#define BLYNK_PRINT Serial
#define BLYNK_TEMPLATE_ID "TMPL6ZULtN3U3"
#define BLYNK_TEMPLATE_NAME "Social Distance Sensor"
#define BLYNK_AUTH_TOKEN "QnTVWVZfqGUGbs3PRSuCq_egnZRHDuMF"

#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>

#define echoPin 18    // attach pin ESP32 GPIO18 to pin Echo of HC-SR04
#define trigPin 5     // attach pin ESP32 GPIO5 to pin Trig of HC-SR04
#define buzzerPin 22  // attach pin ESP32 GPIO22 to the buzzer
#define LEDPin 23     // attach pin ESP32 GPIO23 to the red LED

long duration;  // Variable to store time taken by the pulse to reach the receiver
int distance;   // Variable to store distance calculated using the formula

char auth[] = BLYNK_AUTH_TOKEN;
char ssid[] = "Wokwi-GUEST";  // Replace with your WiFi SSID
char pass[] = "";  // Replace with your WiFi password

BlynkTimer timer;

int buzzerState = 0;

// Blynk virtual write function to control the buzzer and LED manually
BLYNK_WRITE(V0)
{
  buzzerState = param.asInt();  // Get the state of the button (1 or 0)
  
  if (buzzerState == 1) {
    tone(buzzerPin, 1200);      // Start the buzzer with 1200Hz frequency
    digitalWrite(LEDPin, HIGH); // Turn on the LED when the buzzer is on
    Blynk.virtualWrite(V1, 255); // Turn on the LED widget in the Blynk app
    Serial.println("Buzzer ON, LED ON");
  } else {
    noTone(buzzerPin);          // Stop the buzzer
    digitalWrite(LEDPin, LOW);  // Turn off the LED when the buzzer is off
    Blynk.virtualWrite(V1, 0);   // Turn off the LED widget in the Blynk app
    Serial.println("Buzzer OFF, LED OFF");
  }
}

// Function to measure distance using the ultrasonic sensor
void measureDistance()
{
  // Send a 10us pulse to trigger the sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the duration of the echo pulse
  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in centimeters
  distance = duration * 0.0344 / 2;

  Serial.print("Distance: ");
  Serial.print(distance);  // Print the distance on the serial monitor
  Serial.println(" cm");

  // Trigger the buzzer and LED if the distance is 2 cm or less
  if (distance <= 200)
  {
    tone(buzzerPin, 1200);      // Start the buzzer
    digitalWrite(LEDPin, HIGH); // Turn on the LED
    Blynk.virtualWrite(V1, 255); // Turn on the LED widget in the Blynk app
    Serial.println("Buzzer ON, LED ON (Triggered by distance)");
  }
  else if (buzzerState == 0) // Ensure manual control does not interfere
  {
    noTone(buzzerPin);         // Stop the buzzer
    digitalWrite(LEDPin, LOW); // Turn off the LED
    Blynk.virtualWrite(V1, 0);  // Turn off the LED widget in the Blynk app
    Serial.println("Buzzer OFF, LED OFF (Distance safe)");
  }
}

// Setup function
void setup()
{
  pinMode(trigPin, OUTPUT);  // Sets the trigPin as an OUTPUT
  pinMode(echoPin, INPUT);   // Sets the echoPin as an INPUT
  pinMode(buzzerPin, OUTPUT);  // Sets the buzzerPin as an OUTPUT
  pinMode(LEDPin, OUTPUT);  // Sets LEDPin as an OUTPUT

  Serial.begin(9600);  // Start serial communication at 9600 baudrate
  Serial.println("Distance measurement using ESP32");

  Blynk.begin(auth, ssid, pass);  // Connect to Blynk server

  // Setup a function to measure distance every 100ms
  timer.setInterval(100L, measureDistance);
}

// Main loop function
void loop()
{
  Blynk.run();  // Run Blynk
  timer.run();  // Run Blynk timer to measure distance
}