#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""Check if all processes matching a name were started after a config
file's mtime.

--snip--

Tested under Python 2.7 and 3.4
"""

from __future__ import (absolute_import, division, print_function,
                        with_statement, unicode_literals)

__author__ = "Stephan Sokolow (deitarion/SSokolow)"
__appname__ = "restarted_since.py"
__version__ = "0.1"
__license__ = "MIT"

import logging, os, subprocess, sys
log = logging.getLogger(__name__)

# Ticks per second
tick_rate = os.sysconf(os.sysconf_names['SC_CLK_TCK'])

def getpids(procname):
    """Simple abstraction for a couple of ways to get PIDs from names"""
    try:
        pidstr = subprocess.check_output(['pidof', procname])
    except subprocess.CalledProcessError:
        pidstr = subprocess.check_output(['pgrep', procname])
    return [int(x.strip()) for x in pidstr.strip().split()]

def get_start_time(pid):
    """Given a PID, look up the start time in seconds since the epoch

    See `man 5 proc` for references used to implement.

    Passes through IOError with errno=ENOENT if the process went away.
    """
    # Read process start time as clock ticks since system boot
    with open("/proc/{}/stat".format(pid), 'rb') as fobj:
        proc_start_ticks_since_boot = int(fobj.read().strip().split()[21])

    # Read system boot time as seconds since the epoch
    sys_boot_time = None
    with open("/proc/stat", 'rb') as fobj:
        for line in fobj:
            key, val = line.split(None, 1)
            if key == b'btime':
                sys_boot_time = int(val)
    assert sys_boot_time

    # Translate process start time from ticks to seconds
    proc_start_secs_since_boot = proc_start_ticks_since_boot / tick_rate
    # Translate process start time from since-boot to since-epoch
    proc_start_secs_since_epoch = proc_start_secs_since_boot + sys_boot_time

    return proc_start_secs_since_epoch

def get_mtime(path):
    """Thin wrapper for grabbing a file's mtime"""
    assert os.path.exists(path), "Path does not exist: {}".format(path)
    return os.stat(path).st_mtime

def main():
    """The main entry point, compatible with setuptools entry points."""
    # If we're running on Python 2, take responsibility for preventing
    # output from causing UnicodeEncodeErrors. (Done here so it should only
    # happen when not being imported by some other program.)
    if sys.version_info.major < 3:
        reload(sys)
        sys.setdefaultencoding('utf-8')  # pylint: disable=no-member

    from argparse import ArgumentParser
    parser = ArgumentParser(
            description=__doc__.replace('\r\n', '\n').split('\n--snip--\n')[0])
    parser.add_argument('--version', action='version',
            version="%%(prog)s v%s" % __version__)
    parser.add_argument('-v', '--verbose', action="count",
        default=2, help="Increase the verbosity. Use twice for extra effect")
    parser.add_argument('-q', '--quiet', action="count",
        default=0, help="Decrease the verbosity. Use twice for extra effect")
    parser.add_argument('process_name', help="Process name to be checked")
    parser.add_argument('config_file', help="UNIX timestamp to compare")

    args = parser.parse_args()

    # Set up clean logging to stderr
    log_levels = [logging.CRITICAL, logging.ERROR, logging.WARNING,
                  logging.INFO, logging.DEBUG]
    args.verbose = min(args.verbose - args.quiet, len(log_levels) - 1)
    args.verbose = max(args.verbose, 0)
    logging.basicConfig(level=log_levels[args.verbose],
                        format='%(levelname)s: %(message)s')

    earliest_started = min(get_start_time(i)
                           for i in getpids(args.process_name))
    if earliest_started > get_mtime(args.config_file):
        sys.exit(0)
    else:
        sys.exit(1)

if __name__ == '__main__':
    main()

# vim: set sw=4 sts=4 expandtab :