Implemented Server Password feature

src/main/java/hu/ditservices/handlers/LoginCommandHandler.java

@@ -0,0 +1,62 @@
+package hu.ditservices.handlers;
+
+import hu.ditservices.STPlugin;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandExecutor;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+
+import java.util.UUID;
+
+public class LoginCommandHandler implements CommandExecutor {
+
+    private final STPlugin plugin;
+
+    public LoginCommandHandler(STPlugin instance) {
+        this.plugin = instance;
+    }
+
+    // Method to authenticate the player
+    public boolean authenticate(Player player, String password) {
+        if (plugin.getServerPasswordData().getServerPassword().equals(password)) {
+            if (plugin.getConfig().getBoolean("ServerPassword.preventInventory")) {
+                player.getInventory().setContents(plugin.getServerPasswordData().getInventoryMap().get(player.getUniqueId()));
+                player.getInventory().setArmorContents(plugin.getServerPasswordData().getArmorMap().get(player.getUniqueId()));
+            }
+            plugin.getServerPasswordData().getAuthenticatedPlayers().put(player.getUniqueId(), true);
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
+        if (!(sender instanceof Player)) {
+            sender.sendMessage("Only players can execute this command.");
+            return true;
+        }
+
+        Player player = (Player) sender;
+        UUID pUuid = player.getUniqueId();
+
+        if (args.length != 1) {
+            player.sendMessage("Usage: /slogin <PASSWORD>");
+            return true;
+        }
+
+        if (plugin.getServerPasswordData().getAuthenticatedPlayers().getOrDefault(pUuid,false)) {
+            player.sendMessage("You are already authenticated.");
+            return true;
+        }
+
+        if (this.authenticate(player, args[0])) {
+            player.sendMessage("You have been authenticated.");
+            plugin.getServerPasswordData().getInventoryMap().remove(pUuid);
+            plugin.getServerPasswordData().getArmorMap().remove(pUuid);
+        } else {
+            player.sendMessage("Incorrect password. Try again.");
+        }
+        return true;
+    }
+}
+