#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <DHT.h>
#include <ESP32Servo.h>

#define DHTPIN 4
#define DHTTYPE DHT22

#define GAS_PIN 34
#define VIB_PIN 35
#define GREEN_LED 16
#define RED_LED 17
#define BUZZER 19
#define SERVO_PIN 18

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

DHT dht(DHTPIN, DHTTYPE);
Servo fan;

float tempThreshold = 35.0;
int gasThreshold = 500;
int vibrationThreshold = 2000;

void setup() {
  Serial.begin(115200);
  dht.begin();
  fan.attach(SERVO_PIN);
  
  pinMode(GAS_PIN, INPUT);
  pinMode(VIB_PIN, INPUT);
  pinMode(GREEN_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  Wire.begin(21, 22);

  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("OLED failed"));
    while(true);
  }
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.print("System Initializing...");
  display.display();

  delay(2000);
}

void loop() {
  float temp = dht.readTemperature();
  float hum = dht.readHumidity();
  int gasVal = analogRead(GAS_PIN);
  int vibVal = analogRead(VIB_PIN);

  Serial.print("Temp: "); Serial.print(temp);
  Serial.print("  Gas: "); Serial.print(gasVal);
  Serial.print("  Vibration: "); Serial.println(vibVal);

  bool overTemp = temp > tempThreshold;
  bool overGas = gasVal > gasThreshold;

  // Default system state
  digitalWrite(GREEN_LED, HIGH);
  digitalWrite(RED_LED, LOW);
  digitalWrite(BUZZER, LOW);

  // If any threshold exceeded → system shutdown
  if (overTemp || overGas) {
    digitalWrite(GREEN_LED, LOW);
    digitalWrite(RED_LED, HIGH);
  }

  // If gas is high → activate fan (servo sweep) and buzzer
  if (overGas) {
    digitalWrite(BUZZER, HIGH);
    for (int pos = 0; pos <= 180; pos += 10) {
      fan.write(pos);
      delay(15);
    }
    for (int pos = 180; pos >= 0; pos -= 10) {
      fan.write(pos);
      delay(15);
    }
  } else {
    fan.write(90); // center position
  }

  // OLED Display Update
  display.clearDisplay();
  display.setCursor(0, 0);
  display.print("Temp: "); display.print(temp); display.println(" C");
  display.print("Hum : "); display.print(hum); display.println(" %");
  display.print("Gas : "); display.println(gasVal);
  display.print("Vib : "); display.println(vibVal);
  
  if (overTemp || overGas) display.println("⚠️ SYSTEM SHUTDOWN");
  else display.println("✅ NORMAL");
  
  display.display();

  delay(1000);
}