###############################################################################
##
# Copyright 2013 Tavendo GmbH
##
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
##
# http://www.apache.org/licenses/LICENSE-2.0
##
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
##
###############################################################################

from __future__ import absolute_import

import bz2

from autobahn.websocket.compress_base import PerMessageCompressOffer, \
    PerMessageCompressOfferAccept, \
    PerMessageCompressResponse, \
    PerMessageCompressResponseAccept, \
    PerMessageCompress

__all__ = (
    'PerMessageBzip2Mixin',
    'PerMessageBzip2Offer',
    'PerMessageBzip2OfferAccept',
    'PerMessageBzip2Response',
    'PerMessageBzip2ResponseAccept',
    'PerMessageBzip2',
)


class PerMessageBzip2Mixin:
    """
    Mixin class for this extension.
    """

    EXTENSION_NAME = "permessage-bzip2"
    """
   Name of this WebSocket extension.
   """

    COMPRESS_LEVEL_PERMISSIBLE_VALUES = [1, 2, 3, 4, 5, 6, 7, 8, 9]
    """
   Permissible value for compression level parameter.
   """


class PerMessageBzip2Offer(PerMessageCompressOffer, PerMessageBzip2Mixin):
    """
    Set of extension parameters for `permessage-bzip2` WebSocket extension
    offered by a client to a server.
    """

    @classmethod
    def parse(cls, params):
        """
        Parses a WebSocket extension offer for `permessage-bzip2` provided by a client to a server.

        :param params: Output from :func:`autobahn.websocket.WebSocketProtocol._parseExtensionsHeader`.
        :type params: list

        :returns: object -- A new instance of :class:`autobahn.compress.PerMessageBzip2Offer`.
        """
        # extension parameter defaults
        ##
        acceptMaxCompressLevel = False
        requestMaxCompressLevel = 0

        ##
        # verify/parse client ("client-to-server direction") parameters of permessage-bzip2 offer
        ##
        for p in params:

            if len(params[p]) > 1:
                raise Exception("multiple occurrence of extension parameter '%s' for extension '%s'" % (p, cls.EXTENSION_NAME))

            val = params[p][0]

            if p == 'client_max_compress_level':
                # noinspection PySimplifyBooleanCheck
                if val is not True:
                    raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME))
                else:
                    acceptMaxCompressLevel = True

            elif p == 'server_max_compress_level':
                try:
                    val = int(val)
                except:
                    raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME))
                if val not in PerMessageBzip2Mixin.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
                    raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME))
                else:
                    requestMaxCompressLevel = val

            else:
                raise Exception("illegal extension parameter '%s' for extension '%s'" % (p, cls.EXTENSION_NAME))

        offer = cls(acceptMaxCompressLevel,
                    requestMaxCompressLevel)
        return offer

    def __init__(self,
                 acceptMaxCompressLevel=True,
                 requestMaxCompressLevel=0):
        """
        Constructor.

        :param acceptMaxCompressLevel: Iff true, client accepts "maximum compression level" parameter.
        :type acceptMaxCompressLevel: bool
        :param requestMaxCompressLevel: Iff non-zero, client requests given "maximum compression level" - must be 1-9.
        :type requestMaxCompressLevel: int
        """
        if type(acceptMaxCompressLevel) != bool:
            raise Exception("invalid type %s for acceptMaxCompressLevel" % type(acceptMaxCompressLevel))

        self.acceptMaxCompressLevel = acceptMaxCompressLevel

        if requestMaxCompressLevel != 0 and requestMaxCompressLevel not in self.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
            raise Exception("invalid value %s for requestMaxCompressLevel - permissible values %s" % (requestMaxCompressLevel, self.COMPRESS_LEVEL_PERMISSIBLE_VALUES))

        self.requestMaxCompressLevel = requestMaxCompressLevel

    def getExtensionString(self):
        """
        Returns the WebSocket extension configuration string as sent to the server.

        :returns: str -- PMCE configuration string.
        """
        pmceString = self.EXTENSION_NAME
        if self.acceptMaxCompressLevel:
            pmceString += "; client_max_compress_level"
        if self.requestMaxCompressLevel != 0:
            pmceString += "; server_max_compress_level=%d" % self.requestMaxCompressLevel
        return pmceString

    def __json__(self):
        """
        Returns a JSON serializable object representation.

        :returns: object -- JSON serializable representation.
        """
        return {'extension': self.EXTENSION_NAME,
                'acceptMaxCompressLevel': self.acceptMaxCompressLevel,
                'requestMaxCompressLevel': self.requestMaxCompressLevel}

    def __repr__(self):
        """
        Returns Python object representation that can be eval'ed to reconstruct the object.

