import logging
import re

from .errors import TransportError, ResponseMessageError
from .util import xml_to_str, TNS

log = logging.getLogger(__name__)

# Legend for dict:
#   Key: shortname
#   Values: (EWS API version ID, full name)

# 'shortname' comes from types.xsd and is the official version of the server, corresponding to the version numbers
# supplied in SOAP headers. 'API version' is the version name supplied in the RequestServerVersion element in SOAP
# headers and describes the EWS API version the server implements. Valid values for this element are described here:
#    https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/requestserverversion

VERSIONS = {
    'Exchange2007': ('Exchange2007', 'Microsoft Exchange Server 2007'),
    'Exchange2007_SP1': ('Exchange2007_SP1', 'Microsoft Exchange Server 2007 SP1'),
    'Exchange2007_SP2': ('Exchange2007_SP1', 'Microsoft Exchange Server 2007 SP2'),
    'Exchange2007_SP3': ('Exchange2007_SP1', 'Microsoft Exchange Server 2007 SP3'),
    'Exchange2010': ('Exchange2010', 'Microsoft Exchange Server 2010'),
    'Exchange2010_SP1': ('Exchange2010_SP1', 'Microsoft Exchange Server 2010 SP1'),
    'Exchange2010_SP2': ('Exchange2010_SP2', 'Microsoft Exchange Server 2010 SP2'),
    'Exchange2010_SP3': ('Exchange2010_SP2', 'Microsoft Exchange Server 2010 SP3'),
    'Exchange2013': ('Exchange2013', 'Microsoft Exchange Server 2013'),
    'Exchange2013_SP1': ('Exchange2013_SP1', 'Microsoft Exchange Server 2013 SP1'),
    'Exchange2015': ('Exchange2015', 'Microsoft Exchange Server 2015'),
    'Exchange2015_SP1': ('Exchange2015_SP1', 'Microsoft Exchange Server 2015 SP1'),
    'Exchange2016': ('Exchange2016', 'Microsoft Exchange Server 2016'),
    'Exchange2019': ('Exchange2019', 'Microsoft Exchange Server 2019'),
}

# Build a list of unique API versions, used when guessing API version supported by the server. Use reverse order so we
# get the newest API version supported by the server.
API_VERSIONS = sorted({v[0] for v in VERSIONS.values()}, reverse=True)


class Build:
    """Holds methods for working with build numbers."""

    # List of build numbers here: https://docs.microsoft.com/en-us/exchange/new-features/build-numbers-and-release-dates
    API_VERSION_MAP = {
        8: {
            0: 'Exchange2007',
            1: 'Exchange2007_SP1',
            2: 'Exchange2007_SP1',
            3: 'Exchange2007_SP1',
        },
        14: {
            0: 'Exchange2010',
            1: 'Exchange2010_SP1',
            2: 'Exchange2010_SP2',
            3: 'Exchange2010_SP2',
        },
        15: {
            0: 'Exchange2013',  # Minor builds starting from 847 are Exchange2013_SP1, see api_version()
            1: 'Exchange2016',
            2: 'Exchange2019',
            20: 'Exchange2016',  # This is Office365. See issue #221
        },
    }

    __slots__ = 'major_version', 'minor_version', 'major_build', 'minor_build'

    def __init__(self, major_version, minor_version, major_build=0, minor_build=0):
        if not isinstance(major_version, int):
            raise ValueError("'major_version' must be an integer")
        if not isinstance(minor_version, int):
            raise ValueError("'minor_version' must be an integer")
        if not isinstance(major_build, int):
            raise ValueError("'major_build' must be an integer")
        if not isinstance(minor_build, int):
            raise ValueError("'minor_build' must be an integer")
        self.major_version = major_version
        self.minor_version = minor_version
        self.major_build = major_build
        self.minor_build = minor_build
        if major_version < 8:
            raise ValueError("Exchange major versions below 8 don't support EWS (%s)" % self)

    @classmethod
    def from_xml(cls, elem):
        xml_elems_map = {
            'major_version': 'MajorVersion',
            'minor_version': 'MinorVersion',
            'major_build': 'MajorBuildNumber',
            'minor_build': 'MinorBuildNumber',
        }
        kwargs = {}
        for k, xml_elem in xml_elems_map.items():
            v = elem.get(xml_elem)
            if v is None:
                raise ValueError()
            kwargs[k] = int(v)  # Also raises ValueError
        return cls(**kwargs)

    @classmethod
    def from_hex_string(cls, s):
        """Parse a server version string as returned in an autodiscover response. The process is described here:
        https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/serverversion-pox#example

        The string is a hex string that, converted to a 32-bit binary, encodes the server version. The rules are:
            * The first 4 bits contain the version number structure version. Can be ignored
            * The next 6 bits contain the major version number
            * The next 6 bits contain the minor version number
            * The next bit contains a flag. Can be ignored
            * The next 15 bits contain the major build number

