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

#define OLED_RESET    -1
Adafruit_SSD1306 display(OLED_RESET);

#define BUTTON_PIN    4  // Pin untuk tombol
#define SD_CS_PIN     5  // Pin untuk CS kartu microSD

File root;
String currentFileName = "";
bool isFileSelected = false;

void setup() {
  Serial.begin(9600);

  pinMode(BUTTON_PIN, INPUT);
  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), selectFile, FALLING);

  if (!display.begin(SSD1306_I2C_ADDRESS, OLED_RESET)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }

  if (!SD.begin(SD_CS_PIN)) {
    Serial.println(F("Card Mount Failed"));
    return;
  }

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

  root = SD.open("/");
}

void loop() {
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);

  if (isFileSelected) {
    display.clearDisplay();
    display.setCursor(0, 0);
    display.print(F("Reading file: "));
    display.println(currentFileName);

    File file = SD.open(currentFileName);
    if (file) {
      while (file.available()) {
        String line = file.readStringUntil('\n');
        display.println(line);
      }
      file.close();
    }

    isFileSelected = false;
  } else {
    display.setCursor(0, 0);
    display.print(F("Select a file"));
  }

  display.display();
  delay(1000);
  display.clearDisplay();
}

void selectFile() {
  File entry = root.openNextFile();
  if (!entry) {
    root.rewindDirectory();
  } else {
    currentFileName = entry.name();
    isFileSelected = true;
  }
  entry.close();
  delay(500);  // Hindari multiple input dari tombol
}