> 'CIMultiDict[str]':
        return self._headers

    @property
    def cookies(self) -> SimpleCookie:
        return self._cookies

    def set_cookie(self, name: str, value: str, *,
                   expires: Optional[str]=None,
                   domain: Optional[str]=None,
                   max_age: Optional[Union[int, str]]=None,
                   path: str='/',
                   secure: Optional[str]=None,
                   httponly: Optional[str]=None,
                   version: Optional[str]=None) -> None:
        """Set or update response cookie.

        Sets new cookie or updates existent with new value.
        Also updates only those params which are not None.
        """

        old = self._cookies.get(name)
        if old is not None and old.coded_value == '':
            # deleted cookie
            self._cookies.pop(name, None)

        self._cookies[name] = value
        c = self._cookies[name]

        if expires is not None:
            c['expires'] = expires
        elif c.get('expires') == 'Thu, 01 Jan 1970 00:00:00 GMT':
            del c['expires']

        if domain is not None:
            c['domain'] = domain

        if max_age is not None:
            c['max-age'] = str(max_age)
        elif 'max-age' in c:
            del c['max-age']

        c['path'] = path

        if secure is not None:
            c['secure'] = secure
        if httponly is not None:
            c['httponly'] = httponly
        if version is not None:
            c['version'] = version

    def del_cookie(self, name: str, *,
                   domain: Optional[str]=None,
                   path: str='/') -> None:
        """Delete cookie.

        Creates new empty expired cookie.
        """
        # TODO: do we need domain/path here?
        self._cookies.pop(name, None)
        self.set_cookie(name, '', max_age=0,
                        expires="Thu, 01 Jan 1970 00:00:00 GMT",
                        domain=domain, path=path)

    @property
    def content_length(self) -> Optional[int]:
        # Just a placeholder for adding setter
        return super().content_length

    @content_length.setter
    def content_length(self, value: Optional[int]) -> None:
        if value is not None:
            value = int(value)
            if self._chunked:
                raise RuntimeError("You can't set content length when "
                                   "chunked encoding is enable")
            self._headers[hdrs.CONTENT_LENGTH] = str(value)
        else:
            self._headers.pop(hdrs.CONTENT_LENGTH, None)

    @property
    def content_type(self) -> str:
        # Just a placeholder for adding setter
        return super().content_type

    @content_type.setter
    def content_type(self, value: str) -> None:
        self.content_type  # read header values if needed
        self._content_type = str(value)
        self._generate_content_type_header()

    @property
    def charset(self) -> Optional[str]:
        # Just a placeholder for adding setter
        return super().charset

    @charset.setter
    def charset(self, value: Optional[str]) -> None:
        ctype = self.content_type  # read header values if needed
        if ctype == 'application/octet-stream':
            raise RuntimeError("Setting charset for application/octet-stream "
                               "doesn't make sense, setup content_type first")
        assert self._content_dict is not None
        if value is None:
            self._content_dict.pop('charset', None)
        else:
            self._content_dict['charset'] = str(value).lower()
        self._generate_content_type_header()

    @property
    def last_modified(self) -> Optional[datetime.datetime]:
        """The value of Last-Modified HTTP header, or None.

        This header is represented as a `datetime` object.
        """
        httpdate = self._headers.get(hdrs.LAST_MODIFIED)
        if httpdate is not None:
            timetuple = parsedate(httpdate)
            if timetuple is not None:
                return datetime.datetime(*timetuple[:6],
                                         tzinfo=datetime.timezone.utc)
        return None

    @last_modified.setter
    def last_modified(self,
                      value: Optional[
                          Union[int, float, datetime.datetime, str]]) -> None:
        if value is None:
            self._headers.pop(hdrs.LAST_MODIFIED, None)
        elif isinstance(value, (int, float)):
            self._headers[hdrs.LAST_MODIFIED] = time.strftime(
                "%a, %d %b %Y %H:%M:%S GMT", time.gmtime(math.ceil(value)))
        elif isinstance(value, datetime.datetime):
            self._headers[hdrs.LAST_MODIFIED] = time.strftime(
                "%a, %d %b %Y %H:%M:%S GMT", value.utctimetuple())
        elif isinstance(value, str):
            self._headers[hdrs.LAST_MODIFIED] = value

    def _generate_content_type_header(
            self,
            CONTENT_TYPE: istr=hdrs.CONTENT_TYPE) -> None:
        assert self._content_dict is not None
        assert self._content_type is not None
        params = '; '.join("{}={}".format(k, v)
                           for k, v in self._content_dict.items())
        if params:
            ctype = self._content_type + '; ' + params
        else:
            ctype = self._content_type
        self._headers[CONTENT_TYPE] = ctype

    async def _do_start_compression(self, coding: ContentCoding) -> None:
        if coding != ContentCoding.identity:
            assert self._payload_writer is not None
            self._headers[hdrs.CONTENT_ENCODING] = coding.value
            self._payload_writer.enable_compression(coding.value)
            # Compressed payload may have different content length,
            # remove the header
            self._headers.popall(hdrs.CONTENT_LENGTH, None)

    async def _start_compression(self, request: 'BaseRequest') -> None:
        if self._compression_force:
            await self._do_start_compression(self._compression_force)
        else:
            accept_encoding = request.headers.get(
                hdrs.ACCEPT_ENCODING, '').lower()
            for coding in ContentCoding:
                if coding.value in accept_encoding:
                    await self._do_start_compression(coding)
                    return

    async def prepare(
            self,
            request: 'BaseRequest'