# Copyright 2014 Canonical Ltd.
#
# Authors: Hui Xiang <hui.xiang@canonical.com>
#          Joshua Zhang <joshua.zhang@canonical.com>
#          Edward Hope-Morley <edward.hope-morley@canonical.com>
#

"""
Helpers for monitoring Neutron agents, reschedule failed agents,
cleaned resources on failed nodes.
"""

import os
import re
import sys
import signal
import socket
import subprocess
import time

from oslo.config import cfg
from neutron.agent.linux import ovs_lib
from neutron.agent.linux import ip_lib
from neutron.common import exceptions
from neutron.openstack.common import log as logging

LOG = logging.getLogger(__name__)


class Daemon(object):
    """A generic daemon class.

    Usage: subclass the Daemon class and override the run() method
    """
    def __init__(self, stdin='/dev/null', stdout='/dev/null',
                 stderr='/dev/null', procname='python'):
        self.stdin = stdin
        self.stdout = stdout
        self.stderr = stderr
        self.procname = procname

    def _fork(self):
        try:
            pid = os.fork()
            if pid > 0:
                sys.exit(0)
        except OSError:
            LOG.exception('Fork failed')
            sys.exit(1)

    def daemonize(self):
        """Daemonize process by doing Stevens double fork."""
        # fork first time
        self._fork()

        # decouple from parent environment
        os.chdir("/")
        os.setsid()
        os.umask(0)
        # fork second time
        self._fork()

        # redirect standard file descriptors
        sys.stdout.flush()
        sys.stderr.flush()
        stdin = open(self.stdin, 'r')
        stdout = open(self.stdout, 'a+')
        stderr = open(self.stderr, 'a+', 0)
        os.dup2(stdin.fileno(), sys.stdin.fileno())
        os.dup2(stdout.fileno(), sys.stdout.fileno())
        os.dup2(stderr.fileno(), sys.stderr.fileno())

        signal.signal(signal.SIGTERM, self.handle_sigterm)

    def handle_sigterm(self, signum, frame):
        sys.exit(0)

    def start(self):
        """Start the daemon."""
        self.daemonize()
        self.run()

    def run(self):
        """Override this method when subclassing Daemon.

        start() will call this method after the process has daemonized.
        """
        pass


class MonitorNeutronAgentsDaemon(Daemon):
    def __init__(self):
        super(MonitorNeutronAgentsDaemon, self).__init__()
        logging.setup('Neuron-HA-Monitor')
        LOG.info('Monitor Neutron Agent Loop Init')
        self.hostname = None
        self.env = {}

    def get_env(self):
        envrc_f = '/etc/legacy_ha_envrc'
        envrc_f_m = False
        if os.path.isfile(envrc_f):
            ctime = time.ctime(os.stat(envrc_f).st_ctime)
            mtime = time.ctime(os.stat(envrc_f).st_mtime)
            if ctime != mtime:
                envrc_f_m = True

            if not self.env or envrc_f_m:
                with open(envrc_f, 'r') as f:
                    for line in f:
                        data = line.strip().split('=')
                        if data and data[0] and data[1]:
                            self.env[data[0]] = data[1]
                        else:
                            raise Exception("OpenStack env data uncomplete.")
        return self.env

    def get_hostname(self):
        if not self.hostname:
            self.hostname = socket.gethostname()
        return self.hostname

    def get_root_helper(self):
        return 'sudo'

    def list_monitor_res(self):
        # List crm resource 'cl_monitor' running node
        nodes = []
        cmd = ['crm', 'resource', 'show', 'cl_monitor']
        output = subprocess.check_output(cmd)
        pattern = re.compile('resource cl_monitor is running on: (.*) ')
        nodes = pattern.findall(output)
        return nodes

    def get_crm_res_lead_node(self):
        nodes = self.list_monitor_res()
        if nodes:
            return nodes[0].strip()
        else:
            LOG.error('Failed to get crm resource.')
            return None

    def unplug_device(self, device):
        try:
            device.link.delete()
        except RuntimeError:
            root_helper = self.get_root_helper()
            # Maybe the device is OVS port, so try to delete
            bridge_name = ovs_lib.get_bridge_for_iface(root_helper,
                                                       device.name)
            if bridge_name:
                bridge = ovs_lib.OVSBridge(bridge_name, root_helper)
                bridge.delete_port(device.name)
            else:
                LOG.debug('Unable to find bridge for device: %s', device.name)

    def get_pattern(self, key, text):
        if not key or not text:
            LOG.debug('Invalid key(%s) or text(%s)' % (key, text))
            return None

        pattern = re.compile('%s' % key)
        result = pattern.findall(text)
        return result

