#include "qrcode.h" //https://github.com/ricmoo/qrcode/
#include <Adafruit_SSD1306.h>
// Color definitions
#define BLACK    0
#define WHITE    1

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
//### slc/sda d1/d2
#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);
Adafruit_SSD1306 display(128, 64, &Wire, -1);


QRCode qrcode;
int qr_version,xmax, ymax, xa, ya; 


void display_qrcode(char *text, int qr_version=2, int qr_quality =ECC_LOW, float scale=1) {   
// https://github.com/ricmoo/QRCode

    display.clearDisplay();
    //size maximum for one qrcode
    xmax= 64; ymax = 64;
    int inv = 0; 

    uint8_t qrcodeData[qrcode_getBufferSize(qr_version)]; //Version 4 114 byte 33x33 res QR code
    qrcode_initText(&qrcode, qrcodeData, qr_version, qr_quality, text);

//    scale = 2;
    xa = (xmax - qrcode.size * scale) / 2;
    ya = (ymax - qrcode.size * scale) / 2;
    inv = 1;
    display.fillRect(0, 0, xmax, ymax, abs(inv - BLACK));

    for (uint8_t y = 0; y < qrcode.size * scale; y = y + scale) {
        for (uint8_t x = 0; x < qrcode.size * scale; x = x + scale) {
            if (qrcode_getModule(&qrcode, x / scale, y / scale))

                display.fillRect(xa + x, ya + y, scale, scale, abs(inv - WHITE));
         }
    }
    xa = xa + xmax;
    inv = 0;

    display.fillRect(xmax, 0, xmax, ymax, abs(inv - BLACK));

    for (uint8_t y = 0; y < qrcode.size * scale; y = y + scale) {
        for (uint8_t x = 0; x < qrcode.size * scale; x = x + scale) {
            if (qrcode_getModule(&qrcode, x / scale, y / scale))

                display.fillRect(xa + x, ya + y, scale, scale, abs(inv - WHITE));
        }
    }
    display.display();
}

void setup_display(){
  // set display
  display.begin(SSD1306_SWITCHCAPVCC, 0x78>>1);
  display.dim(29);
} 

void setup() {
  setup_display();
  //display_qrcode("http://192.168.2.106", 1, ECC_HIGH, 3);
  display_qrcode("http://shorturl.at/oBN04", 3, ECC_LOW, 2);
  //display_qrcode(char *text, int qr_version=2, int qr_quality =ECC_LOW, float scale=1) 
//  display_qrcode("192.168.2.106", 2);
}

 
void loop() {
}