import network
import time
from machine import Pin, ADC
import urequests # Requires 'urequests' library installed on Pico W

# --- ThingSpeak and WiFi Configuration ---
WIFI_SSID = "pi6b"          # 1. CHANGE THIS to your WiFi network name
WIFI_PASSWORD = "1234567890"  # 2. CHANGE THIS to your WiFi password
THINGSPEAK_API_KEY = "WP1WTNVOAC9LLFUZ" # 3. CHANGE THIS to your ThingSpeak Write API Key
THINGSPEAK_FIELD = 1                    # 4. CHANGE THIS if you use a different field (e.g., field2)
UPDATE_INTERVAL_SECONDS = 15            # ThingSpeak free tier has a 15-second minimum update interval

# --- Sensor Configuration ---
# Define the ADC pin connected to the MQ-2 sensor's analog output (A0)
MQ2_PIN = 26 
adc = ADC(Pin(MQ2_PIN))
# Set ADC attenuation (optional, usually 0-65535 by default)
# The Pico ADC is 12-bit internally but returns a 16-bit value (0-65535)

# --- Wi-Fi Connection Function ---
def connect_to_wifi():
    """Connects the Pico W to the specified WiFi network."""
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    wlan.connect(WIFI_SSID, WIFI_PASSWORD)
    
    max_wait = 20
    while max_wait > 0:
        if wlan.isconnected():
            print("WiFi Connected!")
            print('IP address:', wlan.ifconfig()[0])
            return wlan
        
        print("Waiting for WiFi connection...")
        time.sleep(1)
        max_wait -= 1

    print("Error: Could not connect to WiFi.")
    return None

# --- Sensor Reading Function ---
def read_mq2_sensor():
    """Reads the raw analog value from the MQ-2 sensor."""
    # Read the raw 16-bit value (0-65535)
    raw_value = adc.read_u16()
    return raw_value

# --- ThingSpeak Update Function ---
def send_to_thingspeak(sensor_value):
    """Sends the sensor value to ThingSpeak via HTTP GET request."""
    # Construct the ThingSpeak URL for updating a channel field
    url = (
        f"https://api.thingspeak.com/update?api_key=WP1WTNVOAC9LLFUZ&field1={raw_value}"
    )
    
    print(f"Sending value: {sensor_value} to ThingSpeak...")
    
    try:
        response = urequests.get(url)
        # ThingSpeak returns the entry ID on success (e.g., '12345') or '0' on failure
        if response.status_code == 200 and response.text != '0':
            print(f"Update successful. Entry ID: {response.text}")
        else:
            print(f"ThingSpeak update failed. Status code: {response.status_code}, Response: {response.text}")
            
        response.close() # Always close the response object
        return True
        
    except Exception as e:
        print(f"HTTP request error: {e}")
        return False

# --- Main Application Loop ---
def main():
    wlan = connect_to_wifi()
    if not wlan:
        return

    print("Starting data logging to ThingSpeak...")
    
    try:
        while True:
            if not wlan.isconnected():
                print("WiFi lost, attempting to reconnect...")
                wlan = connect_to_wifi()
                if not wlan:
                    # If reconnect fails, wait and try again next loop
                    time.sleep(UPDATE_INTERVAL_SECONDS)
                    continue

            # 1. Read the Sensor
            mq2_value = read_mq2_sensor()
            print(f"MQ-2 Raw ADC Value: {mq2_value}")
            
            # 2. Send Data to ThingSpeak
            send_to_thingspeak(mq2_value)

            # 3. Wait for the next update
            time.sleep(UPDATE_INTERVAL_SECONDS)
            
    except KeyboardInterrupt:
        print("\nProgram stopped by user.")
    except Exception as e:
        print(f"An unexpected error occurred: {e}")

if __name__ == "__main__":
    main()