#include <ArduinoJson.h>
#include <DHT.h>
#define DHTPIN 15
#define DHTTYPE DHT22
#define HEATER_PIN 18
#define BUZZER_PIN 19
#define TARGET_TEMP 48.0
#define OVERHEAT_TEMP 50.0

DHT dht(DHTPIN,DHTTYPE);
enum SystemState{
  IDLE,
  HEATING,
  STABILIZING,
  TARGET_REACHED,
  OVERHEAT
};
SystemState state=IDLE;

void setup() {
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  dht.begin();
  pinMode(HEATER_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(HEATER_PIN, LOW);
  digitalWrite(BUZZER_PIN, LOW);

}

void loop() {
  float temp=dht.readTemperature();
  if (isnan(temp)){
    Serial.println("failed to read from DHT sensor");
  delay(1000);
  }
  if(temp>OVERHEAT_TEMP)
    state=OVERHEAT;
  else if(temp>=TARGET_TEMP)
    state=TARGET_REACHED;
  else if(temp>=TARGET_TEMP -3)
    state=STABILIZING;
  else if(temp<=TARGET_TEMP -3)
    state=HEATING;
  else
  state=IDLE;
  switch(state){
    case HEATING:
    digitalWrite(HEATER_PIN, HIGH);
    digitalWrite(BUZZER_PIN, LOW);
    break;
    case OVERHEAT:
    digitalWrite(HEATER_PIN, LOW);
    digitalWrite(BUZZER_PIN, HIGH);
    break;
    default:
    digitalWrite(HEATER_PIN,LOW);
    digitalWrite(BUZZER_PIN,LOW);
  }
  Serial.print("Temp:");
  Serial.print(temp);
  Serial.print("degC |state:");
  switch(state){
    case HEATING:Serial.print("heating"); break;
    case STABILIZING:Serial.print("stabilizing"); break;
    case TARGET_REACHED:Serial.print("targetreached"); break;
    case OVERHEAT:Serial.print("OVERHEAT"); break;
    default:Serial.print("IDLE");
  }
  Serial.print("|heater:");
  Serial.print(state==HEATING)? "ON" : "OFF" ;
  Serial.print(" |buzzer:");
  Serial.println(state==OVERHEAT)? "ON" : "OFF";
  delay(1000);
}