#include <DHT.h>
#define DHTPIN 15       
#define DHTTYPE DHT22
#define heater 4    
#define gled 2     
#define buzz 13     
DHT dht(DHTPIN, DHTTYPE);
const float normaltemp = 30.0;
const float lowtemp = 27.0;
const float hightemp = 35.0;
enum state {
  idle,
  heating,
  stable,
  heated,
  overheating
};
state cstate = idle;
unsigned long lrtime = 0;
const unsigned long gap = 1000; 
void setup() {
  Serial.begin(115200);
  dht.begin();
  pinMode(heater, OUTPUT);
  pinMode(gled, OUTPUT);
  pinMode(buzz, OUTPUT);
  Serial.println("Heater Control System Started...");
}
void loop() {
  unsigned long ctime = millis();
  if (ctime - lrtime >= gap) {
    lrtime = ctime;
    float temp = dht.readTemperature();
    if (isnan(temp)) {
      Serial.println("No sensor data!!!!");
      return;
    }
    if (temp >= hightemp) {
      cstate = overheating;
    } else if (temp >= normaltemp) {
      cstate = heated;
    } else if (temp >= lowtemp && temp < normaltemp) {
      cstate = stable;
    } else {
      cstate = heating;
    }
    updatestate(cstate, temp);
  }
}
void updatestate(state state, float temperature) {
  switch (state) {
    case idle:
      digitalWrite(heater, LOW);
      digitalWrite(gled, LOW);
      digitalWrite(buzz, LOW);
      Serial.printf("Heater is idle,Temp : %.2f°C,Heater : OFF\n", temperature);
      break;
    case heating:
      digitalWrite(heater, HIGH);
      digitalWrite(gled, LOW);
      digitalWrite(buzz, LOW);
      Serial.printf("Heating is in process : %.2f°C,Heater: ON\n", temperature);
      break;
    case stable:
      digitalWrite(heater, LOW);
      digitalWrite(gled, LOW);
      digitalWrite(buzz, LOW);
      Serial.printf("Heater Stable ,Temp: %.2f°C,Heater: Pulsed OFF\n", temperature);
      break;
    case heated:
      digitalWrite(heater, LOW);
      digitalWrite(gled, HIGH);
      digitalWrite(buzz, LOW);
      Serial.printf("Finished heating, Temp: %.2f°C,Heater: OFF\n", temperature);
      break;
    case overheating:
      digitalWrite(heater, LOW);
      digitalWrite(gled, LOW);
      digitalWrite(buzz, HIGH);
      Serial.printf("Warning, heater is overheating, Temp: %.2f°C,Heater: OFF | Buzzer: ON\n", temperature);
      break;
  }
}