"""WebSocket protocol versions 13 and 8."""

import collections
import json
import random
import re
import sys
import zlib
from enum import IntEnum
from struct import Struct

from .helpers import NO_EXTENSIONS
from .log import ws_logger


__all__ = ('WS_CLOSED_MESSAGE', 'WS_CLOSING_MESSAGE', 'WS_KEY',
           'WebSocketReader', 'WebSocketWriter', 'WSMessage',
           'WebSocketError', 'WSMsgType', 'WSCloseCode')


class WSCloseCode(IntEnum):
    OK = 1000
    GOING_AWAY = 1001
    PROTOCOL_ERROR = 1002
    UNSUPPORTED_DATA = 1003
    INVALID_TEXT = 1007
    POLICY_VIOLATION = 1008
    MESSAGE_TOO_BIG = 1009
    MANDATORY_EXTENSION = 1010
    INTERNAL_ERROR = 1011
    SERVICE_RESTART = 1012
    TRY_AGAIN_LATER = 1013


ALLOWED_CLOSE_CODES = {int(i) for i in WSCloseCode}


class WSMsgType(IntEnum):
    # websocket spec types
    CONTINUATION = 0x0
    TEXT = 0x1
    BINARY = 0x2
    PING = 0x9
    PONG = 0xa
    CLOSE = 0x8

    # aiohttp specific types
    CLOSING = 0x100
    CLOSED = 0x101
    ERROR = 0x102

    text = TEXT
    binary = BINARY
    ping = PING
    pong = PONG
    close = CLOSE
    closing = CLOSING
    closed = CLOSED
    error = ERROR


WS_KEY = b'258EAFA5-E914-47DA-95CA-C5AB0DC85B11'


UNPACK_LEN2 = Struct('!H').unpack_from
UNPACK_LEN3 = Struct('!Q').unpack_from
UNPACK_CLOSE_CODE = Struct('!H').unpack
PACK_LEN1 = Struct('!BB').pack
PACK_LEN2 = Struct('!BBH').pack
PACK_LEN3 = Struct('!BBQ').pack
PACK_CLOSE_CODE = Struct('!H').pack
MSG_SIZE = 2 ** 14
DEFAULT_LIMIT = 2 ** 16


_WSMessageBase = collections.namedtuple('_WSMessageBase',
                                        ['type', 'data', 'extra'])


class WSMessage(_WSMessageBase):

    def json(self, *, loads=json.loads):
        """Return parsed JSON data.

        .. versionadded:: 0.22
        """
        return loads(self.data)


WS_CLOSED_MESSAGE = WSMessage(WSMsgType.CLOSED, None, None)
WS_CLOSING_MESSAGE = WSMessage(WSMsgType.CLOSING, None, None)


class WebSocketError(Exception):
    """WebSocket protocol parser error."""

    def __init__(self, code, message):
        self.code = code
        super().__init__(message)


class WSHandshakeError(Exception):
    """WebSocket protocol handshake error."""


native_byteorder = sys.byteorder


# Used by _websocket_mask_python
_XOR_TABLE = [bytes(a ^ b for a in range(256)) for b in range(256)]


def _websocket_mask_python(mask, data):
    """Websocket masking function.

    `mask` is a `bytes` object of length 4; `data` is a `bytearray`
    object of any length. The contents of `data` are masked with `mask`,
    as specified in section 5.3 of RFC 6455.

    Note that this function mutates the `data` argument.

    This pure-python implementation may be replaced by an optimized
    version when available.

