/*
  Wokwi | general
  Mau.chalco — 7/20/25 at 6:53 PM
  Could you help me with this project?
  I want to make the buzzer sound and also turn on an LED.
  https://wokwi.com/projects/436785646621448193
*/

// ==========================
// Blynk Configuration (Unique project credentials)
// ==========================
#define BLYNK_PRINT Serial
#define BLYNK_TEMPLATE_ID "TMPL22xzOPhVa"       // Template ID from Blynk.Console
#define BLYNK_TEMPLATE_NAME "Carrito sensor"    // Project name in the Blynk app
#define BLYNK_AUTH_TOKEN "oO-4ijFgIIhbTBR4mY0TIfJRROyACsEM" // Authentication token
// ==========================
// Required libraries
// ==========================
#include <WiFi.h>                    // Enables WiFi connection for the ESP32
#include <BlynkSimpleEsp32.h>        // Allows communication with Blynk
#include <Wire.h>                    // I2C protocol (for LCD)
#include <LiquidCrystal_I2C.h>       // Library for controlling I2C LCD
#include <NewPing.h>                 // Library for precise HC-SR04 readings

// ==========================
// Pin and constant definitions
// ==========================
#define TRIG_PIN 5                   // GPIO5 connected to HC-SR04 Trigger
#define ECHO_PIN 18                  // GPIO18 connected to HC-SR04 Echo
#define LED_PIN 2                    // GPIO2 used for alert LED
#define BUZZER_PIN 19                 // GPIO4 used for active buzzer
#define MAX_DISTANCE 400             // Maximum distance for the sensor (cm)
#define SDA_PIN 21                   // GPIO21 for I2C SDA
#define SCL_PIN 22                   // GPIO22 for I2C SCL
#define BTN_PIN 27

// ==========================
// Global objects
// ==========================
LiquidCrystal_I2C lcd(0x27, 16, 2);  // LCD at I2C address 0x27, 16 columns x 2 rows
NewPing sonar(TRIG_PIN, ECHO_PIN, MAX_DISTANCE); // HC-SR04 sensor object

// ==========================
// WiFi credentials
// ==========================
char ssid[] = "Wokwi-GUEST";         // Network name (Wokwi simulator)
char pass[] = "";                    // Password (empty for Wokwi)

// ==========================
// Blynk virtual pins
// ==========================
#define VPIN_DISTANCE V0             // Virtual pin for displaying distance
#define VPIN_ALERT V1                // Virtual pin for sending alert

bool alerta_enviada = false;         // Prevents sending repeated notifications to Blynk

// ==========================
// Function: Averaging multiple readings to avoid errors
// ==========================
int getStableDistance() {
  int sum = 0;
  for (int i = 0; i < 5; i++) {      // Take 5 readings
    sum += sonar.ping_cm();          // Add each distance reading
    delay(50);                       // Small delay between readings
  }
  return sum / 5;                     // Return the average distance
}

// ==========================
// Initial setup
// ==========================
void setup() {
  Serial.begin(115200);              // Start the serial monitor
  Wire.begin(SDA_PIN, SCL_PIN);      // Start I2C communication with custom pins

  lcd.init();                        // Initialize the LCD
  lcd.backlight();                   // Turn on LCD backlight

  pinMode(LED_PIN, OUTPUT);          // Set LED pin as output
  pinMode(BUZZER_PIN, OUTPUT);       // Set buzzer pin as output

  Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass); // Connect to Blynk server
  lcd.setCursor(0, 0);
  lcd.print("Connecting...");        // Show connecting message

  while (!Blynk.connected()) {       // Wait until connected to Blynk
    delay(500);
    lcd.print(".");
  }

  lcd.clear();
  lcd.print("System OK");            // Confirm system is ready
  delay(1500);
  lcd.clear();
}

// ==========================
// Main loop
// ==========================
void loop() {
  Blynk.run();                       // Keep Blynk connection alive

  int distancia = getStableDistance(); // Get averaged distance

  // Display distance on LCD
  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
  if (distancia == 0 || distancia > MAX_DISTANCE) {
    lcd.print("-- cm   ");           // Error reading
    Blynk.virtualWrite(VPIN_DISTANCE, 0);
  } else {
    lcd.print(distancia);            // Valid distance
    lcd.print(" cm   ");
    Blynk.virtualWrite(VPIN_DISTANCE, distancia);
  }

  // Alert logic (object closer than 200 cm)
  if (distancia > 0 && distancia < 200) {
    digitalWrite(LED_PIN, HIGH);     // Turn on alert LED
    tone(BUZZER_PIN, 1000);     // Beep the buzzer (1kHz tone for 500ms)
    lcd.setCursor(0, 1);
    lcd.print("ALERT! Nearby ");
    Blynk.virtualWrite(VPIN_ALERT, 1);

    if (!alerta_enviada) {
      Blynk.logEvent("alerta_distancia", "🚨 Object at " + String(distancia) + " cm!");
      alerta_enviada = true;
    }
  } else {
    digitalWrite(LED_PIN, LOW);      // Turn off LED
    noTone(BUZZER_PIN);              // Silence buzzer
    lcd.setCursor(0, 1);
    lcd.print("                ");   // Clear second line
    Blynk.virtualWrite(VPIN_ALERT, 0);
    alerta_enviada = false;
  }

  delay(300);                         // Wait before next reading
}