Add CommandsDeclareEvent to declare commands with brigadier API

api/src/main/java/net/md_5/bungee/api/event/CommandsDeclareEvent.java

@@ -0,0 +1,157 @@
+package net.md_5.bungee.api.event;
+
+import com.mojang.brigadier.arguments.ArgumentType;
+import com.mojang.brigadier.arguments.IntegerArgumentType;
+import com.mojang.brigadier.arguments.StringArgumentType;
+import com.mojang.brigadier.builder.ArgumentBuilder;
+import com.mojang.brigadier.builder.RequiredArgumentBuilder;
+import com.mojang.brigadier.suggestion.SuggestionProvider;
+import com.mojang.brigadier.tree.CommandNode;
+import com.mojang.brigadier.tree.RootCommandNode;
+import lombok.AccessLevel;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+import lombok.Setter;
+import lombok.ToString;
+import net.md_5.bungee.api.CommandSender;
+import net.md_5.bungee.api.connection.Connection;
+import net.md_5.bungee.api.plugin.Command;
+import net.md_5.bungee.api.plugin.Plugin;
+import net.md_5.bungee.api.plugin.PluginManager;
+import net.md_5.bungee.api.plugin.TabExecutor;
+
+/**
+ * Event called when a downstream server (on 1.13+) sends the command structure
+ * to a player, but before BungeeCord adds the dummy command nodes of
+ * registered commands.
+ * <p>
+ * BungeeCord will not overwrite the modifications made by the listeners.
+ *
+ * <h2>Usage example</h2>
+ * Here is a usage example of this event, to declare a command structure.
+ * This illustrates the commands /server and /send of Bungee.
+ * <pre>
+ * event.getRoot().addChild( LiteralArgumentBuilder.&lt;CommandSender&gt;literal( "server" )
+ *         .requires( sender -&gt; sender.hasPermission( "bungeecord.command.server" ) )
+ *         .executes( a -&gt; 0 )
+ *         .then( RequiredArgumentBuilder.argument( "serverName", StringArgumentType.greedyString() )
+ *                 .suggests( SuggestionRegistry.ASK_SERVER )
+ *         )
+ *         .build()
+ * );
+ * event.getRoot().addChild( LiteralArgumentBuilder.&lt;CommandSender&gt;literal( "send" )
+ *         .requires( sender -&gt; sender.hasPermission( "bungeecord.command.send" ) )
+ *         .then( RequiredArgumentBuilder.argument( "playerName", StringArgumentType.word() )
+ *                 .suggests( SuggestionRegistry.ASK_SERVER )
+ *                 .then( RequiredArgumentBuilder.argument( "serverName", StringArgumentType.greedyString() )
+ *                         .suggests( SuggestionRegistry.ASK_SERVER )
+ *                 )
+ *         )
+ *         .build()
+ * );
+ * </pre>
+ *
+ * <h2>Flag a {@link CommandNode} as executable or not</h2>
+ * The implementation of a {@link com.mojang.brigadier.Command Command} used in
+ * {@link ArgumentBuilder#executes(com.mojang.brigadier.Command)} will never be
+ * executed. This will only tell to the client if the current node is
+ * executable or not.
+ * <ul>
+ *     <li>
+ *         {@code builder.executes(null)} (default) to mark the node as not
+ *         executable.
+ *     </li>
+ *     <li>
+ *         {@code builder.executes(a -> 0)}, or any non null argument, to mark
+ *         the node as executable (the child arguments are displayed as
+ *         optional).
+ *     </li>
+ * </ul>
+ *
+ * <h2>{@link CommandNode}’s suggestions management</h2>
+ * The implementation of a SuggestionProvider used in
