/*
  Tag format: 1 JSON-formatted text record:
 {
 name: username,
 room: room number (long int),
 checkin: checkin time (unix time, long int),
 checkout: checkout time (unix time, long int),
 }
 */

// Uncomment the SEEED or ADAFRUIT sections below based on which shield you are using

// SEEED STUDIO
//#include <SPI.h>
//#include <PN532_SPI.h>
//#include <PN532.h>
//#include <NfcAdapter.h>
//#include <Time.h>
//
//PN532_SPI pn532spi(SPI, 10);
//NfcAdapter nfc = NfcAdapter(pn532spi);
// end SEEED STUDIO

// ADAFRUIT
#include <Wire.h>
#include <PN532_I2C.h>
#include <PN532.h>
#include <NfcAdapter.h>
#include <Time.h>

PN532_I2C pn532_i2c(Wire);
NfcAdapter nfc = NfcAdapter(pn532_i2c);
// end ADAFRUIT

const int greenLed = 9;         // pin for the green LED
const int redLed = 8;           // pin for the red LED

String inputString = "";        // string for input from serial port
long lightOnTime = 0;           // last time the LEDs were turned on, in ms

boolean readyToWrite = false;   // true when you are ready to write to NFC tag

void setup() {
  Serial.begin(9600);           // initialize serial communications
  nfc.begin();                  // initialize NfcAdapter
  pinMode(greenLed, OUTPUT);    // make pin 9 an output
  pinMode(redLed, OUTPUT);      // make pin 8 an output
}

void loop() {
  // if there's incoming data, read it into a string:
  while (Serial.available() > 0) {
    char thisChar = Serial.read();
    // add incoming character to the end of inputString:
    inputString += thisChar; 
    if (thisChar == '{') {
      // new message, reset buffer
      inputString = "{";
      readyToWrite = false;
    } 
    else if (thisChar == '}') {
      // end of message, ready to write to tag
      Serial.println("Ready to write data to tag");
      readyToWrite = true;
    }
  }
  // keep looking for a tag to write to when
  // you've got a string to write:
  if (readyToWrite) {
    lookForTag();  
  }

  if (millis() - lightOnTime > 3000 ) {   // check every three seconds
    digitalWrite(greenLed, LOW);          // turn off pin 9
    digitalWrite(redLed, LOW);            // turn off pin 8
  }
}

void lookForTag() {
  if (nfc.tagPresent()) {                 // if there's a tag present
    NdefMessage message;                  // make a new NDEF message
    // add the input string as a record:
    message.addMimeMediaRecord("text/hotelkey", inputString); 
    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.");  
      digitalWrite(redLed, LOW);          // turn off the failure light if on
      digitalWrite(greenLed, HIGH);       // turn on the success light
      lightOnTime = millis();
      readyToWrite = false;               // clear write flag
    } 
    else {
      // let the desktop app know you failed:
      Serial.println("Result: failed to write to tag"); 
      digitalWrite(greenLed, LOW);       // turn off the success light if on
      digitalWrite(redLed, HIGH);        // turn on the failure light
      lightOnTime = millis();
    }
  }
}