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

// Definisi Pin
#define RELAY_PIN 2
#define NTC_PIN A0
#define UP_BUTTON_PIN 3
#define DOWN_BUTTON_PIN 4

// Inisialisasi LCD
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Variabel Global
float currentTemp = 0.0;
int setTemp = 25; // Suhu setting awal
const int MIN_TEMP = 20;
const int MAX_TEMP = 90;
long lastUpPress = 0;
long lastDownPress = 0;

// Konstanta Sensor NTC (sesuaikan jika perlu)
const float B_VALUE = 3950;
const float R_NOMINAL = 10000;
const float T_NOMINAL = 25;

//--- Prototipe Fungsi ---
void cek_tombol();
void baca_suhu();
void tampilkan_suhu();
void proses_relay();

void setup() {
  Serial.begin(9600);
  
  // Konfigurasi pin
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(UP_BUTTON_PIN, INPUT_PULLUP);
  pinMode(DOWN_BUTTON_PIN, INPUT_PULLUP);
  
  // Inisialisasi LCD
  lcd.init();
  lcd.backlight();
  lcd.clear();
}

void loop() {
  cek_tombol();
  baca_suhu();
  tampilkan_suhu();
  proses_relay();
}

//--- Implementasi Fungsi ---

void cek_tombol() {
  // Anti-bouncing dengan delay 200ms
  if (digitalRead(UP_BUTTON_PIN) == LOW && (millis() - lastUpPress > 200)) {
    lastUpPress = millis();
    setTemp++;
    if (setTemp > MAX_TEMP) {
      setTemp = MAX_TEMP;
    }
    Serial.println("Tombol UP ditekan. Suhu setting: " + String(setTemp));
    tampilkan_suhu(); // Update tampilan segera
  }

  if (digitalRead(DOWN_BUTTON_PIN) == LOW && (millis() - lastDownPress > 200)) {
    lastDownPress = millis();
    setTemp--;
    if (setTemp < MIN_TEMP) {
      setTemp = MIN_TEMP;
    }
    Serial.println("Tombol DOWN ditekan. Suhu setting: " + String(setTemp));
    tampilkan_suhu(); // Update tampilan segera
  }
}

void baca_suhu() {
  int analogValue = analogRead(NTC_PIN);
  float resistance = 10000.0 * (1023.0 / analogValue - 1.0);
  float steinhart;
  steinhart = resistance / R_NOMINAL;
  steinhart = log(steinhart);
  steinhart /= B_VALUE;
  steinhart += 1.0 / (T_NOMINAL + 273.15);
  steinhart = 1.0 / steinhart;
  steinhart -= 273.15;
  currentTemp = steinhart;
}

void tampilkan_suhu() {
  lcd.setCursor(0, 0);
  lcd.print("Suhu: ");
  lcd.print(currentTemp, 1);
  lcd.print(" C");
  
  lcd.setCursor(0, 1);
  lcd.print("Set: ");
  lcd.print(setTemp);
  lcd.print(" C");
  
  lcd.print("   "); // Hapus sisa karakter
}

void proses_relay() {
  if (currentTemp > setTemp) {
    digitalWrite(RELAY_PIN, HIGH); // Nyalakan kipas
  } else {
    digitalWrite(RELAY_PIN, LOW);  // Matikan kipas
  }
}