#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)
#define OLED_RESET    -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define NUM_PINS 16
const uint8_t pins[NUM_PINS] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, A0, A1, A2, A3}; // Assign digital inputs to pins

void setup() {
  Serial.begin(115200); // Start serial communication at 115200 baud rate

  // Initialize OLED display
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    // SSD1306 allocation failed
    for (;;); // Don't proceed, loop forever
  }
  display.clearDisplay();
  display.setTextSize(1);      // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE); // Draw white text
  display.setCursor(0, 0);     // Start at top-left corner
  display.display();

  for (uint8_t i = 0; i < NUM_PINS; i++) {
    if (pins[i] <= 7) {
      DDRD |= (1 << pins[i]); // Set pins 2-7 as output
    } else if (pins[i] <= 13) {
      DDRB |= (1 << (pins[i] - 8)); // Set pins 8-13 as output
    } else {
      DDRC |= (1 << (pins[i] - 14)); // Set pins A0-A3 as output
    }
  }
}

void loop() {
  static char inputString[17]; // Buffer for 16 characters plus null terminator
  static byte index = 0; // Index for buffer

  while (Serial.available() > 0) {
    char c = Serial.read();
    if (c == '\n') { // Newline character indicates end of input
      inputString[index] = '\0'; // Null-terminate the string
      if (index == 8) { // Check if the input length is 8 characters
        display.clearDisplay();
        display.setCursor(0, 0);
        display.print(inputString); // Display the string on the OLED
        display.display();
      } else if (index == 16) { // Check if the input length is 16 characters
        for (int i = 0; i < 16; i++) {
          if (inputString[i] == '1') {
            if (pins[i] <= 7) {
              PORTD |= (1 << pins[i]);
            } else if (pins[i] <= 13) {
              PORTB |= (1 << (pins[i] - 8));
            } else {
              PORTC |= (1 << (pins[i] - 14));
            }
          } else {
            if (pins[i] <= 7) {
              PORTD &= ~(1 << pins[i]);
            } else if (pins[i] <= 13) {
              PORTB &= ~(1 << (pins[i] - 8));
            } else {
              PORTC &= ~(1 << (pins[i] - 14));
            }
          }
        }
      }
      index = 0; // Reset index for next input
    } else if (index < 16) {
      inputString[index++] = c; // Add character to buffer if within bounds
    } else {
      index = 0; // Reset index if input length exceeds 16 characters
      while (Serial.available() > 0) {
        Serial.read(); // Clear the buffer to remove excess characters
      }
    }
  }
}