#include <DHT.h>

// Pin definitions
#define DHTPIN 15          // DHT22 data pin (D15 in Wokwi)
#define DHTTYPE DHT22
#define RED_LED 4          // Red LED pin (D4 in Wokwi)
#define GREEN_LED 16       // Green LED pin (D16 in Wokwi)
#define YELLOW_LED 2      // Yellow LED (D2 in Wokwi)


// Timing for blinking
unsigned long lastBlinkTime = 0;
bool blinkState = false;

// States
enum State { IDLE, HEATING, STABILIZING, TARGET_REACHED, OVERHEAT };
State currentState = IDLE;

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(115200);
  dht.begin();

  pinMode(RED_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  

  Serial.println("System Initialized");
}

void updateState(float temperature) {
  if (temperature > 56  &&  temperature  <= 80 ) {
    currentState = OVERHEAT;
  } else if (temperature > 32  &&  temperature <= 56  ) {
    currentState = TARGET_REACHED;
  } else if (temperature > 8  &&     temperature  <= 32   ) {
    currentState = STABILIZING;
  } else if (temperature >  -16  &&  temperature <=  8  ) {
    currentState = HEATING;
  } else if(temperature  >=  -40   && temperature <=  -16  ){
    currentState = IDLE;
  }
}//These thresholds are according to the Wokwi simulator

void applyState() {
  switch (currentState) {
    case IDLE:
      analogWrite(RED_LED, 0);
      digitalWrite(GREEN_LED, LOW);
      digitalWrite(YELLOW_LED, LOW);
      Serial.println("[IDLE] Heater OFF");
      break;

    case HEATING:
      analogWrite(RED_LED, 60); 
      digitalWrite(GREEN_LED, HIGH);
      digitalWrite(YELLOW_LED, LOW);
      Serial.println("[HEATING] Heater ON, 60% power");
      break;

    case STABILIZING:
      analogWrite(RED_LED, 120); 
      digitalWrite(GREEN_LED, HIGH);
      digitalWrite(YELLOW_LED, LOW);
      Serial.println("[STABILIZING] Heater ON, 80% power");
      break;

    case TARGET_REACHED:
      analogWrite(RED_LED, 180); 
      digitalWrite(GREEN_LED, HIGH);
      digitalWrite(YELLOW_LED, LOW);
      Serial.println("[TARGET_REACHED] Heater ON, 100% power");
      break;

    case OVERHEAT:
      analogWrite(RED_LED, 255); // keep red LED at full
      digitalWrite(GREEN_LED, LOW);  // heater OFF
      Serial.println("[OVERHEAT] Heater OFF, Buzzer ON, Blinking");
      break;
  }
}

void handleBlinking() {
  if (currentState == OVERHEAT) {
    unsigned long currentMillis = millis();
    if (currentMillis - lastBlinkTime >= 500) { // toggle every 500ms
      blinkState = !blinkState;
      digitalWrite(YELLOW_LED, blinkState);
      lastBlinkTime = currentMillis;
    }
  } else {
    digitalWrite(YELLOW_LED, LOW); // no blink outside overheat
  }
}

void loop() {
  float temp = dht.readTemperature();
  if (isnan(temp)) {
    Serial.println("Failed to read temperature from DHT22!");
    delay(2000);
    return;
  }

  Serial.print("Temperature: ");
  Serial.println(temp);

  updateState(temp);
  applyState();
  handleBlinking(); // run blinking separately

  delay(1000);  // read every second
}