#!/usr/bin/env python

import sys
import redis
import subprocess
import syslog
from swsssdk import ConfigDBConnector


class BGPConfigDaemon:

    def __init__(self):
        self.config_db = ConfigDBConnector()
        self.config_db.connect()
        self.bgp_asn = self.config_db.get_entry('DEVICE_METADATA', 'localhost')['bgp_asn']
        self.bgp_neighbor = self.config_db.get_table('BGP_NEIGHBOR')

    def __run_command(self, command):
        p = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE)
        stdout = p.communicate()[0]
        p.wait()
        if p.returncode != 0:
            syslog.syslog(syslog.LOG_ERR, '[bgp cfgd] command execution returned {}. Command: "{}", stdout: "{}"'.format(
                p.returncode, command, stdout))

    def metadata_handler(self, key, data):
        if key == 'localhost' and data.has_key('bgp_asn'):
            if data['bgp_asn'] != self.bgp_asn:
                syslog.syslog(syslog.LOG_INFO, '[bgp cfgd] ASN changed to {} from {}, restart BGP...'.format(
                    data['bgp_asn'], self.bgp_asn))
                self.__run_command("supervisorctl restart start.sh")
                self.__run_command("service quagga restart")
                self.bgp_asn = data['bgp_asn']

    def bgp_handler(self, key, data):
        syslog.syslog(syslog.LOG_INFO, '[bgp cfgd] value for {} changed to {}'.format(key, data))
        if not data:
            # Neighbor is deleted
            command = "vtysh -c 'configure terminal' -c 'router bgp {}' -c 'no neighbor {}'".format(self.bgp_asn, key)
            self.__run_command(command)
            self.bgp_neighbor.pop(key)
        else:
            command = "vtysh -c 'configure terminal' -c 'router bgp {}' -c 'neighbor {} remote-as {}'".format(
                self.bgp_asn, key, data['asn'])
            self.__run_command(command)
            if data.has_key('name'):
                command = "vtysh -c 'configure terminal' -c 'router bgp {}' -c 'neighbor {} description {}'".format(
                    self.bgp_asn, key, data['name'])
                self.__run_command(command)
            if data.has_key('admin_status'):
                command_mod = 'no ' if data['admin_status'] == 'up' else ''
                command = "vtysh -c 'configure terminal' -c 'router bgp {}' -c '{}neighbor {} shutdown'".format(
                    self.bgp_asn, command_mod, key)
                self.__run_command(command)
            self.bgp_neighbor[key] = data

    def start(self):
        self.config_db.subscribe('BGP_NEIGHBOR',
                                 lambda table, key, data: self.bgp_handler(key, data))
        self.config_db.subscribe('DEVICE_METADATA',
                                 lambda table, key, data: self.metadata_handler(key, data))
        self.config_db.listen()


def main():
    daemon = BGPConfigDaemon()
    daemon.start()


if __name__ == "__main__":
    main()