    """
    assert isinstance(data, bytearray), data
    assert len(mask) == 4, mask

    if data:
        a, b, c, d = (_XOR_TABLE[n] for n in mask)
        data[::4] = data[::4].translate(a)
        data[1::4] = data[1::4].translate(b)
        data[2::4] = data[2::4].translate(c)
        data[3::4] = data[3::4].translate(d)


if NO_EXTENSIONS:
    _websocket_mask = _websocket_mask_python
else:
    try:
        from ._websocket import _websocket_mask_cython
        _websocket_mask = _websocket_mask_cython
    except ImportError:  # pragma: no cover
        _websocket_mask = _websocket_mask_python

_WS_DEFLATE_TRAILING = bytes([0x00, 0x00, 0xff, 0xff])


_WS_EXT_RE = re.compile(r'^(?:;\s*(?:'
                        r'(server_no_context_takeover)|'
                        r'(client_no_context_takeover)|'
                        r'(server_max_window_bits(?:=(\d+))?)|'
                        r'(client_max_window_bits(?:=(\d+))?)))*$')

_WS_EXT_RE_SPLIT = re.compile(r'permessage-deflate([^,]+)?')


def ws_ext_parse(extstr, isserver=False):
    if not extstr:
        return 0, False

    compress = 0
    notakeover = False
    for ext in _WS_EXT_RE_SPLIT.finditer(extstr):
        defext = ext.group(1)
        # Return compress = 15 when get `permessage-deflate`
        if not defext:
            compress = 15
            break
        match = _WS_EXT_RE.match(defext)
        if match:
            compress = 15
            if isserver:
                # Server never fail to detect compress handshake.
                # Server does not need to send max wbit to client
                if match.group(4):
                    compress = int(match.group(4))
                    # Group3 must match if group4 matches
                    # Compress wbit 8 does not support in zlib
                    # If compress level not support,
                    # CONTINUE to next extension
                    if compress > 15 or compress < 9:
                        compress = 0
                        continue
                if match.group(1):
                    notakeover = True
                # Ignore regex group 5 & 6 for client_max_window_bits
                break
            else:
                if match.group(6):
                    compress = int(match.group(6))
                    # Group5 must match if group6 matches
                    # Compress wbit 8 does not support in zlib
                    # If compress level not support,
                    # FAIL the parse progress
                    if compress > 15 or compress < 9:
                        raise WSHandshakeError('Invalid window size')
                if match.group(2):
                    notakeover = True
                # Ignore regex group 5 & 6 for client_max_window_bits
                break
        # Return Fail if client side and not match
        elif not isserver:
            raise WSHandshakeError('Extension for deflate not supported' +
                                   ext.group(1))

    return compress, notakeover


def ws_ext_gen(compress=15, isserver=False,
               server_notakeover=False):
    # client_notakeover=False not used for server
    # compress wbit 8 does not support in zlib
    if compress < 9 or compress > 15:
        raise ValueError('Compress wbits must between 9 and 15, '
                         'zlib does not support wbits=8')
    enabledext = ['permessage-deflate']
    if not isserver:
        enabledext.append('client_max_window_bits')

    if compress < 15:
        enabledext.append('server_max_window_bits=' + str(compress))
    if server_notakeover:
        enabledext.append('server_no_context_takeover')
    # if client_notakeover:
    #     enabledext.append('client_no_context_takeover')
    return '; '.join(enabledext)


class WSParserState(IntEnum):
    READ_HEADER = 1
    READ_PAYLOAD_LENGTH = 2
    READ_PAYLOAD_MASK = 3
    READ_PAYLOAD = 4


class WebSocketReader:

    def __init__(self, queue, compress=True):
        self.queue = queue

        self._exc = None
        self._partial = []
        self._state = WSParserState.READ_HEADER

        self._opcode = None
        self._frame_fin = False
        self._frame_opcode = None
        self._frame_payload = bytearray()

        self._tail = b''
        self._has_mask = False
        self._frame_mask = None
        self._payload_length = 0
        self._payload_length_flag = 0
        self._compressed = None
        self._decompressobj = None
        self._compress = compress

    def feed_eof(self):
        self.queue.feed_eof()

    def feed_data(self, data):
        if self._exc:
            return True, data

        try:
            return self._feed_data(data)
        except Exception as exc:
            self._exc = exc
            self.queue.set_exception(exc)
            return True, b''

