import machine
import time
from machine import Pin, UART, ADC

def main():
    print("--- SENDER Node Started ---")
    
    # --- Config ---
    # จำลอง LoRa ด้วย UART2 (TX=17, RX=16)
    lora_sim = UART(2, baudrate=9600, tx=17, rx=16)

    # Ultrasonic
    trig = Pin(13, Pin.OUT)
    echo = Pin(27, Pin.IN)

    # Battery Sim (Potentiometer)
    adc = ADC(Pin(34))
    adc.atten(ADC.ATTN_11DB) # 0-3.3V range

    # Helper function: วัดระยะ
    def get_distance():
        trig.value(0)
        time.sleep_us(2)
        trig.value(1)
        time.sleep_us(10)
        trig.value(0)
        try:
            t = machine.time_pulse_us(echo, 1, 30000)
            if t < 0: return -1
            return (t * 0.0343) / 2
        except:
            return -1

    # Helper function: อ่านแบต
    def get_battery():
        raw = adc.read()
        sim_volt = 10 + (raw / 4095 * 4.0) 
        return round(sim_volt, 2)

    # --- Main Loop ---
    while True:
        dist = get_distance()
        batt = get_battery()
        
        # คำนวณระดับน้ำ (สมมติเซนเซอร์สูง 200cm)
        water_level = 200 - dist
        if dist == -1: water_level = 0
        
        # สร้างข้อความ Format: "ID,Water,Batt"
        payload = f"FIELD01,{water_level:.1f},{batt}"
        
        print(f"[Sender] Sending: {payload}")
        lora_sim.write(payload + '\n') # ส่งไปหาตัวรับ
        
        time.sleep(2) # ส่งทุก 2 วินาที