#include <Adafruit_GFX.h>        // For drawing on OLED
#include <Adafruit_SSD1306.h>    // For OLED control

#define SCREEN_WIDTH 128         // OLED width in pixels
#define SCREEN_HEIGHT 64         // OLED height in pixels
#define OLED_RESET -1            // No reset pin needed
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET); // Create OLED object

// Mock time variables (simulating 9:00 AM, Sept 4, 2025)
unsigned long currentTime = 1725490800; // Epoch for 9:00 AM IST, Sept 4, 2025
int currentHour = 9;                    // Starting hour (12-hour format)
int currentMinute = 0;                  // Starting minute
bool isPM = false;                      // AM/PM flag

// Structure to hold user data (like a simple database)
struct User {
  String name;       // User's name
  int planDays;      // Membership days (5, 10, 30, or flexible)
  int daysUsed;      // Days used so far
  unsigned long lastVisit; // Last visit timestamp (in seconds)
};

// Example users (hardcoded for simulation – in real life, store in cloud)
User users[3] = {
  {"Alice", 5, 0, 0},    // 5-day plan
  {"Bob", 30, 2, 0},     // 30-day plan, already used 2 days
  {"Charlie", 15, 0, 0}  // Flexible 15-day plan
};

void setup() {
  Serial.begin(115200);  // Start serial monitor for debugging and mock input
  Serial.println("Project starting...");

  // Start OLED
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // 0x3C is common I2C address
    Serial.println("OLED failed to start!");
    while (true); // Stop if OLED fails
  }
  display.clearDisplay();
  display.setTextSize(1);      // Text size
  display.setTextColor(SSD1306_WHITE); // White text
  display.setCursor(0, 0);     // Start at top-left
  display.println("Ready to scan");
  display.display();           // Show on OLED
}

void loop() {
  // Mock time increment (simulate time passing, e.g., 1 second per loop)
  currentTime += 1;  // Add 1 second per loop (for testing, simulates time)
  currentMinute = (currentTime / 60) % 60;  // Update minutes
  currentHour = ((currentTime / 3600) % 24) % 12; // Update hours (12-hour format)
  if (currentHour == 0) currentHour = 12; // Fix 0 to 12 for AM/PM
  isPM = ((currentTime / 3600) % 24) >= 12; // AM/PM flag

  // Mock fingerprint scan: Type "scan:0" for Alice, "scan:1" for Bob, etc. in serial monitor
  if (Serial.available() > 0) {
    String input = Serial.readStringUntil('\n');
    input.trim();  // Remove extra spaces

    if (input.startsWith("scan:")) {
      int userId = input.substring(5).toInt();  // Get number after "scan:"
      if (userId >= 0 && userId < 3) {  // Check valid user
        User &user = users[userId];     // Get user

        // Check if it's a new day (more than 24 hours since last visit)
        if (currentTime - user.lastVisit >= 86400) {  // 86400 seconds = 1 day
          user.daysUsed++;
          user.lastVisit = currentTime;
        }

        // Check if membership is still valid
        if (user.daysUsed > user.planDays) {
          display.clearDisplay();
          display.setCursor(0, 0);
          display.println("Membership expired!");
          display.display();
          Serial.println("Expired for " + user.name);
          return;  // Don't proceed
        }

        // Show on OLED: "Thank you 3/30" (example for Bob)
        display.clearDisplay();
        display.setCursor(0, 0);
        display.print("Thank you ");
        display.print(user.daysUsed);
        display.print("/");
        display.println(user.planDays);
        display.display();

        // Get formatted time (like "9:00 AM")
        String hourStr = String(currentHour);
        String minuteStr = String(currentMinute < 10 ? "0" : "") + String(currentMinute);
        String amPm = isPM ? " PM" : " AM";
        String entryTime = hourStr + ":" + minuteStr + amPm;

        // Simulate sending to app (print to serial as if it's the owner's app)
        Serial.print("App receives (Owner's account): ");
        Serial.print("Time: ");
        Serial.print(entryTime);
        Serial.print(", Name: ");
        Serial.print(user.name);
        Serial.print(", Days: ");
        Serial.print(user.daysUsed);
        Serial.print("/");
        Serial.println(user.planDays);
      } else {
        Serial.println("Invalid user ID!");
      }
    }
  }
  delay(100);  // Small delay to not overload
}