#include <Servo.h>

// Pin Definitions
#define ULTRASONIC_TRIG 3
#define ULTRASONIC_ECHO 4
#define GAS_SENSOR A0
#define RAIN_SENSOR A1
#define GREEN_LED 7
#define SERVO_PIN 9

// Constants
#define GAS_THRESHOLD 600
#define RAIN_THRESHOLD 500
#define DISTANCE_THRESHOLD 10

// Objects
Servo myServo;

void setup() {
  pinMode(GREEN_LED, OUTPUT);
  pinMode(ULTRASONIC_TRIG, OUTPUT);
  pinMode(ULTRASONIC_ECHO, INPUT);
  myServo.attach(SERVO_PIN);
  
  Serial.begin(9600);
}

void loop() {
  // Gas sensor condition
  int gasLevel = analogRead(GAS_SENSOR);
  if (gasLevel > GAS_THRESHOLD) {
    digitalWrite(GREEN_LED, HIGH);
  } else {
    digitalWrite(GREEN_LED, LOW);
  }

  // Rain sensor condition
  int rainLevel = analogRead(RAIN_SENSOR);
  if (rainLevel > RAIN_THRESHOLD) {
    myServo.write(90); // Open position
  } else {
    myServo.write(0);  // Closed position
  }

  // Ultrasonic sensor condition
  int distance = measureDistance();
  if (distance < DISTANCE_THRESHOLD) {
    myServo.write(90); // Open position
  }

  delay(500);
}

// Function to measure distance using Ultrasonic Sensor
int measureDistance() {
  digitalWrite(ULTRASONIC_TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(ULTRASONIC_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(ULTRASONIC_TRIG, LOW);
  int duration = pulseIn(ULTRASONIC_ECHO, HIGH);
  return duration * 0.034 / 2; // Convert to cm
}