Simplify event result structure and add some convenience methods

api/src/main/java/com/velocitypowered/api/event/connection/PluginMessageEvent.java

@@ -20,7 +20,7 @@ import java.io.ByteArrayInputStream;
  * This event is fired when a plugin message is sent to the proxy, either from a client ({@link
  * Player}) or a server ({@link ServerConnection}).
  */
-public interface PluginMessageEvent extends ResultedEvent<PluginMessageEvent.ForwardResult> {
+public interface PluginMessageEvent extends ResultedEvent<ResultedEvent.GenericResult> {
 
   ChannelMessageSource source();
 
@@ -34,36 +34,11 @@ public interface PluginMessageEvent extends ResultedEvent<PluginMessageEvent.For
 
   ByteArrayDataInput messageAsDataInput();
 
-  /**
-   * A result determining whether or not to forward this message on.
-   */
-  public static final class ForwardResult implements Result {
-
-    private static final ForwardResult ALLOWED = new ForwardResult(true);
-    private static final ForwardResult DENIED = new ForwardResult(false);
-
-    private final boolean status;
-
-    private ForwardResult(boolean b) {
-      this.status = b;
-    }
-
-    @Override
-    public boolean isAllowed() {
-      return status;
-    }
-
-    @Override
-    public String toString() {
-      return status ? "forward to sink" : "handled message at proxy";
-    }
-
-    public static ForwardResult forward() {
-      return ALLOWED;
-    }
-
-    public static ForwardResult handled() {
-      return DENIED;
+  default void setHandled(boolean handled) {
+    if (handled) {
+      setResult(ResultedEvent.GenericResult.denied());
+    } else {
+      setResult(ResultedEvent.GenericResult.allowed());
     }
   }
 }

api/src/main/java/com/velocitypowered/api/event/connection/PluginMessageEventImpl.java

@@ -28,7 +28,7 @@ public final class PluginMessageEventImpl implements PluginMessageEvent {
   private final ChannelMessageSink target;
   private final PluginChannelId identifier;
   private final byte[] data;
-  private ForwardResult result;
+  private GenericResult result;
 
   /**
    * Creates a new instance.
@@ -44,16 +44,16 @@ public final class PluginMessageEventImpl implements PluginMessageEvent {
     this.target = Preconditions.checkNotNull(target, "target");
     this.identifier = Preconditions.checkNotNull(identifier, "identifier");
     this.data = Preconditions.checkNotNull(data, "data");
-    this.result = ForwardResult.forward();
+    this.result = GenericResult.allowed();
   }
 
   @Override
-  public ForwardResult result() {
+  public GenericResult result() {
     return result;
   }
 
   @Override
-  public void setResult(ForwardResult result) {
+  public void setResult(GenericResult result) {
     this.result = Preconditions.checkNotNull(result, "result");
   }
 

api/src/main/java/com/velocitypowered/api/event/player/KickedFromServerEvent.java

@@ -42,6 +42,33 @@ public interface KickedFromServerEvent extends
    */
   boolean kickedDuringServerConnect();
 
+  /**
+   * Handles the event by disconnecting the player with the specified {@code reason}.
+   *
+   * @param reason the reason for disconnecting the player
+   */
+  default void handleByDisconnecting(Component reason) {
+    setResult(DisconnectPlayer.create(reason));
+  }
+
+  /**
+   * Handles the event by falling back on the specified server.
+   *
+   * @param server the server to fall back to
+   */
+  default void handleByConnectingToServer(RegisteredServer server) {
+    setResult(RedirectPlayer.create(server));
+  }
+
+  /**
+   * Handles the event by giving the player the specified {@code reason}.
+   *
+   * @param reason the reason for being kicked
+   */
+  default void handleByNotifying(Component reason) {
+    setResult(Notify.create(reason));
+  }
+
   /**
    * Represents the base interface for {@link KickedFromServerEvent} results.
    */

api/src/main/java/com/velocitypowered/api/event/player/PreLoginEvent.java

@@ -7,124 +7,31 @@
 
 package com.velocitypowered.api.event.player;
 
