Implementing database and allowlist system

Common/src/main/java/dev/brighten/antivpn/database/VPNDatabase.java

@@ -0,0 +1,28 @@
+package dev.brighten.antivpn.database;
+
+import dev.brighten.antivpn.utils.VPNResponse;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.UUID;
+import java.util.function.Consumer;
+
+public interface VPNDatabase {
+    Optional<VPNResponse> getStoredResponse(String ip);
+
+    void cacheResponse(VPNResponse toCache);
+
+    boolean isWhitelisted(UUID uuid);
+
+    void setWhitelisted(UUID uuid, boolean whitelisted);
+
+    List<UUID> getAllWhitelisted();
+
+    void getStoredResponseAsync(String ip, Consumer<Optional<VPNResponse>> result);
+
+    void isWhitelistedAsync(UUID uuid, Consumer<Boolean> result);
+
+    void init();
+
+    void shutdown();
+}