# standard imports
import os
import time
import logging
from datetime import datetime

# third-party imports
import pytz
import requests
import telegram

IST = pytz.timezone('Asia/Kolkata')

logging.basicConfig(format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
                    level=logging.INFO)
logger = logging.getLogger(__name__)


# customizable vars
AGE = os.environ.get('AGE', 18)
DIST_CODE = int(os.environ.get('DIST_CODE'))
TELEGRAM_BOT_TOKEN = os.environ.get('TELEGRAM_BOT_TOKEN')
TELEGRAM_CHAT_ID = int(os.environ.get('TELEGRAM_CHAT_ID'))
SLEEP_TIME_SEC = int(os.environ.get('SLEEP_TIME_SEC', 60))


def main():
    message_header = "Atleast 1 new slot seems to have just opened up for vaccination.\n\n"
    message_footer = "Visit [this link](https://selfregistration.cowin.gov.in/appointment) to book a slot for yourself."

    logger.info('Initiating loop')
    while True:
        logger.info('Hitting CoWIN API')
        date_str = datetime.now(IST).strftime("%d-%m-%Y")

        url = "https://cdn-api.co-vin.in/api/v2/appointment/sessions/calendarByDistrict?district_id={}&date={}".format(DIST_CODE, date_str)
        response = requests.get(url)

        available_center_list = []
        if response.ok:
            resp_json = response.json()
            for center in resp_json.get('centers'):
                for session in center.get('sessions'):
                    if session.get('available_capacity') > 0:
                        curr = {
                            'location': center.get('name'),
                            'available_capacity': session.get('available_capacity'),
                            'available_slots': ', '.join(session.get('slots')),
                            'vaccine': session.get('vaccine'),
                            'min_age_limit': session.get('min_age_limit'),
                            'fee_type': center.get('fee_type'),
                        }
                        available_center_list.append(curr)

        bot = telegram.Bot(token=TELEGRAM_BOT_TOKEN)
        message_body = ''
        if available_center_list:
            for center in available_center_list:
                if center.get('min_age_limit') < AGE:
                    msg = f"""Location: {center.get('location')}
Available Capacity: {center.get('available_capacity')}
Available Slots: {center.get('available_slots')}
Vaccine: {center.get('vaccine')}
Age Limit: {center.get('min_age_limit')}
Fee: {center.get('fee_type')}\n\n"""
                    message_body += msg
                    break  # to prevent too long messages
            msg = message_header + message_body + message_footer
            bot.sendMessage(chat_id=TELEGRAM_CHAT_ID, text=msg, parse_mode='markdown')
        time.sleep(SLEEP_TIME_SEC)

if __name__ == '__main__':
    main()