#!/usr/bin/env python
# -*- coding: utf-8 -*-

import argparse
import socket
import struct
import time

MCAST_PORT = 9999
MCAST_GROUP = '225.0.0.250'
MCAST_TTL = 1
MCAST_IF = None


def main():
    parser = argparse.ArgumentParser()

    parser.add_argument('-s', '--send', action='store_true', default=False)
    parser.add_argument('-p', '--port', type=int, default=MCAST_PORT)
    parser.add_argument('-g', '--group', type=str, default=MCAST_GROUP)
    parser.add_argument('-t', '--ttl', type=int, default=MCAST_TTL)
    parser.add_argument('-i', '--interface', type=str, default=MCAST_IF)

    args = parser.parse_args()
    if args.send:
        sender(args)
    else:
        receiver(args)


def sender(args):
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

    if args.interface is None:
        s.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL,
                     struct.pack('@i', args.ttl))
    else:
        s.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_IF,
                     socket.inet_pton(socket.AF_INET, args.interface))

    while True:
        data = repr(time.time())
        s.sendto(data + '\0', (args.group, args.port))
        time.sleep(1)


def receiver(args):
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    s.bind(('', args.port))

    b = socket.inet_pton(socket.AF_INET, args.group)
    if args.interface is None:
        mreq = b + struct.pack('=I', socket.INADDR_ANY)
    else:
        mreq = b + socket.inet_pton(socket.AF_INET, args.interface)
    s.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)

    while True:
        data, sender = s.recvfrom(1500)
        while data[-1:] == '\0':
            data = data[:-1]
        print ('from:' + str(sender[0]) +
               ', port:' + str(sender[1]) +
               ', data:' + repr(data))


if __name__ == '__main__':
    main()