#
# This file is part of LiteEth.
#
# Copyright (c) 2015-2019 Florent Kermarrec <florent@enjoy-digital.fr>
# SPDX-License-Identifier: BSD-2-Clause

import math

from litex.soc.interconnect.stream_sim import *

from liteeth.common import *

from test.model import mac

# Helpers ------------------------------------------------------------------------------------------

def print_arp(s):
    print_with_prefix(s, "[ARP]")

preamble = split_bytes(eth_preamble, 8)


# ARP Packet ---------------------------------------------------------------------------------------

class ARPPacket(Packet):
    def __init__(self, init=[]):
        Packet.__init__(self, init)

    def decode(self):
        header = []
        for byte in self[:arp_header.length]:
            header.append(self.pop(0))
        for k, v in sorted(arp_header.fields.items()):
            setattr(self, k, get_field_data(v, header))

    def encode(self):
        header = 0
        for k, v in sorted(arp_header.fields.items()):
            value = merge_bytes(split_bytes(getattr(self, k),
                                            math.ceil(v.width/8)),
                                            "little")
            header += (value << v.offset+(v.byte*8))
        for d in split_bytes(header, arp_header.length):
            self.insert(0, d)

    def __repr__(self):
        r = "--------\n"
        for k in sorted(arp_header.fields.keys()):
            r += k + " : 0x{:0x}\n".format(getattr(self, k))
        r += "payload: "
        for d in self:
            r += "{:02x}".format(d)
        return r

# ARP ----------------------------------------------------------------------------------------------

class ARP(Module):
    def __init__(self, mac, mac_address, ip_address, debug=False):
        self.mac             = mac
        self.mac_address     = mac_address
        self.ip_address      = ip_address
        self.debug           = debug
        self.tx_packets      = []
        self.tx_packet       = ARPPacket()
        self.rx_packet       = ARPPacket()
        self.table           = {}
        self.request_pending = False

        self.mac.set_arp_callback(self.callback)

    def send(self, packet):
        packet.encode()
        if self.debug:
            print_arp(">>>>>>>>")
            print_arp(packet)
        mac_packet = mac.MACPacket(packet)
        mac_packet.target_mac    = packet.target_mac
        mac_packet.sender_mac    = packet.sender_mac
        mac_packet.ethernet_type = ethernet_type_arp
        self.mac.send(mac_packet)

    def callback(self, packet):
        packet = ARPPacket(packet)
        packet.decode()
        if self.debug:
            print_arp("<<<<<<<<")
            print_arp(packet)
        self.process(packet)

    def process(self, packet):
        if len(packet) != arp_min_length-arp_header.length:
            raise ValueError
        if packet.hwtype != arp_hwtype_ethernet:
            raise ValueError
        if packet.proto != arp_proto_ip:
            raise ValueError
        if packet.hwsize != 6:
            raise ValueError
        if packet.protosize != 4:
            raise ValueError
        if packet.opcode == arp_opcode_request:
            self.process_request(packet)
        elif packet.opcode == arp_opcode_reply:
            self.process_reply(packet)

    def process_request(self, request):
        if request.target_ip == self.ip_address:
            reply = ARPPacket([0]*(arp_min_length-arp_header.length))
            reply.hwtype     = arp_hwtype_ethernet
            reply.proto      = arp_proto_ip
            reply.opcode     = arp_opcode_reply
            reply.hwsize     = 6
            reply.protosize  = 4
            reply.sender_mac = self.mac_address
            reply.sender_ip  = self.ip_address
            reply.target_mac = request.sender_mac
            reply.target_ip  = request.sender_ip
            self.send(reply)

    def process_reply(self, reply):
        self.table[reply.sender_ip] = reply.sender_mac

    def request(self, ip_address):
        request = ARPPacket([0]*(arp_min_length-arp_header.length))
        request.hwtype     = arp_hwtype_ethernet
        request.proto      = arp_proto_ip
        request.opcode     = arp_opcode_request
        request.hwsize     = 6
        request.protosize  = 4
        request.sender_mac = self.mac_address
        request.sender_ip  = self.ip_address
        request.target_mac = 0xffffffffffff
        request.target_ip  = ip_address