#!/usr/bin/env python3

import sys
import argparse
import os
import json
import re

parser = argparse.ArgumentParser()
parser.add_argument("words_file", help="File that contains the words to (de)anonymize")
parser.add_argument("--ignore-missing", "-i", action="store_true", help="treat missing file as empty list")
parser.add_argument("--deanonymize", "-d", action="store_true", help="deanonymize")
config = parser.parse_args()

alphabet="abcdefghijklmnopqrstuvwxyz"

try:
    key = os.environ["ANONYMIZE_KEY"].lower()
    assert all([k in alphabet for k in key])
except KeyError:
    print("Please set ANONYMIZE_KEY as environment variable with only letters", file=sys.stderr)
    sys.exit(1)

if not os.path.isfile(config.words_file):
    if config.ignore_missing:
        print(sys.stdin.read(), end="")
        sys.exit(0)
    else:
        print("Could not find words file", file=sys.stderr)
        sys.exit(1)

words = json.load(open(config.words_file))

if any([len(word) > len(key) for word in words]):
    print("The key needs to be at least as long as the longest word in the list (append to existing one to keep already mangled words)", file=sys.stderr)
    sys.exit(1)

order = -1 if config.deanonymize else 1

def replace(match):
    name = match.group()
    result = []
    for k in range(len(name)):
        if name[k].lower() not in alphabet:
            result.append(name[k])
        else:
            key_index = alphabet.index(key[k])
            letter_index = alphabet.index(name[k].lower())
            new_letter = alphabet[(letter_index + order * key_index) % len(alphabet)]
            if name[k].lower() != name[k]:
                new_letter = new_letter.upper()
            result.append(new_letter)
    return ''.join(result)

regexp = re.compile("(" + '|'.join([r'(\b' + w + r'\b)' for w in words]) + ")")
print(regexp.sub(replace, sys.stdin.read()), end="")