#!/usr/bin/env python
# Extract the ".srf" archives used by "You Don't Know Jack".
# Based on the format spec here:
#   http://wiki.xentax.com/index.php/You_Dont_Know_Jack
# Adam Sampson <ats@offog.org>

import sys, re, os

def die(*s):
	print >>sys.stderr, "srfextract: " + "".join(map(str, s))
	sys.exit(1)

def uint32(s):
	return ord(s[0]) << 24 | ord(s[1]) << 16 | ord(s[2]) << 8 | ord(s[3])

def clean_name(s):
	def encode(m):
		return "_%02x" % ord(m.group(0))
	return re.sub(r'[^A-Za-z0-9_-]', encode, s)

def extract(fn):
	f = open(fn)

	s = f.read(12)
	if s[0:4] != "srf1" or len(s) != 12:
		die(fn, ": bad header")
	file_length = uint32(s[4:8])
	header_length = uint32(s[8:12])
	print >>sys.stderr, "header %d %d" % (file_length, header_length)

	files = []

	while f.tell() < header_length:
		s = f.read(8)
		if s == "":
			break
		elif len(s) != 8:
			die(fn, ": unexpected EOF in file header")

		file_name = clean_name(s[0:4])
		sub_count = uint32(s[4:8])
		print >>sys.stderr, "file %s %d" % (file_name, sub_count)

		for i in range(sub_count):
			s = f.read(12)
			if len(s) != 12:
				die(fn, ": unexpected EOF in sub header")

			sub_id = uint32(s[0:4])
			file_offset = uint32(s[4:8])
			file_size = uint32(s[8:12])

			out_fn = "%s.%s.%04d" % (fn[:-4], file_name, sub_id)
			print >>sys.stderr, "sub %d %d %d -> %s" % (sub_id, file_offset, file_size, out_fn)
			files.append((file_offset, file_size, out_fn))

	for (offset, size, out_fn) in files:
		print >>sys.stderr, "x %s %d" % (out_fn, size)

		f.seek(offset)
		data = f.read(size)
		if len(data) != size:
			die(fn, ": unexpected EOF in file data")

		of = open(out_fn, "w")
		of.write(data)
		of.close()

	f.close()

if __name__ == "__main__":
	for fn in sys.argv[1:]:
		extract(fn)