Add CommandsDeclareEvent to declare commands with brigadier API

protocol/src/main/java/net/md_5/bungee/protocol/packet/Commands.java

@@ -4,6 +4,7 @@ import com.google.common.base.Preconditions;
 import com.mojang.brigadier.Command;
 import com.mojang.brigadier.StringReader;
 import com.mojang.brigadier.arguments.ArgumentType;
+import com.mojang.brigadier.arguments.BoolArgumentType;
 import com.mojang.brigadier.arguments.DoubleArgumentType;
 import com.mojang.brigadier.arguments.FloatArgumentType;
 import com.mojang.brigadier.arguments.IntegerArgumentType;
@@ -36,6 +37,7 @@ import lombok.EqualsAndHashCode;
 import lombok.NoArgsConstructor;
 import net.md_5.bungee.protocol.AbstractPacketHandler;
 import net.md_5.bungee.protocol.DefinedPacket;
+import net.md_5.bungee.protocol.ProtocolConstants;
 
 @Data
 @NoArgsConstructor
@@ -126,7 +128,7 @@ public class Commands extends DefinedPacket
     }
 
     @Override
-    public void write(ByteBuf buf)
+    public void write(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion)
     {
         Map<CommandNode, Integer> indexMap = new LinkedHashMap<>();
         Deque<CommandNode> nodeQueue = new ArrayDeque<>();
@@ -210,7 +212,7 @@ public class Commands extends DefinedPacket
                 ArgumentCommandNode argumentNode = (ArgumentCommandNode) node;
 
                 writeString( argumentNode.getName(), buf );
-                ArgumentRegistry.write( argumentNode.getType(), buf );
+                ArgumentRegistry.write( argumentNode.getType(), buf, protocolVersion );
 
                 if ( argumentNode.getCustomSuggestions() != null )
                 {
@@ -304,11 +306,12 @@ public class Commands extends DefinedPacket
     }
 
     @Data
-    private static class ArgumentRegistry
+    public static class ArgumentRegistry
     {
 
         private static final Map<String, ArgumentSerializer> PROVIDERS = new HashMap<>();
         private static final Map<Class<?>, ProperArgumentSerializer<?>> PROPER_PROVIDERS = new HashMap<>();
+        private static final Map<String, ProtocolConversionProvider> CONVERSION_PROVIDERS = new HashMap<>();
         //
         private static final ArgumentSerializer<Void> VOID = new ArgumentSerializer<Void>()
         {
@@ -323,18 +326,23 @@ public class Commands extends DefinedPacket
             {
             }
         };
-        private static final ArgumentSerializer<Boolean> BOOLEAN = new ArgumentSerializer<Boolean>()
+        private static final ProperArgumentSerializer<BoolArgumentType> BOOLEAN = new ProperArgumentSerializer<BoolArgumentType>()
         {
             @Override
-            protected Boolean read(ByteBuf buf)
+            protected BoolArgumentType read(ByteBuf buf)
             {
-                return buf.readBoolean();
+                return BoolArgumentType.bool();
             }
 
