Add /skript command tab completer

src/main/java/ch/njol/skript/Skript.java

@@ -469,6 +469,7 @@ public void onEnable() {
 		PluginCommand skriptCommand = getCommand("skript");
 		assert skriptCommand != null; // It is defined, unless build is corrupted or something like that
 		skriptCommand.setExecutor(new SkriptCommand());
+		skriptCommand.setTabCompleter(new SkriptCommandTabCompleter());
 
 		// Load Bukkit stuff. It is done after platform check, because something might be missing!
 		new BukkitClasses();

src/main/java/ch/njol/skript/SkriptCommandTabCompleter.java

@@ -0,0 +1,109 @@
+/**
+ *   This file is part of Skript.
+ *
+ *  Skript is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Skript is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with Skript.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright Peter Güttinger, SkriptLang team and contributors
+ */
+package ch.njol.skript;
+
+import ch.njol.skript.tests.runner.TestMode;
+import ch.njol.util.StringUtils;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.command.TabCompleter;
+
+import javax.annotation.Nullable;
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+
+public class SkriptCommandTabCompleter implements TabCompleter {
+
+	@Override
+	@Nullable
+	public List<String> onTabComplete(CommandSender sender, Command command, String alias, String[] args) {
+		ArrayList<String> options = new ArrayList<>();
+
+		if (!command.getName().equalsIgnoreCase("skript")) {
+			return null;
+		}
+
+		if (args[0].equalsIgnoreCase("update") && args.length == 2) {
+			options.add("check");
+			options.add("changes");
+			options.add("download");
+		} else if (args[0].matches("(?i)(reload|disable|enable)") && args.length == 2) {
+			File scripts = new File(Skript.getInstance().getDataFolder(), Skript.SCRIPTSFOLDER);
+			String scriptArg = StringUtils.join(args, " ", 1, args.length); 
+			String fs = File.separator;
+
+			try {
+				// Live update, this will get all old and new (even not loaded) scripts
+				Files.walk(scripts.toPath())
+					.map(Path::toFile)
+					.filter(f -> (!f.isDirectory() && f.getName().toLowerCase().endsWith(".sk")) ||
+						f.isDirectory()) // filter folders and skript files only
+					.filter(f -> { // Filtration for enable, disable and reload
+						if (args[0].equalsIgnoreCase("enable"))
+							return f.getName().startsWith("-");
+						else // reload & disable both accepts only non-hyphened files and not hidden folders
+							return !f.getAbsolutePath().matches(".*?(\\\\-|/-|^-).*") && (f.isDirectory() &&
+								!f.getAbsolutePath().matches(".*?(\\\\\\.|/\\.|^\\.).*") || !f.isDirectory());
+					})
+					.filter(f -> { // Autocomplete incomplete script name arg
+						return scriptArg.length() > 0 ? f.getName().startsWith(scriptArg) : true;
+					})
+					.forEach(f -> {
+						if (!f.toString().equals(scripts.toString()))
+							options.add(f.toString()
+								.replace(scripts.toPath() + (!f.isDirectory() && f.getParentFile().toPath().toString()
+									.equals(scripts.toPath().toString()) ? fs : ""), "") // Extract file short path, and remove '/' from the beginning of files in root only
+								+ (f.isDirectory() && f.toString().length() > 0 ? fs : "")); // add File.separator at the end of directories
+					}); 
+
+			// TODO handle file permissions
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+
+			// These will be added even if there are incomplete script arg
+			options.add("all");
+			if (args[0].equalsIgnoreCase("reload")) {
+				options.add("config");
+				options.add("aliases");
+				options.add("scripts");
+			}
+		} else if (args.length == 1) {
+			options.add("help");
+			options.add("reload");
+			options.add("enable");
+			options.add("disable");
+			options.add("update");
+			options.add("info");
+			if (new File(Skript.getInstance().getDataFolder() + "/doc-templates").exists()) {
+				options.add("gen-docs");
+			}
+			if (TestMode.DEV_MODE) {
+				options.add("test");
+			}
+		}
+
+		return options;
+	}
+
+}