# Copyright (c) 2016 Cisco and/or its affiliates.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""IPv4 setup library"""

from socket import inet_ntoa
from struct import pack
from abc import ABCMeta, abstractmethod

from robot.api.deco import keyword

from resources.libraries.python.ssh import exec_cmd_no_error
from resources.libraries.python.Routing import Routing
from resources.libraries.python.topology import NodeType, Topology
from resources.libraries.python.VatExecutor import VatExecutor


class IPv4Node(object):
    """Abstract class of a node in a topology."""
    __metaclass__ = ABCMeta

    def __init__(self, node_info):
        self.node_info = node_info

    @staticmethod
    def _get_netmask(prefix_length):
        bits = 0xffffffff ^ (1 << 32 - prefix_length) - 1
        return inet_ntoa(pack('>I', bits))

    @abstractmethod
    def set_ip(self, interface, address, prefix_length):
        """Configure IPv4 address on interface.

        :param interface: Interface name.
        :param address: IPv4 address.
        :param prefix_length: IPv4 prefix length.
        :type interface: str
        :type address: str
        :type prefix_length: int
        :return: nothing
        """
        pass

    @abstractmethod
    def set_route(self, network, prefix_length, gateway, interface):
        """Configure IPv4 route.

        :param network: Network IPv4 address.
        :param prefix_length: IPv4 prefix length.
        :param gateway: IPv4 address of the gateway.
        :param interface: Interface name.
        :type network: str
        :type prefix_length: int
        :type gateway: str
        :type interface: str
        :return: nothing
        """
        pass

    @abstractmethod
    def unset_route(self, network, prefix_length, gateway, interface):
        """Remove specified IPv4 route.

        :param network: Network IPv4 address.
        :param prefix_length: IPv4 prefix length.
        :param gateway: IPv4 address of the gateway.
        :param interface: Interface name.
        :type network: str
        :type prefix_length: int
        :type gateway: str
        :type interface: str
        :return: nothing
        """
        pass

    @abstractmethod
    def flush_ip_addresses(self, interface):
        """Flush all IPv4 addresses from specified interface.

        :param interface: Interface name.
        :type interface: str
        :return: nothing
        """
        pass

    @abstractmethod
    def ping(self, destination_address, source_interface):
        """Send an ICMP request to destination node.

        :param destination_address: Address to send the ICMP request.
        :param source_interface: Source interface name.
        :type destination_address: str
        :type source_interface: str
        :return: nothing
        """
        pass


class Tg(IPv4Node):
    """Traffic generator node"""
    def __init__(self, node_info):
        super(Tg, self).__init__(node_info)

    def _execute(self, cmd):
        return exec_cmd_no_error(self.node_info, cmd)

    def _sudo_execute(self, cmd):
        return exec_cmd_no_error(self.node_info, cmd, sudo=True)

    def set_ip(self, interface, address, prefix_length):
        cmd = 'ip -4 addr flush dev {}'.format(interface)
        self._sudo_execute(cmd)
        cmd = 'ip addr add {}/{} dev {}'.format(address, prefix_length,
                                                interface)
        self._sudo_execute(cmd)

    def set_route(self, network, prefix_length, gateway, interface):
        netmask = self._get_netmask(prefix_length)
        cmd = 'route add -net {} netmask {} gw {}'.\
            format(network, netmask, gateway)
        self._sudo_execute(cmd)

    def unset_route(self, network, prefix_length, gateway, interface):
        self._sudo_execute('ip route delete {}/{}'.
                           format(network, prefix_length))

    def arp_ping(self, destination_address, source_interface):
        self._sudo_execute('arping -c 1 -I {} {}'.format(source_interface,
                                                         destination_address))

    def ping(self, destination_address, source_interface):
        self._execute('ping -c 1 -w 5 -I {} {}'.format(source_interface,
                                                       destination_address))

    def flush_ip_addresses(self, interface):
        self._sudo_execute('ip addr flush dev {}'.format(interface))


class Dut(IPv4Node):
    """Device under test"""
    def __init__(self, node_info):
        super(Dut, self).__init__(node_info)

    def get_sw_if_index(self, interface):
        """Get sw_if_index of specified interface from current node.

        :param interface: Interface name.
        :type interface: str
        :return: sw_if_index of the interface or None.
        :rtype: int
        """
        return Topology().get_interface_sw_index(self.node_info, interface)

    def exec_vat(self, script, **args):
        """Wrapper for VAT executor.

        :param script: Script to execute.
        :param args: Parameters to the script.
        :type script: str
        :type args: dict
        :return: nothing
        """
        # TODO: check return value
        VatExecutor.cmd_from_template(self.node_info, script, **args)

    def set_arp(self, interface, ip_address, mac_address):
        """Set entry in ARP cache.

