import struct
import sys
import os

HEADER_SIZE = 16

fin = open(sys.argv[1], 'rb')

fin.seek(0)
header_data = fin.read(HEADER_SIZE)
magic, _, header_start, _ = struct.unpack('<IIII', header_data)

fin.seek(header_start)

class HeaderParser(object):
  def __init__(self):
    self.state = 'name'
    self.filename = []
    self.offset = None
    self.entry_length = None
    self.entries = []

  def feed(self, data):
    for x in data:
      if self.state == 'name':
        if x == 0x0a:
          self.state = 'offset'
          self.offset = []
          self.filename = str(bytes(self.filename), 'ascii')
        else:
          self.filename.append(x)

      elif self.state == 'offset':
        self.offset.append(x)
        if len(self.offset) == 4:
          self.offset, = struct.unpack('<I', bytes(self.offset))
          self.entry_length = []
          self.state = 'entry_length'

      elif self.state == 'entry_length':
        self.entry_length.append(x)
        if len(self.entry_length) == 4:
          self.entry_length, = struct.unpack('<I', bytes(self.entry_length))
          self.emit()

  def emit(self):
    entry = (self.filename, self.offset, self.entry_length)
    sys.stdout.write("File: %r\tOffset: %x\tLength: %x\n" % entry)
    self.entries.append(entry)
    self.state = 'name'
    self.filename = []

parser = HeaderParser()
while True:
  data = fin.read(32)
  if len(data) == 0:
    break
  parser.feed(data)

def expand_path(p):
  parts = p.split('\\')
  # Check for drive letter
  if p[1] == ':':
    parts[0] = 'drive_%s' % (parts[0][0].lower(),)
  elif parts[0] == '.' or parts[0] == '..':
    parts = parts[1:]

  return os.path.join(*parts)

for filename, offset, entry_length in parser.entries:
  converted_filename = expand_path(filename)
  dst = os.path.join(os.environ['HOME'], 'tmp', 'dune2001_assets', converted_filename)
  contained_in, _ = os.path.split(dst)
  os.makedirs(contained_in, exist_ok = True)
  with open(dst, 'wb') as fout:
    fin.seek(offset)
    fout.write(fin.read(entry_length))