# Copyright 2015 Hewlett-Packard Development Company, L.P.
# Copyright 2016 Rackspace
#
# 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.

import ipaddress
import os
import socket
import stat
import subprocess

import jinja2
from oslo_config import cfg
from oslo_log import log as logging
import pyroute2
import six
import webob
from werkzeug import exceptions

import netifaces
from octavia.common import constants as consts


CONF = cfg.CONF

ETH_X_VIP_CONF = 'plug_vip_ethX.conf.j2'
ETH_X_PORT_CONF = 'plug_port_ethX.conf.j2'

LOG = logging.getLogger(__name__)

j2_env = jinja2.Environment(autoescape=True, loader=jinja2.FileSystemLoader(
    os.path.dirname(os.path.realpath(__file__)) + consts.AGENT_API_TEMPLATES))
template_port = j2_env.get_template(ETH_X_PORT_CONF)
template_vip = j2_env.get_template(ETH_X_VIP_CONF)


class Plug(object):
    def __init__(self, osutils):
        self._osutils = osutils

    def plug_vip(self, vip, subnet_cidr, gateway,
                 mac_address, mtu=None, vrrp_ip=None, host_routes=None):
        # Validate vip and subnet_cidr, calculate broadcast address and netmask
        try:
            render_host_routes = []
            ip = ipaddress.ip_address(
                vip if isinstance(vip, six.text_type) else six.u(vip))
            network = ipaddress.ip_network(
                subnet_cidr if isinstance(subnet_cidr, six.text_type)
                else six.u(subnet_cidr))
            vip = ip.exploded
            broadcast = network.broadcast_address.exploded
            netmask = (network.prefixlen if ip.version == 6
                       else network.netmask.exploded)
            vrrp_version = None
            if vrrp_ip:
                vrrp_ip_obj = ipaddress.ip_address(
                    vrrp_ip if isinstance(vrrp_ip, six.text_type)
                    else six.u(vrrp_ip)
                )
                vrrp_version = vrrp_ip_obj.version
            if host_routes:
                for hr in host_routes:
                    network = ipaddress.ip_network(
                        hr['destination'] if isinstance(
                            hr['destination'], six.text_type) else
                        six.u(hr['destination']))
                    render_host_routes.append({'network': network,
                                               'gw': hr['nexthop']})
        except ValueError:
            return webob.Response(json=dict(message="Invalid VIP"),
                                  status=400)

        # Check if the interface is already in the network namespace
        # Do not attempt to re-plug the VIP if it is already in the
        # network namespace
        if self._netns_interface_exists(mac_address):
            return webob.Response(
                json=dict(message="Interface already exists"), status=409)

        # This is the interface prior to moving into the netns
        default_netns_interface = self._interface_by_mac(mac_address)

        # Always put the VIP interface as eth1
        primary_interface = consts.NETNS_PRIMARY_INTERFACE
        secondary_interface = "{interface}:0".format(
            interface=primary_interface)

        interface_file_path = self._osutils.get_network_interface_file(
            primary_interface)

        self._osutils.create_netns_dir()

        self._osutils.write_interfaces_file()
        self._osutils.write_vip_interface_file(
            interface_file_path=interface_file_path,
            primary_interface=primary_interface,
            vip=vip,
            ip=ip,
            broadcast=broadcast,
            netmask=netmask,
            gateway=gateway,
            mtu=mtu,
            vrrp_ip=vrrp_ip,
            vrrp_version=vrrp_version,
            render_host_routes=render_host_routes)

        # Update the list of interfaces to add to the namespace
        # This is used in the amphora reboot case to re-establish the namespace
        self._update_plugged_interfaces_file(primary_interface, mac_address)

        # Create the namespace
        netns = pyroute2.NetNS(consts.AMPHORA_NAMESPACE, flags=os.O_CREAT)
        netns.close()

        # Load sysctl in new namespace
        sysctl = pyroute2.NSPopen(consts.AMPHORA_NAMESPACE,
                                  [consts.SYSCTL_CMD, '--system'],
                                  stdout=subprocess.PIPE)

        sysctl.communicate()
        sysctl.wait()
        sysctl.release()

        cmd_list = [['modprobe', 'ip_vs'],
                    [consts.SYSCTL_CMD, '-w', 'net.ipv4.vs.conntrack=1']]
        if ip.version == 4:
            # For lvs function, enable ip_vs kernel module, enable ip_forward
            # conntrack in amphora network namespace.
            cmd_list.append([consts.SYSCTL_CMD, '-w', 'net.ipv4.ip_forward=1'])
        elif ip.version == 6:
            cmd_list.append([consts.SYSCTL_CMD, '-w',
                             'net.ipv6.conf.all.forwarding=1'])
        for cmd in cmd_list:
            ns_exec = pyroute2.NSPopen(consts.AMPHORA_NAMESPACE, cmd,
                                       stdout=subprocess.PIPE)
            ns_exec.wait()
            ns_exec.release()

        with pyroute2.IPRoute() as ipr:
            # Move the interfaces into the namespace
            idx = ipr.link_lookup(ifname=default_netns_interface)[0]
            ipr.link('set', index=idx, net_ns_fd=consts.AMPHORA_NAMESPACE,
                     IFLA_IFNAME=primary_interface)

