from cachetools import TTLCache
import json

from session import session


__CBR_DAYLY_URL = "https://www.cbr-xml-daily.ru/daily_json.js"
__cache: TTLCache = TTLCache(maxsize=10000, ttl=60 * 10)


def __fetch_currency() -> dict:
    if __CBR_DAYLY_URL in __cache:
        return __cache[__CBR_DAYLY_URL]
    
    resp = session.get(__CBR_DAYLY_URL)
    data = resp.json()
    
    __cache[__CBR_DAYLY_URL] = data["Valute"]
    return data["Valute"]


def get_currency(currency_charcode: str) -> dict:
    if not currency_charcode in __cache:
        currencies = __fetch_currency()
        if currency_charcode in currencies:
            currency = currencies[currency_charcode]
            nominal = int(currency["Nominal"])
            value = float(currency["Value"])
            
            return {f"1_{currency_charcode}": value / nominal, "CharCode": currency_charcode, "Name": currency["Name"]}
        else:
            return {"error": f'Unknow currency charcode {currency_charcode}'}