+ * {@link RequiredArgumentBuilder#suggests(SuggestionProvider)} will never be
+ * executed. This will only tell to the client how to deal with the
+ * auto-completion of the argument.
+ * <ul>
+ *     <li>
+ *         {@code builder.suggests(null)} (default) to disable auto-completion
+ *         for this argument.
+ *     </li>
+ *     <li>
+ *         {@code builder.suggests(SuggestionRegistry.ALL_RECIPES)} to suggest
+ *         Minecraft’s recipes.
+ *     </li>
+ *     <li>
+ *         {@code builder.suggests(SuggestionRegistry.AVAILABLE_SOUNDS)} to
+ *         suggest Minecraft’s default sound identifiers.
+ *     </li>
+ *     <li>
+ *         {@code builder.suggests(SuggestionRegistry.SUMMONABLE_ENTITIES)} to
+ *         suggest Minecraft’s default summonable entities identifiers.
+ *     </li>
+ *     <li>
+ *         {@code builder.suggests(SuggestionRegistry.ASK_SERVER)}, or any
+ *         other non null argument, to make the Minecraft client ask
+ *         auto-completion to the server. Any specified implementation of
+ *         {@link SuggestionProvider} will never be executed.
+ *     </li>
+ * </ul>
+ *
+ * <h2>Argument types</h2>
+ * When building a new argument command node using
+ * {@link RequiredArgumentBuilder#argument(String, ArgumentType)}, you have to
+ * specify an {@link ArgumentType}. You can use all subclasses of
+ * {@link ArgumentType} provided with brigadier (for instance,
+ * {@link StringArgumentType} or {@link IntegerArgumentType}), or call any
+ * {@code ArgumentRegistry.minecraft*()} methods to use a {@code minecraft:*}
+ * argument type.
+ *
+ * <h2>Limitations with brigadier API</h2>
+ * This event is only used for the client to show command syntax, suggest
+ * sub-commands and color the arguments in the chat box. The command execution
+ * needs to be implemented using {@link PluginManager#registerCommand(Plugin,
+ * Command)} and the server-side tab-completion using {@link TabCompleteEvent}
+ * or {@link TabExecutor}.
+ */
+@Data
+@ToString(callSuper = true)
+@EqualsAndHashCode(callSuper = true)
+public class CommandsDeclareEvent extends TargetedEvent
+{
+    /**
+     * Wether or not the command tree is modified by this event.
+     *
+     * If this value is set to true, BungeeCord will ensure that the
+     * modifications made in the command tree, will be sent to the player.
+     * If this is false, the modifications may not be taken into account.
+     *
+     * When calling {@link #getRoot()}, this value is automatically set
+     * to true.
+     */
+    @Setter(value = AccessLevel.NONE)
+    private boolean modified = false;
+
+    /**
+     * The root command node of the command structure that will be send to the
+     * player.
+     */
+    private final RootCommandNode<CommandSender> root;
+
+    public CommandsDeclareEvent(Connection sender, Connection receiver, RootCommandNode<CommandSender> root)
+    {
+        super( sender, receiver );
+        this.root = root;
+    }
+
+    /**
+     * The root command node of the command structure that will be send to the
+     * player.
+     * @return The root command node
+     */
+    public RootCommandNode<CommandSender> getRoot()
+    {
+        modified = true;
+        return root;
+    }
+}

