#!/usr/bin/env python
#
# mmgen = Multi-Mode GENerator, command-line Bitcoin cold storage solution
# Copyright (C) 2013 by philemon <mmgen-py@yandex.com>
#
# 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/>.
"""
mmgen-passchg: Change a mmgen deterministic wallet's passphrase, label or
               hash preset
"""

import sys
from mmgen.Opts import *
from mmgen.utils import *
import mmgen.config as g

help_data = {
	'desc':  """Change the passphrase, hash preset or label of a {}
                  deterministic wallet""".format(g.proj_name),
	'usage':   "[opts] [filename]",
	'options': """
-h, --help                  Print this help message
-d, --outdir             d  Specify an alternate directory 'd' for output
-H, --show-hash-presets     Show information on available hash presets
-k, --keep-old-passphrase   Keep old passphrase (use when changing hash
                            strength or label only)
-L, --label              l  Change the wallet's label to 'l'
-p, --hash-preset        p  Change scrypt.hash() parameters to preset 'p'
                            (default: '{}')
-P, --passwd-file        f  Get new passphrase from file 'f'
-v, --verbose               Produce more verbose output

NOTE: The key ID will change if either the passphrase or hash preset
      are changed
""".format(g.hash_preset)
}

short_opts = "hd:HkL:p:P:v"
long_opts  = "help","outdir=","show_hash_presets","keep_old_passphrase",\
			  "label=","hash_preset=","passwd_file=","verbose"

opts,cmd_args = process_opts(sys.argv,help_data,short_opts,long_opts)

if 'show_hash_presets' in opts: show_hash_presets()

check_opts(opts,long_opts)

if len(cmd_args) != 1:
	msg("One input file must be specified")
	sys.exit(2)
infile = cmd_args[0]

# Old key:
label,metadata,hash_preset,salt,enc_seed = get_data_from_wallet(infile,opts)
seed_id,key_id = metadata[:2]

# Repeat on incorrect pw entry
prompt = "Enter %spassphrase: " % (""
		if 'keep_old_passphrase' in opts else "old ")
while True:
	passwd = get_mmgen_passphrase(prompt,{})
	key = make_key(passwd, salt, hash_preset)
	seed = decrypt_seed(enc_seed, key, seed_id, key_id)
	if seed: break

changed = {}

if 'label' in opts:
	if opts['label'] != label:
		msg("Label changed: '%s' -> '%s'" % (label, opts['label']))
		changed['label'] = True
	else:
		msg("Label is unchanged: '%s'" % (label))
else: opts['label'] = label  # Copy the old label

if 'hash_preset' in opts:
	if hash_preset != opts['hash_preset']:
		msg("Hash preset has changed (%s -> %s)" %
			(hash_preset, opts['hash_preset']))
		changed['preset'] = True
	else:
		msg("Hash preset is unchanged")
else:
	opts['hash_preset'] = hash_preset

if 'keep_old_passphrase' in opts:
	msg("Keeping old passphrase by user request")
else:
	new_passwd = get_new_passphrase("new passphrase", opts)

	if new_passwd == passwd:
		msg("Passphrase is unchanged")
	else:
		msg("Passphrase has changed")
		passwd = new_passwd
		changed['passwd'] = True

if 'preset' in changed or 'passwd' in changed: # Update key ID, salt
	msg("Will update salt and key ID")

	from hashlib import sha256
	from Crypto import Random

	salt = sha256(salt + Random.new().read(128)).digest()[:g.salt_len]
	key = make_key(passwd, salt, opts['hash_preset'])
	new_key_id = make_chksum_8(key)
	msg("Key ID changed: %s -> %s" % (key_id,new_key_id))
	key_id = new_key_id
	enc_seed = encrypt_seed(seed, key, opts)
elif not 'label' in changed:
	msg("Data unchanged.  No file will be written")
	sys.exit(2)

write_wallet_to_file(seed, passwd, key_id, salt, enc_seed, opts)