chore: refactor packet registration

proxy/src/main/java/com/velocitypowered/proxy/protocol/PacketMapper.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2018-2023 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol;
+
+import com.velocitypowered.api.network.ProtocolVersion;
+import org.jspecify.annotations.Nullable;
+
+interface PacketMapper {
+  default void readWrite(final int id, final ProtocolVersion from) {
+    this.readWrite(id, from, null);
+  }
+
+  void readWrite(final int id, final ProtocolVersion from, final @Nullable ProtocolVersion to);
+
+  default void writeOnly(final int id, final ProtocolVersion from) {
+    this.writeOnly(id, from, null);
+  }
+
+  void writeOnly(final int id, final ProtocolVersion from, final @Nullable ProtocolVersion to);
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/PacketMapping.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2018-2023 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol;
+
+import com.velocitypowered.api.network.ProtocolVersion;
+import org.jspecify.annotations.Nullable;
+
+/**
+ * Packet mapping.
+ */
+public record PacketMapping(
+    int id,
+    ProtocolVersion from,
+    @Nullable ProtocolVersion to,
+    boolean writeOnly
+) {
+}

proxy/src/test/java/com/velocitypowered/proxy/protocol/PacketRegistryTest.java

@@ -45,10 +45,11 @@ class PacketRegistryTest {
   private StateRegistry.PacketRegistry setupRegistry() {
     StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(
         ProtocolUtils.Direction.CLIENTBOUND, StateRegistry.PLAY);
-    registry.register(HandshakePacket.class, HandshakePacket::new,
+    registry.register(HandshakePacket.class, HandshakePacket::new, m -> {
-        new StateRegistry.PacketMapping(0x01, MINECRAFT_1_8, null, false),
+      m.readWrite(0x01, MINECRAFT_1_8, null);
-        new StateRegistry.PacketMapping(0x00, MINECRAFT_1_12, null, false),
+      m.readWrite(0x00, MINECRAFT_1_12, null);
-        new StateRegistry.PacketMapping(0x00, MINECRAFT_1_15, MINECRAFT_1_16, false));
+      m.readWrite(0x00, MINECRAFT_1_15, MINECRAFT_1_16);
+    });
     return registry;
   }
 
@@ -86,7 +87,7 @@ class PacketRegistryTest {
     StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(
         ProtocolUtils.Direction.CLIENTBOUND, StateRegistry.PLAY);
     assertThrows(IllegalArgumentException.class,
-        () -> registry.register(HandshakePacket.class, HandshakePacket::new));
+        () -> registry.register(HandshakePacket.class, HandshakePacket::new, m -> {}));
     assertThrows(IllegalArgumentException.class,
         () -> registry.getProtocolRegistry(ProtocolVersion.UNKNOWN)
                 .getPacketId(new HandshakePacket()));
@@ -97,54 +98,62 @@ class PacketRegistryTest {
     StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(
         ProtocolUtils.Direction.CLIENTBOUND, StateRegistry.PLAY);
     assertThrows(IllegalArgumentException.class,
-        () -> registry.register(HandshakePacket.class, HandshakePacket::new,
+        () -> registry.register(HandshakePacket.class, HandshakePacket::new, m -> {
-            new StateRegistry.PacketMapping(0x01, MINECRAFT_1_13, null, false),
+          m.readWrite(0x01, MINECRAFT_1_13, null);
-            new StateRegistry.PacketMapping(0x00, MINECRAFT_1_8, null, false)));
+          m.readWrite(0x00, MINECRAFT_1_8, null);
+        }));
     assertThrows(IllegalArgumentException.class,
-        () -> registry.register(HandshakePacket.class, HandshakePacket::new,
+        () -> registry.register(HandshakePacket.class, HandshakePacket::new, m -> {
-            new StateRegistry.PacketMapping(0x01, MINECRAFT_1_13, null, false),
+          m.readWrite(0x01, MINECRAFT_1_13, null);
-            new StateRegistry.PacketMapping(0x01, MINECRAFT_1_13, null, false)));
+          m.readWrite(0x01, MINECRAFT_1_13, null);
+        }));
     assertThrows(IllegalArgumentException.class,
-        () -> registry.register(HandshakePacket.class, HandshakePacket::new,
+        () -> registry.register(HandshakePacket.class, HandshakePacket::new, m -> {
-            new StateRegistry.PacketMapping(0x01, MINECRAFT_1_13, MINECRAFT_1_8, false)));
+          m.readWrite(0x01, MINECRAFT_1_13, MINECRAFT_1_8);
+        }));
     assertThrows(IllegalArgumentException.class,
-        () -> registry.register(HandshakePacket.class, HandshakePacket::new,
+        () -> registry.register(HandshakePacket.class, HandshakePacket::new, m -> {
-            new StateRegistry.PacketMapping(0x01, MINECRAFT_1_8, MINECRAFT_1_14, false),
+          m.readWrite(0x01, MINECRAFT_1_8, MINECRAFT_1_14);
-            new StateRegistry.PacketMapping(0x00, MINECRAFT_1_16, null, false)));
+          m.readWrite(0x00, MINECRAFT_1_16, null);
+        }));
   }
 