    def _feed_data(self, data):
        for fin, opcode, payload, compressed in self.parse_frame(data):
            if compressed and not self._decompressobj:
                self._decompressobj = zlib.decompressobj(wbits=-zlib.MAX_WBITS)
            if opcode == WSMsgType.CLOSE:
                if len(payload) >= 2:
                    close_code = UNPACK_CLOSE_CODE(payload[:2])[0]
                    if (close_code < 3000 and
                            close_code not in ALLOWED_CLOSE_CODES):
                        raise WebSocketError(
                            WSCloseCode.PROTOCOL_ERROR,
                            'Invalid close code: {}'.format(close_code))
                    try:
                        close_message = payload[2:].decode('utf-8')
                    except UnicodeDecodeError as exc:
                        raise WebSocketError(
                            WSCloseCode.INVALID_TEXT,
                            'Invalid UTF-8 text message') from exc
                    msg = WSMessage(WSMsgType.CLOSE, close_code, close_message)
                elif payload:
                    raise WebSocketError(
                        WSCloseCode.PROTOCOL_ERROR,
                        'Invalid close frame: {} {} {!r}'.format(
                            fin, opcode, payload))
                else:
                    msg = WSMessage(WSMsgType.CLOSE, 0, '')

                self.queue.feed_data(msg, 0)

            elif opcode == WSMsgType.PING:
                self.queue.feed_data(
                    WSMessage(WSMsgType.PING, payload, ''), len(payload))

            elif opcode == WSMsgType.PONG:
                self.queue.feed_data(
                    WSMessage(WSMsgType.PONG, payload, ''), len(payload))

            elif opcode not in (
                    WSMsgType.TEXT, WSMsgType.BINARY) and self._opcode is None:
                raise WebSocketError(
                    WSCloseCode.PROTOCOL_ERROR,
                    "Unexpected opcode={!r}".format(opcode))
            else:
                # load text/binary
                if not fin:
                    # got partial frame payload
                    if opcode != WSMsgType.CONTINUATION:
                        self._opcode = opcode
                    self._partial.append(payload)
                else:
                    # previous frame was non finished
                    # we should get continuation opcode
                    if self._partial:
                        if opcode != WSMsgType.CONTINUATION:
                            raise WebSocketError(
                                WSCloseCode.PROTOCOL_ERROR,
                                'The opcode in non-fin frame is expected '
                                'to be zero, got {!r}'.format(opcode))

                    if opcode == WSMsgType.CONTINUATION:
                        opcode = self._opcode
                        self._opcode = None

                    self._partial.append(payload)

                    payload_merged = b''.join(self._partial)

                    # Decompress process must to be done after all packets
                    # received.
                    if compressed:
                        payload_merged = self._decompressobj.decompress(
                            payload_merged + _WS_DEFLATE_TRAILING)

                    self._partial.clear()

                    if opcode == WSMsgType.TEXT:
                        try:
                            text = payload_merged.decode('utf-8')
                            self.queue.feed_data(
                                WSMessage(WSMsgType.TEXT, text, ''), len(text))
                        except UnicodeDecodeError as exc:
                            raise WebSocketError(
                                WSCloseCode.INVALID_TEXT,
                                'Invalid UTF-8 text message') from exc
                    else:
                        self.queue.feed_data(
                            WSMessage(WSMsgType.BINARY, payload_merged, ''),
                            len(payload_merged))

        return False, b''

    def parse_frame(self, buf):
        """Return the next frame from the socket."""
        frames = []
        if self._tail:
            buf, self._tail = self._tail + buf, b''

        start_pos = 0
        buf_length = len(buf)

        while True:
            # read header
            if self._state == WSParserState.READ_HEADER:
                if buf_length - start_pos >= 2:
                    data = buf[start_pos:start_pos+2]
                    start_pos += 2
                    first_byte, second_byte = data

                    fin = (first_byte >> 7) & 1
                    rsv1 = (first_byte >> 6) & 1
                    rsv2 = (first_byte >> 5) & 1
                    rsv3 = (first_byte >> 4) & 1
                    opcode = first_byte & 0xf

