#include <Wire.h>
#include <U8glib.h>
#include <qrcode.h>

#define OLED_WIDTH 128
#define OLED_HEIGHT 64

U8GLIB_SH1106_128X64 u8g(U8G_I2C_OPT_NONE);

void setup() {
  u8g.begin();
  u8g.setFont(u8g_font_unifont);
}

void loop() {
  // UPI payment parameters
  const char* payeeVPA = "abhishekgn985@okaxis";    // Replace with the payee's VPA
  double amount = 50.00;            // Replace with the payment amount as a double
  const char* currency = "INR";            // Replace with the currency code
  
  // Generate and display the QR code for UPI payment
  displayQRCode(payeeVPA, amount, currency);
  delay(5000); // Display for 5 seconds before generating a new QR code
}

void displayQRCode(const char* payeeVPA, double amount, const char* currency) {
  // Construct the UPI payment link
  String upiLink = "upi://pay?pa=" + String(payeeVPA) + "&am=" + String(amount, 2) + "&cu=" + String(currency); // 2 decimal places for the amount
  QRCode qrcode;
  uint8_t qrcodeData[qrcode_getBufferSize(3)];
  qrcode_initText(&qrcode, qrcodeData, 3, 0, upiLink.c_str());
  int scale = min(OLED_WIDTH / qrcode.size, OLED_HEIGHT / qrcode.size);
  int shiftX = (OLED_WIDTH - qrcode.size * scale) / 2;
  int shiftY = (OLED_HEIGHT - qrcode.size * scale) / 2;
  u8g.firstPage();
  do {
    drawQRCode(qrcode, scale, shiftX, shiftY);
  } while (u8g.nextPage());
}

void drawQRCode(QRCode &qrcode, int scale, int shiftX, int shiftY) {
  for (uint8_t y = 0; y < qrcode.size; y++) {
    for (uint8_t x = 0; x < qrcode.size; x++) {
      if (qrcode_getModule(&qrcode, x, y)) {
        u8g.drawBox(x * scale + shiftX, y * scale + shiftY, scale, scale);
      }
    }
  }
}