# BSD-3 Clause:
# Copyright 2020 Erwin Kooi
# Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
# 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
# 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
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# This program generates codebooks for the Enigma-E emulator in *M4* mode
# https://www.cryptomuseum.com/kits/enigma/

import calendar
import random
import sys, getopt

def main(argv):
    argv = sys.argv[1:]
    year = 1970
    yearPresent = 0

    try:
        opts, args = getopt.getopt(argv, "hy:")
    except:
        fnUsage()
        sys.exit(2)

    for opt, arg in opts:
        if opt == "-h":
            fnUsage()
            sys.exit()
        elif opt == "-y":
            yearPresent = 1
            year = int(arg)
    if yearPresent == 0:
        fnUsage()
        sys.exit(2)

    # Generate key sheet per monthrandom
    for month in range(1, 13):
        print("+-----------------------------------------------------------------------------------------+")
        print("| Enigma-E Key sheet for *M3* emulation                                                   |")
        print("+----------+-------------+--------------+-------------------------------+-----------------+")
        print("| Date     | Wheel order | Ring setting | Plugboard setting             | Indicator group |")
        print("+----------+-------------+--------------+-------------------------------+-----------------+")
        for day in range(1, (calendar.monthrange(year, month)[1] + 1)):
            print("| %04d%02d%02d | %s    %s|        %s| %s| %s|" %(year, month, day, fnReflectorSetting(), fnRotorSetting(), fnRingSetting(), fnPlugboardSetting(), fnIndicatorGroup()))
        print("+----------+-------------+--------------+-------------------------------+-----------------+")
        print("")

def fnUsage():
    print('enigma-e_m3.py -y <year>')

# Generate random reflector settings (Umkehrwalze)
# There are two reflectors, B and C
def fnReflectorSetting():
    returnstring = ""
    reflectorList = random.sample('BC', 1)
    returnstring += "{} ".format(reflectorList[0])
    return returnstring

# Generate random rotor settings (Walzenlage)
# There are four rotors, one a/b and three 1 - 8
def fnRotorSetting():
    returnstring = ""
    rotorList = random.sample(range(1,6), 3)
    for i in range (len(rotorList)):
        returnstring += "{} ".format(rotorList[i])
    return returnstring

# Generate random internal ring settings (Ringstellung)
# Each ring can be shifted internally by a - z amount.
def fnRingSetting():
    returnstring = ""
    ringList = random.sample(range(ord('A'), ord('Z')), 3)
    for i in range (len(ringList)):
        returnstring += "{} ".format(chr(ringList[i]))
    return returnstring

# Generate random plugboard settings (Steckerverbindungen)
# Each letter maps to another letter. Letters can occur only once.
def fnPlugboardSetting():
    success = 0
    while success == 0:
        plugboardListCharL = random.sample(range(ord('A'), ord('Z')), 10)
        plugboardListCharR = random.sample(range(ord('A'), ord('Z')), 10)
        success = 1
        for i in range (len(plugboardListCharL)):
            for j in range (len(plugboardListCharR)):
                if plugboardListCharL[i] == plugboardListCharR[j]:
                    success = 0
    returnstring = ""
    for i in range (len(plugboardListCharL)):
        returnstring += "{}{} ".format(chr(plugboardListCharL[i]), chr(plugboardListCharR[i]))
    return returnstring

# Generate random indicator groups (Kenngruppen)
# Four three-letter groups indicating the used key.
def fnIndicatorGroup():
    returnstring = ""
    indicatorGroup = ["","","",""]
    for i in range(0, 4):
        indicatorGroup = random.sample(range(ord('A'), ord('Z')), 4)
        for j in range(0, 4):
            returnstring += "{}".format(chr(indicatorGroup[j]))
        returnstring += " "
    return returnstring

if __name__ == "__main__":
   main(sys.argv[1:])