#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Define the LCD object with its I2C address, columns, and rows
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define the button pin
const int buttonPin = 2; // Connect your button to digital pin D8

// Define SR-HC04 pins
const int trigPin = 5; // Trigger pin connected to D5
const int echoPin = 6; // Echo pin connected to D6

// Define the threshold distance in centimeters
const int DISTANCE_THRESHOLD_CM = 10;

// Setup function: runs once when the Arduino starts
void setup() {
  Wire.begin(8,9);
  Serial.begin(9600);
  lcd.init();      // Initialize the LCD
  lcd.backlight(); // Turn on the backlight

  // Set the button pin as an input with an internal pull-up resistor
  pinMode(buttonPin, INPUT_PULLUP);

  // Set SR-HC04 pins
  pinMode(trigPin, OUTPUT); // Trigger pin as an output
  pinMode(echoPin, INPUT);  // Echo pin as an input

  lcd.print("Hola Diego"); // Display "Hola Diego"
  Serial.println("Hola Diego"); // Display "Hola Diego"
  delay(2000);             // Keep it on for 2 seconds
  lcd.clear();             // Clear the screen
}

// Function to measure distance using the SR-HC04
long measureDistance() {
  // Clear the trigPin by setting it LOW for 2 microseconds
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Set the trigPin HIGH for 10 microseconds to send a pulse
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the echoPin, returns the sound wave travel time in microseconds
  long duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in cm (speed of sound ~0.034 cm/microsecond)
  // Divide by 2 because the sound travels to the object and back
  long distanceCm = duration * 0.034 / 2;
  return distanceCm;
}

// Loop function: runs repeatedly after setup
void loop() {
  int eventCount = 0; // Variable to count events (button press or distance)
  bool lastButtonState = HIGH; // Track the previous state of the button
  bool lastDistanceState = false; // Track if distance was previously below threshold

  lcd.print("Presiona o Acerca"); // Prompt the user
  Serial.println("Presiona o Acerca"); // Prompt the user
  lcd.setCursor(0,1);
  lcd.println("2 Veces");
  Serial.print("2 Veces\n");

  // Loop until two events are detected
  while (eventCount < 2) {
    // Read button state
    bool currentButtonState = digitalRead(buttonPin);

    // Read distance
    long distance = measureDistance();
    bool currentDistanceState = (distance > 0 && distance < DISTANCE_THRESHOLD_CM); // True if object is within threshold

    // Check for a button press (transition from HIGH to LOW)
    if (lastButtonState == HIGH && currentButtonState == LOW) {
      eventCount++; // Increment the counter
      lcd.clear();
      lcd.print("Conteo (Boton):");
      Serial.println("Conteo (Boton):\n");
      lcd.setCursor(0, 1);
      lcd.print(eventCount);
      delay(300); // Debounce delay for the button
    }

    // Check for distance event (transition from NOT within threshold to WITHIN threshold)
    if (lastDistanceState == false && currentDistanceState == true) {
      eventCount++; // Increment the counter
      lcd.clear();
      lcd.print("Conteo (Dist):");
      Serial.println("Conteo (Dist):\n");
      lcd.setCursor(0, 1);
      lcd.print(eventCount);
      Serial.print(eventCount);
      delay(500); // Delay for distance event to avoid rapid counting
    }

    // Update last states
    lastButtonState = currentButtonState;
    lastDistanceState = currentDistanceState;

    delay(50); // Small general delay to keep things stable
  }

  // After two events, clear the screen and display "Buenas noches Diego"
  lcd.clear();
  lcd.print("Buenas noches");
  Serial.println("Buenas noches\n");
  lcd.setCursor(0,1);
  lcd.print("Diego");
  Serial.println("Diego\n");
  delay(5000); // Display "Buenas noches Diego" for 5 seconds
  lcd.clear(); // Clear the screen before repeating the loop

  // The loop will then restart, prompting for two more events.
}