#include <OneWire.h>
#include <DallasTemperature.h>
#include <LiquidCrystal_I2C.h>

// Pin definitions
#define ONE_WIRE_BUS 2     // DS18B20 data pin
#define RELAY_PIN 6        // Relay control pin
#define CLK_PIN 3          // Rotary encoder CLK
#define DT_PIN 4           // Rotary encoder DT
#define SW_PIN 5           // Rotary encoder switch (optional)

// Temperature limits
#define MIN_TEMP 0.0
#define MAX_TEMP 85.0
#define TEMP_STEP 0.5      // Temperature adjustment step

// Initialize components
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
LiquidCrystal_I2C lcd(0x27, 16, 2);  // Adjust I2C address if needed

// Variables
float setTemp = 75.0;      // Default set temperature
float currentTemp = 0.0;
int encoderPos = 0;
int lastClkState = HIGH;
unsigned long lastUpdate = 0;

void setup() {
  Serial.begin(9600);
  sensors.begin();
  
  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.print("Temp Controller");
  delay(2000);
  lcd.clear();
  
  // Set pin modes in arduino
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(CLK_PIN, INPUT);
  pinMode(DT_PIN, INPUT);
  pinMode(SW_PIN, INPUT_PULLUP);
  
  digitalWrite(RELAY_PIN, LOW);  // Start with relay off
}

void loop() {
  unsigned long currentMillis = millis();
  
  // Read temperature every second
  if (currentMillis - lastUpdate >= 1000) {
    lastUpdate = currentMillis;
    readTemperature();
    controlRelay();
    updateDisplay();
  }
  
  // Handle rotary encoder input
  handleEncoder();
}

void readTemperature() {
  sensors.requestTemperatures();
  currentTemp = sensors.getTempCByIndex(0);
  
  // Check for sensor errors
  if (currentTemp == DEVICE_DISCONNECTED_C) {
    Serial.println("Error: Sensor disconnected");
    lcd.setCursor(0, 1);
    lcd.print("Sensor Error!   ");
    return;
  }
  
  Serial.print("Current Temp: ");
  Serial.print(currentTemp);
  Serial.print("°C | Set Temp: ");
  Serial.print(setTemp);
  Serial.println("°C");
}

void controlRelay() {
  // Hysteresis of ±0.1°C to prevent rapid cycling
if (currentTemp < (setTemp - 0.1)) {  // Heat if below 82.9°C
  digitalWrite(RELAY_PIN, HIGH);
} 
else if (currentTemp > (setTemp + 0.1)) {  // Stop if above 83.1°C
  digitalWrite(RELAY_PIN, LOW);
}
}

void updateDisplay() {
  lcd.setCursor(0, 0);
  lcd.print("Set:");
  lcd.print(setTemp, 1);
  lcd.print((char)223);  // Degree symbol
  lcd.print("C  ");
  
  lcd.setCursor(0, 1);
  lcd.print("Cur:");
  lcd.print(currentTemp, 1);
  lcd.print((char)223);  // Degree symbol
  lcd.print("C  ");
}

void handleEncoder() {
  int clkState = digitalRead(CLK_PIN);
  
  if (clkState != lastClkState && clkState == HIGH) {
    // Encoder was turned
    if (digitalRead(DT_PIN) != clkState) {
      setTemp += TEMP_STEP;  // Clockwise turn
    } else {
      setTemp -= TEMP_STEP;  // Counter-clockwise turn
    }
    
    // Constrain temperature to limits
    setTemp = constrain(setTemp, MIN_TEMP, MAX_TEMP);
    
    // Update display immediately when changing set temp
    updateDisplay();
  }
  
  lastClkState = clkState;
  
  // Optional: Handle encoder button press
  if (digitalRead(SW_PIN) == LOW) {
    delay(50);  // Simple debounce
    while (digitalRead(SW_PIN) == LOW);  // Wait for release
    // Could add button functionality here
  }
}