hosts_time.py

#!/usr/bin/env python3

# Script for planing /etc/hosts to disable time wasting sites (like lichess.org or youtube for me) during some time period in day

# Created: 2018 September 26
# Author: Aleksandar Josifoski https://about.me/josifsk

# how to start python script with sudo without asking password for specific script
# https://askubuntu.com/questions/155791/how-do-i-sudo-a-command-in-a-script-without-being-asked-for-a-password

# my crontab settings (set to check script on every 30min)
# 0,30 * * * * sudo /data/bash_scripts/hosts_time.py

# program assumes that 
#0.0.0.1    lichess.org
#0.0.0.1    www.lichess.org
#0.0.0.1    youtube.com
#0.0.0.1    www.youtube.com
# are in 4.th - 7.th line in /etc/hosts file where first line count is 1

import datetime
import sys
import fileinput
import codecs

# following dictionary will enable lichess.org in time intervals 5:30-59, 14:00-29, 20:00-29
dlichess_time_enabled = {5: range(30, 60), 14: range(30), 20: range(30)}
dyoutube_time_enabled = {20: range(60)}
ldicts = [dlichess_time_enabled, dyoutube_time_enabled]
observed_lines = [4, 5, 6, 7]

def get_state(linenums):
    lret = []
    with codecs.open('/etc/hosts', 'r', 'utf8') as fs:
        lhostslines = fs.readlines()
        for linenum in linenums:
            if lhostslines[linenum - 1].strip()[0] == '#':
                lret.append(True)
            else:
                lret.append(False)
    return lret

def disable_site(linenum):
    for i, line in enumerate(fileinput.input('/etc/hosts', inplace=1), start = 0):
        if i == linenum - 1:
            sys.stdout.write(line.lstrip('#'))
        else:
            sys.stdout.write(line)

def enable_site(linenum):
    for i, line in enumerate(fileinput.input('/etc/hosts', inplace=1), start = 0):
        if i == linenum - 1:
            towrite = '#' + line.lstrip('#')
            sys.stdout.write(towrite)
        else:
            sys.stdout.write(line)

prevstates = get_state(observed_lines)
#print(prevstates)
now = str(datetime.datetime.now())
#print(now)
h = now.split()[1].split(':')[0]
m = now.split()[1].split(':')[1]
if h == '00': # this is for using bellow lstrip('0'). Hmm, that should be time for sleeping. 
    h = '1'
if m == '00':
    m = '1'
#print(h, m)
linesstate = [False] * len(observed_lines)
j = -2
for d in ldicts:
    j += 2
    for key in d.keys():
        if int(h.lstrip('0')) == key:
            if int(m.lstrip('0')) in d[key]:
                linesstate[j] = True
                linesstate[j+1] = True
                break
    
for j in range(len(observed_lines)):
    if prevstates[j] != linesstate[j]:
        if linesstate[j]:
            enable_site(observed_lines[j])
        else:
            disable_site(observed_lines[j])

It seems that for youtube is bit more complex
https://gist.github.com/marshymarsh/5c34b5a6530d46fa0f3076bed52d293a