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from cachetools import TTLCache, cached
import requests
class Singleton(type):
_instances = {}
def __call__(cls, *args, **kwargs):
if cls not in cls._instances:
cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
return cls._instances[cls]
class CurrencyConverter(object, metaclass=Singleton):
# Get exchange rates
no_currency = "XXX"
api_url = "https://api.exchangeratesapi.io/latest?base=USD"
def __init__(self):
pass
@cached(cache=TTLCache(maxsize=1, ttl=86400))
def get_rates(self):
rates = requests.get(self.api_url).json()["rates"]
rates[self.no_currency] = 1.0
return rates
def get_currencies(self, with_no_currency=True):
rates = [
rate
for rate in self.get_rates()
if with_no_currency or rate != self.no_currency
]
rates.sort(key=lambda rate: "" if rate == self.no_currency else rate)
return rates
def exchange_currency(self, amount, source_currency, dest_currency):
if (
source_currency == dest_currency
or source_currency == self.no_currency
or dest_currency == self.no_currency
):
return amount
rates = self.get_rates()
source_rate = rates[source_currency]
dest_rate = rates[dest_currency]
new_amount = (float(amount) / source_rate) * dest_rate
# round to two digits because we are dealing with money
return round(new_amount, 2)
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