             @Override
-            protected void write(ByteBuf buf, Boolean t)
+            protected void write(ByteBuf buf, BoolArgumentType t)
             {
-                buf.writeBoolean( t );
+            }
+
+            @Override
+            protected String getKey()
+            {
+                return "brigadier:bool";
             }
         };
         private static final ArgumentSerializer<Byte> BYTE = new ArgumentSerializer<Byte>()
@@ -351,7 +359,7 @@ public class Commands extends DefinedPacket
                 buf.writeByte( t );
             }
         };
-        private static final ArgumentSerializer<FloatArgumentType> FLOAT = new ArgumentSerializer<FloatArgumentType>()
+        private static final ProperArgumentSerializer<FloatArgumentType> FLOAT = new ProperArgumentSerializer<FloatArgumentType>()
         {
             @Override
             protected FloatArgumentType read(ByteBuf buf)
@@ -379,8 +387,14 @@ public class Commands extends DefinedPacket
                     buf.writeFloat( t.getMaximum() );
                 }
             }
+
+            @Override
+            protected String getKey()
+            {
+                return "brigadier:float";
+            }
         };
-        private static final ArgumentSerializer<DoubleArgumentType> DOUBLE = new ArgumentSerializer<DoubleArgumentType>()
+        private static final ProperArgumentSerializer<DoubleArgumentType> DOUBLE = new ProperArgumentSerializer<DoubleArgumentType>()
         {
             @Override
             protected DoubleArgumentType read(ByteBuf buf)
@@ -408,8 +422,14 @@ public class Commands extends DefinedPacket
                     buf.writeDouble( t.getMaximum() );
                 }
             }
+
+            @Override
+            protected String getKey()
+            {
+                return "brigadier:double";
+            }
         };
-        private static final ArgumentSerializer<IntegerArgumentType> INTEGER = new ArgumentSerializer<IntegerArgumentType>()
+        private static final ProperArgumentSerializer<IntegerArgumentType> INTEGER = new ProperArgumentSerializer<IntegerArgumentType>()
         {
             @Override
             protected IntegerArgumentType read(ByteBuf buf)
@@ -437,8 +457,14 @@ public class Commands extends DefinedPacket
                     buf.writeInt( t.getMaximum() );
                 }
             }
+
+            @Override
+            protected String getKey()
+            {
+                return "brigadier:integer";
+            }
         };
-        private static final ArgumentSerializer<LongArgumentType> LONG = new ArgumentSerializer<LongArgumentType>()
+        private static final ProperArgumentSerializer<LongArgumentType> LONG = new ProperArgumentSerializer<LongArgumentType>()
         {
             @Override
             protected LongArgumentType read(ByteBuf buf)
@@ -466,6 +492,12 @@ public class Commands extends DefinedPacket
                     buf.writeLong( t.getMaximum() );
                 }
             }
+
+            @Override
+            protected String getKey()
+            {
+                return "brigadier:long";
+            }
         };
         private static final ProperArgumentSerializer<StringArgumentType> STRING = new ProperArgumentSerializer<StringArgumentType>()
         {
@@ -501,11 +533,31 @@ public class Commands extends DefinedPacket
 
         static
         {
-            PROVIDERS.put( "brigadier:bool", VOID );
+            PROVIDERS.put( "brigadier:bool", BOOLEAN );
+            PROPER_PROVIDERS.put( BoolArgumentType.class, BOOLEAN );
+
             PROVIDERS.put( "brigadier:float", FLOAT );
+            PROPER_PROVIDERS.put( FloatArgumentType.class, FLOAT );
+
             PROVIDERS.put( "brigadier:double", DOUBLE );
+            PROPER_PROVIDERS.put( DoubleArgumentType.class, DOUBLE );
+
             PROVIDERS.put( "brigadier:integer", INTEGER );
-            PROVIDERS.put( "brigadier:long", LONG );
+            PROPER_PROVIDERS.put( IntegerArgumentType.class, INTEGER );
+
+            PROVIDERS.put( "brigadier:long", LONG ); // 1.14+
+            PROPER_PROVIDERS.put( LongArgumentType.class, LONG );
+            CONVERSION_PROVIDERS.put( "brigadier:long", ( originalType, protocolVersion ) ->
+            {
+                if ( protocolVersion < ProtocolConstants.MINECRAFT_1_14 )
+                {
+                    LongArgumentType type = (LongArgumentType) originalType;
+                    int min = (int) Math.max( Integer.MIN_VALUE, Math.min( Integer.MAX_VALUE, type.getMinimum() ) );
+                    int max = (int) Math.max( Integer.MIN_VALUE, Math.min( Integer.MAX_VALUE, type.getMaximum() ) );
+                    return IntegerArgumentType.integer( min, max );
+                }
+                return originalType;
+            } );
 
