import network
import urequests as requests
from machine import Pin, time_pulse_us
from time import sleep_ms

# WiFi credentials (Wokwi default)
WIFI_SSID = "Wokwi-GUEST"
WIFI_PASS = ""

# ThingSpeak Write API Key
THINGSPEAK_API_KEY = "Z8OOISBIVZOMB05J"
THINGSPEAK_URL = "http://api.thingspeak.com/update"

# Pins for 3 ultrasonic sensors
trig_pins = [Pin(2, Pin.OUT), Pin(3, Pin.OUT), Pin(4, Pin.OUT)]
echo_pins = [Pin(5, Pin.IN), Pin(6, Pin.IN), Pin(7, Pin.IN)]

# Red/Green LEDs for each slot
red_leds = [Pin(8, Pin.OUT), Pin(9, Pin.OUT), Pin(10, Pin.OUT)]
green_leds = [Pin(11, Pin.OUT), Pin(12, Pin.OUT), Pin(13, Pin.OUT)]

def connect_wifi():
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    wlan.connect(WIFI_SSID, WIFI_PASS)
    print("Connecting to WiFi", end="")
    while not wlan.isconnected():
        sleep_ms(500)
        print(".", end="")
    print("\n✅ Connected:", wlan.ifconfig())

def measure_distance(trig, echo):
    trig.low()
    sleep_ms(2)
    trig.high()
    sleep_ms(10)
    trig.low()
    duration = time_pulse_us(echo, 1, 30000)  # 30ms timeout
    if duration < 0:
        return None
    return (duration / 2) / 29.1  # cm

def update_thingspeak(available, slot_status):
    try:
        url = (
            f"https://api.thingspeak.com/update"
            f"?api_key={THINGSPEAK_API_KEY}"
            f"&field1={available}"
            f"&field2={slot_status[0]}"
            f"&field3={slot_status[1]}"
            f"&field4={slot_status[2]}"
        )
        res = requests.get(url)
        print("ThingSpeak Response:", res.text)
        res.close()
    except Exception as e:
        print("⚠️ ThingSpeak update failed:", e)

# MAIN PROGRAM
connect_wifi()

while True:
    slot_status = []
    available = 0

    # Measure all slots
    for i in range(3):
        dist = measure_distance(trig_pins[i], echo_pins[i])
        if dist is not None and dist < 100:  # threshold (cm)
            red_leds[i].high()
            green_leds[i].low()
            slot_status.append(0)  # occupied
            print(f"🚗 Slot {i+1}: Occupied ({dist:.1f} cm)")
        else:
            red_leds[i].low()
            green_leds[i].high()
            slot_status.append(1)  # empty
            available += 1
            print(f"✅ Slot {i+1}: Empty")

    # Update ThingSpeak
    update_thingspeak(available, slot_status)
    print(f"📊 Available Slots: {available}")

    print("-----------------------------")
    sleep_ms(1000)  # ThingSpeak: minimum 1s between updates