RFID Smart Door Access

#include <Arduino.h>
#include <SPI.h>
#include <Wire.h>
#include <WiFi.h>
#include <HTTPClient.h>
#include <WiFiClientSecure.h>
#include <MFRC522.h>
#include <LiquidCrystal_I2C.h>
#include <ESP32Servo.h>
#include <Preferences.h>
#include <time.h>


// Forward declarations
String uidToString(const MFRC522::Uid &uid);
void showMessage(const String &line1, const String &line2);
void beep(unsigned int ms);
void startWiFi();
void maintainWiFi();
void logScanToGoogleSheet(const String &uid, const String &result);
String currentTimestamp();
void lockDoor(bool announce);
void unlockDoor();
void denyAccess();

constexpr char WIFI_SSID[] = "IPhone 5s";
constexpr char WIFI_PASSWORD[] = "1234567890";
constexpr char GOOGLE_SCRIPT_URL[] = "https://script.google.com/macros/s/AKfycbyDitjRo6nuP5iI0ySkcBCJDonuQdhfz68IBGGZKU9PeMGLiAVGJkK66xaCuCws-noP/exec";
constexpr uint8_t RFID_SS_PIN = 4, RFID_RST_PIN = 26, RFID_SCK_PIN = 18, RFID_MISO_PIN = 19, RFID_MOSI_PIN = 23;
constexpr uint8_t LCD_SDA_PIN = 21, LCD_SCL_PIN = 22, SERVO_PIN = 25, BUZZER_PIN = 33;
constexpr int LOCK_ANGLE = 10, UNLOCK_ANGLE = 90;
constexpr unsigned long UNLOCK_TIME_MS = 5000, CARD_COOLDOWN_MS = 1200, WIFI_RETRY_MS = 10000;

MFRC522 rfid(RFID_SS_PIN, RFID_RST_PIN);
LiquidCrystal_I2C lcd(0x27, 16, 2);
Servo latchServo;
Preferences preferences;
String enrolledUid, lastMessage;
unsigned long unlockStartedAt = 0, lastCardAt = 0, lastWiFiAttemptAt = 0;
bool doorUnlocked = false;

String uidToString(const MFRC522::Uid &uid) {
  String value;
  for (byte i = 0; i < uid.size; ++i) { if (uid.uidByte[i] < 0x10) value += "0"; value += String(uid.uidByte[i], HEX); }
  value.toUpperCase();
  return value;
}
void showMessage(const String &line1, const String &line2) {
  String message = line1 + "\n" + line2;
  if (message == lastMessage) return;
  lastMessage = message;
  lcd.clear(); lcd.setCursor(0, 0); lcd.print(line1.substring(0, 16));
  lcd.setCursor(0, 1); lcd.print(line2.substring(0, 16));
}
void beep(unsigned int ms) { digitalWrite(BUZZER_PIN, HIGH); delay(ms); digitalWrite(BUZZER_PIN, LOW); }
void startWiFi() {
  if (WiFi.status() == WL_CONNECTED) return;
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  lastWiFiAttemptAt = millis();
}
void maintainWiFi() {
  if (WiFi.status() != WL_CONNECTED && millis() - lastWiFiAttemptAt >= WIFI_RETRY_MS) startWiFi();
}
String currentTimestamp() {
  struct tm timeInfo;
  if (!getLocalTime(&timeInfo, 1000)) return "";
  char buffer[25];
  strftime(buffer, sizeof(buffer), "%Y-%m-%dT%H:%M:%SZ", &timeInfo);
  return String(buffer);
}
void logScanToGoogleSheet(const String &uid, const String &result) {
  if (WiFi.status() != WL_CONNECTED) { Serial.println("Sheet not updated: Wi-Fi disconnected."); return; }
  WiFiClientSecure client;
  client.setInsecure();
  HTTPClient http;
  String url = String(GOOGLE_SCRIPT_URL) + "?uid=" + uid + "&result=" + result + "&timestamp=" + currentTimestamp();
  http.setFollowRedirects(HTTPC_STRICT_FOLLOW_REDIRECTS);
  http.setConnectTimeout(5000);
  http.setTimeout(5000);
  if (http.begin(client, url)) { Serial.printf("Google Sheet response: %d\n", http.GET()); http.end(); }
}
void lockDoor(bool announce = true) {
  latchServo.write(LOCK_ANGLE); doorUnlocked = false;
  if (announce) showMessage("Door locked", "Present card");
}
void unlockDoor() {
  latchServo.write(UNLOCK_ANGLE); doorUnlocked = true; unlockStartedAt = millis();
  showMessage("Access granted", "Door unlocked"); beep(90); delay(70); beep(90);
}
void denyAccess() { showMessage("Access denied", "Unknown card"); beep(600); }

void setup() {
  Serial.begin(115200);
  pinMode(BUZZER_PIN, OUTPUT); digitalWrite(BUZZER_PIN, LOW);
  Wire.begin(LCD_SDA_PIN, LCD_SCL_PIN); lcd.init(); lcd.backlight(); showMessage("Smart Door", "Starting...");
  latchServo.setPeriodHertz(50); latchServo.attach(SERVO_PIN, 500, 2400); lockDoor(false);
  SPI.begin(RFID_SCK_PIN, RFID_MISO_PIN, RFID_MOSI_PIN, RFID_SS_PIN); rfid.PCD_Init();
  preferences.begin("door-access", false); enrolledUid = preferences.getString("adminUid", "");
  WiFi.mode(WIFI_STA); startWiFi();
  configTime(0, 0, "pool.ntp.org", "time.nist.gov"); // UTC time from the internet.
  if (enrolledUid.length() == 0) showMessage("Enroll first card", "Scan RFID card");
  else showMessage("Door locked", "Present card");
}
void loop() {
  maintainWiFi();
  if (doorUnlocked && millis() - unlockStartedAt >= UNLOCK_TIME_MS) lockDoor();
  if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial()) return;
  if (millis() - lastCardAt < CARD_COOLDOWN_MS) { rfid.PICC_HaltA(); rfid.PCD_StopCrypto1(); return; }
  lastCardAt = millis();
  String scannedUid = uidToString(rfid.uid);
  if (enrolledUid.length() == 0) {
    enrolledUid = scannedUid; preferences.putString("adminUid", enrolledUid);
    showMessage("Card enrolled", "Scan to unlock"); beep(120); delay(80); beep(120);
    logScanToGoogleSheet(scannedUid, "Enrolled");
  } else if (scannedUid == enrolledUid) { unlockDoor(); logScanToGoogleSheet(scannedUid, "Granted"); }
  else { denyAccess(); logScanToGoogleSheet(scannedUid, "Denied"); }
  rfid.PICC_HaltA(); rfid.PCD_StopCrypto1();
}