        :returns: str -- Python string representation.
        """
        return "PerMessageBzip2Offer(acceptMaxCompressLevel = %s, requestMaxCompressLevel = %s)" % (self.acceptMaxCompressLevel, self.requestMaxCompressLevel)


class PerMessageBzip2OfferAccept(PerMessageCompressOfferAccept, PerMessageBzip2Mixin):
    """
    Set of parameters with which to accept an `permessage-bzip2` offer
    from a client by a server.
    """

    def __init__(self,
                 offer,
                 requestMaxCompressLevel=0,
                 compressLevel=None):
        """
        Constructor.

        :param offer: The offer being accepted.
        :type offer: Instance of :class:`autobahn.compress.PerMessageBzip2Offer`.
        :param requestMaxCompressLevel: Iff non-zero, server requests given "maximum compression level" - must be 1-9.
        :type requestMaxCompressLevel: int
        :param compressLevel: Override server ("server-to-client direction") compress level (this must be compatible with offer).
        :type compressLevel: int
        """
        if not isinstance(offer, PerMessageBzip2Offer):
            raise Exception("invalid type %s for offer" % type(offer))

        self.offer = offer

        if requestMaxCompressLevel != 0 and requestMaxCompressLevel not in self.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
            raise Exception("invalid value %s for requestMaxCompressLevel - permissible values %s" % (requestMaxCompressLevel, self.COMPRESS_LEVEL_PERMISSIBLE_VALUES))

        if requestMaxCompressLevel != 0 and not offer.acceptMaxCompressLevel:
            raise Exception("invalid value %s for requestMaxCompressLevel - feature unsupported by client" % requestMaxCompressLevel)

        self.requestMaxCompressLevel = requestMaxCompressLevel

        if compressLevel is not None:
            if compressLevel not in self.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
                raise Exception("invalid value %s for compressLevel - permissible values %s" % (compressLevel, self.COMPRESS_LEVEL_PERMISSIBLE_VALUES))

            if offer.requestMaxCompressLevel != 0 and compressLevel > offer.requestMaxCompressLevel:
                raise Exception("invalid value %s for compressLevel - client requested lower maximum value" % compressLevel)

        self.compressLevel = compressLevel

    def getExtensionString(self):
        """
        Returns the WebSocket extension configuration string as sent to the server.

        :returns: str -- PMCE configuration string.
        """
        pmceString = self.EXTENSION_NAME
        if self.offer.requestMaxCompressLevel != 0:
            pmceString += "; server_max_compress_level=%d" % self.offer.requestMaxCompressLevel
        if self.requestMaxCompressLevel != 0:
            pmceString += "; client_max_compress_level=%d" % self.requestMaxCompressLevel
        return pmceString

    def __json__(self):
        """
        Returns a JSON serializable object representation.

        :returns: object -- JSON serializable representation.
        """
        return {'extension': self.EXTENSION_NAME,
                'offer': self.offer.__json__(),
                'requestMaxCompressLevel': self.requestMaxCompressLevel,
                'compressLevel': self.compressLevel}

    def __repr__(self):
        """
        Returns Python object representation that can be eval'ed to reconstruct the object.

        :returns: str -- Python string representation.
        """
        return "PerMessageBzip2Accept(offer = %s, requestMaxCompressLevel = %s, compressLevel = %s)" % (self.offer.__repr__(), self.requestMaxCompressLevel, self.compressLevel)


class PerMessageBzip2Response(PerMessageCompressResponse, PerMessageBzip2Mixin):
    """
    Set of parameters for `permessage-bzip2` responded by server.
    """

    @classmethod
    def parse(cls, params):
        """
        Parses a WebSocket extension response for `permessage-bzip2` provided by a server to a client.

        :param params: Output from :func:`autobahn.websocket.WebSocketProtocol._parseExtensionsHeader`.
        :type params: list

        :returns: object -- A new instance of :class:`autobahn.compress.PerMessageBzip2Response`.
        """
        client_max_compress_level = 0
        server_max_compress_level = 0

        for p in params:

            if len(params[p]) > 1:
                raise Exception("multiple occurrence of extension parameter '%s' for extension '%s'" % (p, cls.EXTENSION_NAME))

            val = params[p][0]

            if p == 'client_max_compress_level':
                try:
                    val = int(val)
                except:
                    raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME))
                if val not in PerMessageBzip2Mixin.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
                    raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME))
                else:
                    client_max_compress_level = val

            elif p == 'server_max_compress_level':
                try:
                    val = int(val)
                except:
                    raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME))
                if val not in PerMessageBzip2Mixin.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
                    raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME))
                else:
                    server_max_compress_level = val

            else:
                raise Exception("illegal extension parameter '%s' for extension '%s'" % (p, cls.EXTENSION_NAME))

        response = cls(client_max_compress_level,
                       server_max_compress_level)
        return response

    def __init__(self,
                 client_max_compress_level,
                 server_max_compress_level):
        self.client_max_compress_level = client_max_compress_level
        self.server_max_compress_level = server_max_compress_level

    def __json__(self):
        """
        Returns a JSON serializable object representation.