             PROVIDERS.put( "brigadier:string", STRING );
             PROPER_PROVIDERS.put( StringArgumentType.class, STRING );
@@ -523,9 +575,37 @@ public class Commands extends DefinedPacket
             PROVIDERS.put( "minecraft:color", VOID );
             PROVIDERS.put( "minecraft:component", VOID );
             PROVIDERS.put( "minecraft:message", VOID );
-            PROVIDERS.put( "minecraft:nbt_compound_tag", VOID ); // 1.14
-            PROVIDERS.put( "minecraft:nbt_tag", VOID ); // 1.14
+
+            PROVIDERS.put( "minecraft:nbt_compound_tag", VOID ); // 1.14+, replaces minecraft:nbt
+            CONVERSION_PROVIDERS.put( "minecraft:nbt_compound_tag", ( originalType, protocolVersion ) ->
+            {
+                if ( protocolVersion < ProtocolConstants.MINECRAFT_1_14 )
+                {
+                    return minecraftNBT();
+                }
+                return originalType;
+            } );
+
+            PROVIDERS.put( "minecraft:nbt_tag", VOID ); // 1.14+
+            CONVERSION_PROVIDERS.put( "minecraft:nbt_tag", ( originalType, protocolVersion ) ->
+            {
+                if ( protocolVersion < ProtocolConstants.MINECRAFT_1_14 )
+                {
+                    return minecraftNBT();
+                }
+                return originalType;
+            } );
+
             PROVIDERS.put( "minecraft:nbt", VOID ); // 1.13
+            CONVERSION_PROVIDERS.put( "minecraft:nbt", ( originalType, protocolVersion ) ->
+            {
+                if ( protocolVersion >= ProtocolConstants.MINECRAFT_1_14 )
+                {
+                    return minecraftNBTCompoundTag();
+                }
+                return originalType;
+            } );
+
             PROVIDERS.put( "minecraft:nbt_path", VOID );
             PROVIDERS.put( "minecraft:objective", VOID );
             PROVIDERS.put( "minecraft:objective_criteria", VOID );
@@ -546,11 +626,417 @@ public class Commands extends DefinedPacket
             PROVIDERS.put( "minecraft:item_enchantment", VOID );
             PROVIDERS.put( "minecraft:entity_summon", VOID );
             PROVIDERS.put( "minecraft:dimension", VOID );
-            PROVIDERS.put( "minecraft:time", VOID ); // 1.14
-            PROVIDERS.put( "minecraft:uuid", VOID ); // 1.16
-            PROVIDERS.put( "minecraft:test_argument", VOID ); // 1.16, debug
-            PROVIDERS.put( "minecraft:test_class", VOID ); // 1.16, debug
-            PROVIDERS.put( "minecraft:angle", VOID ); // 1.16.2
+
+            PROVIDERS.put( "minecraft:time", VOID ); // 1.14+
+            CONVERSION_PROVIDERS.put( "minecraft:time", ( originalType, protocolVersion ) ->
+            {
+                if ( protocolVersion < ProtocolConstants.MINECRAFT_1_14 )
+                {
+                    return StringArgumentType.word();
+                }
+                return originalType;
+            } );
+
+            PROVIDERS.put( "minecraft:uuid", VOID ); // 1.16+
+            CONVERSION_PROVIDERS.put( "minecraft:uuid", ( originalType, protocolVersion ) ->
+            {
+                if ( protocolVersion < ProtocolConstants.MINECRAFT_1_16 )
+                {
+                    return StringArgumentType.word();
+                }
+                return originalType;
+            } );
+
+            PROVIDERS.put( "minecraft:test_argument", VOID ); // 1.16+, debug
+            PROVIDERS.put( "minecraft:test_class", VOID ); // 1.16+, debug
+
+            PROVIDERS.put( "minecraft:angle", VOID ); // 1.16.2+
+            CONVERSION_PROVIDERS.put( "minecraft:angle", ( originalType, protocolVersion ) ->
+            {
+                if ( protocolVersion < ProtocolConstants.MINECRAFT_1_16_2 )
+                {
+                    return FloatArgumentType.floatArg();
+                }
+                return originalType;
+            } );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:entity}.
+         * @param singleEntity if the argument restrict to only one entity
+         * @param onlyPlayers if the argument restrict to players only
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftEntity(boolean singleEntity, boolean onlyPlayers)
+        {
+            byte flags = 0;
+            if ( singleEntity )
+            {
+                flags |= 1;
+            }
+            if ( onlyPlayers )
+            {
+                flags |= 2;
+            }
+
+            return minecraftArgumentType( "minecraft:entity", flags );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:game_profile}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftGameProfile()
+        {
+            return minecraftArgumentType( "minecraft:game_profile", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:block_pos}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftBlockPos()
+        {
+            return minecraftArgumentType( "minecraft:block_pos", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:column_pos}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftColumnPos()
+        {
+            return minecraftArgumentType( "minecraft:column_pos", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:vec3}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftVec3()
+        {
+            return minecraftArgumentType( "minecraft:vec3", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:vec2}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftVec2()
+        {
+            return minecraftArgumentType( "minecraft:vec2", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:block_state}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftBlockState()
+        {
+            return minecraftArgumentType( "minecraft:block_state", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:block_predicate}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftBlockPredicate()
+        {
+            return minecraftArgumentType( "minecraft:block_predicate", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:item_stack}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftItemStack()
+        {
+            return minecraftArgumentType( "minecraft:item_stack", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:item_predicate}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftItemPredicate()
+        {
+            return minecraftArgumentType( "minecraft:item_predicate", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:color}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftColor()
+        {
