#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define Button1_PIN 16
#define Button2_PIN 15

volatile unsigned long button1PressTime = 0;
volatile unsigned long button2PressTime = 0;
volatile bool button1Pressed = false;
volatile bool button2Pressed = false;
unsigned long lastPrintTime = 0;
const float distance_cm = 5.0; // Jarak antara dua tombol (dalam cm)

void IRAM_ATTR handleButton1Interrupt() {
  if (digitalRead(Button1_PIN) == LOW) {
    button1PressTime = millis();
    button1Pressed = true;
  }
}

void IRAM_ATTR handleButton2Interrupt() {
  if (digitalRead(Button2_PIN) == LOW) {
    button2PressTime = millis();
    button2Pressed = true;
  }
}

void setup() {
  Serial.begin(9600);
  
  // Set up buttons
  pinMode(Button1_PIN, INPUT_PULLUP);
  pinMode(Button2_PIN, INPUT_PULLUP);
  
  attachInterrupt(digitalPinToInterrupt(Button1_PIN), handleButton1Interrupt, FALLING);
  attachInterrupt(digitalPinToInterrupt(Button2_PIN), handleButton2Interrupt, FALLING);
  
  // Set up OLED display
  Wire.begin(21, 22);
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }

  display.display();
  delay(2000);
  display.clearDisplay();
}

void loop() {
  unsigned long currentTime = millis();

  if (button1Pressed && button2Pressed) {
    unsigned long timeDifference = button2PressTime - button1PressTime;
    float speed_cm_per_sec = 0.0;
    if (timeDifference > 0) {
      speed_cm_per_sec = distance_cm / (timeDifference / 1000.0); // Kecepatan dalam cm/detik
    }

    float speed_cm_per_min = speed_cm_per_sec * 60; // Kecepatan dalam cm/menit

    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.setCursor(0, 0);
    display.print("Speed: ");
    display.print(speed_cm_per_min);
    display.print(" cm/min");

    // Menampilkan status tombol yang ditekan
    display.setCursor(0, 10);
    if (button1Pressed) {
      display.print("Button 1 pressed");
    } else if (button2Pressed) {
      display.print("Button 2 pressed");
    }

    display.display();

    button1Pressed = false;
    button2Pressed = false;
  }

  // Print data to OLED every half second
  if (currentTime - lastPrintTime >= 500) {
    lastPrintTime = currentTime;

    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.setCursor(0, 0);
    display.print("Speed: ");
    display.print("0.0");
    display.print(" cm/min");

    // Menampilkan status tombol yang ditekan
    display.setCursor(0, 10);
    display.print("No sensor detected");

    display.display();
  }
}