from hcsr04 import HCSR04
import time
from machine import Pin

import network, ubinascii
from umqtt.simple import MQTTClient
import ujson

print("Connecting to WiFi", end="")
sta_if = network.WLAN(network.STA_IF)
sta_if.active(True)
sta_if.connect('Wokwi-GUEST', '')
while not sta_if.isconnected():
  print(".", end="")
  time.sleep(0.1)
print(" Connected!")

MQTT_BROKER    = "f708b6b31c2b4a12bc09a1c954ab4b14.s1.eu.hivemq.cloud"
MQTT_USER      = "hivemq.webclient.1719895637306"
MQTT_PASSWORD  = ""
MQTT_TOPIC     = "wokwi-distance/data"
MQTT_CMD_TOPIC     = "wokwi-relay/command"

wlan_mac = sta_if.config('mac')
mac_id = ubinascii.hexlify(wlan_mac).decode().upper()

print("Mac Id", mac_id)

relay_pin = Pin(32, Pin.OUT)

def sub_cb(topic, msg):
    decoded = ujson.loads(msg.decode())
    print("received message ", decoded)

    relay = decoded.get('relay', -1)
    target_device_id = decoded.get('deviceMacId', "")

    if relay == -1 or target_device_id == "": return

    relay_pin(relay == 1)

MQTT_CLIENT_ID = "fullstack-iot-" + mac_id

ssl_params = {"server_hostname": MQTT_BROKER}

print("Connecting to MQTT server with id {}... ".format(MQTT_CLIENT_ID), end="")

client = MQTTClient(MQTT_CLIENT_ID, MQTT_BROKER, port=8883, ssl=True, ssl_params=ssl_params, user=MQTT_USER, password=MQTT_PASSWORD)

client.set_callback(sub_cb)
client.connect()
client.subscribe(MQTT_CMD_TOPIC)

print("Connected to HiveMQ")

sensor = HCSR04(trigger_pin=18, echo_pin=5)

prev_distance = -1
delta_threshold = 0.2
while True:
    client.check_msg()
    time.sleep(5)
    distance = sensor.distance_cm()
    delta = abs(distance - prev_distance)

    print('Distance:', distance, 'cm')
    
    if delta > delta_threshold:
        message = ujson.dumps({
        "deviceMacId": mac_id,
        "Distance": distance
        })

        print("Reporting to MQTT topic {}: {}".format(MQTT_TOPIC, message))
        client.publish(MQTT_TOPIC, message)

        prev_distance = distance