content: /*
   * Copyright (c) 2016-2017 Daniel Ennis (Aikar) - MIT License
   *
   *  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 co.aikar.commands;
  
  import com.destroystokyo.paper.event.server.AsyncTabCompleteEvent;
  import org.bukkit.command.CommandSender;
  import org.bukkit.event.EventHandler;
  import org.bukkit.event.Listener;
  
  import java.util.Arrays;
  import java.util.List;
  
  class PaperAsyncTabCompleteHandler implements Listener {
      private final PaperCommandManager manager;
  
      PaperAsyncTabCompleteHandler(PaperCommandManager manager) {
          this.manager = manager;
          manager.log(LogLevel.INFO, "Enabled Asynchronous Tab Completion Support!");
      }
  
      @EventHandler(ignoreCancelled = true)
      public void onAsyncTabComplete(AsyncTabCompleteEvent event) {
          String buffer = event.getBuffer();
          if ((!event.isCommand() && !buffer.startsWith("/")) || buffer.indexOf(' ') == -1) {
              return;
          }
          try {
              //noinspection ConstantConditions,ConstantIfStatement
              if (false) throw new CommandCompletions.SyncCompletionRequired(); // fake compiler due to SneakyThrows
              List<String> completions = getCompletions(buffer, event.getCompletions(), event.getSender(), true);
              if (completions != null) {
                  // if we have no completion data, client will display an error, lets just send a space instead (https://bugs.mojang.com/browse/MC-165562)
                  if (completions.size() == 1 && completions.get(0).equals("")) {
                      completions.set(0, " ");
                  }
                  event.setCompletions(completions);
                  event.setHandled(true);
              }
          } catch (Exception e) {
              if (!(e instanceof CommandCompletions.SyncCompletionRequired)) {
                  throw e;
              }
          }
      }
  
      private List<String> getCompletions(String buffer, List<String> existingCompletions, CommandSender sender, boolean async) {
          String[] args = ACFPatterns.SPACE.split(buffer, -1);
  
          String commandLabel = stripLeadingSlash(args[0]);
          args = args.length > 1 ? Arrays.copyOfRange(args, 1, args.length) : new String[]{""};
  
          RootCommand rootCommand = this.manager.getRootCommand(commandLabel);
          if (rootCommand == null) {
              return null;
          }
  
          BukkitCommandIssuer issuer = this.manager.getCommandIssuer(sender);
          List<String> completions = rootCommand.getTabCompletions(issuer, commandLabel, args, false, async);
  
          return ACFUtil.preformOnImmutable(existingCompletions, (list) -> list.addAll(completions));
      }
  
      private static String stripLeadingSlash(String arg) {
          return arg.startsWith("/") ? arg.substring(1) : arg;
      }
  }
  