#/usr/bin/env python3
# Embed parameters to Flash Lite 1.1/2.0
# It works with Python 3.x.
# Author - Hajime Nakagami<nakagami@da2.so-net.ne.jp>
# License - BSD licence (http://www.opensource.org/licenses/bsd-license.php)
# Version 0.1 (2010/02/02) Initial release
# Version 0.2 (2010/02/26) For Flash Lite 2.0
import zlib

def _ib(v, n):
    "Convert from little endian int v to n bytes bytes"
    return bytes([(v >> (8*i)) & 0xff for i in range(n)])

def _calctaglen(d, encoding):
    n = 0
    for k in d:
        n += len(k.encode(encoding)) + len(str(d[k]).encode(encoding)) + 11
    return n + 1

def _maketag(d, encoding):
    tag = b'\x3f\x03'
    tag += _ib(_calctaglen(d, encoding), 4)
    for k in d:
        kv = k.encode(encoding)
        v = str(d[k]).encode(encoding)
        tag += b'\x96'+_ib(len(kv)+2, 2)+b'\x00'+kv+b'\x00'
        tag += b'\x96'+_ib(len(v)+2, 2)+b'\x00'+v+b'\x00'
        tag += b'\x1d'
    return tag + b'\x00'

def create_swf(src_swf, params):
    "Create Flash Lite 1.1/2.0 swf file with embeded params."
    base_swf = src_swf[:]
    if base_swf[0] == 0x43:  #CWS
        base_swf = base_swf[:8] + zlib.decompress(base_swf[8:])
    if base_swf[3] > 6:
        encoding = 'utf8'
    else:
        encoding = 'cp932'
    tag = _maketag(params, encoding)
        
    rectbit = base_swf[8] >> 3
    head_len = int(((( 8 - ((rectbit*4+5)&7) )&7)+ rectbit*4 + 5 )/8) + 12 + 5;
    head = base_swf[:head_len]
    tail = base_swf[head_len:]
    newhead = head[:4] + _ib(len(base_swf) + len(tag), 4) + head[8:]
    new_swf = newhead + tag + tail
    if new_swf[0] == 0x43:  #CWS
        new_swf = new_swf[:8] + zlib.compress(new_swf[8:])
    return new_swf

if __name__ == '__main__':
    import urllib.request
    # See http://libpanda.s18.xrea.com/test_insert/sample.html
    src_swf = urllib.request.urlopen(
        'http://libpanda.s18.xrea.com/test_insert/x/base.swf').read()
    params = {
        'serif': 'Jump',
        'jumpsound': 'Doom!',
    }
    out_file = open('output.swf', 'wb')
    out_file.write(create_swf(src_swf, params))