// Forum:
//   https://forum.arduino.cc/t/more-than-one-shift-is-not-executed-arduino-uno/1085899

#include <LiquidCrystal.h>

#define dataPin 4   // Pin for data input to 74HC595 shifter
#define latchPin 3  // Pin for latch signal to 74HC595 shifter
#define clockPin 2  // Pin for clock signal to 74HC595 shifter

#define buttonLeft 5   // Pin for the left button
#define buttonRight 6  // Pin for the right button

#define rs 12  // RS pin of the LCD
#define en 11  // Enable pin of the LCD
#define d4 10  // D4 pin of the LCD
#define d5 9   // D5 pin of the LCD
#define d6 8
#define d7 7   // D7 pin of the LCD

// Initialize the LCD with the defined pins
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

byte currentValue = 0;  // Current value of LEDs

int buttonLeftValue = 0;
int buttonRightValue = 0;

int buttonLeftOldValue = 0;
int buttonRightOldValue = 0;

int stateLeft = 0;
int stateRight = 0;

void setup() {
  // Set the input/output modes for the pins
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
  pinMode(buttonLeft, INPUT);
  pinMode(buttonRight, INPUT);
  lcd.begin(16, 2);
  lcd.print("000");
}

void loop() {
  int analogValue = analogRead(A0);                      // Read the analog value from the potentiometer
  int digitalValue = map(analogValue, 0, 1023, 0, 256);  // Map the analog value to a digital value between 1 and 255

  buttonLeftValue = digitalRead(buttonLeft);    // Read the input value of the left button and store it
  buttonRightValue = digitalRead(buttonRight);  // Read the input value of the right button and store it

  // If the digital value has changed
  if (digitalValue != currentValue) {
    currentValue = digitalValue;                          // Update the current value
    digitalWrite(latchPin, LOW);                          // Set latchPin to LOW
    shiftOut(dataPin, clockPin, LSBFIRST, currentValue);  // Send the data
    digitalWrite(latchPin, HIGH);                         // Set latchPin to HIGH to transfer the data to the output pins
    lcd.setCursor(7, 0);
    char buffer[5];
    sprintf(buffer, "%03d", currentValue);
    lcd.print(buffer);  // Print the value on the LCD
  }

  // If the left button is pressed and its old value was LOW
  if ((buttonLeftValue == HIGH) && (buttonLeftOldValue == LOW)) {
    stateLeft = abs(1 - stateLeft);  // Change the state of the left button
    delay(50);                       // Add a delay to avoid accidental multiple presses
  }

  buttonLeftOldValue = buttonLeftValue;

  // If the state of the left button is 1 (pressed)
  if (stateLeft == 1) {
    currentValue = currentValue << 1;                     // Perform left shift
    if (currentValue > 255) currentValue = 0;             // Set the value to 0 if it exceeds 255
    digitalWrite(latchPin, LOW);                          // Set latchPin to LOW
    shiftOut(dataPin, clockPin, LSBFIRST, currentValue);  // Send the data
    digitalWrite(latchPin, HIGH);                         // Set latchPin to HIGH to transfer the data to the output pins
    lcd.setCursor(7, 0);
    char buffer[5];
    sprintf(buffer, "%03d", currentValue);
    lcd.print(buffer);
    delay(200);  // Add a delay to avoid accidental multiple presses
  }
  // If the left button is pressed and its old value was LOW
  if ((buttonRightValue == HIGH) && (buttonRightOldValue == LOW)) {
    stateRight = abs(1 - stateRight);  // Change the state of the left button
    delay(50);                         // Add a delay to avoid accidental multiple presses
  }
  buttonRightOldValue = buttonRightValue;

  // If the state of the right button is pressed
  if (stateRight == 1) {
    currentValue = currentValue >> 1;                     // Perform left shift
    digitalWrite(latchPin, LOW);                          // Set latchPin to LOW
    shiftOut(dataPin, clockPin, LSBFIRST, currentValue);  // Send the data
    digitalWrite(latchPin, HIGH);                         // Set latchPin to HIGH to transfer the data to the output pins
    lcd.setCursor(7, 0);
    char buffer[5];
    sprintf(buffer, "%03d", currentValue);
    lcd.print(buffer);
    delay(200);  // add delay
  }
}