# Copyright 2016  Lars Wirzenius
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# =*= License: GPL-3+ =*=


import pgpwordlist

_words = pgpwordlist.pgp_word_list


def _make_reverse_lookup(words):
    rev = {}
    for hexstr, t in words.items():
        rev[t[0]] = hexstr
        rev[t[1]] = hexstr
    return rev


_w2hex = _make_reverse_lookup(_words)


def get_word(hexstr, offset):
    t = _words[hexstr.lower()]
    return t[offset % 2]


def get_hex(word):
    return _w2hex[word.lower()]


def hex_to_words(hexstr):
    words = [get_word(h, i) for i, h in enumerate(_hex_bytes(hexstr))]
    return ' '.join(words)


def _hex_bytes(hexstr):
    for i in range(0, len(hexstr), 2):
        yield hexstr[i:i+2]


def words_to_hex(wordstr):
    return ''.join(get_hex(w) for w in wordstr.split())