#!/usr/local/bin/python
"""Watch an Aspen website to make sure it stays up.

Only works on *NIX.

"""
import commands
import os
import sys
import syslog
import time
import traceback
from os.path import isdir, isfile, join

from aspen.daemon import Daemon


# Configure logging
# =================

syslog.openlog('aspen.monitord')


# Get the root of the website we are tracking.
# ============================================

try:
    root = sys.argv[1]
except IndexError:
    print >> sys.stderr, "please tell us the website root"
    raise SystemExit(1)
root = os.path.realpath(root)
if not isdir(root):
    print >> sys.stderr, "couldn't find %s" % root
    raise SystemExit(1)


# Daemonize
# =========
# We keep our own pidfile around, but just use kill if you want to stop us.

_pidfile = join(root, '__', 'var', 'aspen.monitord.pid')
daemon = Daemon(stdout='/dev/null', stderr='/dev/null', pidfile=_pidfile)
daemon.start()
syslog.syslog(syslog.LOG_NOTICE, "daemon now tracking %s" % root)


# Keep it up.
# ===========

pidfile = join(root, '__', 'var', 'aspen.pid')

class Restart(SystemExit):
    """Propagate a termination of the monitored process.
    """

while 1:
    try:
        if not isfile(pidfile):
            syslog.syslog(syslog.LOG_NOTICE, "missing pidfile %s" % pidfile)
            raise Restart
        else:
            pid = open(pidfile).read()
            raw = commands.getoutput('ps -p%s' % pid)
            if raw.count('\n') == 0: # 2 lines == process is running
                syslog.syslog(syslog.LOG_NOTICE, "dead pid %s" % pid)
                raise Restart        #  running
    except Restart: # syslog the error and then restart the sucker
        syslog.syslog(syslog.LOG_EMERG, "restarting %s" % root)
        if isfile(pidfile):
            os.remove(pidfile)
        os.system("aspen start --root=%s" % root)
        time.sleep(20) # give it time to restart
    except: # syslog traceback
        syslog.syslog(syslog.LOG_EMERG, traceback.format_exc())
        time.sleep(5)
    else:
        time.sleep(1)