// #include <SPI.h>
// funziona
#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     4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

void setup() {
  
  Serial.begin(9600);

  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }
  
  // Show initial display buffer contents on the screen --
  // the library initializes this with an Adafruit splash screen.
  display.display();
  delay(10); // Pause for 2 seconds
  
  display.setTextSize(3);             // Draw 2X-scale text
  display.setTextColor(SSD1306_WHITE);
  display.clearDisplay();
  waiting (10,59);
  
}

void waiting (int t_delay, int start)
{
  int i=start;
  long tmp,tsec;
  t_delay*=1000;
  tmp=millis();
  tsec=tmp;
  do
  { if( (millis()-tsec)>1000 ) 
    { tsec=millis();
      display.clearDisplay();
      for(int16_t j=21; j<35; j+=3) 
      { display.drawCircle(64, 32, j, SSD1306_WHITE);
        display.display();
      }
    
      display.setCursor(48,22);
      if (i<10) display.print(F("0"));
      display.print(i);
      i--;
      display.display();
    }
    delay(100);
  } while((millis()-tmp)<t_delay);
} 

void loop() {
}

void drawcircle(void) {
  


}

void testdrawchar(void) {
  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.cp437(true);         // Use full 256 char 'Code Page 437' font

  // Not all the characters will fit on the display. This is normal.
  // Library will draw what it can and the rest will be clipped.
  for(int16_t i=0; i<256; i++) {
    if(i == '\n') display.write(' ');
    else          display.write(i);
  }

  display.display();
  delay(800);
}

void testdrawstyles(void) {
  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.println(F("Hello, world!")); display.println("");

  display.setTextColor(SSD1306_BLACK, SSD1306_WHITE); // Draw 'inverse' text
  display.println(3.141592);display.println("");

  display.setTextSize(2);             // Draw 2X-scale text
  display.setTextColor(SSD1306_WHITE);
  display.print(F("0x")); display.println(0xDEADBEEF, HEX);

  display.display();
  delay(1200);
}