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

#define SCREEN_WIDTH 128 // OLED width, in pixels
#define SCREEN_HEIGHT 32 // OLED height, in pixels
#define GRAPH_X 60
#define GRAPH_Y 8
#define GRAPH_WIDTH 36
#define FILL_WIDTH 32
#define GRAPH_HEIGHT 15

// Create an OLED display object connected to I2C
Adafruit_SSD1306 oled(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

const float Vref = 5.0; // VCC Board

void setup() {
  Serial.begin(9600); // Initialize serial communication
  delay(1000);
  oled.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  oled.clearDisplay(); // Clear the display buffer
  oled.display(); // Display the cleared buffer
  oled.setTextSize(2);         // Set text size
  oled.setTextColor(WHITE);    // Set text color
  oled.setCursor(1, 8);       // Set position to display (x,y)
  oled.println("ATG LOADER"); // Set text
  oled.display();              // Display on OLED
  delay(2000); // Wait 2 seconds for loading screen
  
}

void loop() {
  int batteryLevel = analogRead(A0); // Battery Voltage
  int lower = 640; //raw A0 voltage reading
  int upper = 840; //raw A0 voltage reading
  if (batteryLevel > upper) batteryLevel = upper;
  else if (batteryLevel < lower) batteryLevel = lower;
  int batteryPercent = map(batteryLevel, lower, upper, 0, 100);
  float v = (float) (analogRead(A0) * Vref / 1023);   // calculate voltage
  int graphWidth = batteryPercent / 100.0 * FILL_WIDTH;
  oled.clearDisplay();
// Battery Indicator  
  oled.drawRect(GRAPH_X, GRAPH_Y, GRAPH_WIDTH, GRAPH_HEIGHT, SSD1306_WHITE); 
  oled.fillRect(62, 10, graphWidth, 11, SSD1306_WHITE); // Battery Indicator
  oled.fillRect(96, 12, 4, 7, SSD1306_WHITE); // Battery Indicator
// Battery Percent
  oled.setTextColor(SSD1306_WHITE);
  oled.setTextSize(2);
  oled.setCursor(1, 9);
  oled.print(batteryPercent);
  oled.print("%");
  oled.setCursor(48, 9);
  oled.print("|");
// Battery Voltage  
  oled.setTextSize(1);
  oled.setCursor(104, 12);
  oled.setTextColor(SSD1306_WHITE);
  oled.print(v,1);
  oled.print("v");
  oled.display();
  delay(5000);
  }