#!/usr/bin/python -u
"""Watch squid's log file for user-specified patterns."""

import re
from subprocess import Popen, PIPE
import os.path
import sys
import time

__author__ = 'Faried Nawaz'
__copyright__ = 'This file is in the public domain.'
__version__ = '20090219'

# where is the access.log file?
LOGFILE = '/var/log/squid/access.log'
# sleep for a while between reads (in seconds)
SLEEPFOR = 0.5


def usage(msg=None):
    """Tell the user how to use us."""

    progname = os.path.basename(sys.argv[0])
    if msg:
        sys.stderr.write(msg + '\n')
    sys.stderr.write('''\
usage: %s pattern [pattern ...]
examples:
%s HIT
        -- show all lines with "HIT" in them
%s \'192.168.1.15.*flickr\'
        -- show all lines with requests from 192.168.1.15 to flickr
%s yahoo gmail hotmail
        -- show all lines with the words yahoo, gmail, or hotmail in them
%s \'text\/plain\' \'text\/javascript\'
        -- show all lines with requests for plain-text or javascript files
note: capitalization matters.
''' % (progname, progname, progname, progname, progname))
    sys.exit(1)


def watchlogfile(patterns):
    """Watch a log file for a pattern match."""

    pipe = Popen(['tail', '-0f', LOGFILE], stdout=PIPE).stdout
    while True:
        time.sleep(SLEEPFOR)
        line = pipe.readline().strip()
        if line != '':
            for pattern in patterns:
                if pattern.search(line):
                    print line
                    break


def main(args):
    """Main branching logic."""

    if len(args) == 0:
        usage()
    patterns = [ re.compile(arg) for arg in args ]
    try:
        watchlogfile(patterns)
    except KeyboardInterrupt:
        sys.exit(0)

    

if __name__ == '__main__':
    main(sys.argv[1:])

# eof