#!/usr/bin/env python3
# Мини raw-MQTT subscriber: коннект к брокеру, SUBSCRIBE guard/#, ждём 1 PUBLISH.
import socket, struct, sys, time

HOST, PORT = "10.50.0.48", 1883
TOPIC = "guard/#"

def rl(n):
    o=bytearray()
    while True:
        b=n%128; n//=128
        if n>0: b|=0x80
        o.append(b)
        if n==0: break
    return bytes(o)
def s(x):
    b=x.encode(); return struct.pack("!H",len(b))+b

sock=socket.create_connection((HOST,PORT),timeout=8)
# CONNECT
body=s("MQTT")+bytes([0x04,0x02])+struct.pack("!H",60)+s("pcn-subtest")
sock.sendall(bytes([0x10])+rl(len(body))+body)
ca=sock.recv(4)
assert ca[0]==0x20 and ca[3]==0x00, ("CONNACK",ca)
# SUBSCRIBE (packet id 1, qos0)
sb=struct.pack("!H",1)+s(TOPIC)+bytes([0x00])
sock.sendall(bytes([0x82])+rl(len(sb))+sb)
# SUBACK
sock.recv(5)
print("SUBSCRIBED", flush=True)
# ждём PUBLISH до 12с
sock.settimeout(12)
buf=b""
try:
    data=sock.recv(4096)
    print("GOT_FROM_BROKER:", repr(data[:300]))
except socket.timeout:
    print("TIMEOUT_NO_MESSAGE")
sock.close()