#!/bin/env python

##   Copyright 2023 Aleteoryx
##
##   Licensed under the Apache License, Version 2.0 (the "License");
##   you may not use this file except in compliance with the License.
##   You may obtain a copy of the License at
##
##       http://www.apache.org/licenses/LICENSE-2.0
##
##   Unless required by applicable law or agreed to in writing, software
##   distributed under the License is distributed on an "AS IS" BASIS,
##   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
##   See the License for the specific language governing permissions and
##   limitations under the License.

from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler
from os import scandir
from datetime import datetime

HOSTS = '/etc/hosts'
HOSTS_D = '/etc/hosts.d/'

def regen():
  try:
   now = datetime.now().strftime('%a %d %b %Y, %H:%M:%S.%f')
   print(f'[{now}] -- Regenerating hosts...')
   acc = [f"### Generated @ {now}.\n"]
   for file in scandir(HOSTS_D):
    if file.is_file():
     acc = [*acc, f"## BEGIN `{file.path}`\n", *open(file.path, encoding='L1').readlines(), f"## END   `{file.path}`\n"]
   open(HOSTS, 'wt').writelines(acc)
   now = datetime.now().strftime('%a %d %b %Y, %H:%M:%S.%f')
   print(f'[{now}] -- Done.')
  except Exception as e:
   print(f'caught {e} while regenerating')

class FSWatcher(FileSystemEventHandler):
  def on_modified(self, ev):
    if ev.is_directory: return
    regen()
  def on_deleted(self, ev):
    if ev.is_directory: return
    regen()
  def on_created(self, ev):
    if ev.is_directory: return
    regen()

regen()

observer = Observer()
observer.schedule(FSWatcher(), HOSTS_D, recursive=True)
observer.start()
observer.join()