#include <ctype.h>

const int SR_DATA_PIN  = PA0; 
const int SR_LATCH_PIN = PA1; 
const int SR_CLOCK_PIN = PA2; 
const int BTN_NEXT = PB10;     
const int BTN_PREV = PB11;     

const int NUM_CELLS = 6; 
String fileContent = "BRAILLE TEST"; 
int currentIndex = 0;

const uint8_t brailleLUT[26] = {
  0b000001, 0b000011, 0b001001, 0b011001, 0b010001, 0b001011, 0b011011, 0b010011,
  0b001010, 0b011010, 0b000101, 0b000111, 0b001101, 0b011101, 0b010101,
  0b001111, 0b011111, 0b010111, 0b001110, 0b011110, 0b100101, 0b100111,
  0b111010, 0b101101, 0b111101, 0b110101
};

uint8_t charToBraille(char c) {
  c = tolower(c);
  if (c >= 'a' && c <= 'z') return brailleLUT[c - 'a'];
  return 0x00; 
}

void updateDisplay() {
  digitalWrite(SR_LATCH_PIN, LOW);
  for (int i = 5; i >= 0; i--) {
    int charIdx = currentIndex + i;
    char c = (charIdx < fileContent.length()) ? fileContent[charIdx] : ' ';
    shiftOut(SR_DATA_PIN, SR_CLOCK_PIN, MSBFIRST, charToBraille(c));
  }
  digitalWrite(SR_LATCH_PIN, HIGH);
}

void setup() {
  pinMode(SR_DATA_PIN, OUTPUT);
  pinMode(SR_LATCH_PIN, OUTPUT);
  pinMode(SR_CLOCK_PIN, OUTPUT);
  pinMode(BTN_NEXT, INPUT_PULLUP);
  pinMode(BTN_PREV, INPUT_PULLUP);
  updateDisplay();
}

void loop() {
  if (digitalRead(BTN_NEXT) == LOW) {
    delay(200); 
    if (currentIndex + 6 < fileContent.length()) currentIndex += 6;
    updateDisplay();
    while(digitalRead(BTN_NEXT) == LOW);
  }
  if (digitalRead(BTN_PREV) == LOW) {
    delay(200); 
    if (currentIndex - 6 >= 0) currentIndex -= 6;
    else currentIndex = 0;
    updateDisplay();
    while(digitalRead(BTN_PREV) == LOW);
  }
}