#include <Arduino.h>

#define DATA_PIN 22 // Data Pin (DS)
#define CLOCK_PIN 23 // Clock Pin (SHCP)
#define LATCH_PIN 21 // Latch Pin (STCP)

void setup() {
  // Initialize the shift register pins as OUTPUT
  pinMode(DATA_PIN, OUTPUT);
  pinMode(CLOCK_PIN, OUTPUT);
  pinMode(LATCH_PIN, OUTPUT);

  // Set all LEDs initially on
  setAllLeds();
  delay(1000); // Delay for 1 second to display the initial state
}

void loop() {
  // Display a light pattern from left to right
  for (int i = 0; i < 8; i++) {
    setLed(i, HIGH); // Turn on LED i
    delay(2000);      // Delay for 200 milliseconds
    setLed(i, LOW);  // Turn off LED i
  }

  // Reset the pattern by turning off all LEDs
  setAllLeds();
  delay(1000); // Delay for 1 second before repeating the pattern
}

void setLed(int index, int state) {
  digitalWrite(LATCH_PIN, LOW);
  byte dataToSend = 0;

  // Set the state of the LED at the specified index
  bitWrite(dataToSend, index, state);
  
  // Send the data to the shift register
  for (int i = 7; i >= 0; i--) {
    digitalWrite(DATA_PIN, bitRead(dataToSend, i));
    digitalWrite(CLOCK_PIN, HIGH);
    digitalWrite(CLOCK_PIN, LOW);
  }
  
  digitalWrite(LATCH_PIN, HIGH);
}

void setAllLeds() {
  digitalWrite(LATCH_PIN, LOW);
  byte dataToSend = 0xFF; // Set all LEDs to HIGH
  
  // Send the data to the shift register
  for (int i = 7; i >= 0; i--) {
    digitalWrite(DATA_PIN, bitRead(dataToSend, i));
    digitalWrite(CLOCK_PIN, HIGH);
    digitalWrite(CLOCK_PIN, LOW);
  }
  
  digitalWrite(LATCH_PIN, HIGH);
}