#!/usr/bin/env python3

####################
# Inspiration / Further Reading
####################
# https://github.com/chrisjbillington/inotify_simple
# https://stackoverflow.com/questions/16148735/how-to-implement-a-watchdog-timer-in-python

####################
# Dependencies
####################
# apt install python3 python3-pip python3-dbus
# pip3 install inotify_simple

from inotify_simple import INotify, flags
import os
from threading import Timer

####################
# Simple watchdog timer class
####################
class Watchdog:
    def __init__(self, timeout, userHandler=None):  # timeout in seconds
        self.timeout = timeout
        self.handler = userHandler if userHandler is not None else self.defaultHandler
        self.timer = Timer(self.timeout, self.handler)
        # Do NOT start timer by default ; we want this triggered by reset events that come through
        #     via the inotify filesystem watcher
        #self.timer.start()

    def reset(self):
        self.timer.cancel()
        self.timer = Timer(self.timeout, self.handler)
        self.timer.start()

    def stop(self):
        self.timer.cancel()

    def defaultHandler(self):
        raise self

####################
# Setup inotify on folder(s)
####################
inotify = INotify()
watch_flags = flags.CREATE | flags.DELETE
wd = inotify.add_watch('/tank/pictures', watch_flags)

####################
# Restart fim slideshow once inotify storm is over (3s timeout)
####################
def inotify_handler():
    print('restarting fim slideshow')
    import dbus
    sysbus = dbus.SystemBus()
    systemd1 = sysbus.get_object('org.freedesktop.systemd1', '/org/freedesktop/systemd1')
    manager = dbus.Interface(systemd1, 'org.freedesktop.systemd1.Manager')
    job = manager.RestartUnit('fim.service', 'fail')

####################
# Watch for inotify events in an infinate loop
# This will BLOCK waiting for events within inotify.read(None)
#     This makes it pretty safe for an infinate loop scenario
####################
watchdog = Watchdog(3.0, inotify_handler)
while True:
    for event in inotify.read(None):
        print(event)
        watchdog.reset()
        for flag in flags.from_mask(event.mask):
            print('    ' + str(flag))