# ---------------- IMPORTS ----------------
import network
import time
import urequests
from machine import Pin, ADC


# ---------------- WIFI CONFIG -----------------
SSID = "Wokwi-GUEST"
PASSWORD = ""

# ---------------- THINGSPEAK CONFIG ----------------
API_KEY = "VBKV78DIV4T379S2"   # <-- PUT YOUR Write API Key HERE
BASE_URL = "https://api.thingspeak.com/update"

# ---------------- HARDWARE SETUP ----------------
# Ultrasonic Sensor (HC-SR04)
trigger = Pin(3, Pin.OUT)
echo = Pin(2, Pin.IN)

# LDR (Analog Output connected to ADC)
ldr = ADC(26)

# Brake Light LED
brake_light = Pin(15, Pin.OUT)

# ---------------- THRESHOLDS ----------------
CRITICAL_DISTANCE = 50      # cm
NIGHT_THRESHOLD = 30000     # LDR ADC value (for reference)

# ---------------- WIFI CONNECTION ----------------
print("Connecting to WiFi...")
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect(SSID, PASSWORD)

while not wlan.isconnected():
    time.sleep(1)

print("WiFi Connected")
print("System Active: Tesla Autopilot Simulation")
print("-" * 50)

# ---------------- FUNCTIONS ----------------
def measure_distance():
    trigger.low()
    time.sleep_us(2)
    trigger.high()
    time.sleep_us(10)
    trigger.low()

    while echo.value() == 0:
        signal_off = time.ticks_us()
    while echo.value() == 1:
        signal_on = time.ticks_us()

    time_passed = signal_on - signal_off
    distance = (time_passed * 0.0343) / 2
    return distance

def send_to_cloud(dist, light_level, event_type):
    print(f"CLOUD: Uploading {event_type} event...")
    try:
        url = (
            f"{BASE_URL}?api_key={API_KEY}"
            f"&field1={dist:.1f}"
            f"&field2={light_level}"
            f"&field3={1 if event_type == 'BRAKE' else 0}"
        )
        response = urequests.get(url)
        response.close()
        print("CLOUD: Upload successful")
    except:
        print("CLOUD: Upload failed")

# ---------------- MAIN LOOP ----------------
last_cloud_update = 0
last_state = "DRIVING"

while True:
    # 1️⃣ PERCEPTION (EDGE SENSING)
    distance = measure_distance()
    light_level = ldr.read_u16()

    # 2️⃣ EDGE DECISION (REAL-TIME)
    if distance < CRITICAL_DISTANCE:
        brake_light.value(1)
        current_state = "EMERGENCY_STOP"
        print(f"EDGE: CRITICAL OBSTACLE at {distance:.1f} cm")
    else:
        brake_light.value(0)
        current_state = "DRIVING"
        print(f"EDGE: Driving safely ({distance:.1f} cm)")

    # 3️⃣ CLOUD COMMUNICATION (OPTIMIZED)
    current_time = time.time()

    # Event-based upload
    if current_state == "EMERGENCY_STOP" and last_state == "DRIVING":
        send_to_cloud(distance, light_level, "BRAKE")
        last_cloud_update = current_time

    # Heartbeat upload every 20 seconds
    elif (current_time - last_cloud_update) > 20:
        send_to_cloud(distance, light_level, "HEARTBEAT")
        last_cloud_update = current_time

    last_state = current_state
    time.sleep(0.5)