#!/usr/bin/env python

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

# Returns BGP ASN as a string
def _get_bgp_asn_from_minigraph():
    # Get BGP ASN from minigraph
    proc = subprocess.Popen(
            ['sonic-cfggen', '-m', '/etc/sonic/minigraph.xml', '-v', 'minigraph_bgp_asn'],
            stdout=subprocess.PIPE,
            shell=False,
            stderr=subprocess.STDOUT)
    stdout = proc.communicate()[0]
    proc.wait()
    return stdout.rstrip('\n')

def bgp_config(asn, ip, config):
    syslog.syslog(syslog.LOG_INFO, '[bgp cfgd] value for {} changed to {}'.format(ip, config))
    # Currently dynamic config is supported only for bgp admin status
    if config.has_key('admin_status'):
        command_mod = 'no ' if config['admin_status'] == 'up' else ''
        command = "vtysh -c 'configure terminal' -c 'router bgp {}' -c '{}neighbor {} shutdown'".format(asn, command_mod, ip)
        
        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 main():
    sub = ConfigDBConnector()
    bgp_asn = _get_bgp_asn_from_minigraph()
    handler = lambda table, key, data: bgp_config(bgp_asn, key, data)
    sub.subscribe('BGP_NEIGHBOR', handler)
    sub.connect()
    sub.listen()

main()