Add OAuth in AuthenticationSystem

src/main/java/emu/grasscutter/auth/OAuthAuthenticator.java

@@ -0,0 +1,28 @@
+package emu.grasscutter.auth;
+
+import emu.grasscutter.auth.AuthenticationSystem.AuthenticationRequest;
+
+/**
+ * Handles authentication via OAuth routes.
+ */
+public interface OAuthAuthenticator {
+
+    /**
+     * Called when an OAuth login request is made.
+     * @param request The authentication request.
+     */
+    void handleLogin(AuthenticationRequest request);
+
+    /**
+     * Called when an client requests to redirect to login page.
+     * @param request The authentication request.
+     */
+    void handleDesktopRedirection(AuthenticationRequest request);
+    void handleMobileRedirection(AuthenticationRequest request);
+
+    /**
+     * Called when an OAuth login requests callback.
+     * @param request The authentication request.
+     */
+    void handleTokenProcess(AuthenticationRequest request);
+}