    def _cleanup(self, key1, key2):
        namespaces = []
        if key1:
            for k in key1.iterkeys():
                namespaces.append(key2 + '-' + k)
        else:
            try:
                cmd = ['sudo', 'ip', 'netns']
                ns = subprocess.check_output(cmd)
                namespaces = self.get_pattern('(%s.*)' % key2, ns)
            except RuntimeError as e:
                LOG.error('Failed to list namespace, (%s)' % e)

        if namespaces:
            LOG.info('Namespaces: %s is going to be deleted.' % namespaces)
            self.destroy_namespaces(namespaces)

    def cleanup_dhcp(self, networks):
        self._cleanup(networks, 'qdhcp')

    def cleanup_router(self, routers):
        self._cleanup(routers, 'qrouter')

    def destroy_namespaces(self, namespaces):
        try:
            root_helper = self.get_root_helper()
            for namespace in namespaces:
                ip = ip_lib.IPWrapper(root_helper, namespace)
                if ip.netns.exists(namespace):
                    for device in ip.get_devices(exclude_loopback=True):
                        self.unplug_device(device)

            ip.garbage_collect_namespace()
        except Exception:
            LOG.exception('Error unable to destroy namespace: %s', namespace)

    def is_same_host(self, host):
        return str(host).strip() == self.get_hostname()

    def validate_reschedule(self):
        crm_no_1_node = self.get_crm_res_lead_node()
        if not crm_no_1_node:
            LOG.error('No crm first node could be found.')
            return False

        if not self.is_same_host(crm_no_1_node):
            LOG.warn('Only the first crm node %s could reschedule. '
                     % crm_no_1_node)
            return False
        return True

    def l3_agents_reschedule(self, l3_agents, routers, quantum):
        if not self.validate_reschedule():
            return

        index = 0
        for router_id in routers:
            agent = index % len(l3_agents)
            LOG.info('Moving router %s from %s to %s' %
                     (router_id, routers[router_id], l3_agents[agent]))
            try:
                quantum.remove_router_from_l3_agent(l3_agent=routers[router_id],
                                                    router_id=router_id)
            except exceptions.NeutronException as e:
                LOG.error('Remove router raised exception: %s' % e)
            try:
                quantum.add_router_to_l3_agent(l3_agent=l3_agents[agent],
                                               body={'router_id': router_id})
            except exceptions.NeutronException as e:
                LOG.error('Add router raised exception: %s' % e)
            index += 1

    def dhcp_agents_reschedule(self, dhcp_agents, networks, quantum):
        if not self.validate_reschedule():
            return

        index = 0
        for network_id in networks:
            agent = index % len(dhcp_agents)
            LOG.info('Moving network %s from %s to %s' % (network_id,
                     networks[network_id], dhcp_agents[agent]))
            try:
                quantum.remove_network_from_dhcp_agent(
                    dhcp_agent=networks[network_id], network_id=network_id)
            except exceptions.NeutronException as e:
                LOG.error('Remove network raised exception: %s' % e)
            try:
                quantum.add_network_to_dhcp_agent(
                    dhcp_agent=dhcp_agents[agent],
                    body={'network_id': network_id})
            except exceptions.NeutronException as e:
                LOG.error('Add network raised exception: %s' % e)
            index += 1

    def get_quantum_client(self):
        env = self.get_env()
        if not env:
            LOG.info('Unable to re-assign resources at this time')
            return None

        try:
            from quantumclient.v2_0 import client
        except ImportError:
            # Try to import neutronclient instead for havana+
            from neutronclient.v2_0 import client

        auth_url = '%(auth_protocol)s://%(keystone_host)s:%(auth_port)s/v2.0' \
                   % env
        quantum = client.Client(username=env['service_username'],
                                password=env['service_password'],
                                tenant_name=env['service_tenant'],
                                auth_url=auth_url,
                                region_name=env['region'])
        return quantum

    def reassign_agent_resources(self, quantum=None):
        """Use agent scheduler API to detect down agents and re-schedule"""
        if not quantum:
            LOG.error('Failed to get quantum client.')
            return

        try:
            DHCP_AGENT = "DHCP Agent"
            L3_AGENT = "L3 Agent"
            agents = quantum.list_agents(agent_type=DHCP_AGENT)
        except exceptions.NeutronException as e:
            LOG.error('Failed to get quantum agents, %s' % e)
            return

        dhcp_agents = []
        l3_agents = []
        networks = {}
        for agent in agents['agents']:
            hosted_networks = quantum.list_networks_on_dhcp_agent(
                agent['id'])['networks']
            if not agent['alive']:
                LOG.info('DHCP Agent %s down' % agent['id'])
                for network in hosted_networks:
                    networks[network['id']] = agent['id']
                if self.is_same_host(agent['host']):
                    self.cleanup_dhcp(networks)
            else:
                dhcp_agents.append(agent['id'])
                LOG.info('Active dhcp agents: %s' % agent['id'])
                if not hosted_networks and self.is_same_host(agent['host']):
                    self.cleanup_dhcp(None)

