import hashlib

MAGIC = '$1$'
ITOA64 = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"

def to64(v, n):
    ret = ''
    while n > 0:
        ret += ITOA64[v & 0x3f]
        v >>= 6
        n -= 1
    return ret

def apache_md5_crypt(pw, salt):
    return unix_md5_crypt(pw, salt, '$apr1$')

def unix_md5_crypt(pw, salt, magic=None):
    if magic is None:
        magic = MAGIC

    if salt.startswith(magic):
        salt = salt[len(magic):]

    salt = salt.split('$', 1)[0][:8]

    pw_bytes = pw.encode('utf-8')
    salt_bytes = salt.encode('utf-8')
    magic_bytes = magic.encode('utf-8')

    ctx = pw_bytes + magic_bytes + salt_bytes
    final = hashlib.md5(pw_bytes + salt_bytes + pw_bytes).digest()

    for pl in range(len(pw_bytes), 0, -16):
        ctx += final[:min(16, pl)]

    i = len(pw_bytes)
    while i:
        if i & 1:
            ctx += b'\x00'
        else:
            ctx += pw_bytes[:1]
        i >>= 1

    final = hashlib.md5(ctx).digest()

    for i in range(1000):
        ctx1 = b''
        if i & 1:
            ctx1 += pw_bytes
        else:
            ctx1 += final
        if i % 3:
            ctx1 += salt_bytes
        if i % 7:
            ctx1 += pw_bytes
        if i & 1:
            ctx1 += final
        else:
            ctx1 += pw_bytes
        final = hashlib.md5(ctx1).digest()

    passwd = ''
    passwd += to64((final[0] << 16) | (final[6] << 8) | final[12], 4)
    passwd += to64((final[1] << 16) | (final[7] << 8) | final[13], 4)
    passwd += to64((final[2] << 16) | (final[8] << 8) | final[14], 4)
    passwd += to64((final[3] << 16) | (final[9] << 8) | final[15], 4)
    passwd += to64((final[4] << 16) | (final[10] << 8) | final[5], 4)
    passwd += to64(final[11], 2)

    return magic + salt + '$' + passwd

md5crypt = unix_md5_crypt

if __name__ == "__main__":
    print(unix_md5_crypt("cat", "hat"))