        :returns: object -- JSON serializable representation.
        """
        return {'extension': self.EXTENSION_NAME,
                'client_max_compress_level': self.client_max_compress_level,
                'server_max_compress_level': self.server_max_compress_level}

    def __repr__(self):
        """
        Returns Python object representation that can be eval'ed to reconstruct the object.

        :returns: str -- Python string representation.
        """
        return "PerMessageBzip2Response(client_max_compress_level = %s, server_max_compress_level = %s)" % (self.client_max_compress_level, self.server_max_compress_level)


class PerMessageBzip2ResponseAccept(PerMessageCompressResponseAccept, PerMessageBzip2Mixin):
    """
    Set of parameters with which to accept an `permessage-bzip2` response
    from a server by a client.
    """

    def __init__(self,
                 response,
                 compressLevel=None):
        """
        Constructor.

        :param response: The response being accepted.
        :type response: Instance of :class:`autobahn.compress.PerMessageBzip2Response`.
        :param compressLevel: Override client ("client-to-server direction") compress level (this must be compatible with response).
        :type compressLevel: int
        """
        if not isinstance(response, PerMessageBzip2Response):
            raise Exception("invalid type %s for response" % type(response))

        self.response = response

        if compressLevel is not None:
            if compressLevel not in self.WINDOW_SIZE_PERMISSIBLE_VALUES:
                raise Exception("invalid value %s for compressLevel - permissible values %s" % (compressLevel, self.COMPRESS_LEVEL_PERMISSIBLE_VALUES))

            if response.client_max_compress_level != 0 and compressLevel > response.client_max_compress_level:
                raise Exception("invalid value %s for compressLevel - server requested lower maximum value" % compressLevel)

        self.compressLevel = compressLevel

    def __json__(self):
        """
        Returns a JSON serializable object representation.

        :returns: object -- JSON serializable representation.
        """
        return {'extension': self.EXTENSION_NAME,
                'response': self.response.__json__(),
                'compressLevel': self.compressLevel}

    def __repr__(self):
        """
        Returns Python object representation that can be eval'ed to reconstruct the object.

        :returns: str -- Python string representation.
        """
        return "PerMessageBzip2ResponseAccept(response = %s, compressLevel = %s)" % (self.response.__repr__(), self.compressLevel)


class PerMessageBzip2(PerMessageCompress, PerMessageBzip2Mixin):
    """
    `permessage-bzip2` WebSocket extension processor.
    """
    DEFAULT_COMPRESS_LEVEL = 9

    @classmethod
    def createFromResponseAccept(cls, isServer, accept):
        pmce = cls(isServer,
                   accept.response.server_max_compress_level,
                   accept.compressLevel if accept.compressLevel is not None else accept.response.client_max_compress_level)
        return pmce

    @classmethod
    def createFromOfferAccept(cls, isServer, accept):
        pmce = cls(isServer,
                   accept.compressLevel if accept.compressLevel is not None else accept.offer.requestMaxCompressLevel,
                   accept.requestMaxCompressLevel)
        return pmce

    def __init__(self,
                 isServer,
                 server_max_compress_level,
                 client_max_compress_level):
        self._isServer = isServer
        self._compressor = None
        self._decompressor = None

        self.server_max_compress_level = server_max_compress_level if server_max_compress_level != 0 else self.DEFAULT_COMPRESS_LEVEL
        self.client_max_compress_level = client_max_compress_level if client_max_compress_level != 0 else self.DEFAULT_COMPRESS_LEVEL

    def __json__(self):
        return {'extension': self.EXTENSION_NAME,
                'isServer': self._isServer,
                'server_max_compress_level': self.server_max_compress_level,
                'client_max_compress_level': self.client_max_compress_level}

    def __repr__(self):
        return "PerMessageBzip2(isServer = %s, server_max_compress_level = %s, client_max_compress_level = %s)" % (self._isServer, self.server_max_compress_level, self.client_max_compress_level)

    def startCompressMessage(self):
        if self._isServer:
            if self._compressor is None:
                self._compressor = bz2.BZ2Compressor(self.server_max_compress_level)
        else:
            if self._compressor is None:
                self._compressor = bz2.BZ2Compressor(self.client_max_compress_level)

    def compressMessageData(self, data):
        return self._compressor.compress(data)

    def endCompressMessage(self):
        data = self._compressor.flush()

        # there seems to be no "flush without close stream", and after
        # full flush, compressor must not be reused
        self._compressor = None

        return data

    def startDecompressMessage(self):
        if self._decompressor is None:
            self._decompressor = bz2.BZ2Decompressor()

    def decompressMessageData(self, data):
        return self._decompressor.decompress(data)

    def endDecompressMessage(self):
        self._decompressor = None
