[BREAKING] Refactor OAuth handler

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

@@ -131,16 +131,4 @@ public interface AuthenticationSystem {
         return AuthenticationRequest.builder().request(request)
                 .response(response).build();
     }
-
-
-    /**
-     * Generates an authentication request from a {@link Response} object.
-     * @param request The Express request.
-     * @param jsonData The JSON data.
-     * @return An authentication request.
-     */
-    static AuthenticationRequest fromOAuthRequest(Request request, Response response) {
-        return AuthenticationRequest.builder().request(request)
-                .response(response).build();
-    }
 }

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

@@ -14,15 +14,22 @@ public interface OAuthAuthenticator {
     void handleLogin(AuthenticationRequest request);
 
     /**
-     * Called when an client requests to redirect to login page.
+     * Called when a client requests to redirect to login page.
      * @param request The authentication request.
      */
-    void handleDesktopRedirection(AuthenticationRequest request);
-    void handleMobileRedirection(AuthenticationRequest request);
+    void handleRedirection(AuthenticationRequest request, ClientType clientType);
 
     /**
      * Called when an OAuth login requests callback.
      * @param request The authentication request.
      */
     void handleTokenProcess(AuthenticationRequest request);
+
+    /**
+     * The type of the client.
+     * Used for handling redirection.
+     */
+    enum ClientType {
+        DESKTOP, MOBILE
+    }
 }

src/main/java/emu/grasscutter/server/http/dispatch/DispatchHandler.java

@@ -2,6 +2,8 @@ package emu.grasscutter.server.http.dispatch;
 
 import emu.grasscutter.Grasscutter;
 import emu.grasscutter.auth.AuthenticationSystem;
+import emu.grasscutter.auth.OAuthAuthenticator;
+import emu.grasscutter.auth.OAuthAuthenticator.ClientType;
 import emu.grasscutter.server.http.Router;
 import emu.grasscutter.server.http.objects.*;
 import emu.grasscutter.server.http.objects.ComboTokenReqJson.LoginTokenData;
@@ -34,13 +36,15 @@ public final class DispatchHandler implements Router {
         express.post("/authentication/change_password", (request, response) -> Grasscutter.getAuthenticationSystem().getExternalAuthenticator()
                 .handlePasswordReset(AuthenticationSystem.fromExternalRequest(request, response)));
 
-        // OAuth login
-        express.post("/hk4e_global/mdk/shield/api/loginByThirdparty", (request, response) -> Grasscutter.getAuthenticationSystem().getOAuthAuthenticator().handleLogin(AuthenticationSystem.fromOAuthRequest(request, response)));
-        // OAuth querystring convert redirection
-        express.get("/authentication/openid/redirect", (request, response) -> Grasscutter.getAuthenticationSystem().getOAuthAuthenticator().handleTokenProcess(AuthenticationSystem.fromOAuthRequest(request, response)));
-        // OAuth redirection
-        express.get("/Api/twitter_login", (request, response) -> Grasscutter.getAuthenticationSystem().getOAuthAuthenticator().handleDesktopRedirection(AuthenticationSystem.fromOAuthRequest(request, response)));
-        express.get("/sdkTwitterLogin.html", (request, response) -> Grasscutter.getAuthenticationSystem().getOAuthAuthenticator().handleMobileRedirection(AuthenticationSystem.fromOAuthRequest(request, response)));
+        // External login (from OAuth2).
+        express.post("/hk4e_global/mdk/shield/api/loginByThirdparty", (request, response) -> Grasscutter.getAuthenticationSystem().getOAuthAuthenticator()
+                .handleLogin(AuthenticationSystem.fromExternalRequest(request, response)));
+        express.get("/authentication/openid/redirect", (request, response) -> Grasscutter.getAuthenticationSystem().getOAuthAuthenticator()
+                .handleTokenProcess(AuthenticationSystem.fromExternalRequest(request, response)));
+        express.get("/Api/twitter_login", (request, response) -> Grasscutter.getAuthenticationSystem().getOAuthAuthenticator()
+                .handleRedirection(AuthenticationSystem.fromExternalRequest(request, response), ClientType.DESKTOP));
+        express.get("/sdkTwitterLogin.html", (request, response) -> Grasscutter.getAuthenticationSystem().getOAuthAuthenticator()
+                .handleRedirection(AuthenticationSystem.fromExternalRequest(request, response), ClientType.MOBILE));
     }
 
     /**