Add dynamic usage messages for commands

src/main/java/ch/njol/skript/command/CommandUsage.java

@@ -0,0 +1,82 @@
+/**
+ *   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.command;
+
+import ch.njol.skript.lang.VariableString;
+import ch.njol.skript.util.Utils;
+import com.google.errorprone.annotations.Var;
+import org.bukkit.event.Event;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Holds info about the usage of a command.
+ * TODO: replace with record when java 17
+ */
+public class CommandUsage {
+
+	/**
+	 * A dynamic usage message that can contain expressions.
+	 */
+	private final VariableString usage;
+
+	/**
+	 * A fallback usage message that can be used in non-event environments,
+	 * like when registering the Bukkit command.
+	 */
+	private final String defaultUsage;
+
+	/**
+	 * @param usage The dynamic usage message, can contain expressions.
+	 * @param defaultUsage A fallback usage message for use in non-event environments.
+	 */
+	public CommandUsage(@Nullable VariableString usage, String defaultUsage) {
+		if (usage == null) {
+			usage = VariableString.newInstance(defaultUsage);
+			assert usage != null;
+		}
+		this.usage = usage;
+		this.defaultUsage = Utils.replaceChatStyles(defaultUsage);
+	}
+
+	/**
+	 * @return The usage message as a {@link VariableString}.
+	 */
+	public VariableString getRawUsage() {
+		return usage;
+	}
+	/**
+	 * Get the usage message without an event to evaluate it.
+	 * @return The evaluated usage message.
+	 */
+	public String getUsage() {
+		return getUsage(null);
+	}
+
+	/**
+	 * @param event The event used to evaluate the usage message.
+	 * @return The evaluated usage message.
+	 */
+	public String getUsage(@Nullable Event event) {
+		if (event != null || usage.isSimple())
+			return usage.toString(event);
+		return defaultUsage;
+	}
+
+}

src/main/java/ch/njol/skript/command/ScriptCommand.java

@@ -101,7 +101,7 @@ public class ScriptCommand implements TabExecutor {
 	private final String cooldownBypass;
 	@Nullable
 	private final Expression<String> cooldownStorage;
-	final String usage;
+	final CommandUsage usage;
 
 	private final Trigger trigger;
 
@@ -131,7 +131,7 @@ public class ScriptCommand implements TabExecutor {
 	 */
 	public ScriptCommand(
 		Script script, String name, String pattern, List<Argument<?>> arguments,
-		String description, @Nullable String prefix, String usage, List<String> aliases,
+		String description, @Nullable String prefix, CommandUsage usage, List<String> aliases,
 		String permission, @Nullable VariableString permissionMessage, @Nullable Timespan cooldown,
 		@Nullable VariableString cooldownMessage, String cooldownBypass,
 		@Nullable VariableString cooldownStorage, int executableBy, SectionNode node
@@ -180,7 +180,7 @@ public ScriptCommand(
 		activeAliases = new ArrayList<>(aliases);
 
 		this.description = Utils.replaceEnglishChatStyles(description);
-		this.usage = Utils.replaceEnglishChatStyles(usage);
+		this.usage = usage;
 
 		this.executableBy = executableBy;
 
@@ -205,7 +205,7 @@ private PluginCommand setupBukkitCommand() {
 			// We can only set the message if it's simple (doesn't contains expressions)
 			if (permissionMessage.isSimple())
 				bukkitCommand.setPermissionMessage(permissionMessage.toString(null));
-			bukkitCommand.setUsage(usage);
+			bukkitCommand.setUsage(usage.getUsage());
 			bukkitCommand.setExecutor(this);
 			return bukkitCommand;
 		} catch (final Exception e) {
@@ -300,7 +300,7 @@ boolean execute2(final ScriptCommandEvent event, final CommandSender sender, fin
 				final LogEntry e = log.getError();
 				if (e != null)
 					sender.sendMessage(ChatColor.DARK_RED + e.toString());
-				sender.sendMessage(usage);
+				sender.sendMessage(usage.getUsage(event));
 				log.clear();
 				return false;
 			}
@@ -342,7 +342,7 @@ public boolean checkPermissions(CommandSender sender, Event event) {
 	public void sendHelp(final CommandSender sender) {
 		if (!description.isEmpty())
 			sender.sendMessage(description);
-		sender.sendMessage(ChatColor.GOLD + "Usage" + ChatColor.RESET + ": " + usage);
+		sender.sendMessage(ChatColor.GOLD + "Usage" + ChatColor.RESET + ": " + usage.getUsage());
 	}
 
 	/**

src/main/java/ch/njol/skript/structures/StructCommand.java

@@ -24,6 +24,7 @@
 import ch.njol.skript.classes.ClassInfo;
 import ch.njol.skript.classes.Parser;
 import ch.njol.skript.command.Argument;
+import ch.njol.skript.command.CommandUsage;
 import ch.njol.skript.command.Commands;
 import ch.njol.skript.command.ScriptCommand;
 import ch.njol.skript.command.ScriptCommandEvent;
@@ -34,6 +35,7 @@
 import ch.njol.skript.doc.Since;
 import ch.njol.skript.lang.Literal;
 import ch.njol.skript.lang.ParseContext;
+import org.bukkit.command.Command;
 import org.skriptlang.skript.lang.script.Script;
 import ch.njol.skript.lang.SkriptParser;
 import ch.njol.skript.lang.SkriptParser.ParseResult;
@@ -92,10 +94,10 @@ public class StructCommand extends Structure {
 		Skript.registerStructure(
 			StructCommand.class,
 			EntryValidator.builder()
-				.addEntry("usage", null, true)
 				.addEntry("description", "", true)
 				.addEntry("prefix", null, true)
 				.addEntry("permission", "", true)
+				.addEntryData(new VariableStringEntryData("usage", null, true))
 				.addEntryData(new VariableStringEntryData("permission message", null, true))
 				.addEntryData(new KeyValueEntryData<List<String>>("aliases", new ArrayList<>(), true) {
 					private final Pattern pattern = Pattern.compile("\\s*,\\s*/?");
@@ -261,10 +263,9 @@ public boolean load() {
 		});
 		desc = Commands.unescape(desc).trim();
 
-		String usage = entryContainer.getOptional("usage", String.class, false);
-		if (usage == null) {
-			usage = Commands.m_correct_usage + " " + desc;
-		}
+		VariableString usageMessage = entryContainer.getOptional("usage", VariableString.class, false);
+		String defaultUsageMessage = Commands.m_correct_usage + " " + desc;
+		CommandUsage usage = new CommandUsage(usageMessage, defaultUsageMessage);
 
 		String description = entryContainer.get("description", String.class, true);
 		String prefix = entryContainer.getOptional("prefix", String.class, false);