# This file is part of FreedomBox.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
import os
import re

import augeas

I2P_CONF_DIR = '/var/lib/i2p/i2p-config'
FILE_TUNNEL_CONF = os.path.join(I2P_CONF_DIR, 'i2ptunnel.config')
TUNNEL_IDX_REGEX = re.compile(r'tunnel.(\d+).name$')


class TunnelEditor(object):
    """

    :type aug: augeas.Augeas
    """

    def __init__(self, conf_filename=None, idx=None):
        self.conf_filename = conf_filename or FILE_TUNNEL_CONF
        self.idx = idx
        self.aug = None

    @property
    def lines(self):
        if self.aug:
            return self.aug.match('/files{}/*'.format(self.conf_filename))
        else:
            return []

    def read_conf(self):
        """Return an instance of Augeaus for processing APT configuration."""
        self.aug = augeas.Augeas(flags=augeas.Augeas.NO_LOAD +
                                       augeas.Augeas.NO_MODL_AUTOLOAD)
        self.aug.set('/augeas/load/Properties/lens', 'Properties.lns')
        self.aug.set('/augeas/load/Properties/incl[last() + 1]', self.conf_filename)
        self.aug.load()

        return self

    def write_conf(self):
        self.aug.save()
        return self

    def set_tunnel_idx(self, name):

        """
        Finds the index of the tunnel with the given name.

        Chainable method.

        :type name: basestring
        """

        for prop in self.aug.match('/files{}/*'.format(self.conf_filename)):
            match = TUNNEL_IDX_REGEX.search(prop)

            if match and self.aug.get(prop) == name:
                self.idx = int(match.group(1))
                return self
        raise ValueError('No tunnel with that name')

    def calc_prop_path(self, tunnel_prop):
        """
        Calculates the property name as found in the properties files
        :type tunnel_prop: str
        :rtype: basestring
        """
        calced_prop_path = '/files{filepath}/tunnel.{idx}.{tunnel_prop}'.format(
            idx=self.idx, tunnel_prop=tunnel_prop,
            filepath=self.conf_filename
        )
        return calced_prop_path

    def set_tunnel_prop(self, tunnel_prop, value):
        """
        Updates a tunnel's property.

        The idx has to be set and the property has to exist in the config file and belong to the tunnel's properties.

        see calc_prop_path

        Chainable method.

        :param tunnel_prop:
        :type tunnel_prop: str
        :param value:
        :type value: basestring | int
        :return:
        :rtype:
        """
        if self.idx is None:
            raise ValueError('Please init the tunnel index before calling this method')

        calc_prop_path = self.calc_prop_path(tunnel_prop)
        self.aug.set(calc_prop_path, value)
        return self

    def __getitem__(self, tunnel_prop):
        ret = self.aug.get(self.calc_prop_path(tunnel_prop))
        if ret is None:
            raise KeyError('Unknown property {}'.format(tunnel_prop))
        return ret

    def __setitem__(self, tunnel_prop, value):
        self.aug.set(self.calc_prop_path(tunnel_prop), value)