-import com.google.common.base.Preconditions;
 import com.velocitypowered.api.event.ResultedEvent;
+import com.velocitypowered.api.event.ResultedEvent.ComponentResult;
 import com.velocitypowered.api.proxy.connection.InboundConnection;
-import java.util.Optional;
 import net.kyori.adventure.text.Component;
-import org.checkerframework.checker.nullness.qual.NonNull;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * This event is fired when a player has initiated a connection with the proxy but before the proxy
  * authenticates the player with Mojang or before the player's proxy connection is fully established
  * (for offline mode).
  */
-public interface PreLoginEvent extends ResultedEvent<PreLoginEvent.PreLoginComponentResult> {
+public interface PreLoginEvent extends ResultedEvent<ComponentResult> {
 
   InboundConnection connection();
 
   String username();
 
-  /**
-   * Represents an "allowed/allowed with forced online\offline mode/denied" result with a reason
-   * allowed for denial.
-   */
-  final class PreLoginComponentResult implements Result {
+  boolean onlineMode();
 
-    private static final PreLoginComponentResult ALLOWED = new PreLoginComponentResult(
-        Result.ALLOWED, null);
-    private static final PreLoginComponentResult FORCE_ONLINEMODE = new PreLoginComponentResult(
-        Result.FORCE_ONLINE, null);
-    private static final PreLoginComponentResult FORCE_OFFLINEMODE = new PreLoginComponentResult(
-        Result.FORCE_OFFLINE, null);
+  void setOnlineMode(boolean onlineMode);
 
-    private final Result result;
-    private final Component reason;
+  default void allow() {
+    setResult(ComponentResult.allowed());
+  }
 
-    private PreLoginComponentResult(Result result,
-        @Nullable Component reason) {
-      this.result = result;
-      this.reason = reason;
-    }
-
-    @Override
-    public boolean isAllowed() {
-      return result != Result.DISALLOWED;
-    }
-
-    public Optional<Component> denialReason() {
-      return Optional.ofNullable(reason);
-    }
-
-    public boolean isOnlineModeAllowed() {
-      return result == Result.FORCE_ONLINE;
-    }
-
-    public boolean isForceOfflineMode() {
-      return result == Result.FORCE_OFFLINE;
-    }
-
-    @Override
-    public String toString() {
-      switch (result) {
-        case ALLOWED:
-          return "allowed";
-        case FORCE_OFFLINE:
-          return "allowed with force offline mode";
-        case FORCE_ONLINE:
-          return "allowed with online mode";
-        default:
-          return "denied";
-      }
-    }
-
-    /**
-     * Returns a result indicating the connection will be allowed through the proxy.
-     *
-     * @return the allowed result
-     */
-    public static PreLoginComponentResult allowed() {
-      return ALLOWED;
-    }
-
-    /**
-     * Returns a result indicating the connection will be allowed through the proxy, but the
-     * connection will be forced to use online mode provided that the proxy is in offline mode. This
-     * acts similarly to {@link #allowed()} on an online-mode proxy.
-     *
-     * @return the result
-     */
-    public static PreLoginComponentResult forceOnlineMode() {
-      return FORCE_ONLINEMODE;
-    }
-
-    /**
-     * Returns a result indicating the connection will be allowed through the proxy, but the
-     * connection will be forced to use offline mode even when the proxy is running in online mode.
-     *
-     * @return the result
-     */
-    public static PreLoginComponentResult forceOfflineMode() {
-      return FORCE_OFFLINEMODE;
-    }
-
-    /**
-     * Denies the login with the specified reason.
-     *
-     * @param reason the reason for disallowing the connection
-     * @return a new result
-     */
-    public static PreLoginComponentResult denied(Component reason) {
-      Preconditions.checkNotNull(reason, "reason");
-      return new PreLoginComponentResult(Result.DISALLOWED, reason);
-    }
-
-    private enum Result {
-      ALLOWED,
-      FORCE_ONLINE,
-      FORCE_OFFLINE,
-      DISALLOWED
-    }
+  default void reject(Component component) {
+    setResult(ComponentResult.denied(component));
   }
 }

api/src/main/java/com/velocitypowered/api/event/player/PreLoginEventImpl.java

@@ -20,17 +20,20 @@ public final class PreLoginEventImpl implements PreLoginEvent {
 
   private final InboundConnection connection;
   private final String username;
-  private PreLoginComponentResult result;
+  private ComponentResult result;
+  private boolean onlineMode;
 
