Script for calculating rollover fees (Kraken)

rollover_fees.py

#!/usr/bin/env python3.6
"""Script for calculating rollover fees"""

import argparse
import requests

# One rollover for every 4 hours
ROLLOVER_RATE = 4

# 0.02% for most currency pairs
KRAKEN_ROLLOVER_FEE = 0.00002

def calc_fee(amount, step, fee):
    """Returns the fee for a given step"""
    return round(amount-round(amount*step*fee, 5), 5)

def calc_sum(amount, rollover_count, fee):
    """Returns the sum of the fees"""
    rollovers = range(rollover_count)

    sum_fees = 0
    remaining_amount = amount

    for step in rollovers:
        fee_diff = remaining_amount-calc_fee(remaining_amount, step, fee)
        sum_fees += fee_diff
        remaining_amount -= fee_diff

    return remaining_amount, sum_fees

def print_btc_rate(btc):
    """Prints the current exchange rate of BTC for multiple currencies"""
    url = 'https://blockchain.info/ticker'
    res = requests.get(url)

    if not 200 <= res.status_code <= 299:
        raise Exception(f"GET request for {url} failed with status code {res.status_code}")

    json = res.json()

    def print_for_currency(last, symbol):
        value = last * btc
        print(f"{value:.2f}{symbol}")

    print_for_currency(json['USD']['last'], json['USD']['symbol'])
    print_for_currency(json['EUR']['last'], json['EUR']['symbol'])


def main():
    """Entry point"""
    parser = argparse.ArgumentParser(description="Calculate sum of rollover fees")
    parser.add_argument('-a', '--amount', type=float, help="The base amount from which the "
                                               "rollover fees will be derived.",
                                               required=True)
    parser.add_argument('-d', '--days', type=int, help="Number of days", required=True)
    parser.add_argument('-f', '--fee', type=float, default=KRAKEN_ROLLOVER_FEE,
            help="Define fee (as decimal value)", required=False)

    args = parser.parse_args()
    rollover_count = int((args.days * 24) / ROLLOVER_RATE)
    remaining_amount, sum_fees = calc_sum(args.amount, rollover_count, args.fee)

    print("Total fees")
    print(f"{sum_fees:.5f}฿")
    print_btc_rate(sum_fees)

    print()

    print("Remaining amount")
    print(f"{remaining_amount:.5f}฿")
    print_btc_rate(remaining_amount)


if __name__ == '__main__':
    main()