gistfile1.txt

import click
import requests


def parse_rates(data):
    header, names, *lines = data.splitlines()
    rates = {}
    for line in lines:
        _, _, amount, currency, value = line.replace(",", ".").split("|")
        rates[currency] = float(value) / float(amount)
    return rates


def get_exchange_rates(date=None):
    query = {}
    if date:
        query["date"] = date
    response = requests.get("http://www.cnb.cz/cs/financni_trhy/devizovy_trh/kurzy_devizoveho_trhu/denni_kurz.txt", params=query)
    return parse_rates(response.text)


@click.command()
@click.option("--date")
@click.option("--to", multiple=True)
@click.argument("amount", type=click.FLOAT)
def cnb(amount, date=None, to=None):
    rates = get_exchange_rates(date)
    for currency in sorted(rates):
        if not to or currency in to:
            converted = amount / rates[currency]
            click.echo(f"{amount} CZK = {converted} {currency}")


if __name__ == "__main__":
    cnb()