"""ATA over Ethernet Protocol."""

import struct


import dpkt


class AOE(dpkt.Packet):
    __hdr__ = (
        ('ver_fl', 'B', 0x10),
        ('err', 'B', 0),
        ('maj', 'H', 0),
        ('min', 'B', 0),
        ('cmd', 'B', 0),
        ('tag', 'I', 0),
        )
    _cmdsw = {}
    
    def _get_ver(self): return self.ver_fl >> 4
    def _set_ver(self, ver): self.ver_fl = (ver << 4) | (self.ver_fl & 0xf)
    ver = property(_get_ver, _set_ver)

    def _get_fl(self): return self.ver_fl & 0xf
    def _set_fl(self, fl): self.ver_fl = (self.ver_fl & 0xf0) | fl
    fl = property(_get_fl, _set_fl)

    def set_cmd(cls, cmd, pktclass):
        cls._cmdsw[cmd] = pktclass
    set_cmd = classmethod(set_cmd)

    def get_cmd(cls, cmd):
        return cls._cmdsw[cmd]
    get_cmd = classmethod(get_cmd)

    def unpack(self, buf):
        dpkt.Packet.unpack(self, buf)
        try:
            self.data = self._cmdsw[self.cmd](self.data)
            setattr(self, self.data.__class__.__name__.lower(), self.data)
        except (KeyError, struct.error, dpkt.UnpackError):
            pass

    def pack_hdr(self):
        try:
            return dpkt.Packet.pack_hdr(self)
        except struct.error, e:
            raise dpkt.PackError(str(e))


AOE_CMD_ATA = 0
AOE_CMD_CFG = 1
AOE_FLAG_RSP = 1 << 3


def __load_cmds():
    prefix = 'AOE_CMD_'
    g = globals()
    for k, v in g.iteritems():
        if k.startswith(prefix):
            name = 'aoe' + k[len(prefix):].lower()
            try:
                mod = __import__(name, g)
            except ImportError:
                continue
            AOE.set_cmd(v, getattr(mod, name.upper()))


if not AOE._cmdsw:
    __load_cmds()