base58 encoder and decoder with Python.

base58.py

"""
Foked from ( * Javascript ) :
    inflammable/base58.js : ( https://gist.github.com/inflammable/2929362 )

Description:
    - Base58 encoder and decoder, but re-written with Python. This is very covenient to generating 'shorting URL' from integer value ( like, article or post ID based database).
    - you can encode to base58 string from Integer value.
    - you can decode to Integer from base 58 String value.

Usage:
    encode(integer) :
        ```
        shortURL = ShortURL()

        num = 335555555

        # vDNYB
        shortURL.encode(num)
        ```
    decode(string) :
        ```
        shortURL = ShortURL()

        # 335555555
        shortURL.encode('vDNYB')
        ```

Tested:
    - python 3.6.3
"""

import math


class ShortURL(object):

    def __init__(self):
        self.baseString = "123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPRSTUVWXYZ"
        self.baseLength = len(self.baseString)

    def encode(self, num):
        if not int(num):
            raise ValueError('must be integer')
            pass

        encode = ''

        while num:
            remainder = (num % self.baseLength)
            num = math.floor(num / self.baseLength)
            encode += self.baseString[remainder]
            pass

        return encode[::-1]
        pass

    def decode(self, key):

        if not str(key):
            raise ValueError('must be String')
            pass

        decode = 0

        while key:
            position = self.baseString.index(key[0])

            if position < 0:
                raise ValueError("'decode' can not find in the baseString")
                pass

            powerOf = len(key) - 1
            decode += position * math.pow(self.baseLength, powerOf)
            key = key[1::1]

            pass

        return int(decode)

        pass

exampleBase58.py

# call ShortURL class
shortURL = ShortURL()

num = 335555555
# vDNYB
print(shortURL.encode(num))
# 335555555
print(num)

# 335555555
print(shortURL.decode("vDNYB"))