        # bring interfaces up
        self._osutils.bring_interfaces_up(
            ip, primary_interface, secondary_interface)

        return webob.Response(json=dict(
            message="OK",
            details="VIP {vip} plugged on interface {interface}".format(
                vip=vip, interface=primary_interface)), status=202)

    def _check_ip_addresses(self, fixed_ips):
        if fixed_ips:
            for ip in fixed_ips:
                try:
                    socket.inet_pton(socket.AF_INET, ip.get('ip_address'))
                except socket.error:
                    socket.inet_pton(socket.AF_INET6, ip.get('ip_address'))

    def plug_network(self, mac_address, fixed_ips, mtu=None):
        # Check if the interface is already in the network namespace
        # Do not attempt to re-plug the network if it is already in the
        # network namespace
        if self._netns_interface_exists(mac_address):
            return webob.Response(json=dict(
                message="Interface already exists"), status=409)

        # This is the interface as it was initially plugged into the
        # default network namespace, this will likely always be eth1

        try:
            self._check_ip_addresses(fixed_ips=fixed_ips)
        except socket.error:
            return webob.Response(json=dict(
                message="Invalid network port"), status=400)

        default_netns_interface = self._interface_by_mac(mac_address)

        # We need to determine the interface name when inside the namespace
        # to avoid name conflicts
        with pyroute2.NetNS(consts.AMPHORA_NAMESPACE,
                            flags=os.O_CREAT) as netns:

            # 1 means just loopback, but we should already have a VIP. This
            # works for the add/delete/add case as we don't delete interfaces
            # Note, eth0 is skipped because that is the VIP interface
            netns_interface = 'eth{0}'.format(len(netns.get_links()))

        LOG.info('Plugged interface %s will become %s in the namespace %s',
                 default_netns_interface, netns_interface,
                 consts.AMPHORA_NAMESPACE)
        interface_file_path = self._osutils.get_network_interface_file(
            netns_interface)
        self._osutils.write_port_interface_file(
            netns_interface=netns_interface,
            fixed_ips=fixed_ips,
            mtu=mtu,
            interface_file_path=interface_file_path)

        # Update the list of interfaces to add to the namespace
        self._update_plugged_interfaces_file(netns_interface, mac_address)

        with pyroute2.IPRoute() as ipr:
            # Move the interfaces into the namespace
            idx = ipr.link_lookup(ifname=default_netns_interface)[0]
            ipr.link('set', index=idx,
                     net_ns_fd=consts.AMPHORA_NAMESPACE,
                     IFLA_IFNAME=netns_interface)

        self._osutils._bring_if_down(netns_interface)
        self._osutils._bring_if_up(netns_interface, 'network')

        return webob.Response(json=dict(
            message="OK",
            details="Plugged on interface {interface}".format(
                interface=netns_interface)), status=202)

    def _interface_by_mac(self, mac):
        for interface in netifaces.interfaces():
            if netifaces.AF_LINK in netifaces.ifaddresses(interface):
                for link in netifaces.ifaddresses(
                        interface)[netifaces.AF_LINK]:
                    if link.get('addr', '').lower() == mac.lower():
                        return interface
        # Poke the kernel to re-enumerate the PCI bus.
        # We have had cases where nova hot plugs the interface but
        # the kernel doesn't get the memo.
        filename = '/sys/bus/pci/rescan'
        flags = os.O_WRONLY
        if os.path.isfile(filename):
            with os.fdopen(os.open(filename, flags), 'w') as rescan_file:
                rescan_file.write('1')
        raise exceptions.HTTPException(
            response=webob.Response(json=dict(
                details="No suitable network interface found"), status=404))

    def _update_plugged_interfaces_file(self, interface, mac_address):
        # write interfaces to plugged_interfaces file and prevent duplicates
        plug_inf_file = consts.PLUGGED_INTERFACES
        flags = os.O_RDWR | os.O_CREAT
        # mode 0644
        mode = stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH
        with os.fdopen(os.open(plug_inf_file, flags, mode), 'r+') as text_file:
            inf_list = [inf.split()[0].rstrip() for inf in text_file]
            if mac_address not in inf_list:
                text_file.write("{mac_address} {interface}\n".format(
                    mac_address=mac_address, interface=interface))

    def _netns_interface_exists(self, mac_address):
        with pyroute2.NetNS(consts.AMPHORA_NAMESPACE,
                            flags=os.O_CREAT) as netns:
            for link in netns.get_links():
                for attr in link['attrs']:
                    if attr[0] == 'IFLA_ADDRESS' and attr[1] == mac_address:
                        return True
        return False
