#define BLYNK_TEMPLATE_ID "TMPL30_hM_YfN"
#define BLYNK_TEMPLATE_NAME "Proximity Alert"
#define BLYNK_AUTH_TOKEN "tlrYTo9dGBgAsFOzdl688BgBxq5AkZyN"
#include <BlynkSimpleEsp32.h>
#include <WiFi.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define TRIG_PIN 5
#define ECHO_PIN 18
#define ALERT_LED_PIN 2
#define BUZZER_PIN 4

LiquidCrystal_I2C lcd(0x27, 16, 2);

long duration;
float distanceCM;

unsigned long previousMillis = 0;
const long interval = 100; // 100ms for fast refresh

void setup() {
  Serial.begin(115200);
  
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Proximity Alert");

  WiFi.begin("Wokwi-GUEST", "");
  Blynk.config(BLYNK_AUTH_TOKEN);
  Blynk.connect();

  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(ALERT_LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  digitalWrite(ALERT_LED_PIN, LOW);
  digitalWrite(BUZZER_PIN, LOW);
}

void loop() {
  Blynk.run();
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis;

    distanceCM = getDistance();

    lcd.setCursor(0, 1);
    lcd.print("Dist: ");
    lcd.print(distanceCM);
    lcd.print(" cm   ");

    Serial.print("Distance: ");
    Serial.print(distanceCM);
    Serial.println(" cm");

    // Alert Conditions
    if (distanceCM < 5) {
      digitalWrite(ALERT_LED_PIN, HIGH);
      digitalWrite(BUZZER_PIN, HIGH);
      Blynk.virtualWrite(V1, 255); // LED ON
      Serial.println("Warning: Too Close");
    }
    else if (distanceCM < 10) {
      digitalWrite(ALERT_LED_PIN, HIGH);
      digitalWrite(BUZZER_PIN, HIGH);
      Blynk.virtualWrite(V1, 255); // LED ON
      Serial.println("Alert: Close");
    }
    else {
      digitalWrite(ALERT_LED_PIN, LOW);
      digitalWrite(BUZZER_PIN, LOW);
      Blynk.virtualWrite(V1, 0); // LED OFF
    }
  }
}

float getDistance() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  duration = pulseIn(ECHO_PIN, HIGH, 30000); // 30ms timeout
  float distance = duration * 0.034 / 2;

  Blynk.virtualWrite(V2, distance); // Send distance to Blynk
  return distance;
}