#!/usr/bin/python -tt

# pgp -> numbers station generator
# Copyright (c) 2009, John Morrissey <jwm@horde.net>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
#   * Redistributions of source code must retain the above copyright notice,
#     this list of conditions and the following disclaimer.
#   * 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.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# Accepts a PGP-encrypted message on stdin and emits a numbers station-like
# .wav on stdout.

LOCKFILE = 'numbers-lock'
WAVS = './numbers'

from base64 import b64decode
from email import message_from_string
import fcntl
import os
import re
import struct
import sys
from tempfile import mkstemp
import wave

def b26encode(msg):
	str = []
	for byte in msg:
		byte = ord(byte)
		for i in range(0, 2):
			str.append("abcdefghijklmnopqrstuvwxyz"[byte % 26])
			byte /= 26
	return ''.join(str)

msg = message_from_string(''.join(sys.stdin.readlines()))
if msg.is_multipart():
	part = msg.get_payload()[0]
else:
	part = msg.get_payload()

swav = wave.open('%s/silence.wav' % WAVS, 'r')
silence = swav.readframes(swav.getnframes())
swav.close()

part = part.strip()
if not part.startswith('-----BEGIN PGP MESSAGE-----'):
	sys.exit(0)

begin = re.compile(r'^-----BEGIN PGP MESSAGE-----$\s*', re.MULTILINE)
end = re.compile(r'\s*^-----END PGP MESSAGE-----$\s*', re.MULTILINE)
part = message_from_string(end.sub('', begin.sub('', part))).get_payload()

fd, outfile = mkstemp(prefix=os.path.basename(sys.argv[0]), suffix='.wav')
os.close(fd)

out = wave.open(outfile, 'w')
out.setnchannels(1)
out.setsampwidth(2)
out.setframerate(11025)

begin = wave.open('%s/begin.wav' % WAVS, 'r')
out.writeframes(silence)
out.writeframes(silence)
out.writeframes(silence)
out.writeframes(silence)
out.writeframes(silence)
out.writeframes(begin.readframes(begin.getnframes()))
begin.rewind()
out.writeframes(silence)
out.writeframes(begin.readframes(begin.getnframes()))
out.writeframes(silence)
out.writeframes(silence)
out.writeframes(silence)

for char in b26encode(b64decode(part)):
	char = wave.open('%s/%s.wav' % (WAVS, char), 'r')
	out.writeframes(char.readframes(char.getnframes()))
	char.close()
	out.writeframes(silence)

end = wave.open('%s/end.wav' % WAVS, 'r')
out.writeframes(end.readframes(end.getnframes()))

out.close()

lockfd = os.open(LOCKFILE, os.O_RDWR + os.O_CREAT, 0600)
lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 0, 0, 0)
rv = fcntl.fcntl(lockfd, fcntl.F_SETLKW, lockdata)

fp = open(outfile, 'r')
sys.stdout.write(''.join(fp.readlines()))
fp.close()