import sys
import telegram
import time
import strings
import worker
import configloader

def main():
    """The core code of the program. Should be run only in the main process!"""

    # Create a bot instance
    bot = telegram.Bot(configloader.config["Telegram"]["token"])

    # Test the specified token
    try:
        bot.get_me()
    except telegram.error.Unauthorized:
        print("The token you have entered in the config file is invalid.\n"
              "Fix it, then restart this script.")
        sys.exit(1)

    # Create a dictionary linking the chat ids to the ChatWorker objects
    # {"1234": <ChatWorker>}
    chat_workers = {}

    # Current update offset; if None it will get the last 100 unparsed messages
    next_update = None

    # TimedOut / NetworkError counter, increases by 1 every time get_updates fails and resets to 0 when it succedes
    timed_out_counter = 0

    # Main loop of the program
    while True:
        # Get a new batch of 100 updates and mark the last 100 parsed as read
        try:
            updates = bot.get_updates(offset=next_update, timeout=int(configloader.config["Telegram"]["long_polling_timeout"]))
        # If the method times out...
        except telegram.error.TimedOut:
            # Increase the TimedOut counter
            timed_out_counter += 1
            # Notify on stdout
            print(f"WARNING: get_updates timed out ({timed_out_counter} time{'s' if timed_out_counter != 1 else ''})")
            # Try again
            continue
        # If the method raises a NetworkError (connection problems)...
        except telegram.error.NetworkError:
            # Increase the TimedOut counter
            timed_out_counter += 1
            # Notify on stdout
            print(f"ERROR: get_updates raised a NetworkError ({timed_out_counter} time{'s' if timed_out_counter != 1 else ''})")
            # Wait some time before retrying
            time.sleep(3)
            continue
        # If Telegram returns an error...
        except telegram.error.TelegramError as e:
            # Increase the TimedOut counter
            timed_out_counter += 1
            # Notify on stdout
            print(f"ERROR: telegram returned an error while trying to get_updates ({e.message}) ({timed_out_counter} time{'s' if timed_out_counter != 1 else ''})")
            # Wait some time before retrying
            time.sleep(3)
            continue
        # If all goes well...
        else:
            # Reset the TimedOut counter
            timed_out_counter = 0
        # Parse all the updates
        for update in updates:
            # If the update is a message...
            if update.message is not None:
                # Ensure the message has been sent in a private chat
                if update.message.chat.type != "private":
                    # Notify the chat
                    bot.send_message(update.message.chat.id, strings.error_nonprivate_chat)
                    # Skip the update
                    continue
                # If the message is a start command...
                if update.message.text is not None and update.message.text == "/start":
                    # Check if a worker already exists for that chat
                    old_worker = chat_workers.get(update.message.chat.id)
                    # If it exists, gracefully stop the worker
                    if old_worker:
                        old_worker.stop()
                    # Initialize a new worker for the chat
                    new_worker = worker.ChatWorker(bot, update.message.chat)
                    # Start the worker
                    new_worker.start()
                    # Store the worker in the dictionary
                    chat_workers[update.message.chat.id] = new_worker
                    # Skip the update
                    continue
                # Otherwise, forward the update to the corresponding worker
                receiving_worker = chat_workers.get(update.message.chat.id)
                # Ensure a worker exists for the chat and is alive
                if receiving_worker is None or not receiving_worker.is_alive():
                    # Suggest that the user restarts the chat with /start
                    bot.send_message(update.message.chat.id, strings.error_no_worker_for_chat, reply_markup=telegram.ReplyKeyboardRemove())
                    # Skip the update
                    continue
                # Forward the update to the worker
                receiving_worker.queue.put(update)
            # If the update is a inline keyboard press...
            if update.callback_query is not None:
                # Forward the update to the corresponding worker
                receiving_worker = chat_workers.get(update.callback_query.chat.id)
                # Ensure a worker exists for the chat
                if receiving_worker is None:
                    # Suggest that the user restarts the chat with /start
                    bot.send_message(update.callback_query.chat.id, strings.error_no_worker_for_chat)
                    # Skip the update
                    continue
                # Forward the update to the worker
                receiving_worker.queue.put(update)
        # If there were any updates...
        if len(updates):
            # Mark them as read by increasing the update_offset
            next_update = updates[-1].update_id + 1


# Run the main function only in the main process
if __name__ == "__main__":
    main()