   /**
    * Creates a new instance.
    * @param connection the connection logging into the proxy
    * @param username the player's username
+   * @param onlineMode whether or not the connection is online mode
    */
-  public PreLoginEventImpl(InboundConnection connection, String username) {
+  public PreLoginEventImpl(InboundConnection connection, String username, boolean onlineMode) {
     this.connection = Preconditions.checkNotNull(connection, "connection");
     this.username = Preconditions.checkNotNull(username, "username");
-    this.result = PreLoginComponentResult.allowed();
+    this.onlineMode = onlineMode;
+    this.result = ComponentResult.allowed();
   }
 
   @Override
@@ -44,12 +47,22 @@ public final class PreLoginEventImpl implements PreLoginEvent {
   }
 
   @Override
-  public PreLoginComponentResult result() {
+  public boolean onlineMode() {
+    return this.onlineMode;
+  }
+
+  @Override
+  public void setOnlineMode(boolean onlineMode) {
+    this.onlineMode = onlineMode;
+  }
+
+  @Override
+  public ComponentResult result() {
     return result;
   }
 
   @Override
-  public void setResult(@NonNull PreLoginComponentResult result) {
+  public void setResult(@NonNull ComponentResult result) {
     this.result = Preconditions.checkNotNull(result, "result");
   }
 

api/src/main/java/com/velocitypowered/api/event/player/ServerPreConnectEvent.java

@@ -37,6 +37,10 @@ public interface ServerPreConnectEvent extends ResultedEvent<ServerPreConnectEve
    */
   RegisteredServer originalTarget();
 
+  default void reject() {
+    setResult(ServerResult.DENIED);
+  }
+
   /**
    * Represents the result of the {@link ServerPreConnectEvent}.
    */

proxy/src/main/java/com/velocitypowered/proxy/connection/client/LoginSessionHandler.java

@@ -25,6 +25,7 @@ import static com.velocitypowered.proxy.util.EncryptionUtils.decryptRsa;
 import static com.velocitypowered.proxy.util.EncryptionUtils.generateServerId;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.event.ResultedEvent.ComponentResult;
 import com.velocitypowered.api.event.permission.PermissionsSetupEventImpl;
 import com.velocitypowered.api.event.player.DisconnectEvent.LoginStatus;
 import com.velocitypowered.api.event.player.DisconnectEventImpl;
@@ -35,7 +36,6 @@ import com.velocitypowered.api.event.player.PlayerChooseInitialServerEvent;
 import com.velocitypowered.api.event.player.PlayerChooseInitialServerEventImpl;
 import com.velocitypowered.api.event.player.PostLoginEventImpl;
 import com.velocitypowered.api.event.player.PreLoginEvent;
-import com.velocitypowered.api.event.player.PreLoginEvent.PreLoginComponentResult;
 import com.velocitypowered.api.event.player.PreLoginEventImpl;
 import com.velocitypowered.api.permission.PermissionFunction;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
@@ -180,7 +180,8 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
     if (login == null) {
       throw new IllegalStateException("No ServerLogin packet received yet.");
     }
-    PreLoginEvent event = new PreLoginEventImpl(inbound, login.getUsername());
+    PreLoginEvent event = new PreLoginEventImpl(inbound, login.getUsername(),
+        server.configuration().isOnlineMode());
     server.eventManager().fire(event)
         .thenRunAsync(() -> {
           if (mcConnection.isClosed()) {
@@ -188,16 +189,15 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
             return;
           }
 
-          PreLoginComponentResult result = event.result();
-          Optional<Component> disconnectReason = result.denialReason();
+          ComponentResult result = event.result();
+          Optional<Component> disconnectReason = result.reason();
           if (disconnectReason.isPresent()) {
             // The component is guaranteed to be provided if the connection was denied.
             inbound.disconnect(disconnectReason.get());
             return;
           }
 
-          if (!result.isForceOfflineMode() && (server.configuration().isOnlineMode() || result
-              .isOnlineModeAllowed())) {
+          if (event.onlineMode()) {
             // Request encryption.
             ClientboundEncryptionRequestPacket request = generateEncryptionRequest();
             this.verify = Arrays.copyOf(request.getVerifyToken(), 4);