#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 TEXT_LEFT       0
#define TEXT_CENTER     1
#define TEXT_RIGHT      2

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
// The pins for I2C are defined by the Wire-library. 
// On an arduino UNO:       A4(SDA), A5(SCL)
// On an arduino MEGA 2560: 20(SDA), 21(SCL)
// On an arduino LEONARDO:   2(SDA),  3(SCL), ...
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);


void drawTextAlign(const String &buf, int row_top, int alignment)
{
    int16_t x1, y1;
    uint16_t w, h;
    
    display.setTextWrap(false);
    display.getTextBounds(buf, 0, row_top, &x1, &y1, &w, &h); //calc width of new string

    if (alignment == TEXT_RIGHT)
      display.setCursor(SCREEN_WIDTH - w, row_top);
    else
    if (alignment == TEXT_CENTER)
      display.setCursor((SCREEN_WIDTH - w)/2, row_top);
    else
    if (alignment == TEXT_LEFT)
      display.setCursor(0, row_top);

    display.print(buf);
}

void setup()
{
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");

  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS))
  {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);    // Don't proceed, loop forever
  }
  display.clearDisplay();     // first delete buffer content
}

void loop()
{
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);

  display.clearDisplay();
  drawTextAlign("Hello World",  0, TEXT_LEFT);
  drawTextAlign("2023",  8, TEXT_LEFT);
  display.display();
  delay(1000);

  display.clearDisplay();
  drawTextAlign("Hello World",  0, TEXT_CENTER);
  drawTextAlign("2023",  8, TEXT_CENTER);
  display.display();
  delay(1000);

  display.clearDisplay();
  drawTextAlign("Hello World",  0, TEXT_RIGHT);
  drawTextAlign("2023",  8, TEXT_RIGHT);
  display.display();
  delay(1000);
}