        :param interface: Interface name.
        :param ip_address: IP address.
        :param mac_address: MAC address.
        :type interface: str
        :type ip_address: str
        :type mac_address: str
        """
        self.exec_vat('add_ip_neighbor.vat',
                      sw_if_index=self.get_sw_if_index(interface),
                      ip_address=ip_address, mac_address=mac_address)

    def set_ip(self, interface, address, prefix_length):
        self.exec_vat('add_ip_address.vat',
                      sw_if_index=self.get_sw_if_index(interface),
                      address=address, prefix_length=prefix_length)

    def set_route(self, network, prefix_length, gateway, interface):
        Routing.vpp_route_add(self.node_info,
                              network=network, prefix_len=prefix_length,
                              gateway=gateway, interface=interface)

    def unset_route(self, network, prefix_length, gateway, interface):
        self.exec_vat('del_route.vat', network=network,
                      prefix_length=prefix_length, gateway=gateway,
                      sw_if_index=self.get_sw_if_index(interface))

    def arp_ping(self, destination_address, source_interface):
        pass

    def flush_ip_addresses(self, interface):
        self.exec_vat('flush_ip_addresses.vat',
                      sw_if_index=self.get_sw_if_index(interface))

    def ping(self, destination_address, source_interface):
        pass


def get_node(node_info):
    """Creates a class instance derived from Node based on type.

    :param node_info: Dictionary containing information on nodes in topology.
    :type node_info: dict
    :return: Class instance that is derived from Node.
    """
    if node_info['type'] == NodeType.TG:
        return Tg(node_info)
    elif node_info['type'] == NodeType.DUT:
        return Dut(node_info)
    else:
        raise NotImplementedError('Node type "{}" unsupported!'.
                                  format(node_info['type']))


class IPv4Setup(object):
    """IPv4 setup in topology."""

    @staticmethod
    def vpp_nodes_set_ipv4_addresses(nodes, nodes_addr):
        """Set IPv4 addresses on all VPP nodes in topology.

        :param nodes: Nodes of the test topology.
        :param nodes_addr: Available nodes IPv4 addresses.
        :type nodes: dict
        :type nodes_addr: dict
        :return: Affected interfaces as list of (node, interface) tuples.
        :rtype: list
        """
        interfaces = []
        for net in nodes_addr.values():
            for port in net['ports'].values():
                host = port.get('node')
                if host is None:
                    continue
                topo = Topology()
                node = topo.get_node_by_hostname(nodes, host)
                if node is None:
                    continue
                if node['type'] != NodeType.DUT:
                    continue
                get_node(node).set_ip(port['if'], port['addr'], net['prefix'])
                interfaces.append((node, port['if']))

        return interfaces

    @staticmethod
    @keyword('Get IPv4 address of node "${node}" interface "${port}" '
             'from "${nodes_addr}"')
    def get_ip_addr(node, interface, nodes_addr):
        """Return IPv4 address of the node port.

        :param node: Node in the topology.
        :param interface: Interface name of the node.
        :param nodes_addr: Nodes IPv4 addresses.
        :type node: dict
        :type interface: str
        :type nodes_addr: dict
        :return: IPv4 address.
        :rtype: str
        """
        for net in nodes_addr.values():
            for port in net['ports'].values():
                host = port.get('node')
                dev = port.get('if')
                if host == node['host'] and dev == interface:
                    ip = port.get('addr')
                    if ip is not None:
                        return ip
                    else:
                        raise Exception(
                            'Node {n} port {p} IPv4 address is not set'.format(
                                n=node['host'], p=interface))

        raise Exception('Node {n} port {p} IPv4 address not found.'.format(
            n=node['host'], p=interface))

    @staticmethod
    def setup_arp_on_all_duts(nodes_info, nodes_addr):
        """For all DUT nodes extract MAC and IP addresses of adjacent
        interfaces from topology and use them to setup ARP entries.

        :param nodes_info: Dictionary containing information on all nodes
        in topology.
        :param nodes_addr: Nodes IPv4 addresses.
        :type nodes_info: dict
        :type nodes_addr: dict
        """
        for node in nodes_info.values():
            if node['type'] == NodeType.TG:
                continue
            for interface, interface_data in node['interfaces'].iteritems():
                interface_name = interface_data['name']
                adj_node, adj_int = Topology.\
                    get_adjacent_node_and_interface(nodes_info, node,
                                                    interface_name)
                ip_address = IPv4Setup.get_ip_addr(adj_node, adj_int['name'],
                                                   nodes_addr)
                mac_address = adj_int['mac_address']
                get_node(node).set_arp(interface_name, ip_address, mac_address)