"""
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ An example code to interact with a temperature sensor    ┃
┃ Raspberry Pi Pico.                                       ┃
┃                                                          ┃
┃ Copyright (c) 2023 Vinh Bui                              ┃
┃ License: MIT                                             ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
"""
#import libraries
from machine import Pin, ADC
import utime
import math
import network
import time
from machine import Pin
import dht
import ujson
from umqttsimple import MQTTClient

# WiFi Network Parameters
# SSID: Wokwi-GUEST
# Security: Open
print("Connecting to WiFi", end="")
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect("Wokwi-GUEST", "")
while not wlan.isconnected():
  print(".", end="")
  time.sleep(0.1)
print(wlan.ifconfig())
print("WiFi Connected!")

# MQTT Server Parameters
MQTT_CLIENT_ID = "picow-01"
MQTT_BROKER    = "80230f1c0f6147308f8792b5ec91e45b.s1.eu.hivemq.cloud"
MQTT_USER      = "client-1"
MQTT_PASSWORD  = "CEghmV31K4HC678HH5Pd81Tp"
MQTT_TOPIC     = "prog6002/test"
print("Connecting to MQTT server... ", end="")
client = MQTTClient(client_id=MQTT_CLIENT_ID, 
server=MQTT_BROKER, user=MQTT_USER, 
password=MQTT_PASSWORD, 
keepalive=7200,
ssl=True,
ssl_params={'server_hostname':'80230f1c0f6147308f8792b5ec91e45b.s1.eu.hivemq.cloud'})

# The callback function
def sub_callback(topic, msg):
  print("Received: {}:{}".format(topic.decode(), msg.decode()))
  led.high() #turn the led ON

client.set_callback(sub_callback)
client.connect()
client.subscribe(topic = MQTT_TOPIC)
print("MQTT Connected!")

#define the temperature sensor input pin
TSENSOR_INPUT_PIN =  28
LED_OUTPUT_PIN = 27

#convert the sensor reading to temperature in celsius
def adc2celsius(x):
    BETA = 3950
    KELVIN = 273.15
    return (1 / (math.log(1 / (65535/x-1)) / BETA + 1/298.15) - KELVIN)

def main():
    prev = ""
    tempsensor = machine.ADC(TSENSOR_INPUT_PIN)
    warning_led = Pin(27, Pin.OUT)
    while True:
        reading = tempsensor.read_u16()
        celsius = adc2celsius(reading)
        print("Temp: {:.2f} c".format(celsius))

        # new: send to cloud using MQTT
        message = ujson.dumps({
            "temp": celsius,
        })
        if message != prev:
            print("Reporting to MQTT topic {}: {}".format(MQTT_TOPIC, message))
            client.publish(MQTT_TOPIC, message)
            prev = message
        else:
            print(".")

        if celsius < 24:
            warning_led.high()
        else:
            warning_led.low()

        utime.sleep(1.0)

if __name__ == "__main__":
    main()