#include <WiFi.h>               // For WiFi connectivity (ESP32 / Arduino WiFi library)
#include <PubSubClient.h>       // For MQTT functions
#include <SPI.h>                // For RFID (MFRC522) and possibly LCD
#include <MFRC522.h>            // For RFID
#include <Wire.h>               // For I2C LCD
#include <LiquidCrystal_I2C.h>  // For the 20x4 I2C LCD

// ---------------------
// RFID and LCD Definitions
// ---------------------
#define SS_PIN 10
#define RST_PIN 9
MFRC522 mfrc522(SS_PIN, RST_PIN);       // Create MFRC522 instance
LiquidCrystal_I2C MyLCD(0x27, 20, 4);   // I2C LCD at address 0x27, 20 columns, 4 rows

// ---------------------
// WiFi Settings
// ---------------------
const char* ssid = "Wokwi-GUEST";       // Replace with your WiFi SSID
const char* password = "";   // Replace with your WiFi Password

// ---------------------
// MQTT Settings
// ---------------------
const char* mqttServer = "192.168.1.100";  // MQTT broker IP or hostname
const int   mqttPort   = 1883;             // MQTT broker port (default: 1883)
WiFiClient wifiClient;                     // WiFi client for PubSubClient
PubSubClient client(wifiClient);           // Wrap the WiFi client in PubSubClient

// ---------------------
// Function Prototypes
// ---------------------
void setupWiFi();
void reconnectMQTT();

// ---------------------
// Arduino Setup
// ---------------------
void setup() {
  // Initialize Serial
  Serial.begin(9600);

  // Initialize LCD
  MyLCD.init();
  MyLCD.backlight();

  // Initialize SPI and RFID
  SPI.begin();
  mfrc522.PCD_Init();

  // Print startup messages to Serial and LCD
  Serial.println("RFID Based Passport - WiFi & MQTT");
  Serial.println("Scan your card to the RFID reader...");
  Serial.println();

  MyLCD.setCursor(0, 0);
  MyLCD.print("RFID Passport via WiFi");
  MyLCD.setCursor(0, 1);
  MyLCD.print("   Scan Your Card ");
  MyLCD.setCursor(0, 2);
  MyLCD.print(" To The RFID Reader");

  // Connect to WiFi
  setupWiFi();

  // Initialize MQTT
  client.setServer(mqttServer, mqttPort);
}

// ---------------------
// Arduino Main Loop
// ---------------------
void loop() {
  // Ensure we stay connected to MQTT
  if (!client.connected()) {
    reconnectMQTT();
  }
  client.loop();  // Process incoming MQTT messages (if subscribed) and keep the connection alive

  // Check for a new RFID card
  if (!mfrc522.PICC_IsNewCardPresent()) {
    return;
  }

  // Select one of the cards
  if (!mfrc522.PICC_ReadCardSerial()) {
    return;
  }

  // Read the UID and convert it to a String
  Serial.print("UID tag: ");
  String content = "";
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    Serial.print(mfrc522.uid.uidByte[i], HEX);
    content.concat(String(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " "));
    content.concat(String(mfrc522.uid.uidByte[i], HEX));
  }
  Serial.println();

  // Convert the UID string to uppercase
  content.toUpperCase();
  Serial.print("Message: ");
  Serial.println(content);

  // Publish the UID to MQTT
  client.publish("rfid/uid", content.c_str());

  // Check if the UID is the authorized one
  if (content.substring(1) == "BD 31 15 2B") {  
    Serial.println("Authorized access");
    client.publish("rfid/access", "Authorized");
  } else {
    Serial.println("Access denied");
    client.publish("rfid/access", "Denied");
  }
  Serial.println();

  // Delay to let the user see the result
  delay(3000);
}

// ---------------------
// WiFi Setup
// ---------------------
void setupWiFi() {
  // Begin WiFi connection
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);
  Serial.print(WiFi.status());
  // Wait until connected
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  // Print local IP
  Serial.println();
  Serial.println("WiFi connected. IP address: ");
  Serial.println(WiFi.localIP());
}

// ---------------------
// MQTT Reconnection
// ---------------------
void reconnectMQTT() {
  // Keep trying to connect until successful
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection... ");
    // Attempt to connect (clientID must be unique on the broker)
    if (client.connect("ArduinoRFIDClient")) {
      Serial.println("connected to MQTT!");
      // Optionally, subscribe to topics if needed:
      // client.subscribe("some/topic");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" -> trying again in 5 seconds");
      delay(5000);  // Retry after 5 seconds
    }
  }
}