#!/usr/bin/env python

"""
Start up a Simple topology for CS144
"""

import mininet.net
import mininet.node

from mininet.log import setLogLevel, info
from mininet.cli import CLI
from mininet.topo import Topo
from mininet.util import quietRun
from mininet.moduledeps import pathCheck

from sys import exit
import os.path
from subprocess import Popen, STDOUT, PIPE, check_call

IPBASE = '10.3.0.0/16'
ROOTIP = '10.3.0.100/16'
IPCONFIG_FILE = './IP_CONFIG'
IP_SETTING={}

class TwoServerClientAndRouterTopology(Topo):
    "Topology with 2 servers and 1 client connected with a switch/router"

    def __init__( self, *args, **kwargs ):
        Topo.__init__( self, *args, **kwargs )
        server1 = self.addHost( 'server1' )
        server2 = self.addHost( 'server2' )
        router = self.addSwitch( 'sw0' )
        client = self.addHost('client')
        for h in server1, server2, client:
            self.addLink( h, router )

def set_default_route(host):
    info('*** setting default gateway of host %s\n' % host.name)
    if(host.name == 'server1'):
        routerip = IP_SETTING['sw0-eth1']
    elif(host.name == 'server2'):
        routerip = IP_SETTING['sw0-eth2']
    elif(host.name == 'client'):
        routerip = IP_SETTING['sw0-eth3']
    print host.name, routerip
    host.cmd('route add %s/32 dev %s-eth0' % (routerip, host.name))
    host.cmd('route add default gw %s dev %s-eth0' % (routerip, host.name))
    ips = IP_SETTING[host.name].split(".")
    host.cmd('route del -net %s.0.0.0/8 dev %s-eth0' % (ips[0], host.name))

def set_default_route_client(host):
    info('*** setting default gateway of client %s\n' % host.name)
    routerip = IP_SETTING['sw0-eth3']
    print host.name, routerip
    for eth in ['sw0-eth1', 'sw0-eth2', 'sw0-eth3']:
        swip = IP_SETTING[eth]
        pref = ".".join(swip.split(".")[:-1]) + ".0"
        print pref
        check_call('route add -net %s/24 gw %s dev client-eth0' % (pref, IP_SETTING['sw0-eth3']), shell = True)

def get_ip_setting():
    try:
        with open(IPCONFIG_FILE, 'r') as f:
            for line in f:
                if( len(line.split()) == 0):
                  break
                name, ip = line.split()
                print name, ip
                IP_SETTING[name] = ip
            info( '*** Successfully loaded ip settings for hosts\n %s\n' % IP_SETTING)
    except EnvironmentError:
        exit("Couldn't load config file for ip addresses, check whether %s exists" % IPCONFIG_FILE)

def starthttp( host ):
    "Start simple Python web server on hosts"
    info( '*** Starting SimpleHTTPServer on host', host, '\n' )
    host.cmd( 'cd ./http_%s/; nohup python2.7 ./webserver.py &' % (host.name) )


def stophttp():
    "Stop simple Python web servers"
    info( '*** Shutting down stale SimpleHTTPServers', 
          quietRun( "pkill -9 -f SimpleHTTPServer" ), '\n' )    
    info( '*** Shutting down stale webservers', 
          quietRun( "pkill -9 -f webserver.py" ), '\n' )   

def start_topo():
    "Create a simple network"
    get_ip_setting()
    topo = TwoServerClientAndRouterTopology()
    info( '*** Creating network\n' )
    net = mininet.net.Mininet(topo=topo, controller=mininet.node.RemoteController, ipBase=IPBASE )
    net.start()
    server1, server2, client, router = net.get( 'server1', 'server2', 'client', 'sw0')
    s1intf = server1.defaultIntf()
    s1intf.setIP('%s/8' % IP_SETTING['server1'])
    s2intf = server2.defaultIntf()
    s2intf.setIP('%s/8' % IP_SETTING['server2'])
    clintf = client.defaultIntf()
    clintf.setIP('%s/8' % IP_SETTING['client'])

    for host in server1, server2, client:
        set_default_route(host)
    # set_default_route_client(client)
    starthttp( server1 )
    starthttp( server2 )
    return net

def stop_topo(net):
    stophttp()
    net.stop()

def main():
    net = start_topo()
    CLI( net )
    stop_topo(net)

if __name__ == '__main__':
    setLogLevel( 'info' )
    main()