#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// LCD: 0x27 (ubah ke 0x3F jika tidak muncul)
LiquidCrystal_I2C lcd(0x27, 16, 2);

#define trigPin 9
#define echoPin 10
#define relayPin 8     // Relay aktif HIGH sekarang
#define ledOn 6        // LED Hijau = Pompa ON
#define ledOff 7       // LED Merah = Pompa OFF

// Parameter tangki
#define TANK_HEIGHT_CM 200
#define BASE_AREA_CM2 40000
#define FULL_VOLUME_L 8000

#define MIN_PERCENT 30
#define MAX_PERCENT 90

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(relayPin, OUTPUT);
  pinMode(ledOn, OUTPUT);
  pinMode(ledOff, OUTPUT);

  // Mulai: Pompa OFF
  digitalWrite(relayPin, LOW);
  digitalWrite(ledOn, LOW);
  digitalWrite(ledOff, HIGH);

  lcd.init();
  lcd.begin(16, 2);
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("Water Tank Sys");
  lcd.setCursor(0,1);
  lcd.print("Starting...");
  delay(2000);

  Serial.begin(9600);
}

float readDistanceCM() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(5);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);
  return duration * 0.034 / 2;
}

void loop() {
  float distance = readDistanceCM();
  if(distance > TANK_HEIGHT_CM) distance = TANK_HEIGHT_CM;

  float waterHeight = TANK_HEIGHT_CM - distance;
  float percent = (waterHeight / TANK_HEIGHT_CM) * 100;
  float volume_liters = (waterHeight * BASE_AREA_CM2) / 1000.0;

  String statusPompa;

  // ---- Kontrol pompa dengan relay ON = pompa ON ----
  if(percent < MIN_PERCENT) {
    digitalWrite(relayPin, HIGH);   // Pompa ON
    digitalWrite(ledOn, HIGH);
    digitalWrite(ledOff, LOW);
    statusPompa = "PUMP: ON ";
  }
  else if(percent > MAX_PERCENT) {
    digitalWrite(relayPin, LOW);    // Pompa OFF
    digitalWrite(ledOn, LOW);
    digitalWrite(ledOff, HIGH);
    statusPompa = "PUMP: OFF";
  }

  // ---- Serial Debug ----
  Serial.print("Level: ");
  Serial.print(percent,1);
  Serial.print("% | Volume: ");
  Serial.print(volume_liters);
  Serial.println(" L");

  // ---- LCD Display ----
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Lvl:");
  lcd.print(percent,1);
  lcd.print("% ");
  lcd.print((int)volume_liters);
  lcd.print("L");

  lcd.setCursor(0,1);
  lcd.print(statusPompa);

  delay(1000);
}