#!/usr/bin/python
import re
import time
import thread
import getopt
import signal
import sys
from subprocess import Popen, PIPE, STDOUT

# TODO print not refreshing correctly

def get_bytes_from_tcpdump(interface, src, byte_values):
    command = Popen(['tcpdump', '-n', '-e', '-p', '-l', '-v', '-i',
                     interface, 'src', src], stdout=PIPE, stderr=PIPE,
                     bufsize=0)
    while 1:
        line = command.stdout.readline()
        if not line:
            # time.sleep(1)
            continue
        bytes_pattern = re.search('length \d*', line)
        # dest_pattern = re.search('> .*: ', line)

        if bytes_pattern:
            s = bytes_pattern.group(0)
            bytes = int(s[7:]) + 5
        else:
            # ARP packet
            bytes = 28 + 14

        byte_values[0] += bytes
        byte_values[1] += 1
        # time.sleep(1)

        # if dest_pattern:
        #     s = dest_pattern.group()
        #     dest = s[2:len(s)-2]

def get_bytes_from_proc(interface, byte_values):
    wrap = 2**32
    offset = read_proc(interface)
    while(1):
        current_bytes = read_proc(interface)
        increase = current_bytes - offset
        if increase < 0:
            increase = (wrap - (byte_values[0] % wrap)) + current_bytes
        byte_values[0] += increase
        offset = current_bytes
        time.sleep(1)

def get_bytes_from_ifconfig(interface, byte_values):
    offset = read_ifconfig(interface)
    while(1):
        bytes = read_ifconfig(interface)
        byte_values[0] += (bytes - offset)
        offset = bytes
        time.sleep(1)

def read_ifconfig(interface):
    command = Popen(['/sbin/ifconfig', interface], stdout=PIPE, stderr=PIPE)
    # received bytes
    # lines = command.communicate()[0].split()[34]
    # transmitted bytes
    try:
        s = command.communicate()
    except Exception, e:
        print "failed: %r" % e
    bytes = int(s[0].split()[38].split(':')[1])
    return bytes

def read_proc(interface):
    f = open('/proc/net/dev')
    for line in f:
        values = line.split()
        i = values[0].split(':')[0]
        if interface == i:
            bytes = int(values[8])
            # received bytes
            # bytes = int(values[0].split(':')[1])
            f.close()
            return bytes
    f.close()

def signal_handler(signum, frame):
#    print "bye"
    sys.exit(0)

def main(interface, host):
    signal.signal(signal.SIGINT, signal_handler)

    byte_value_tcpdump = [0, 0]
    byte_value_proc = [0]
    byte_value_ifconfig = [0]

    thread.start_new_thread(get_bytes_from_tcpdump,
                            (interface, host, byte_value_tcpdump))
    thread.start_new_thread(get_bytes_from_proc, (interface, byte_value_proc))
    # thread.start_new_thread(get_bytes_from_ifconfig, (interface,
    #                                                   byte_value_ifconfig))

    while 1:
        s = "TCPDUMP: %d (%d packets)\nPROC:    %d" % (byte_value_tcpdump[0],
                                                       byte_value_tcpdump[1],
                                                       byte_value_proc[0])
        print s
        time.sleep(1)

def usage():
    print "Usage: monitor -i interface (e.g. eth0) -m host_ip"

if __name__ == "__main__":
    interface = None
    ip = None
    opts, args = getopt.getopt(sys.argv[1:], "hi:m:", ["help"])
    for o, a in opts:
        if o == '-i':
            interface = a
        elif o == '-m':
            ip = a
        elif o in ['-h', '--help']:
            usage()
            sys.exit()
    if not interface or not ip:
        usage()
        sys.exit()

    main(interface, ip)