# 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
import jmespath

from vyos.configdict import dict_merge
from vyos.configverify import verify_dhcpv6
from vyos.ifconfig.control import Control
from vyos.template import render

class _DHCPv4 (Control):
    def __init__(self, ifname):
        super().__init__()
        config_base = r'/var/lib/dhcp/dhclient'
        self._conf_file = f'{config_base}_{ifname}.conf'
        self._options_file = f'{config_base}_{ifname}.options'
        self._pid_file = f'{config_base}_{ifname}.pid'
        self._lease_file = f'{config_base}_{ifname}.leases'
        self.options = {'ifname' : ifname}

    # 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 jmespath.search('dhcp_options.host_name', self.options) == None:
            # read configured system hostname.
            # maybe change to vyos hostd client ???
            hostname = 'vyos'
            with open('/etc/hostname', 'r') as f:
                hostname = f.read().rstrip('\n')
                tmp = {'dhcp_options' : { 'host_name' : hostname}}
                self.options = dict_merge(tmp, self.options)

        render(self._options_file, 'dhcp-client/daemon-options.tmpl',
               self.options, trim_blocks=True)
        render(self._conf_file, 'dhcp-client/ipv4.tmpl',
               self.options, trim_blocks=True)

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

    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._pid_file):
            self._debug_msg('No DHCP client PID found')
            return None

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

        # cleanup old config files
        for file in [self._conf_file, self._options_file, self._pid_file, self._lease_file]:
            if os.path.isfile(file):
                os.remove(file)

class _DHCPv6 (Control):
    def __init__(self, ifname):
        super().__init__()
        self.options = {'ifname' : ifname}
        self._config = f'/run/dhcp6c/dhcp6c.{ifname}.conf'

    def set(self):
        """
        Configure interface as DHCPv6 client. The client is automatically
        started in background when address is configured as DHCP.

        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!
        verify_dhcpv6(self.options)

        render(self._config, 'dhcp-client/ipv6.tmpl',
               self.options, trim_blocks=True)

        # We must ignore any return codes. This is required to enable DHCPv6-PD
        # for interfaces which are yet not up and running.
        return self._popen('systemctl restart dhcp6c@{ifname}.service'.format(
            **self.options))

    def delete(self):
        """
        De-configure interface as DHCPv6 client. 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()
        """
        self._cmd('systemctl stop dhcp6c@{ifname}.service'.format(**self.options))

        # cleanup old config files
        if os.path.isfile(self._config):
            os.remove(self._config)

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