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

int sensorValue = 0;
int previousPercentage = -1; // To store the previous percentage value

void setup() {
  pinMode(A0, INPUT);
  
  // Initialize the SSD1306 display with I2C address 0x3C
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  
  // Set up the text color
  display.setTextColor(SSD1306_WHITE);
  
  // Display startup messages
  display.clearDisplay();
  // Draw the border around the screen
  display.drawRect(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, SSD1306_WHITE);
  display.setTextSize(3);
  display.setCursor((SCREEN_WIDTH - 87) / 2, 7); // Center "System On"
  display.println(F("Power"));
  display.setTextSize(3);
  display.setCursor((SCREEN_WIDTH - 83) / 1, 35);
  display.println(F("On"));
  display.display();
  delay(2000);  
  display.clearDisplay();
}

void loop() {
  // Read the potentiometer value and convert to percentage
  sensorValue = analogRead(A0);
  int percentage = map(sensorValue, 0, 1023, 0, 100);
  
  // Update the percentage on the OLED only if it has changed
  if (percentage != previousPercentage) {
    display.clearDisplay();

    // Draw the border around the screen
    display.drawRect(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, SSD1306_WHITE);

    // Draw a horizontal line between "Master Volume" and the percentage
    display.drawLine(0, 18, SCREEN_WIDTH, 18, SSD1306_WHITE);

    // Display "Master Volume" at the top
    display.setTextSize(1); // Set text size to 1
    display.setCursor((SCREEN_WIDTH - 85) / 2, 6); // Center "Master Volume"
    display.println(F("Master Volume"));
    
    // Display the percentage in larger text at the bottom
    display.setTextSize(4); // Set text size to 4
    display.setCursor((SCREEN_WIDTH - 70) / 2, 28); // Center the percentage text at the bottom
    display.print(percentage);
    display.print(F("%"));
    
    display.display();
    previousPercentage = percentage;
  }

  delay(20); // Short delay to improve response time
}