#!/usr/bin/env python

from telegram import Update
from telegram.ext import Application, MessageHandler, filters
import re
import logging
import json

def load_config(filename: str = "config.json"):
    retval = {}
    with open(filename) as config_file:
        config = json.load(config_file)
        retval["telegramApiKey"] = config["telegramApiKey"]
        retval["allowedChats"] = config["allowedChats"]
        retval["regexes"] = list(map(lambda r: re.compile(r, re.I), config["regexes"]))
        return retval

async def new_msg(update, context, regexes, allowed_chats):
    if update.message is None and update.edited_message is None:
        logging.info(f"Got following unknown update: {update}")
        return
    message = update.message
    if update.edited_message is not None:
        message = update.edited_message
    if message is None:
        return
    if message.chat.id not in allowed_chats:
        return
    for regex in regexes:
        if message.text is not None and  regex.search(message.text) is not None:
            logging.info(f"Banning {message.from_user.name} from {message.chat.effective_name} for posting a message matching {regex.pattern}")
            await message.chat.ban_member(message.from_user.id)
            await message.delete()
            return

async def handle_error(update, context):
    logging.error("Exception while handling an update:", exc_info=context.error)

if __name__ == '__main__':
    logging.basicConfig(format='%(asctime)s|%(levelname)s|%(message)s', level=logging.INFO)
    logging.getLogger("httpx").setLevel(logging.WARNING)
    logging.info("Starting")
    config = load_config()
    application = Application.builder().token(config["telegramApiKey"]).build()

    application.add_handler(MessageHandler(filters.ALL, (
        lambda update, context: new_msg(update, context, config['regexes'], config['allowedChats'])
    )))
    application.add_error_handler(handle_error, block=False)

    application.run_polling(allowed_updates=Update.ALL_TYPES)