#!/usr/bin/python
# -*- coding: iso-8859-1 -*-
#
# stakeout - run a command when a file in a given set changes
# Copyright (C) 2004 Sami Kyöstilä <http://kempele.fi/~skyostil>
# idea pillaged from: Michael McCracken <http://michael-mccracken.net/blog/>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

import sys
import os
from signal import signal, pause, SIGUSR1
from fcntl import fcntl, DN_MODIFY, DN_MULTISHOT, F_SETSIG, F_NOTIFY

def trigger(callback, fileMap):
  for f, mt in fileMap.items():
    if os.stat(f).st_mtime > mt:
      callback(f)
      fileMap[f] = os.stat(f).st_mtime
      
def stakeout(callback, files):
  fileMap = {}
  signal(SIGUSR1, lambda sig, frame: trigger(callback, fileMap))
  dirs = []
  for f in files:
    fileMap[f] = os.stat(f).st_mtime
    d = os.path.dirname(f)
    if not len(d):
      d = "."
    if not d in dirs:
      dirs.append(d)
      fd = os.open(d, os.O_RDONLY)
      fcntl(fd, F_SETSIG, SIGUSR1)
      fcntl(fd, F_NOTIFY, DN_MODIFY | DN_MULTISHOT)
  while 1:
    try:
      pause()
    except KeyboardInterrupt:
      sys.exit(0)

if __name__ == "__main__":
  if len(sys.argv) > 2:
    if "-a" in sys.argv:
      sys.argv = filter(lambda a: a != "-a", sys.argv)
      callback = lambda f: os.system("%s '%s'" % (sys.argv[1], f))
    else:
      callback = lambda f: os.system(sys.argv[1])
    stakeout(callback, sys.argv[2:])
  else:
    print """Runs the given command when any of the files change.
Usage:   stakeout.py [-a] [command] [files]..."
Options:
     -a  Pass the changed file as an argument for the command."""
    sys.exit(1)