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

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

int selectedItem = 0;

int up = 7;
int ok = 6;
int down = 5;


void setup() {
  Serial.begin(115200);
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  delay(1000);
  display.clearDisplay();

  int i = 0;

  while (i < 2) {
    display.setTextSize(2);
    display.setTextColor(WHITE);
    display.setCursor(10, 15);
    display.println("AutoCart");
    display.display();
    display.startscrollright(0x00, 0x0F);
    delay(1000);
    display.stopscroll();
    delay(100);
    display.startscrollleft(0x00, 0x0F);
    delay(1000);
    i++;
  }
  display.setTextSize(1);
  display.setCursor(0, 10);
  display.stopscroll();
  display.clearDisplay();

  display.setCursor(5, 0);
  display.setTextColor(BLACK,WHITE);
  display.println("Total Amount :- ");
  display.display();

  pinMode(up, INPUT_PULLUP);
  pinMode(ok, INPUT_PULLUP);
  pinMode(down, INPUT_PULLUP);

}

void loop() {
  String arr[] = {"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"};
  int size = sizeof(arr) / sizeof(arr[0]);
  printList(arr, size);
  checkButtons(size);
}


void checkButtons(int size) {
  if (digitalRead(down) == LOW && selectedItem < size - 1) {
    display.clearDisplay();
    selectedItem++;
    delay(100);
  }
  if (digitalRead(up) == LOW  && selectedItem > 0) {
    display.clearDisplay();
    selectedItem--;
    delay(100);
  }
}


void printList(String arr[], int size) {
  for (int i = 0; i < size; i++) {
    display.setCursor(5, 0);
    display.setTextColor(BLACK,WHITE);
    display.println("Total Amount :- ");
    display.setCursor(0, i * 10 + 11);
    display.setTextColor(WHITE);
    display.println((i == selectedItem) ? "> " + arr[i] : "  " + arr[i]);
  }
  display.display();
}