#!/usr/bin/env python3
"""Minimal BEP-15 UDP tracker for the Phase 4 integration test."""
import socket
import struct
import sys

peer_port = int(sys.argv[1])
connection_id = 0x0102030405060708
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(("127.0.0.1", 0))
print("PORT %d" % sock.getsockname()[1], flush=True)

while True:
    packet, addr = sock.recvfrom(2048)
    if len(packet) >= 16 and packet[8:12] == b"\x00\x00\x00\x00":
        sock.sendto(struct.pack("!IIQ", 0, struct.unpack("!I", packet[12:16])[0],
                                connection_id), addr)
        continue
    if len(packet) >= 98 and packet[8:12] == b"\x00\x00\x00\x01":
        txid = struct.unpack("!I", packet[12:16])[0]
        response = (
            struct.pack("!IIIII", 1, txid, 1800, 0, 1)
            + socket.inet_aton("127.0.0.1")
            + struct.pack("!H", peer_port)
        )
        sock.sendto(response, addr)
        print("REQUEST announce", flush=True)