#include <Wire.h>
#include <PN532_I2C.h>
#include <PN532.h>
#include <NfcAdapter.h>

PN532_I2C pn532_i2c(Wire);
NfcAdapter nfc = NfcAdapter(pn532_i2c);

#define Content_Type "text/admin"

String string2write = "myUsername";

#define LED_PIN 8         // pin for the LED

boolean already_write = false;

void setup() {
  Serial.begin(9600);           // initialize serial communications
  nfc.begin();                  // initialize NfcAdapter
  pinMode(LED_PIN, OUTPUT);      // make the led pin an output
  digitalWrite(LED_PIN, HIGH);    // set it low turn off the led

  Serial.println("Ready to write data to tag");

}

void loop() {
  if (nfc.tagPresent() && !already_write) {                 // if there's a tag present
    digitalWrite(LED_PIN, LOW);       // turn off the success light if on
    delay(100);
    digitalWrite(LED_PIN, HIGH);       // turn off the success light if on
    NdefMessage message;                  // make a new NDEF message
    // add the input string as a record:
    message.addMimeMediaRecord(Content_Type, string2write);
    boolean success = nfc.write(message); // attempt to write to the tag

    if (success) {
      // let the desktop app know you succeeded:
      Serial.println("Result: tag written.");
      already_write = true;
      digitalWrite(LED_PIN, LOW);       // turn off the success light if on
    }
    else {
      // let the desktop app know you failed:
      Serial.println("Result: failed to write to tag");
    }

  }

  delay(1000);
}