#!/usr/bin/env python
# Run a program for a period of time, sending it SIGTERM once done.
# Usage: timer 08:00 10:00 arecord prog.wav

import sys, os, time, signal
import mx.DateTime as mxtime

def warn(*s):
	print >>sys.stderr, " ".join(map(str, s))

def die(*s):
	warn(*s)
	sys.exit(1)

def parse_date(s):
	if s is None or s == "unknown":
		return -1
	return int(mxtime.DateTimeFrom(s).ticks())

def make_date(t):
	if t == -1:
		return "unknown"
	return mxtime.ISO.str(mxtime.localtime(t))

def main(args):
	if len(args) < 3:
		die("Usage: timer START END COMMAND ...")
	start = parse_date(args[0])
	end = parse_date(args[1])
	cmd = args[2:]
	now = time.time()
	if end < start:
		die("End before start")
	if start < now or end < now:
		die("Times must be in the future")
	warn("Time now is", make_date(now), "- sleeping until", make_date(start))
	while time.time() < start:
		time.sleep(1)
	warn("Starting", *cmd)
	pid = os.fork()
	if pid == 0:
		os.execvp(cmd[0], cmd)
		os._exit(20)
	warn("Started as", pid, " - running until", make_date(end))
	while time.time() < end:
		time.sleep(1)
	warn("Stopping", pid)
	os.kill(pid, signal.SIGTERM)
	(dpid, dstat) = os.waitpid(pid, 0)
	if os.WIFSIGNALED(dstat):
		sig = os.WTERMSIG(dstat)
		if sig == signal.SIGTERM:
			warn("Process signalled as expected")
			return 0
		else:
			warn("Process killed with signal", sig)
			return 1
	elif os.WIFEXITED(dstat):
		status = os.WEXITSTATUS(dstat)
		warn("Process exited with status", status)
		return status
	else:
		warn("Process died mysteriously with dstat", dstat)
		return 1

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