                    # frame-fin = %x0 ; more frames of this message follow
                    #           / %x1 ; final frame of this message
                    # frame-rsv1 = %x0 ;
                    #    1 bit, MUST be 0 unless negotiated otherwise
                    # frame-rsv2 = %x0 ;
                    #    1 bit, MUST be 0 unless negotiated otherwise
                    # frame-rsv3 = %x0 ;
                    #    1 bit, MUST be 0 unless negotiated otherwise
                    #
                    # Remove rsv1 from this test for deflate development
                    if rsv2 or rsv3 or (rsv1 and not self._compress):
                        raise WebSocketError(
                            WSCloseCode.PROTOCOL_ERROR,
                            'Received frame with non-zero reserved bits')

                    if opcode > 0x7 and fin == 0:
                        raise WebSocketError(
                            WSCloseCode.PROTOCOL_ERROR,
                            'Received fragmented control frame')

                    has_mask = (second_byte >> 7) & 1
                    length = second_byte & 0x7f

                    # Control frames MUST have a payload
                    # length of 125 bytes or less
                    if opcode > 0x7 and length > 125:
                        raise WebSocketError(
                            WSCloseCode.PROTOCOL_ERROR,
                            'Control frame payload cannot be '
                            'larger than 125 bytes')

                    # Set compress status if last package is FIN
                    # OR set compress status if this is first fragment
                    # Raise error if not first fragment with rsv1 = 0x1
                    if self._frame_fin or self._compressed is None:
                        self._compressed = True if rsv1 else False
                    elif rsv1:
                        raise WebSocketError(
                            WSCloseCode.PROTOCOL_ERROR,
                            'Received frame with non-zero reserved bits')

                    self._frame_fin = fin
                    self._frame_opcode = opcode
                    self._has_mask = has_mask
                    self._payload_length_flag = length
                    self._state = WSParserState.READ_PAYLOAD_LENGTH
                else:
                    break

            # read payload length
            if self._state == WSParserState.READ_PAYLOAD_LENGTH:
                length = self._payload_length_flag
                if length == 126:
                    if buf_length - start_pos >= 2:
                        data = buf[start_pos:start_pos+2]
                        start_pos += 2
                        length = UNPACK_LEN2(data)[0]
                        self._payload_length = length
                        self._state = (
                            WSParserState.READ_PAYLOAD_MASK
                            if self._has_mask
                            else WSParserState.READ_PAYLOAD)
                    else:
                        break
                elif length > 126:
                    if buf_length - start_pos >= 8:
                        data = buf[start_pos:start_pos+8]
                        start_pos += 8
                        length = UNPACK_LEN3(data)[0]
                        self._payload_length = length
                        self._state = (
                            WSParserState.READ_PAYLOAD_MASK
                            if self._has_mask
                            else WSParserState.READ_PAYLOAD)
                    else:
                        break
                else:
                    self._payload_length = length
                    self._state = (
                        WSParserState.READ_PAYLOAD_MASK
                        if self._has_mask
                        else WSParserState.READ_PAYLOAD)

            # read payload mask
            if self._state == WSParserState.READ_PAYLOAD_MASK:
                if buf_length - start_pos >= 4:
                    self._frame_mask = buf[start_pos:start_pos+4]
                    start_pos += 4
                    self._state = WSParserState.READ_PAYLOAD
                else:
                    break

            if self._state == WSParserState.READ_PAYLOAD:
                length = self._payload_length
                payload = self._frame_payload

                chunk_len = buf_length - start_pos
                if length >= chunk_len:
                    self._payload_length = length - chunk_len
                    payload.extend(buf[start_pos:])
                    start_pos = buf_length
                else:
                    self._payload_length = 0
                    payload.extend(buf[start_pos:start_pos+length])
                    start_pos = start_pos + length

