#
# (c) 2016 Red Hat Inc.
#
# This file is part of Ansible
#
# Ansible 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.
#
# Ansible 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 Ansible.  If not, see <http://www.gnu.org/licenses/>.
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

import os
import logging
import json

from ansible import constants as C
from ansible.errors import AnsibleConnectionFailure, AnsibleError
from ansible.module_utils._text import to_bytes, to_native, to_text
from ansible.module_utils.parsing.convert_bool import BOOLEANS_TRUE
from ansible.plugins.loader import netconf_loader
from ansible.plugins.connection import ConnectionBase, ensure_connect
from ansible.utils.jsonrpc import Rpc

try:
    from ncclient import manager
    from ncclient.operations import RPCError
    from ncclient.transport.errors import SSHUnknownHostError
    from ncclient.xml_ import to_ele, to_xml
except ImportError:
    raise AnsibleError("ncclient is not installed")

try:
    from __main__ import display
except ImportError:
    from ansible.utils.display import Display
    display = Display()

logging.getLogger('ncclient').setLevel(logging.INFO)


class Connection(Rpc, ConnectionBase):
    """NetConf connections"""

    transport = 'netconf'
    has_pipelining = False

    def __init__(self, play_context, new_stdin, *args, **kwargs):
        super(Connection, self).__init__(play_context, new_stdin, *args, **kwargs)

        self._network_os = self._play_context.network_os or 'default'
        display.display('network_os is set to %s' % self._network_os, log_only=True)

        self._manager = None
        self._connected = False

    def _connect(self):
        super(Connection, self)._connect()

        display.display('ssh connection done, stating ncclient', log_only=True)

        self.allow_agent = True
        if self._play_context.password is not None:
            self.allow_agent = False

        self.key_filename = None
        if self._play_context.private_key_file:
            self.key_filename = os.path.expanduser(self._play_context.private_key_file)

        network_os = self._play_context.network_os

        if not network_os:
            for cls in netconf_loader.all(class_only=True):
                network_os = cls.guess_network_os(self)
                if network_os:
                    display.display('discovered network_os %s' % network_os, log_only=True)

        if not network_os:
            raise AnsibleConnectionFailure('Unable to automatically determine host network os. Please ansible_network_os value')

        ssh_config = os.getenv('ANSIBLE_NETCONF_SSH_CONFIG', False)
        if ssh_config in BOOLEANS_TRUE:
            ssh_config = True
        else:
            ssh_config = None

        try:
            self._manager = manager.connect(
                host=self._play_context.remote_addr,
                port=self._play_context.port or 830,
                username=self._play_context.remote_user,
                password=self._play_context.password,
                key_filename=str(self.key_filename),
                hostkey_verify=C.HOST_KEY_CHECKING,
                look_for_keys=C.PARAMIKO_LOOK_FOR_KEYS,
                allow_agent=self.allow_agent,
                timeout=self._play_context.timeout,
                device_params={'name': network_os},
                ssh_config=ssh_config
            )
        except SSHUnknownHostError as exc:
            raise AnsibleConnectionFailure(str(exc))

        if not self._manager.connected:
            return 1, b'', b'not connected'

        display.display('ncclient manager object created successfully', log_only=True)

        self._connected = True

        self._netconf = netconf_loader.get(network_os, self)
        if self._netconf:
            self._rpc.add(self._netconf)
            display.display('loaded netconf plugin for network_os %s' % network_os, log_only=True)
        else:
            display.display('unable to load netconf for network_os %s' % network_os)

        return 0, to_bytes(self._manager.session_id, errors='surrogate_or_strict'), b''

    def close(self):
        if self._manager:
            self._manager.close_session()
            self._connected = False
        super(Connection, self).close()

    @ensure_connect
    def exec_command(self, request):
        """Sends the request to the node and returns the reply
        The method accepts two forms of request.  The first form is as a byte
        string that represents xml string be send over netconf session.
        The second form is a json-rpc (2.0) byte string.
        """
        try:
            obj = json.loads(to_text(request, errors='surrogate_or_strict'))

            if 'jsonrpc' in obj:
                if self._netconf:
                    out = self._exec_rpc(obj)
                else:
                    out = self.internal_error("netconf plugin is not supported for network_os %s" % self._play_context.network_os)
                return 0, to_bytes(out, errors='surrogate_or_strict'), b''
            else:
                err = self.invalid_request(obj)
                return 1, b'', to_bytes(err, errors='surrogate_or_strict')

        except (ValueError, TypeError):
            # to_ele operates on native strings
            request = to_native(request, errors='surrogate_or_strict')

        req = to_ele(request)
        if req is None:
            return 1, b'', b'unable to parse request'

        try:
            reply = self._manager.rpc(req)
        except RPCError as exc:
            return 1, b'', to_bytes(to_xml(exc.xml), errors='surrogate_or_strict')

        return 0, to_bytes(reply.data_xml, errors='surrogate_or_strict'), b''

    def put_file(self, in_path, out_path):
        """Transfer a file from local to remote"""
        pass

    def fetch_file(self, in_path, out_path):
        """Fetch a file from remote to local"""
        pass