Add asynchronous tab completion to the paper module

cloud-minecraft/cloud-paper/src/main/java/com/intellectualsites/commands/paper/AsyncCommandSuggestionsListener.java

@@ -0,0 +1,62 @@
+//
+// MIT License
+//
+// Copyright (c) 2020 Alexander Söderberg
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//
+package com.intellectualsites.commands.paper;
+
+import com.destroystokyo.paper.event.server.AsyncTabCompleteEvent;
+import org.bukkit.command.CommandSender;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+
+import javax.annotation.Nonnull;
+import java.util.ArrayList;
+import java.util.List;
+
+class AsyncCommandSuggestionsListener<C> implements Listener {
+
+    private static final long CACHE_EXPIRATION_TIME = 30L;
+
+    private final PaperCommandManager<C> paperCommandManager;
+
+    AsyncCommandSuggestionsListener(@Nonnull final PaperCommandManager<C> paperCommandManager) {
+        this.paperCommandManager = paperCommandManager;
+    }
+
+    @EventHandler
+    void onTabCompletion(@Nonnull final AsyncTabCompleteEvent event) throws Exception {
+        if (event.getBuffer().isEmpty() || !event.getBuffer().startsWith("/")) {
+            return;
+        }
+        final String[] arguments = event.getBuffer().substring(1).split(" ");
+        if (paperCommandManager.getCommandTree().getNamedNode(arguments[0]) == null) {
+            return;
+        }
+        final CommandSender sender = event.getSender();
+        final C cloudSender = this.paperCommandManager.getCommandSenderMapper().apply(sender);
+        final List<String> suggestions = new ArrayList<>(this.paperCommandManager.suggest(cloudSender,
+                                                                                          event.getBuffer().substring(1)));
+        event.setCompletions(suggestions);
+        event.setHandled(true);
+    }
+
+}

cloud-minecraft/cloud-paper/src/main/java/com/intellectualsites/commands/paper/PaperCommandManager.java

@@ -82,4 +82,12 @@ public class PaperCommandManager<C> extends BukkitCommandManager<C> {
         }
     }
 
+    /**
+     * Register asynchronous completions. This requires all argument parsers to be thread safe, and it
+     * is up to the caller to guarantee that such is the case
+     */
+    public void registerAsynchronousCompletions() {
+        Bukkit.getServer().getPluginManager().registerEvents(new AsyncCommandSuggestionsListener<>(this), this.getOwningPlugin());
+    }
+
 }