   @Test
   void failOnDuplicate() {
     StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(
         ProtocolUtils.Direction.CLIENTBOUND, StateRegistry.PLAY);
-    registry.register(HandshakePacket.class, HandshakePacket::new,
+    registry.register(HandshakePacket.class, HandshakePacket::new, m -> {
-        new StateRegistry.PacketMapping(0x00, MINECRAFT_1_8, null, false));
+      m.readWrite(0x00, MINECRAFT_1_8, null);
+    });
     assertThrows(IllegalArgumentException.class,
-        () -> registry.register(HandshakePacket.class, HandshakePacket::new,
+        () -> registry.register(HandshakePacket.class, HandshakePacket::new, m -> {
-            new StateRegistry.PacketMapping(0x01, MINECRAFT_1_12, null, false)));
+          m.readWrite(0x01, MINECRAFT_1_12, null);
+        }));
     assertThrows(IllegalArgumentException.class,
-        () -> registry.register(StatusPingPacket.class, StatusPingPacket::new,
+        () -> registry.register(StatusPingPacket.class, StatusPingPacket::new, m -> {
-            new StateRegistry.PacketMapping(0x00, MINECRAFT_1_13, null, false)));
+          m.readWrite(0x00, MINECRAFT_1_13, null);
+        }));
   }
 
   @Test
   void shouldNotFailWhenRegisterLatestProtocolVersion() {
     StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(
         ProtocolUtils.Direction.CLIENTBOUND, StateRegistry.PLAY);
-    assertDoesNotThrow(() -> registry.register(HandshakePacket.class, HandshakePacket::new,
+    assertDoesNotThrow(() -> registry.register(HandshakePacket.class, HandshakePacket::new, m -> {
-        new StateRegistry.PacketMapping(0x00, MINECRAFT_1_8, null, false),
+      m.readWrite(0x00, MINECRAFT_1_8, null);
-        new StateRegistry.PacketMapping(0x01, getLast(ProtocolVersion.SUPPORTED_VERSIONS),
+      m.readWrite(0x01, getLast(ProtocolVersion.SUPPORTED_VERSIONS), null);
-            null, false)));
+    }));
   }
 
   @Test
   void registrySuppliesCorrectPacketsByProtocol() {
     StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(
         ProtocolUtils.Direction.CLIENTBOUND, StateRegistry.PLAY);
-    registry.register(HandshakePacket.class, HandshakePacket::new,
+    registry.register(HandshakePacket.class, HandshakePacket::new, m -> {
-        new StateRegistry.PacketMapping(0x00, MINECRAFT_1_12, null, false),
+      m.readWrite(0x00, MINECRAFT_1_12, null);
-        new StateRegistry.PacketMapping(0x01, MINECRAFT_1_12_1, null, false),
+      m.readWrite(0x01, MINECRAFT_1_12_1, null);
-        new StateRegistry.PacketMapping(0x02, MINECRAFT_1_13, null, false));
+      m.readWrite(0x02, MINECRAFT_1_13, null);
+    });
     assertEquals(HandshakePacket.class,
         registry.getProtocolRegistry(MINECRAFT_1_12).createPacket(0x00).getClass());
     assertEquals(HandshakePacket.class,