                if self._payload_length == 0:
                    if self._has_mask:
                        _websocket_mask(self._frame_mask, payload)

                    frames.append((
                        self._frame_fin,
                        self._frame_opcode,
                        payload,
                        self._compressed))

                    self._frame_payload = bytearray()
                    self._state = WSParserState.READ_HEADER
                else:
                    break

        self._tail = buf[start_pos:]

        return frames


class WebSocketWriter:

    def __init__(self, protocol, transport, *,
                 use_mask=False, limit=DEFAULT_LIMIT, random=random.Random(),
                 compress=0, notakeover=False):
        self.protocol = protocol
        self.transport = transport
        self.use_mask = use_mask
        self.randrange = random.randrange
        self.compress = compress
        self.notakeover = notakeover
        self._closing = False
        self._limit = limit
        self._output_size = 0
        self._compressobj = None

    async def _send_frame(self, message, opcode, compress=None):
        """Send a frame over the websocket with message as its payload."""
        if self._closing:
            ws_logger.warning('websocket connection is closing.')

        rsv = 0

        # Only compress larger packets (disabled)
        # Does small packet needs to be compressed?
        # if self.compress and opcode < 8 and len(message) > 124:
        if (compress or self.compress) and opcode < 8:
            if compress:
                # Do not set self._compress if compressing is for this frame
                compressobj = zlib.compressobj(wbits=-compress)
            else:  # self.compress
                if not self._compressobj:
                    self._compressobj = zlib.compressobj(wbits=-self.compress)
                compressobj = self._compressobj

            message = compressobj.compress(message)
            message = message + compressobj.flush(
                zlib.Z_FULL_FLUSH if self.notakeover else zlib.Z_SYNC_FLUSH)
            if message.endswith(_WS_DEFLATE_TRAILING):
                message = message[:-4]
            rsv = rsv | 0x40

        msg_length = len(message)

        use_mask = self.use_mask
        if use_mask:
            mask_bit = 0x80
        else:
            mask_bit = 0

        if msg_length < 126:
            header = PACK_LEN1(0x80 | rsv | opcode, msg_length | mask_bit)
        elif msg_length < (1 << 16):
            header = PACK_LEN2(0x80 | rsv | opcode, 126 | mask_bit, msg_length)
        else:
            header = PACK_LEN3(0x80 | rsv | opcode, 127 | mask_bit, msg_length)
        if use_mask:
            mask = self.randrange(0, 0xffffffff)
            mask = mask.to_bytes(4, 'big')
            message = bytearray(message)
            _websocket_mask(mask, message)
            self.transport.write(header + mask + message)
            self._output_size += len(header) + len(mask) + len(message)
        else:
            if len(message) > MSG_SIZE:
                self.transport.write(header)
                self.transport.write(message)
            else:
                self.transport.write(header + message)

            self._output_size += len(header) + len(message)

        if self._output_size > self._limit:
            self._output_size = 0
            await self.protocol._drain_helper()

    async def pong(self, message=b''):
        """Send pong message."""
        if isinstance(message, str):
            message = message.encode('utf-8')
        return await self._send_frame(message, WSMsgType.PONG)

    async def ping(self, message=b''):
        """Send ping message."""
        if isinstance(message, str):
            message = message.encode('utf-8')
        return await self._send_frame(message, WSMsgType.PING)

    async def send(self, message, binary=False, compress=None):
        """Send a frame over the websocket with message as its payload."""
        if isinstance(message, str):
            message = message.encode('utf-8')
        if binary:
            return await self._send_frame(message, WSMsgType.BINARY, compress)
        else:
            return await self._send_frame(message, WSMsgType.TEXT, compress)

    async def close(self, code=1000, message=b''):
        """Close the websocket, sending the specified code and message."""
        if isinstance(message, str):
            message = message.encode('utf-8')
        try:
            return await self._send_frame(
                PACK_CLOSE_CODE(code) + message, opcode=WSMsgType.CLOSE)
        finally:
            self._closing = True
