import struct, zlib, os, datetime

TYPE_NORMAL, TYPE_DEMV1, TYPE_TXT, TYPE_PAK, TYPE_DZ, TYPE_DEM, \
	TYPE_NEHAHRA, TYPE_DIR, TYPE_STORE, TYPE_LAST = range(10)

class DzipReadError(Exception):
    pass


class Binary(object):
    def __init__(self, f):
        names, codes = zip(*self.layout)
        code = '<' + ''.join(codes)
        s = struct.calcsize(code)
        data = struct.unpack(code, f.read(s))
        for n, d in zip(names, data):
            setattr(self, n, d)


class DzDirectory(Binary):
    layout = [('ptr',   'I'),
              ('size',  'I'),
              ('real',  'I'),
              ('len',   'H'),
              ('pak',   'H'),
              ('crc',   'i'),
              ('type',  'I'),
              ('date',  'I'),
              ('inter', 'I')]
    def __init__(self, f):
        super(DzDirectory, self).__init__(f)
        self.name = f.read(self.len)[:-1]


class PakEntry(Binary):
    layout = [('name', '56s'),
              ('ptr',  'I'),
              ('len',  'I')]
    def __init__(self, f):
        super(DzDirectory, self).__init__(f)
        self.name = self.name[:self.name.index('\0')]


class DzFile(object):
    def __init__(self, fname):
        if isinstance(fname, str):
            self.f = open(fname)
        else:
            self.f = fname
        d, z, self.major, self.minor, offset, numfiles = struct.unpack(
            '<ccBBII', self.f.read(12))
        if d != 'D' or z != 'Z':
            raise DzipReadError, "%s is not a valid dz file"%(fname,)
        if self.major != 2:
            raise DzipReadError("can only open files created by dzip 2, not "
                                " %d."%self.major)
        self.dirs = []
        self.f.seek(offset)
        for i in range(numfiles):
            self.dirs.append(DzDirectory(self.f))

    def extract(self, dir):
        if dir.type not in [TYPE_NORMAL, TYPE_STORE]:
            raise DzipReadError, "can't extract yet"
        else:
            self.f.seek(dir.ptr)
            data = self.f.read(dir.size)
            if dir.type == TYPE_STORE:
                undata = data
            else:
                undata = zlib.decompress(data)
            if ~zlib.crc32(undata) != dir.crc:
                raise DzipReadError, "crc failed!"
            return undata

def parseDate(date):
    day, month, year, hour, min, secs = \
         (date >> 16 & 0x1f,
          (date >> 21 & 0x0f) + 1,
          (date >> 25 & 0x7f) + 1980,
          date >> 11 & 0x1f,
          date >> 5 & 0x3f,
          (date & 0x1f) << 1)
    return year, month, day, hour, min, secs

def dzList(fname):
    dzf = DzFile(fname)
    print "contents of %s, created using version %u.%u:"%(
        fname, dzf.major, dzf.minor)
    for d in dzf.dirs:
        if d.type == TYPE_DIR:
            print " %s"%d.name
        elif d.pak and d.type != TYPE_PAK:
            print "  %-17s size: %-8u packed: %-8u"%(d.name, d.real, d.size)
        else:
            print " %-18s size: %-8u packed: %-8u"%(d.name, d.real, d.size),
            year, month, day, hour, min, secs = parseDate(d.date)
            print "%02u.%02u.%4u %02u:%02u:%02u"%(day, month, year, hour, min, secs)
    print


def dzUncompress(fname):
    dzf = DzFile(fname)
    print "%s created using v%u.%u"%(
        fname, dzf.major, dzf.minor)
    for d in dzf.dirs:
        if d.type not in [TYPE_NORMAL, TYPE_STORE]:
            print "can't decompress %s yet"%(d.name,)
        else:
            if os.path.exists(d.name):
                print "%s exists; will not overwrite"%(d.name,)
            else:
                print "extracting", d.name
                open(d.name, 'wb').write(dzf.extract(d))
    print


def dzExtract(fname, name):
    dzf = DzFile(fname)
    for d in dzf.dirs:
        if d.name != name:
            continue
        return dzf.extract(d)
    raise DzipReadError, "failed to find"


def gettxt(dzname):
    dzf = DzFile(dzname)
    for d in dzf.dirs:
        if d.name.endswith('.txt'):
            return d.name, dzf.extract(d)


def getdemdate(dzf):
    for d in dzf.dirs:
        if d.name.endswith('.dem') and '_' in d.name:
            return datetime.datetime(*parseDate(d.date))
    raise DzipReadError, "not found!"
def getdemdate(dzf):
    for d in dzf.dirs:
        if d.name.endswith('.dem') and '_' in d.name:
            return datetime.datetime(*parseDate(d.date))
    raise DzipReadError, "not found!"

if __name__ == '__main__':
    import sys
    try:
        print getdemdate(sys.argv[1])
    except DzipReadError, e:
        print e.args[0]