#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Keypad.h>
#include <RTClib.h>
#include <SPI.h>
#include <SD.h>
#include <ESP32Servo.h>

// ======================= OLED CONFIG =======================
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// ======================= RTC CONFIG ========================
RTC_DS1307 rtc;

// ======================= SERVO CONFIG ======================
Servo gateServo;
#define SERVO_PIN 14
#define SERVO_OPEN 90
#define SERVO_CLOSED 0

// ======================= SD CARD CONFIG ====================
#define SD_CS 5

// ======================= KEYPAD CONFIG =====================
const byte ROWS = 4;
const byte COLS = 4;

// Keypad layout
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

// Updated safe GPIO mapping for ESP32
byte rowPins[ROWS] = {26, 27, 25, 15};  // R1, R2, R3, R4
byte colPins[COLS] = {16, 17, 34, 35};  // C1, C2, C3, C4 (input only)

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// ======================= GLOBAL VARIABLES ==================
String lastRFID = "";   // To store simulated RFID input
bool adminMode = false; // Admin mode toggle

// ======================= FUNCTIONS =========================

// Display message on OLED
void displayMessage(String line1, String line2) {
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0, 0);
  display.println(line1);
  display.setCursor(0, 20);
  display.println(line2);
  display.display();
}

// Log attendance to SD card
void logAttendance(String rfidTag) {
  if (!rtc.isrunning()) {
    displayMessage("RTC ERROR!", "Check DS1307");
    return;
  }

  DateTime now = rtc.now();
  String timestamp = String(now.year()) + "-" + 
                     String(now.month()) + "-" + 
                     String(now.day()) + " " + 
                     String(now.hour()) + ":" + 
                     String(now.minute()) + ":" + 
                     String(now.second());

  File file = SD.open("/attendance.txt", FILE_APPEND);
  if (file) {
    file.println(rfidTag + "," + timestamp);
    file.close();
    displayMessage("Access Granted", "Logged Successfully");
    Serial.println("Logged: " + rfidTag + " at " + timestamp);
  } else {
    displayMessage("SD ERROR!", "Check SD Card");
  }
}

// Open and close servo gate
void openGate() {
  gateServo.write(SERVO_OPEN);
  delay(2000);  // Keep gate open for 2 seconds
  gateServo.write(SERVO_CLOSED);
}

// Reset attendance data
void resetAttendanceData() {
  if (SD.exists("/attendance.txt")) {
    SD.remove("/attendance.txt");
    displayMessage("Admin Mode", "Data Reset Done");
    Serial.println("Attendance log file deleted.");
  } else {
    displayMessage("Admin Mode", "No Data Found");
    Serial.println("No data to reset.");
  }
  delay(1500);
}

// View logs in serial monitor
void viewLogs() {
  displayMessage("Logs:", "Check Serial Monitor");
  File file = SD.open("/attendance.txt");
  if (file) {
    Serial.println("----- Attendance Logs -----");
    while (file.available()) {
      Serial.write(file.read());
    }
    Serial.println("\n----------------------------");
    file.close();
  } else {
    Serial.println("No logs found.");
  }
  delay(2000);
}

// ======================= SETUP =============================
void setup() {
  Serial.begin(115200);

  // OLED initialization
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("SSD1306 allocation failed");
    for (;;); // Stop here if OLED fails
  }
  displayMessage("Initializing...", "");

  // RTC initialization
  if (!rtc.begin()) {
    displayMessage("RTC ERROR", "Check DS1307");
    Serial.println("Couldn't find RTC module!");
    while (1);
  }
  if (!rtc.isrunning()) {
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__))); // Set to compile time
  }

  // Servo initialization
  gateServo.attach(SERVO_PIN);
  gateServo.write(SERVO_CLOSED);

  // SD Card initialization
  if (!SD.begin(SD_CS)) {
    displayMessage("SD ERROR", "Check wiring");
    Serial.println("SD Card initialization failed!");
  } else {
    Serial.println("SD Card initialized successfully.");
  }

  displayMessage("System Ready", "Scan Your RFID");
  Serial.println("System initialized and ready.");
}

// ======================= LOOP ==============================
void loop() {
  char key = keypad.getKey();

  if (key) {
    Serial.print("Key Pressed: ");
    Serial.println(key);

    if (adminMode) {
      // Admin Mode Menu
      if (key == 'A') {
        viewLogs();
      } else if (key == 'B') {
        resetAttendanceData();
      } else if (key == 'C') {
        adminMode = false;
        displayMessage("Admin Mode", "Exited");
        delay(1000);
      }
    } else {
      // Normal User Mode
      if (key == '#') {
        adminMode = true;
        displayMessage("Admin Mode", "A:View B:Reset C:Exit");
      } else {
        // Simulate RFID scan using keypad input
        lastRFID += key;
        displayMessage("Scanning...", lastRFID);

        // Assuming a valid tag has 4 digits
        if (lastRFID.length() >= 4) {
          logAttendance(lastRFID);
          openGate();
          lastRFID = ""; // Reset for next scan
          displayMessage("System Ready", "Scan Next");
          delay(1000);
        }
      }
    }
  }
}