        :param s:
        """
        bin_s = '{:032b}'.format(int(s, 16))  # Convert string to 32-bit binary string
        major_version = int(bin_s[4:10], 2)
        minor_version = int(bin_s[10:16], 2)
        build_number = int(bin_s[17:32], 2)
        return cls(major_version=major_version, minor_version=minor_version, major_build=build_number)

    def api_version(self):
        if EXCHANGE_2013_SP1 <= self < EXCHANGE_2016:
            return 'Exchange2013_SP1'
        try:
            return self.API_VERSION_MAP[self.major_version][self.minor_version]
        except KeyError:
            raise ValueError('API version for build %s is unknown' % self)

    def fullname(self):
        return VERSIONS[self.api_version()][1]

    def __cmp__(self, other):
        # __cmp__ is not a magic method in Python3. We'll just use it here to implement comparison operators
        c = (self.major_version > other.major_version) - (self.major_version < other.major_version)
        if c != 0:
            return c
        c = (self.minor_version > other.minor_version) - (self.minor_version < other.minor_version)
        if c != 0:
            return c
        c = (self.major_build > other.major_build) - (self.major_build < other.major_build)
        if c != 0:
            return c
        return (self.minor_build > other.minor_build) - (self.minor_build < other.minor_build)

    def __eq__(self, other):
        return self.__cmp__(other) == 0

    def __hash__(self):
        return hash(repr(self))

    def __ne__(self, other):
        return self.__cmp__(other) != 0

    def __lt__(self, other):
        return self.__cmp__(other) < 0

    def __le__(self, other):
        return self.__cmp__(other) <= 0

    def __gt__(self, other):
        return self.__cmp__(other) > 0

    def __ge__(self, other):
        return self.__cmp__(other) >= 0

    def __str__(self):
        return '%s.%s.%s.%s' % (self.major_version, self.minor_version, self.major_build, self.minor_build)

    def __repr__(self):
        return self.__class__.__name__ \
               + repr((self.major_version, self.minor_version, self.major_build, self.minor_build))


# Helpers for comparison operations elsewhere in this package
EXCHANGE_2007 = Build(8, 0)
EXCHANGE_2007_SP1 = Build(8, 1)
EXCHANGE_2010 = Build(14, 0)
EXCHANGE_2010_SP1 = Build(14, 1)
EXCHANGE_2010_SP2 = Build(14, 2)
EXCHANGE_2013 = Build(15, 0)
EXCHANGE_2013_SP1 = Build(15, 0, 847)
EXCHANGE_2016 = Build(15, 1)
EXCHANGE_2019 = Build(15, 2)
EXCHANGE_O365 = Build(15, 20)


class Version:
    """Holds information about the server version."""

    __slots__ = 'build', 'api_version'

    def __init__(self, build, api_version=None):
        if not isinstance(build, (Build, type(None))):
            raise ValueError("'build' must be a Build instance")
        self.build = build
        if api_version is None:
            self.api_version = build.api_version()
        else:
            if not isinstance(api_version, str):
                raise ValueError("'api_version' must be a string")
            self.api_version = api_version

    @property
    def fullname(self):
        return VERSIONS[self.api_version][1]

    @classmethod
    def guess(cls, protocol, api_version_hint=None):
        """Ask the server which version it has. We haven't set up an Account object yet, so we generate requests
        by hand. We only need a response header containing a ServerVersionInfo element.

        To get API version and build numbers from the server, we need to send a valid SOAP request. We can't do that
        without a valid API version. To solve this chicken-and-egg problem, we try all possible API versions that this
        package supports, until we get a valid response.

        :param protocol:
        :param api_version_hint:  (Default value = None)
        """
        from .services import ResolveNames
        # The protocol doesn't have a version yet, so default to latest supported version if we don't have a hint.
        api_version = api_version_hint or API_VERSIONS[0]
        log.debug('Asking server for version info using API version %s', api_version)
        # We don't know the build version yet. Hopefully, the server will report it in the SOAP header. Lots of
        # places expect a version to have a build, so this is a bit dangerous, but passing a fake build around is also
        # dangerous. Make sure the call to ResolveNames does not require a version build.
        protocol.config.version = Version(build=None, api_version=api_version)
        # Use ResolveNames as a minimal request to the server to test if the version is correct. If not, ResolveNames
        # will try to guess the version automatically.
        name = str(protocol.credentials) if protocol.credentials and str(protocol.credentials) else 'DUMMY'
        try:
            list(ResolveNames(protocol=protocol).call(unresolved_entries=[name]))
        except ResponseMessageError as e:
            # We may have survived long enough to get a new version
            if not protocol.config.version.build:
                raise TransportError('No valid version headers found in response (%r)' % e)
        if not protocol.config.version.build:
            raise TransportError('No valid version headers found in response')
        return protocol.version

    @staticmethod
    def _is_invalid_version_string(version):
        # Check if a version string is bogus, e.g. V2_, V2015_ or V2018_
        return re.match(r'V[0-9]{1,4}_.*', version)

    @classmethod
    def from_soap_header(cls, requested_api_version, header):
        info = header.find('{%s}ServerVersionInfo' % TNS)
        if info is None:
            raise TransportError('No ServerVersionInfo in header: %r' % xml_to_str(header))
        try:
            build = Build.from_xml(elem=info)
        except ValueError:
            raise TransportError('Bad ServerVersionInfo in response: %r' % xml_to_str(header))
        # Not all Exchange servers send the Version element
        api_version_from_server = info.get('Version') or build.api_version()
        if api_version_from_server != requested_api_version:
            if cls._is_invalid_version_string(api_version_from_server):
                # For unknown reasons, Office 365 may respond with an API version strings that is invalid in a request.
                # Detect these so we can fallback to a valid version string.
                log.debug('API version "%s" worked but server reports version "%s". Using "%s"', requested_api_version,
                          api_version_from_server, requested_api_version)
                api_version_from_server = requested_api_version
            else:
                # Trust API version from server response
                log.debug('API version "%s" worked but server reports version "%s". Using "%s"', requested_api_version,
                          api_version_from_server, api_version_from_server)
        return cls(build=build, api_version=api_version_from_server)

    def __eq__(self, other):
        if self.api_version != other.api_version:
            return False
        if self.build and not other.build:
            return False
        if other.build and not self.build:
            return False
        return self.build == other.build

    def __repr__(self):
        return self.__class__.__name__ + repr((self.build, self.api_version))

    def __str__(self):
        return 'Build=%s, API=%s, Fullname=%s' % (self.build, self.api_version, self.fullname)
