3dsmstr.py

#!/usr/bin/python3
#Decode Nintendo 3DS Game Card mastering codes
#To use interactive mode, pass '-i' as the argument instead of a mastering code.
from sys import argv
import string
from datetime import datetime

def print_decoded_mstr(input_var):
    input_striped = input_var.strip()

    if len(input_striped) != 10:
        raise ValueError('Mastering code is the wrong length.')

    factory = input_striped[0]

    year = int('20' + input_striped[1:3])

    if not input_striped[3].isupper():
        raise ValueError('Month code is not uppercase.')

    month = int(string.ascii_uppercase.index(input_striped[3]) + 1)

    day = int(input_striped[4:6])

    date = datetime(year, month, day)
    
    prodrun = input_striped[6:8].lstrip('0')
    
    print('Factory: {}\nProduction Date: {}\nProduction Run: {}\n'\
    .format(factory,date.strftime('%d %B, %Y').lstrip('0'),prodrun))

def interactive_mode():
    while True:
        print_decoded_mstr(raw_input('Input: '))
        
arg = argv[1]

try:
    if arg == '-i':
        interactive_mode()
    else:
        print_decoded_mstr(arg)
except IndexError:
    print('No valid argument entered.')