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;
@@ -303,7 +304,7 @@ public class Commands extends DefinedPacket
     }
 
     @Data
-    private static class ArgumentRegistry
+    public static class ArgumentRegistry
     {
 
         private static final Map<String, ArgumentSerializer> PROVIDERS = new HashMap<>();
@@ -325,18 +326,29 @@ 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 int getIntKey()
+            {
+                return 0;
+            }
+
+            @Override
+            protected String getKey()
+            {
+                return "brigadier:bool";
             }
         };
         private static final ArgumentSerializer<Byte> BYTE = new ArgumentSerializer<Byte>()
@@ -353,7 +365,7 @@ public class Commands extends DefinedPacket
                 buf.writeByte( t );
             }
         };
-        private static final ArgumentSerializer<FloatArgumentType> FLOAT_RANGE = new ArgumentSerializer<FloatArgumentType>()
+        private static final ProperArgumentSerializer<FloatArgumentType> FLOAT_RANGE = new ProperArgumentSerializer<FloatArgumentType>()
         {
             @Override
             protected FloatArgumentType read(ByteBuf buf)
@@ -381,8 +393,20 @@ public class Commands extends DefinedPacket
                     buf.writeFloat( t.getMaximum() );
                 }
             }
+
+            @Override
+            protected int getIntKey()
+            {
+                return 1;
+            }
+
+            @Override
+            protected String getKey()
+            {
+                return "brigadier:float";
+            }
         };
-        private static final ArgumentSerializer<DoubleArgumentType> DOUBLE_RANGE = new ArgumentSerializer<DoubleArgumentType>()
+        private static final ProperArgumentSerializer<DoubleArgumentType> DOUBLE_RANGE = new ProperArgumentSerializer<DoubleArgumentType>()
         {
             @Override
             protected DoubleArgumentType read(ByteBuf buf)
@@ -410,8 +434,20 @@ public class Commands extends DefinedPacket
                     buf.writeDouble( t.getMaximum() );
                 }
             }
+
+            @Override
+            protected int getIntKey()
+            {
+                return 2;
+            }
+
+            @Override
+            protected String getKey()
+            {
+                return "brigadier:double";
+            }
         };
-        private static final ArgumentSerializer<IntegerArgumentType> INTEGER_RANGE = new ArgumentSerializer<IntegerArgumentType>()
+        private static final ProperArgumentSerializer<IntegerArgumentType> INTEGER_RANGE = new ProperArgumentSerializer<IntegerArgumentType>()
         {
             @Override
             protected IntegerArgumentType read(ByteBuf buf)
@@ -439,6 +475,18 @@ public class Commands extends DefinedPacket
                     buf.writeInt( t.getMaximum() );
                 }
             }
+
+            @Override
+            protected int getIntKey()
+            {
+                return 3;
+            }
+
+            @Override
+            protected String getKey()
+            {
+                return "brigadier:integer";
+            }
         };
         private static final ArgumentSerializer<Integer> INTEGER = new ArgumentSerializer<Integer>()
         {
@@ -454,7 +502,7 @@ public class Commands extends DefinedPacket
                 buf.writeInt( t );
             }
         };
-        private static final ArgumentSerializer<LongArgumentType> LONG_RANGE = new ArgumentSerializer<LongArgumentType>()
+        private static final ProperArgumentSerializer<LongArgumentType> LONG_RANGE = new ProperArgumentSerializer<LongArgumentType>()
         {
             @Override
             protected LongArgumentType read(ByteBuf buf)
@@ -482,6 +530,18 @@ public class Commands extends DefinedPacket
                     buf.writeLong( t.getMaximum() );
                 }
             }
+
+            @Override
+            protected int getIntKey()
+            {
+                return 4;
+            }
+
+            @Override
+            protected String getKey()
+            {
+                return "brigadier:long";
+            }
         };
         private static final ProperArgumentSerializer<StringArgumentType> STRING = new ProperArgumentSerializer<StringArgumentType>()
         {
@@ -537,11 +597,20 @@ public class Commands extends DefinedPacket
 
         static
         {
-            register( "brigadier:bool", VOID );
+            register( "brigadier:bool", BOOLEAN );
+            PROPER_PROVIDERS.put( BoolArgumentType.class, BOOLEAN );
+
             register( "brigadier:float", FLOAT_RANGE );
+            PROPER_PROVIDERS.put( FloatArgumentType.class, FLOAT_RANGE );
+
             register( "brigadier:double", DOUBLE_RANGE );
+            PROPER_PROVIDERS.put( DoubleArgumentType.class, DOUBLE_RANGE );
+
             register( "brigadier:integer", INTEGER_RANGE );
-            register( "brigadier:long", LONG_RANGE );
+            PROPER_PROVIDERS.put( IntegerArgumentType.class, INTEGER_RANGE );
+
+            register( "brigadier:long", LONG_RANGE ); // 1.14+
+            PROPER_PROVIDERS.put( LongArgumentType.class, LONG_RANGE );
 
             register( "brigadier:string", STRING );
             PROPER_PROVIDERS.put( StringArgumentType.class, STRING );
@@ -756,6 +825,404 @@ public class Commands extends DefinedPacket
             return serializer;
         }
 
+        /**
+         * 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 );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:resource}.
+         * @param rawString the raw string for the argument
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftResource(String rawString)
+        {
+            return minecraftArgumentType( "minecraft:resource", rawString );
+        }
+
+        /**
+         * Returns the Minecraft ArgumentType {@code minecraft:resource_or_tag}.
+         * @param rawString the raw string for the argument
+         * @return an ArgumentType instance
+         */
+        public static ArgumentType<?> minecraftResourceOrTag(String rawString)
+        {
+            return minecraftArgumentType( "minecraft:resource_or_tag", rawString );
+        }
+
+        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(ByteBuf buf, int protocolVersion)
         {
             Object key;
@@ -879,11 +1346,15 @@ 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) ASK_SERVER ).key;
+        }
+
         @Data
         private static final class DummyProvider implements SuggestionProvider<DummyProvider>
         {

