Add new authentication system

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

@@ -0,0 +1,101 @@
+package emu.grasscutter.auth;
+
+import emu.grasscutter.server.http.objects.*;
+import express.http.Request;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+
+import javax.annotation.Nullable;
+
+/**
+ * Defines an authenticator for the server.
+ * Can be changed by plugins.
+ */
+public interface AuthenticationSystem {
+    
+    /**
+     * Called when a user requests to make an account.
+     * @param username The provided username.
+     * @param password The provided password. (SHA-256'ed)
+     */
+    void createAccount(String username, String password);
+
+    /**
+     * Called when a user requests to reset their password.
+     * @param username The username of the account to reset.
+     */
+    void resetPassword(String username);
+
+    /**
+     * This is the authenticator used for password authentication.
+     * @return An authenticator.
+     */
+    Authenticator<LoginResultJson> getPasswordAuthenticator();
+
+    /**
+     * This is the authenticator used for token authentication.
+     * @return An authenticator.
+     */
+    Authenticator<LoginResultJson> getTokenAuthenticator();
+
+    /**
+     * This is the authenticator used for session authentication.
+     * @return An authenticator.
+     */
+    Authenticator<ComboTokenResJson> getSessionKeyAuthenticator();
+
+    /**
+     * A data container that holds relevant data for authenticating a client.
+     * Call {@link AuthenticationRequest#builder()} to create a builder.
+     */
+    @Builder @AllArgsConstructor @Getter
+    class AuthenticationRequest {
+        private final Request request;
+        @Nullable private final LoginAccountRequestJson passwordRequest;
+        @Nullable private final LoginTokenRequestJson tokenRequest;
+        @Nullable private final ComboTokenReqJson sessionKeyRequest;
+        @Nullable private final ComboTokenReqJson.LoginTokenData sessionKeyData;
+    }
+
+    /**
+     * Generates an authentication request from a {@link LoginAccountRequestJson} object.
+     * @param request The Express request.
+     * @param jsonData The JSON data.
+     * @return An authentication request.
+     */
+    static AuthenticationRequest fromPasswordRequest(Request request, LoginAccountRequestJson jsonData) {
+        return AuthenticationRequest.builder()
+                .request(request)
+                .passwordRequest(jsonData)
+                .build();
+    }
+
+    /**
+     * Generates an authentication request from a {@link LoginTokenRequestJson} object.
+     * @param request The Express request.
+     * @param jsonData The JSON data.
+     * @return An authentication request.
+     */
+    static AuthenticationRequest fromTokenRequest(Request request, LoginTokenRequestJson jsonData) {
+        return AuthenticationRequest.builder()
+                .request(request)
+                .tokenRequest(jsonData)
+                .build();
+    }
+
+    /**
+     * Generates an authentication request from a {@link ComboTokenReqJson} object.
+     * @param request The Express request.
+     * @param jsonData The JSON data.
+     * @return An authentication request.
+     */
+    static AuthenticationRequest fromComboTokenRequest(Request request, ComboTokenReqJson jsonData, 
+                                                       ComboTokenReqJson.LoginTokenData tokenData) {
+        return AuthenticationRequest.builder()
+                .request(request)
+                .sessionKeyRequest(jsonData)
+                .sessionKeyData(tokenData)
+                .build();
+    }
+}