+            return minecraftArgumentType( "minecraft:color", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:component}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftComponent()
+        {
+            return minecraftArgumentType( "minecraft:component", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:message}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftMessage()
+        {
+            return minecraftArgumentType( "minecraft:message", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:nbt_compound_tag}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftNBTCompoundTag()
+        {
+            return minecraftArgumentType( "minecraft:nbt_compound_tag", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:nbt_tag}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftNBTTag()
+        {
+            return minecraftArgumentType( "minecraft:nbt_tag", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:nbt}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftNBT()
+        {
+            return minecraftArgumentType( "minecraft:nbt", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:nbt_path}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftNBTPath()
+        {
+            return minecraftArgumentType( "minecraft:nbt_path", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:objective}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftObjective()
+        {
+            return minecraftArgumentType( "minecraft:objective", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:objective_criteria}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftObjectiveCriteria()
+        {
+            return minecraftArgumentType( "minecraft:objective_criteria", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:operation}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftOperation()
+        {
+            return minecraftArgumentType( "minecraft:operation", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:particle}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftParticle()
+        {
+            return minecraftArgumentType( "minecraft:particle", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:rotation}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftRotation()
+        {
+            return minecraftArgumentType( "minecraft:rotation", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:scoreboard_slot}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftScoreboardSlot()
+        {
+            return minecraftArgumentType( "minecraft:scoreboard_slot", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:score_holder}.
+         * @param allowMultiple if the argument allows multiple entities
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftScoreHolder(boolean allowMultiple)
+        {
+            byte flags = 0;
+            if ( allowMultiple )
+            {
+                flags |= 1;
+            }
+
+            return minecraftArgumentType( "minecraft:score_holder", flags );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:swizzle}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftSwizzle()
+        {
+            return minecraftArgumentType( "minecraft:swizzle", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:team}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftTeam()
+        {
+            return minecraftArgumentType( "minecraft:team", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:item_slot}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftItemSlot()
+        {
+            return minecraftArgumentType( "minecraft:item_slot", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:resource_location}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftResourceLocation()
+        {
+            return minecraftArgumentType( "minecraft:resource_location", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:mob_effect}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftMobEffect()
+        {
+            return minecraftArgumentType( "minecraft:mob_effect", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:function}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftFunction()
+        {
+            return minecraftArgumentType( "minecraft:function", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:entity_anchor}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftEntityAnchor()
+        {
+            return minecraftArgumentType( "minecraft:entity_anchor", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:int_range}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftIntRange()
+        {
+            return minecraftArgumentType( "minecraft:int_range", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:float_range}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftFloatRange()
+        {
+            return minecraftArgumentType( "minecraft:float_range", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:item_enchantment}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftItemEnchantment()
+        {
+            return minecraftArgumentType( "minecraft:item_enchantment", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:entity_summon}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftEntitySummon()
+        {
+            return minecraftArgumentType( "minecraft:entity_summon", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:dimension}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftDimension()
+        {
+            return minecraftArgumentType( "minecraft:dimension", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:time}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftTime()
+        {
+            return minecraftArgumentType( "minecraft:time", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:uuid}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftUUID()
+        {
+            return minecraftArgumentType( "minecraft:uuid", null );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:angle}.
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftAngle()
+        {
+            return minecraftArgumentType( "minecraft:angle", null );
+        }
+
+        private static ArgumentType<?> minecraftArgumentType(String key, Object rawValue)
+        {
+            ArgumentSerializer reader = PROVIDERS.get( key );
+            Preconditions.checkArgument( reader != null, "No provider for argument " + key );
+
+            return new DummyType( key, reader, rawValue );
         }
 
