InstagramIdCodec

class InstagramIdCodec:
    ENCODING_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"

    @staticmethod
    def encode(num, alphabet=ENCODING_CHARS):
        """Covert a numeric value to a shortcode."""
        num = int(num)
        if num == 0:
            return alphabet[0]
        arr = []
        base = len(alphabet)
        while num:
            rem = num % base
            num //= base
            arr.append(alphabet[rem])
        arr.reverse()
        return "".join(arr)

    @staticmethod
    def decode(shortcode, alphabet=ENCODING_CHARS):
        """Covert a shortcode to a numeric value."""
        base = len(alphabet)
        strlen = len(shortcode)
        num = 0
        idx = 0
        for char in shortcode:
            power = strlen - (idx + 1)
            num += alphabet.index(char) * (base ** power)
            idx += 1
        return num