        agents = quantum.list_agents(agent_type=L3_AGENT)
        routers = {}
        for agent in agents['agents']:
            hosted_routers = quantum.list_routers_on_l3_agent(
                agent['id'])['routers']
            if not agent['alive']:
                LOG.info('L3 Agent %s down' % agent['id'])
                for router in hosted_routers:
                    routers[router['id']] = agent['id']
                if self.is_same_host(agent['host']):
                    self.cleanup_router(routers)
            else:
                l3_agents.append(agent['id'])
                LOG.info('Active l3 agents: %s' % agent['id'])
                if not hosted_routers and self.is_same_host(agent['host']):
                    self.cleanup_router(None)

        if not networks and not routers:
            LOG.info('No networks and routers hosted on failed agents.')
            return

        if len(dhcp_agents) == 0 and len(l3_agents) == 0:
            LOG.error('Unable to relocate resources, there are %s dhcp_agents '
                      'and %s l3_agents in this cluster' % (len(dhcp_agents),
                                                            len(l3_agents)))
            return

        if len(l3_agents) > 0:
            self.l3_agents_reschedule(l3_agents, routers, quantum)
            # new l3 node will not create a tunnel if don't restart ovs process

        if len(dhcp_agents) > 0:
            self.dhcp_agents_reschedule(dhcp_agents, networks, quantum)


    def check_ovs_tunnel(self, quantum=None):
        '''
        Work around for Bug #1411163
        No fdb entries added when failover dhcp and l3 agent together.
        '''
        if not quantum:
            LOG.error('Failed to get quantum client.')
            return

        try:
            OVS_AGENT = 'Open vSwitch agent'
            agents = quantum.list_agents(agent_type=OVS_AGENT)
        except exceptions.NeutronException as e:
            LOG.error('No ovs agent found on localhost, error:%s.' % e)
            return

        for agent in agents['agents']:
            if self.is_same_host(agent['host']) and agent['alive']:
                conf = agent['configurations']
                if 'gre' in conf['tunnel_types'] and conf['l2_population'] \
                        and conf['devices']:
                    LOG.debug('local ovs agent:%s' % agent)
                    ovs_output = subprocess.check_output(['ovs-vsctl',
                                                          'list-ports', 'br-tun'])
                    ports = ovs_output.strip().split('\n')
                    look_up_gre_port = False
                    for port in ports:
                        if port.startswith('gre-'):
                            look_up_gre_port = True
                            break
                    if not look_up_gre_port:
                        try:
                            LOG.error('Local agent has devices, but no ovs tunnel is created,'
                                      'restart ovs agent.')
                            cmd = ['sudo', 'service', 'neutron-plugin-openvswitch-agent',
                                   'restart']
                            subprocess.call(cmd)
                        except subprocess.CalledProcessError:
                            LOG.error('Failed to restart neutron-plugin-openvswitch-agent.')

    def check_local_agents(self):
        services = ['openvswitch-switch', 'neutron-dhcp-agent',
                    'neutron-metadata-agent', 'neutron-vpn-agent']
        for s in services:
            status = ['sudo', 'service', s, 'status']
            restart = ['sudo', 'service', s, 'restart']
            start = ['sudo', 'service', s, 'start']
            stop = '%s stop/waiting' % s
            try:
                output = subprocess.check_output(status)
                if output.strip() == stop:
                    subprocess.check_output(start)
                    LOG.error('Restart service: %s' % s)
                    if s == 'neutron-metadata-agent':
                        subprocess.check_output(['sudo', 'service',
                                                 'neutron-vpn-agent',
                                                 'restart'])
                        LOG.error('Restart neutron-vpn-agent')
            except subprocess.CalledProcessError:
                LOG.error('Restart service: %s' % s)
                subprocess.check_output(restart)
                if s == 'neutron-metadata-agent':
                    subprocess.check_output(['sudo', 'service',
                                             'neutron-vpn-agent',
                                             'restart'])

    def run(self):
        while True:
            LOG.info('Monitor Neutron HA Agent Loop Start')
            quantum = self.get_quantum_client()
            self.reassign_agent_resources(quantum=quantum)
            self.check_ovs_tunnel(quantum=quantum)
            self.check_local_agents()
            LOG.info('sleep %s' % cfg.CONF.check_interval)
            time.sleep(float(cfg.CONF.check_interval))


if __name__ == '__main__':
    opts = [
        cfg.StrOpt('check_interval',
                   default=8,
                   help='Check Neutron Agents interval.'),
    ]

    cfg.CONF.register_cli_opts(opts)
    cfg.CONF(project='monitor_neutron_agents', default_config_files=[])
    logging.setup('Neuron-HA-Monitor')
    monitor_daemon = MonitorNeutronAgentsDaemon()
    monitor_daemon.start()