#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Simple Bot to reply to Telegram messages
# This program is dedicated to the public domain under the CC0 license.

import logging
import telegram
from telegram.error import NetworkError, Unauthorized
from time import sleep


def main():
    # Telegram Bot Authorization Token
    bot = telegram.Bot('TOKEN')

    # get the first pending update_id, this is so we can skip over it in case
    # we get an "Unauthorized" exception.
    try:
        update_id = bot.getUpdates()[0].update_id
    except IndexError:
        update_id = None

    logging.basicConfig(
        format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')

    while True:
        try:
            update_id = echo(bot, update_id)
        except NetworkError:
            sleep(1)
        except Unauthorized:
            # The user has removed or blocked the bot.
            update_id += 1


def echo(bot, update_id):

    # Request updates after the last update_id
    for update in bot.getUpdates(offset=update_id, timeout=10):
        # chat_id is required to reply to any message
        chat_id = update.message.chat_id
        update_id = update.update_id + 1
        message = update.message.text

        if message:
            # Reply to the message
            bot.sendMessage(chat_id=chat_id,
                            text=message)

    return update_id


if __name__ == '__main__':
    main()