#include <Arduino.h>

#define DATA_PIN  5   // SER pin of the 74HC595
#define CLOCK_PIN 19  // SRCLK pin of the 74HC595
#define LATCH_PIN 18  // RCLK pin of the 74HC595

// Define row pins connected directly to the ESP32
#define ROW1_PIN  35
#define ROW2_PIN  32
#define ROW3_PIN  33

void setup() {
  // Initialize shift register pins
  pinMode(DATA_PIN, OUTPUT);
  pinMode(CLOCK_PIN, OUTPUT);
  pinMode(LATCH_PIN, OUTPUT);
  
  // Initialize row pins as inputs with internal pull-ups
  pinMode(ROW1_PIN, INPUT_PULLUP);
  pinMode(ROW2_PIN, INPUT_PULLUP);
  pinMode(ROW3_PIN, INPUT_PULLUP);
    
  Serial.begin(115200);
}

void loop() {
  // Loop through each column
  for (int col = 0; col < 8; col++) {
    setColumn(col); // Set the specific column LOW
    
    // Check each row to detect key presses
    for (int row = 0; row < 3; row++) {
      int rowPin = getRowPin(row); // Get the specific row pin
      if (isKeyPressed(rowPin)) {  // Use the helper function to check if key is pressed
        int keyNumber = (row * 8) + col + 1; // Calculate key number
        Serial.printf("Key %d is pressed\n", keyNumber);
      }
    }
  }
  delay(50); // Small delay for debounce
}

void setColumn(int col) {
  byte data = 0xFF; // Start with all HIGH

  // Set the specific column to LOW
  data &= ~(1 << col);

  shiftOutData(data); // Send the data to the shift register
}

void shiftOutData(byte data) {
  digitalWrite(LATCH_PIN, LOW);
  shiftOut(DATA_PIN, CLOCK_PIN, MSBFIRST, data); // Send data to shift register
  digitalWrite(LATCH_PIN, HIGH);
}

bool isKeyPressed(int rowPin) {
  return digitalRead(rowPin) == LOW; // Return true if the key is pressed (LOW)
}

int getRowPin(int row) {
  switch (row) {
    case 0: return ROW1_PIN;
    case 1: return ROW2_PIN;
    case 2: return ROW3_PIN;
    default: return -1; // Invalid row
  }
}