/*
  Wokwi | projects
  HELP! me make rfid attendence system with

  SKINNN Friday, November 28, 2025 9:24 AM
  never mind done with it on my own
  https://wokwi.com/projects/448874581428084737
*/

// -------------------- Libraries --------------------
#include <Wire.h>               // For I2C Communication (RTC & LCD)
#include <RTClib.h>             // For RTC Module (DS3231)
#include <LiquidCrystal_I2C.h>  // For 16x2 I2C LCD
#include <Servo.h>

// -------------------- Pin Definitions --------------------
#define GRN_LED_PIN 7   // Digital Pin for Green LED (Access Granted)
#define RED_LED_PIN 6   // Digital Pin for Red LED (Access Denied)
#define BUZZER_PIN  5   // Digital Pin for 5V Buzzer
#define SERVO_PIN   2

// -------------------- Objects --------------------
LiquidCrystal_I2C lcd(0x27, 16, 2);
RTC_DS3231 rtc;
Servo servo;

// -------------------- Student Data --------------------
// Structure to hold student UID and Name
struct Student {
  String uid;
  String name;
};

// Define your authorized students here:
const Student authorizedStudents[] = {
  {"BD 31 15 2B", "Student 1"},
  {"C1 4A 92 1F", "Student 2"},
  {"88 77 66 55", "Student 3"}
};
const int NUM_STUDENTS = sizeof(authorizedStudents) / sizeof(authorizedStudents[0]);

// -------------------- Functions --------------------

// Function to check if the scanned UID is authorized
String checkAuthorization(String inputUID) {
  for (int i = 0; i < NUM_STUDENTS; i++) {
    // Compare the input UID (case-insensitive) against the stored UIDs
    if (inputUID.equalsIgnoreCase(authorizedStudents[i].uid)) {
      return authorizedStudents[i].name; // Found a match, return the name
    }
  }
  return ""; // No match found
}

void accessGranted(String studentName) {
  DateTime now = rtc.now();
  Serial.print("✅ Access Granted for: ");
  Serial.print(studentName);
  Serial.print(" at ");
  char timeBuff[9];
  snprintf(timeBuff, 9, "%02d:%02d:%02d", now.hour(), now.minute(), now.second());
  Serial.println(timeBuff);
  // Visual/Audio Feedback
  digitalWrite(GRN_LED_PIN, HIGH);
  tone(BUZZER_PIN, 1000, 200); // 1KHz beep for 200ms
  // Display on LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("WELCOME");
  lcd.setCursor(0, 1);
  lcd.print(studentName);
  servo.write(90);
  delay(2000); // Keep message displayed for 2 seconds
  servo.write(0);
  digitalWrite(GRN_LED_PIN, LOW);
  noTone(BUZZER_PIN);
}

void accessDenied(String uid) {
  Serial.print("❌ Access Denied. UID: ");
  Serial.println(uid);
  // Visual/Audio Feedback
  digitalWrite(RED_LED_PIN, HIGH);
  tone(BUZZER_PIN, 500, 500); // 500Hz beep for 500ms
  // Display on LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("WRONG ID!");
  lcd.setCursor(0, 1);
  lcd.print("ACCESS DENIED");
  delay(2000); // Keep message displayed for 2 seconds
  digitalWrite(RED_LED_PIN, LOW);
  noTone(BUZZER_PIN);
}

void handleSerialInput() {
  if (Serial.available() > 0) {
    String inputUID = Serial.readStringUntil('\n');
    inputUID.trim();

    Serial.print("\n--- Card Scan Simulated --- ");

    String studentName = checkAuthorization(inputUID);

    if (studentName != "") {
      accessGranted(studentName);
    } else {
      accessDenied(inputUID);
    }
  }
}

// -------------------- Main Logic --------------------

void setup() {
  Serial.begin(9600);
  Wire.begin();
  // Initialize LCD
  lcd.init();
  lcd.backlight();
  // Initialize RTC
  if (!rtc.begin()) {
    Serial.println("Couldn't find RTC! Please check I2C wiring (A4/A5).");
  }
  // OPTIONAL: Uncomment the line below ONCE to set the RTC time to the compile time.
  // rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  servo.attach(SERVO_PIN);
  // Initialize Pins
  pinMode(GRN_LED_PIN, OUTPUT);
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(SERVO_PIN, OUTPUT);
  servo.write(0);
  // Set initial display
  lcd.setCursor(0, 0);
  lcd.print("RFID ATTENDANCE");
  lcd.setCursor(4, 1);
  lcd.print("Ready...");
  Serial.println("\n--- WOKWI SIMULATION READY ---");
  Serial.println("Enter a student UID (e.g., BD 31 15 2B) and press Enter to scan.");
  delay(2000);
}

void loop() {
  // 1. Handle Serial Input
  handleSerialInput();
  // 2. Display the clock and "SCAN CARD" prompt when the system is idle
  char buffer[17];
  DateTime now = rtc.now();
  snprintf(buffer, 17, "%2d/%2d/%4d %2d:%02d", now.month(), now.day(), now.year(), now.hour(), now.minute());
  lcd.setCursor(0, 0);
  lcd.print(buffer);
  // Display prompt on bottom line
  lcd.setCursor(0, 1);
  lcd.print("  SCAN CARD... ");
}