#include <SPI.h>
#include <RFID.h>
#include <Servo.h>

RFID rfid(10, 4);       //D10:pin of tag reader SDA. D9:pin of tag reader RST
unsigned char status;
unsigned char str[MAX_LEN]; //MAX_LEN is 16: size of the array

String accessGranted [2] = {"310988016", "271011115139"};  //RFID serial numbers to grant access to
int accessGrantedSize = 2;                                //The number of serial numbers

Servo lockServo;                //Servo for locking mechanism
int lockPos = 15;               //Locked position limit
int unlockPos = 400;   //Unlocked position limit
bool locked = true;

int redLEDPin = 5;
int greenLEDPin = 6;

void setup()
{
  Serial.begin(9600);     //Serial monitor is only required to get tag ID numbers and for troubleshooting
  SPI.begin();            //Start SPI communication with reader
  rfid.init();            //initialization
  pinMode(redLEDPin, OUTPUT);     //LED startup sequence
  pinMode(greenLEDPin, OUTPUT);
  digitalWrite(redLEDPin, HIGH);
  delay(200);
  digitalWrite(greenLEDPin, HIGH);
  delay(200);
  digitalWrite(redLEDPin, LOW);
  delay(200);
  digitalWrite(greenLEDPin, LOW);
  lockServo.attach(8);
  lockServo.write(lockPos);         //Move servo into locked position
  Serial.println("Place card/tag near reader...");
}

void loop()
{
  if (rfid.findCard(PICC_REQIDL, str) == MI_OK)   //Wait for a tag to be placed near the reader
  {
    Serial.println("Card found");
    String temp = "";                             //Temporary variable to store the read RFID number
    if (rfid.anticoll(str) == MI_OK)              //Anti-collision detection, read tag serial number
    {
      Serial.print("The card's ID number is : ");
      for (int i = 0; i < 4; i++)                 //Record and display the tag serial number
      {
        temp = temp + (0x0F & (str[i] >> 4));
        temp = temp + (0x0F & str[i]);
      }
      Serial.println (temp);
      checkAccess (temp);     //Check if the identified tag is an allowed to open tag
    }
    rfid.selectTag(str); //Lock card to prevent a redundant read, removing the line will make the sketch read cards continually
  }
  rfid.halt();
}

void checkAccess (String temp)    //Function to check if an identified tag is registered to allow access
{
  bool granted = false;
  for (int i=0; i <= (accessGrantedSize-1); i++)    //Runs through all tag ID numbers registered in the array
  {
    if(accessGranted[i] == temp)            //If a tag is found then open/close the lock
    {
      Serial.println ("Access Granted");
      granted = true;
      if (locked == true)         //If the lock is closed then open it
      {
          lockServo.write(unlockPos);
          locked = false;
      }
      else if (locked == false)   //If the lock is open then close it
      {
          lockServo.write(lockPos);
          locked = true;
      }
      digitalWrite(greenLEDPin, HIGH);    //Green LED sequence
      delay(200);
      digitalWrite(greenLEDPin, LOW);
      delay(200);
      digitalWrite(greenLEDPin, HIGH);
      delay(200);
      digitalWrite(greenLEDPin, LOW);
      delay(200);
    }
  }
  if (granted == false)     //If the tag is not found
  {
    Serial.println ("Access Denied");
    for (int blinks = 0; blinks < 2; blinks++){
      digitalWrite(redLEDPin, HIGH);      //Red LED sequence
      delay(200);
      digitalWrite(redLEDPin, LOW);
      delay(200);
    }
  }
}