# -*- coding: utf-8 -*-
# eipconfig.py
# Copyright (C) 2013 LEAP
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
Provider configuration
"""
import logging
import os
import re
import datetime
import time

import ipaddr

from leap.common.check import leap_assert, leap_assert_type
from leap.common.config.baseconfig import BaseConfig
from leap.config.providerconfig import ProviderConfig
from leap.services.eip.eipspec import eipservice_config_spec

logger = logging.getLogger(__name__)


class VPNGatewaySelector(object):
    """
    VPN Gateway selector.
    """

    def __init__(self, eipconfig):
        '''
        Constructor for VPNGatewaySelector.

        :param eipconfig: a valid EIP Configuration.
        :type eipconfig: EIPConfig
        '''
        leap_assert_type(eipconfig, EIPConfig)
        self._local_offset = 0  # defaults to GMT
        self._local_timezone = None
        self._set_local_offset()
        self._eipconfig = eipconfig

    def get_gateways(self):
        """
        Returns the 4 best gateways, sorted by timezone proximity.

        :rtype: list of IPv4Address or IPv6Address object.
        """
        gateways_timezones = []
        locations = self._eipconfig.get_locations()
        gateways = self._eipconfig.get_gateways()

        for idx, gateway in enumerate(gateways):
            gateway_location = gateway.get('location')
            gateway_distance = 99  # if hasn't location -> should go last

            if gateway_location is not None:
                gw_offset = int(locations[gateway['location']]['timezone'])
                gateway_distance = self._get_timezone_distance(gw_offset)

            ip = self._eipconfig.get_gateway_ip(idx)
            gateways_timezones.append((ip, gateway_distance))

        gateways_timezones = sorted(gateways_timezones,
                                    key=lambda gw: gw[1])[:4]

        gateways = [ip for ip, dist in gateways_timezones]
        return gateways

    def _get_timezone_distance(self, offset):
        '''
        Returns the distance between the local timezone and
        the one with offset 'offset'.

        :param offset: the distance of a timezone to GMT.
        :type offset: int
        :returns: distance between local offset and param offset.
        :rtype: int
        '''
        delta1 = datetime.timedelta(hours=offset)
        delta2 = self._local_offset
        diff = abs(delta1 - delta2)
        hours = diff.seconds / (60 * 60)
        return hours

    def _set_local_offset(self):
        '''
        Sets the distance between GMT and the local timezone.
        '''
        local_offset = time.timezone
        if time.daylight:
            local_offset = time.altzone

        self._local_offset = datetime.timedelta(seconds=-local_offset)


class EIPConfig(BaseConfig):
    """
    Provider configuration abstraction class
    """
    OPENVPN_ALLOWED_KEYS = ("auth", "cipher", "tls-cipher")
    OPENVPN_CIPHERS_REGEX = re.compile("[A-Z0-9\-]+")

    def __init__(self):
        BaseConfig.__init__(self)

    def _get_spec(self):
        """
        Returns the spec object for the specific configuration
        """
        return eipservice_config_spec

    def get_clusters(self):
        # TODO: create an abstraction for clusters
        return self._safe_get_value("clusters")

    def get_gateways(self):
        # TODO: create an abstraction for gateways
        return self._safe_get_value("gateways")

    def get_locations(self):
        '''
        Returns a list of locations

        :rtype: dict
        '''
        return self._safe_get_value("locations")

    def get_openvpn_configuration(self):
        """
        Returns a dictionary containing the openvpn configuration
        parameters.

        These are sanitized with alphanumeric whitelist.

        :returns: openvpn configuration dict
        :rtype: C{dict}
        """
        ovpncfg = self._safe_get_value("openvpn_configuration")
        config = {}
        for key, value in ovpncfg.items():
            if key in self.OPENVPN_ALLOWED_KEYS and value is not None:
                sanitized_val = self.OPENVPN_CIPHERS_REGEX.findall(value)
                if len(sanitized_val) != 0:
                    _val = sanitized_val[0]
                    config[str(key)] = str(_val)
        return config

    def get_serial(self):
        return self._safe_get_value("serial")

    def get_version(self):
        return self._safe_get_value("version")

    def get_gateway_ip(self, index=0):
        """
        Returns the ip of the gateway.

        :rtype: An IPv4Address or IPv6Address object.
        """
        gateways = self.get_gateways()
        leap_assert(len(gateways) > 0, "We don't have any gateway!")
        if index > len(gateways):
            index = 0
            logger.warning("Provided an unknown gateway index %s, " +
                           "defaulting to 0")
        ip_addr_str = gateways[0]["ip_address"]

        try:
            ipaddr.IPAddress(ip_addr_str)
            return ip_addr_str
        except ValueError:
            logger.error("Invalid ip address in config: %s" % (ip_addr_str,))
            return None

    def get_client_cert_path(self,
                             providerconfig=None,
                             about_to_download=False):
        """
        Returns the path to the certificate used by openvpn
        """

        leap_assert(providerconfig, "We need a provider")
        leap_assert_type(providerconfig, ProviderConfig)

        cert_path = os.path.join(self.get_path_prefix(),
                                 "leap",
                                 "providers",
                                 providerconfig.get_domain(),
                                 "keys",
                                 "client",
                                 "openvpn.pem")

        if not about_to_download:
            leap_assert(os.path.exists(cert_path),
                        "You need to download the certificate first")
            logger.debug("Using OpenVPN cert %s" % (cert_path,))

        return cert_path


if __name__ == "__main__":
    logger = logging.getLogger(name='leap')
    logger.setLevel(logging.DEBUG)
    console = logging.StreamHandler()
    console.setLevel(logging.DEBUG)
    formatter = logging.Formatter(
        '%(asctime)s '
        '- %(name)s - %(levelname)s - %(message)s')
    console.setFormatter(formatter)
    logger.addHandler(console)

    eipconfig = EIPConfig()

    try:
        eipconfig.get_clusters()
    except Exception as e:
        assert isinstance(e, AssertionError), "Expected an assert"
        print "Safe value getting is working"

    if eipconfig.load("leap/providers/bitmask.net/eip-service.json"):
        print eipconfig.get_clusters()
        print eipconfig.get_gateways()
        print eipconfig.get_openvpn_configuration()
        print eipconfig.get_serial()
        print eipconfig.get_version()