proxy/src/main/java/net/md_5/bungee/connection/DownstreamBridge.java

@@ -6,6 +6,7 @@ import com.google.common.collect.Lists;
 import com.google.common.io.ByteArrayDataOutput;
 import com.google.common.io.ByteStreams;
 import com.mojang.brigadier.arguments.StringArgumentType;
+import com.mojang.brigadier.builder.ArgumentBuilder;
 import com.mojang.brigadier.builder.LiteralArgumentBuilder;
 import com.mojang.brigadier.builder.RequiredArgumentBuilder;
 import com.mojang.brigadier.context.StringRange;
@@ -19,10 +20,13 @@ import io.netty.channel.unix.DomainSocketAddress;
 import java.io.DataInput;
 import java.net.InetSocketAddress;
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.IdentityHashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.stream.Collectors;
+import java.util.logging.Level;
 import lombok.RequiredArgsConstructor;
 import net.md_5.bungee.ServerConnection;
 import net.md_5.bungee.ServerConnection.KeepAliveData;
@@ -35,6 +39,7 @@ import net.md_5.bungee.api.chat.TextComponent;
 import net.md_5.bungee.api.config.ServerInfo;
 import net.md_5.bungee.api.connection.ProxiedPlayer;
 import net.md_5.bungee.api.connection.Server;
+import net.md_5.bungee.api.event.CommandsDeclareEvent;
 import net.md_5.bungee.api.event.PluginMessageEvent;
 import net.md_5.bungee.api.event.ServerConnectEvent;
 import net.md_5.bungee.api.event.ServerDisconnectEvent;
@@ -729,6 +734,11 @@ public class DownstreamBridge extends PacketHandler
     {
         boolean modified = false;
 
+        CommandsDeclareEvent commandsDeclareEvent = new CommandsDeclareEvent( server, con, commands.getRoot() );
+        bungee.getPluginManager().callEvent( commandsDeclareEvent );
+
+        modified = commandsDeclareEvent.isModified();
+
         for ( Map.Entry<String, Command> command : bungee.getPluginManager().getCommands() )
         {
             if ( !bungee.getDisabledCommands().contains( command.getKey() ) && commands.getRoot().getChild( command.getKey() ) == null && command.getValue().hasPermission( con ) )
@@ -745,11 +755,65 @@ public class DownstreamBridge extends PacketHandler
 
         if ( modified )
         {
+            commands.setRoot( (com.mojang.brigadier.tree.RootCommandNode) filterCommandNode( commands.getRoot(), new IdentityHashMap<>() ) );
             con.unsafe().sendPacket( commands );
             throw CancelSendSignal.INSTANCE;
         }
     }
 
+    /*
+     * Create a deep copy of the provided command node but removes any node that are not accessible by the player
+     * (using {@link CommandNode#getRequirement()})
+     */
+    private CommandNode filterCommandNode(CommandNode source, IdentityHashMap<CommandNode, CommandNode> commandNodeMapping)
+    {
+        CommandNode dest;
+        if ( source instanceof com.mojang.brigadier.tree.RootCommandNode )
+        {
+            dest = new com.mojang.brigadier.tree.RootCommandNode();
+        } else
+        {
+            if ( source.getRequirement() != null )
+            {
+                try
+                {
+                    if ( !source.getRequirement().test( con ) )
+                    {
+                        commandNodeMapping.put( source, null );
+                        return null;
+                    }
+                } catch ( Throwable t )
+                {
+                    ProxyServer.getInstance().getLogger().log( Level.SEVERE, "Requirement test for command node " + source + " encountered an exception", t );
+                }
+            }
+
+            ArgumentBuilder destChildBuilder = source.createBuilder();
+            destChildBuilder.requires( sender -> true );
+            if ( destChildBuilder.getRedirect() != null )
+            {
+                if ( commandNodeMapping.containsKey( destChildBuilder.getRedirect() ) )
+                    destChildBuilder.redirect( commandNodeMapping.get( destChildBuilder.getRedirect() ) );
+                else
+                    destChildBuilder.redirect( filterCommandNode( destChildBuilder.getRedirect(), commandNodeMapping ) );
+            }
+
+            dest = destChildBuilder.build();
+        }
+
+        commandNodeMapping.put( source, dest );
+
+        for ( CommandNode sourceChild : (Collection<CommandNode>) source.getChildren() )
+        {
+            CommandNode destChild = filterCommandNode( sourceChild, commandNodeMapping );
+            if ( destChild == null )
+                continue;
+            dest.addChild( destChild );
+        }
+
+        return dest;
+    }
+
     @Override
     public void handle(ServerData serverData) throws Exception
     {