Expose registered aliases in API (#549)

api/src/main/java/com/velocitypowered/api/command/CommandManager.java

@@ -8,6 +8,7 @@
 package com.velocitypowered.api.command;
 
 import com.velocitypowered.api.event.command.CommandExecuteEvent;
+import java.util.Collection;
 import java.util.concurrent.CompletableFuture;
 
 /**
@@ -94,11 +95,19 @@ public interface CommandManager {
    */
   CompletableFuture<Boolean> executeImmediatelyAsync(CommandSource source, String cmdLine);
 
+  /**
+   * Returns an immutable collection of the case-insensitive aliases registered
+   * on this manager.
+   *
+   * @return the registered aliases
+   */
+  Collection<String> getAliases();
+
   /**
    * Returns whether the given alias is registered on this manager.
    *
    * @param alias the command alias to check
-   * @return {@code true} if the alias is registered
+   * @return true if the alias is registered; false otherwise
    */
   boolean hasCommand(String alias);
 }

proxy/src/main/java/com/velocitypowered/proxy/command/VelocityCommandManager.java

@@ -24,6 +24,7 @@ import com.mojang.brigadier.CommandDispatcher;
 import com.mojang.brigadier.ParseResults;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.brigadier.suggestion.Suggestion;
+import com.mojang.brigadier.tree.CommandNode;
 import com.mojang.brigadier.tree.RootCommandNode;
 import com.spotify.futures.CompletableFutures;
 import com.velocitypowered.api.command.BrigadierCommand;
@@ -38,11 +39,13 @@ import com.velocitypowered.proxy.command.registrar.CommandRegistrar;
 import com.velocitypowered.proxy.command.registrar.RawCommandRegistrar;
 import com.velocitypowered.proxy.command.registrar.SimpleCommandRegistrar;
 import com.velocitypowered.proxy.event.VelocityEventManager;
+import java.util.Collection;
 import java.util.List;
 import java.util.Locale;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.stream.Collectors;
 import net.kyori.adventure.identity.Identity;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.format.NamedTextColor;
@@ -249,12 +252,19 @@ public class VelocityCommandManager implements CommandManager {
     }
   }
 
-  /**
-   * Returns whether the given alias is registered on this manager.
-   *
-   * @param alias the command alias to check
-   * @return true if the alias is registered; false otherwise
-   */
+  @Override
+  public Collection<String> getAliases() {
+    lock.readLock().lock();
+    try {
+      // A RootCommandNode may only contain LiteralCommandNode children instances
+      return dispatcher.getRoot().getChildren().stream()
+              .map(CommandNode::getName)
+              .collect(ImmutableList.toImmutableList());
+    } finally {
+      lock.readLock().unlock();
+    }
+  }
+
   @Override
   public boolean hasCommand(final String alias) {
     Preconditions.checkNotNull(alias, "alias");

proxy/src/test/java/com/velocitypowered/proxy/command/CommandManagerTests.java

@@ -17,11 +17,13 @@
 
 package com.velocitypowered.proxy.command;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
+import com.google.common.collect.ImmutableList;
 import com.mojang.brigadier.builder.LiteralArgumentBuilder;
 import com.velocitypowered.api.command.BrigadierCommand;
 import com.velocitypowered.api.command.CommandSource;
@@ -41,6 +43,7 @@ public class CommandManagerTests extends CommandTestSuite {
     manager.register(meta, DummyCommand.INSTANCE);
 
     assertTrue(manager.hasCommand("hello"));
+    assertRegisteredAliases("hello");
   }
 
   @Test
@@ -55,6 +58,7 @@ public class CommandManagerTests extends CommandTestSuite {
     assertTrue(manager.hasCommand("bar"));
     assertTrue(manager.hasCommand("baz"));
     assertTrue(manager.hasCommand("qux"));
+    assertRegisteredAliases("foo", "bar", "baz", "qux");
   }
 
   @Test
@@ -66,6 +70,7 @@ public class CommandManagerTests extends CommandTestSuite {
 
     assertTrue(manager.hasCommand("foo"));
     assertTrue(manager.hasCommand("bar"));
+    assertRegisteredAliases("foo", "bar");
   }
 
   @Test
@@ -76,6 +81,7 @@ public class CommandManagerTests extends CommandTestSuite {
     manager.register(new BrigadierCommand(node));
 
     assertTrue(manager.hasCommand("hello"));
+    assertRegisteredAliases("hello");
   }
 
   @Test
@@ -125,6 +131,7 @@ public class CommandManagerTests extends CommandTestSuite {
     manager.unregister("hello");
 
     assertFalse(manager.hasCommand("hello"));
+    assertRegisteredAliases();
   }
 
   @Test
@@ -133,6 +140,7 @@ public class CommandManagerTests extends CommandTestSuite {
     manager.unregister("hello");
 
     assertFalse(manager.hasCommand("hello"));
+    assertRegisteredAliases();
   }
 
   @Test
@@ -145,6 +153,7 @@ public class CommandManagerTests extends CommandTestSuite {
 
     assertFalse(manager.hasCommand("bar"));
     assertTrue(manager.hasCommand("foo"));
+    assertRegisteredAliases("foo");
   }
 
   // Execution

proxy/src/test/java/com/velocitypowered/proxy/command/CommandTestSuite.java

@@ -30,6 +30,7 @@ import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.proxy.event.MockEventManager;
 import com.velocitypowered.proxy.event.VelocityEventManager;
 import java.util.Arrays;
+import java.util.Collection;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.BeforeEach;
@@ -80,4 +81,12 @@ abstract class CommandTestSuite {
     final var actual = manager.offerSuggestions(player, input).join();
     assertEquals(Arrays.asList(expectedSuggestions), actual);
   }
+
+  final void assertRegisteredAliases(final String... expected) {
+    final Collection<String> actual = manager.getAliases();
+    assertEquals(expected.length, actual.size());
+    final Collection<String> asList = Arrays.asList(expected);
+    assertTrue(asList.containsAll(actual));
+    assertTrue(actual.containsAll(asList));
+  }
 }