#!/usr/bin/env python3
#
#  Copyright (c) 2019, The OpenThread Authors.
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#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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import logging
import sys
from typing import Iterable, List, Union, Callable

from pyshark.packet.layer import Layer as RawLayer
from pyshark.packet.packet import Packet as RawPacket

from pktverify import errors
from pktverify.addrs import EthAddr
from pktverify.coap import CoapLayer
from pktverify.consts import VALID_LAYER_NAMES
from pktverify.decorators import cached_property
from pktverify.layers import Layer, ThreadMeshcopLayer, Icmpv6Layer, WpanLayer, ThreadNetworkDataLayer
from pktverify.utils import make_filter_func


class Packet(object):

    def __init__(self, packet: RawPacket):
        self._packet = packet
        self._strip_wpan_eth_wrapper(packet)

    def __str__(self) -> str:
        return str(self._packet)

    def __repr__(self) -> str:
        return repr(self._packet)

    def __dir__(self) -> Iterable[str]:
        return dir(self._packet)

    def _strip_wpan_eth_wrapper(self, packet: RawPacket):
        if not hasattr(packet, 'wpan'):
            return

        for layer in packet.layers:
            if layer.layer_name == 'eth':
                packet.layers.remove(layer)
                eth_src = EthAddr(layer.get_field('eth.src'))
                eth_dst = EthAddr(layer.get_field('eth.dst'))
                logging.debug("stripping eth: src=%s, dst=%s", eth_src, eth_dst)
                channel = eth_src[5]
                self.wpan._add_field('wpan.channel', hex(channel))

        return

    @property
    def layers(self) -> Iterable[RawLayer]:
        for l in self._packet.layers:
            if l.layer_name != 'data':
                yield getattr(self, l.layer_name)

    @property
    def layer_names(self) -> List[str]:
        return [l.layer_name for l in self._packet.layers if l.layer_name != 'data']

    @cached_property
    def wpan(self) -> WpanLayer:
        return WpanLayer(self._packet, 'wpan')

    @cached_property
    def coap(self) -> CoapLayer:
        return CoapLayer(self._packet, 'coap')

    @cached_property
    def icmpv6(self) -> Icmpv6Layer:
        return Icmpv6Layer(self._packet, 'icmpv6')

    @cached_property
    def thread_meshcop(self) -> ThreadMeshcopLayer:
        return ThreadMeshcopLayer(self._packet, 'thread_meshcop')

    @cached_property
    def thread_nwd(self) -> ThreadNetworkDataLayer:
        return ThreadNetworkDataLayer(self._packet, 'thread_nwd')

    def __getattr__(self, layer_name: str) -> Layer:

        real_layer_name = layer_name
        if layer_name == 'lowpan':
            real_layer_name = '6lowpan'

        assert real_layer_name in VALID_LAYER_NAMES, '%s is not a valid layer name' % real_layer_name
        _layer = getattr(self._packet, real_layer_name, None)
        assert _layer is None or isinstance(_layer, RawLayer)

        layer = Layer(self._packet, real_layer_name)
        setattr(self, layer_name, layer)
        if real_layer_name != layer_name:
            setattr(self, real_layer_name, layer)

        return layer

    def verify(self, func: Union[str, Callable], **vars) -> bool:
        print("\n>>> verifying packet:", file=sys.stderr, flush=False)
        func = make_filter_func(func, **vars)
        ok = func(self)
        print("\t=> %s" % ok, file=sys.stderr)
        return ok

    def must_verify(self, func: Union[str, Callable], **vars):
        if not self.verify(func, **vars):
            self.debug_fields()
            raise errors.VerifyFailed(self)

        return self

    def must_not_verify(self, func: Union[str, Callable], **vars):
        if self.verify(func, **vars):
            raise errors.VerifyFailed(self)

        return self

    @property
    def sniff_timestamp(self) -> float:
        return float(self._packet.sniff_timestamp)

    def show(self):
        self._packet.show()

    def debug_fields(self):
        for layer in self._packet.layers:
            print("### Layer %s ###" % layer.layer_name)
            for k, v in layer._all_fields.items():
                print("\t\t%r = %r" % (k, v))