         private static ArgumentType<?> read(String key, ByteBuf buf)
@@ -562,8 +1048,10 @@ public class Commands extends DefinedPacket
             return val != null && PROPER_PROVIDERS.containsKey( val.getClass() ) ? (ArgumentType<?>) val : new DummyType( key, reader, val );
         }
 
-        private static void write(ArgumentType<?> arg, ByteBuf buf)
+        private static void write(ArgumentType<?> arg, ByteBuf buf, int protocolVersion)
         {
+            arg = convertToVersion( arg, protocolVersion );
+
             ProperArgumentSerializer proper = PROPER_PROVIDERS.get( arg.getClass() );
             if ( proper != null )
             {
@@ -579,6 +1067,34 @@ public class Commands extends DefinedPacket
             }
         }
 
+        // Convert the provided argument type to a new one compatible with the provided protocol version
+        private static ArgumentType<?> convertToVersion(ArgumentType<?> arg, int protocolVersion)
+        {
+            ProperArgumentSerializer proper = PROPER_PROVIDERS.get( arg.getClass() );
+            String key;
+            if ( proper != null )
+            {
+                key = proper.getKey();
+            } else
+            {
+                Preconditions.checkArgument( arg instanceof DummyType, "Non dummy arg " + arg.getClass() );
+                key = ( (DummyType) arg ).key;
+            }
+
+            ProtocolConversionProvider converter = CONVERSION_PROVIDERS.get( key );
+
+            if ( converter != null )
+            {
+                return converter.convert( arg, protocolVersion );
+            }
+            return arg;
+        }
+
+        private interface ProtocolConversionProvider
+        {
+            public ArgumentType<?> convert(ArgumentType<?> originalType, int protocolVersion);
+        }
+
         @Data
         private static class DummyType<T> implements ArgumentType<T>
         {
@@ -612,17 +1128,39 @@ public class Commands extends DefinedPacket
     @Data
     public static class SuggestionRegistry
     {
-
+        /**
+         * Tells the client to ask suggestions to the server.
+         */
         public static final SuggestionProvider ASK_SERVER = new DummyProvider( "minecraft:ask_server" );
+
+        /**
+         * Tells the client to suggest all the available recipes. The suggestions are stored client side.
+         */
+        public static final SuggestionProvider ALL_RECIPES = new DummyProvider( "minecraft:all_recipes" );
+
+        /**
+         * Tells the client to suggest all the available sounds. The suggestions are stored client side.
+         */
+        public static final SuggestionProvider AVAILABLE_SOUNDS = new DummyProvider( "minecraft:available_sounds" );
+
+        /**
+         * Tells the client to suggest all the available biomes. The suggestions are stored client side.
+         */
+        public static final SuggestionProvider AVAILABLE_BIOMES = new DummyProvider( "minecraft:available_biomes" );
+
+        /**
+         * Tells the client to suggest all the available entities. The suggestions are stored client side.
+         */
+        public static final SuggestionProvider SUMMONABLE_ENTITIES = new DummyProvider( "minecraft:summonable_entities" );
         private static final Map<String, SuggestionProvider<DummyProvider>> PROVIDERS = new HashMap<>();
 
         static
         {
             PROVIDERS.put( "minecraft:ask_server", ASK_SERVER );
-            registerDummy( "minecraft:all_recipes" );
-            registerDummy( "minecraft:available_sounds" );
-            registerDummy( "minecraft:available_biomes" );
-            registerDummy( "minecraft:summonable_entities" );
+            PROVIDERS.put( "minecraft:all_recipes", ALL_RECIPES );
+            PROVIDERS.put( "minecraft:available_sounds", AVAILABLE_SOUNDS );
+            PROVIDERS.put( "minecraft:available_biomes", AVAILABLE_BIOMES );
+            PROVIDERS.put( "minecraft:summonable_entities", SUMMONABLE_ENTITIES );
         }
 
         private static void registerDummy(String name)
@@ -640,9 +1178,13 @@ public class Commands extends DefinedPacket
 
         private static String getKey(SuggestionProvider<DummyProvider> provider)
         {
-            Preconditions.checkArgument( provider instanceof DummyProvider, "Non dummy provider " + provider );
+            Preconditions.checkNotNull( provider );
+            if ( provider instanceof DummyProvider )
+            {
+                return ( (DummyProvider) provider ).key;
+            }
 
-            return ( (DummyProvider) provider ).key;
+            return ( (DummyProvider) ASK_SERVER ).key;
         }
 
         @Data