#!/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-walletgen: Generate a mmgen deterministic wallet
"""

import sys, os
from hashlib import sha256

from mmgen.Opts import *
from mmgen.license import *
from mmgen.config import *
from mmgen.walletgen import *
from mmgen.utils import *
prog_name = sys.argv[0].split("/")[-1]

help_data = {
	'prog_name': prog_name,
	'desc':    "Generate a {} deterministic wallet".format(proj_name),
	'usage':   "[opts] [infile]",
	'options': """
-h, --help                 Print this help message
-d, --outdir            d  Specify an alternate directory 'd' for output
-e, --echo-passphrase      Print passphrase to screen when typing it
-l, --seed-len          n  Create seed of length 'n'. Options: {}
                           (default: {})
-L, --label             l  Label to identify this wallet (32 chars max.
                           Allowed symbols: A-Z, a-z, 0-9, " ", "_", ".")
-p, --hash-preset       p  Use scrypt.hash() parameters from preset 'p'
                           (default: '{}')
-P, --show-hash-presets    Show information on available hash presets
-q, --quiet                Suppress warnings; overwrite files without asking
-u, --usr-randlen       n  Get 'n' characters of randomness from the user
                           (default: {})

-b, --from-brain       l,p Generate wallet from a user-created passphrase,
                           i.e. a "brainwallet", using seed length 'l' and
                           hash preset 'p' (comma-separated)
-m, --from-mnemonic        Generate wallet from an Electrum-like mnemonic
-s, --from-seed            Generate wallet from a seed in .{S} format

By default (i.e. when invoked without any of the '--from-<what>' options),
{} generates a wallet based on a random seed.

Data for the --from-<what> options will be taken from <infile> if <infile>
is specified.  Otherwise, the user will be prompted to enter the data.

For passphrases all combinations of whitespace are equal, and leading and
trailing space are ignored.  This permits reading passphrase data from a
multi-line file with free spacing and indentation.  This is particularly
convenient for long brainwallet passphrases, for example.

BRAINWALLET NOTE:

As brainwallets require especially strong hashing to thwart dictionary
attacks, the brainwallet hash preset must be specified by the user, using
the 'p' parameter of the '--from-brain' option.  This preset should be
stronger than the one used for hashing the seed (i.e. the default value or
the one specified in the '--hash-preset' option).

The '--from-brain' option also requires the user to specify a seed length
(the 'l' parameter), which overrides both the default and any one given in
the '--seed-len' option.

For a brainwallet passphrase to always generate the same keys and addresses,
the same 'l' and 'p' parameters to '--from-brain' must be used in all future
invocations with that passphrase.
""".format(
		", ".join([str(i) for i in seed_lens]),
		seed_len,
		hash_preset,
		usr_randlen,
		prog_name,
		S=seed_ext,
	)
}

short_opts = "hd:el:L:p:Pqu:b:ms"
long_opts  = "help","outdir=","echo_passphrase","seed_len=","label=",\
		"hash_preset=","show_hash_presets","quiet","usr_randlen=",\
		"from_brain=","from_mnemonic","from_seed"

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

if 'show_hash_presets' in opts: show_hash_presets()

# Argument sanity checks and processing:

set_if_unset_and_typeconvert(opts,(
	('usr_randlen',usr_randlen,'int'),
	('hash_preset',hash_preset,'str'),
	('seed_len',seed_len,'int')
))

# Exits on invalid input
check_opts(opts,
	('usr_randlen','hash_preset','seed_len','outdir','label','from_brain')
)

if debug:
	print "Processed options:     %s" % repr(opts)
	print "Cmd args:              %s" % repr(cmd_args)

if len(cmd_args) == 1 and (
		'from_brain' in opts or
		'from_mnemonic' in opts or
		'from_seed' in opts):
	infile = cmd_args[0]
	check_infile(infile)
elif len(cmd_args) == 0: infile = ""
else: usage(help_data)

# Begin execution

if not 'quiet' in opts: do_license_msg()

msg_r("Acquiring random data from your computer...")

try:
	from Crypto import Random
	r = Random.new()
	os_rand_data = (r.read(256),r.read(128))
except:
	msg("FAILED\nUnable to generate random numbers. Exiting")
	sys.exit(2)

msg("OK")

if debug: display_os_random_data(os_rand_data)

usr_keys,key_timings = get_random_data_from_user(opts)
msg("")

if debug: display_user_random_data(usr_keys,key_timings)

usr_rand_data = sha256(usr_keys).digest() + \
				sha256("".join(key_timings)).digest()

s = get_seed(infile,opts,no_wallet=True)
if s: seed = s
else:
	# Truncate random data for smaller seed lengths
	seed = os_rand_data[0] + usr_rand_data
	seed = sha256(seed).digest()[:opts['seed_len']/8]

salt = os_rand_data[1] + usr_rand_data
salt = sha256(salt).digest()[:salt_len]

passwd = get_first_passphrase_from_user(
		"{} wallet passphrase".format(proj_name), opts)

key = make_key(passwd, salt, opts['hash_preset'])

enc_seed = encrypt_seed(seed, key, opts)

write_wallet_to_file(seed,passwd,make_chksum_8(key),salt,enc_seed,opts)