# Copyright 2020 VyOS maintainers and contributors <maintainers@vyos.io>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library.  If not, see <http://www.gnu.org/licenses/>.

import os

from vyos.dicts import FixedDict
from vyos.ifconfig.control import Control
from vyos.template import render

class _DHCP (Control):
    def __init__(self, ifname, **kargs):
        super().__init__(**kargs)
        self.file = {
            'ifname': ifname,
            'conf': self.client_base + f'/{ifname}.conf',
            'options': self.client_base + f'/{ifname}.options',
            'pid': self.client_base + f'/{ifname}.pid',
            'lease': self.client_base + f'/{ifname}.leases',
        }

class _DHCPv4 (_DHCP):
    client_base = r'/run/dhclient'

    def __init__(self, ifname):
        super().__init__(ifname)
        self.options = FixedDict(**{
            'ifname': ifname,
            'config_path': self.client_base,
            'hostname': '',
            'client_id': '',
            'vendor_class_id': ''
        })

    # replace dhcpv4/v6 with systemd.networkd?
    def set(self):
        """
        Configure interface as DHCP client. The dhclient binary is automatically
        started in background!

        Example:

        >>> from vyos.ifconfig import Interface
        >>> j = Interface('eth0')
        >>> j.dhcp.v4.set()
        """

        if not self.options['hostname']:
            # read configured system hostname.
            # maybe change to vyos hostd client ???
            with open('/etc/hostname', 'r') as f:
                self.options['hostname'] = f.read().rstrip('\n')

        render(self.file['options'], 'dhcp-client/daemon-options.tmpl', self.options)
        render(self.file['conf'], 'dhcp-client/ipv4.tmpl', self.options)

        return self._cmd('systemctl restart dhclient@{ifname}.service'.format(**self.file))

    def delete(self):
        """
        De-configure interface as DHCP clinet. All auto generated files like
        pid, config and lease will be removed.

        Example:

        >>> from vyos.ifconfig import Interface
        >>> j = Interface('eth0')
        >>> j.dhcp.v4.delete()
        """
        if not os.path.isfile(self.file['pid']):
            self._debug_msg('No DHCP client PID found')
            return None

        return self._cmd('systemctl stop dhclient@{ifname}.service'.format(**self.file))

        # cleanup old config files
        for name in ('conf', 'options', 'pid', 'lease'):
            if os.path.isfile(self.file[name]):
                os.remove(self.file[name])

class _DHCPv6 (_DHCP):
    client_base = r'/run/dhclient6'

    def __init__(self, ifname):
        super().__init__(ifname)
        self.options = FixedDict(**{
            'ifname': ifname,
            'config_path': self.client_base,
            'dhcpv6_prm_only': False,
            'dhcpv6_temporary': False,
        })
        self.file.update({
            'accept_ra': f'/proc/sys/net/ipv6/conf/{ifname}/accept_ra',
        })

    def set(self):
        """
        Configure interface as DHCPv6 client. The dhclient binary is automatically
        started in background!

        Example:

        >>> from vyos.ifconfig import Interface
        >>> j = Interface('eth0')
        >>> j.dhcp.v6.set()
        """

        # better save then sorry .. should be checked in interface script
        # but if you missed it we are safe!
        if self.options['dhcpv6_prm_only'] and self.options['dhcpv6_temporary']:
            raise Exception(
                'DHCPv6 temporary and parameters-only options are mutually exclusive!')

        render(self.file['options'], 'dhcp-client/daemon-options.tmpl', self.options)
        render(self.file['conf'], 'dhcp-client/ipv6.tmpl', self.options)

        # no longer accept router announcements on this interface
        self._write_sysfs(self.file['accept_ra'], 0)

        return self._cmd('systemctl restart dhclient6@{ifname}.service'.format(**self.file))

    def delete(self):
        """
        De-configure interface as DHCPv6 clinet. All auto generated files like
        pid, config and lease will be removed.

        Example:

        >>> from vyos.ifconfig import Interface
        >>> j = Interface('eth0')
        >>> j.dhcp.v6.delete()
        """
        if not os.path.isfile(self.file['pid']):
            self._debug_msg('No DHCPv6 client PID found')
            return None

        return self._cmd('systemctl stop dhclient6@{ifname}.service'.format(**self.file))

        # accept router announcements on this interface
        self._write_sysfs(self.file['accept_ra'], 1)

        # cleanup old config files
        for name in ('conf', 'options', 'pid', 'lease'):
            if os.path.isfile(self.file[name]):
                os.remove(self.file[name])


class DHCP(object):
    def __init__(self, ifname):
        self.v4 = _DHCPv4(ifname)
        self.v6 = _DHCPv6(ifname)