Configurable aliases for the /sellgui command

src/main/java/net/mackenziemolloy/shopguiplus/sellgui/SellGUI.java

@@ -48,6 +48,10 @@ public void onEnable() {
         scheduler = foliaLib.getScheduler();
 
         new CommandSellGUI(this).register();
+        new net.mackenziemolloy.shopguiplus.sellgui.utility.CommandRegistrar(this).registerAliases();
+        getServer().getPluginManager()
+                .registerEvents(new net.mackenziemolloy.shopguiplus.sellgui.listeners.SellCommandListener(this), this);
+
         Logger logger = getLogger();
 
         checkCompatibility();

src/main/java/net/mackenziemolloy/shopguiplus/sellgui/listeners/SellCommandListener.java

@@ -0,0 +1,36 @@
+package net.mackenziemolloy.shopguiplus.sellgui.listeners;
+
+import net.mackenziemolloy.shopguiplus.sellgui.SellGUI;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerCommandPreprocessEvent;
+
+import java.util.Locale;
+
+public class SellCommandListener implements Listener {
+
+    private final SellGUI plugin;
+
+    public SellCommandListener(SellGUI plugin) {
+        this.plugin = plugin;
+    }
+
+    @EventHandler(priority = EventPriority.LOWEST)
+    public void onCommandPreProcess(PlayerCommandPreprocessEvent event) {
+        String message = event.getMessage();
+        String[] args = message.split(" ");
+
+        if (args.length != 1) {
+            return;
+        }
+
+        String command = args[0].substring(1).toLowerCase(Locale.US);
+        java.util.List<String> aliases = plugin.getConfiguration().getStringList("options.commands.aliases");
+
+        if (aliases.contains(command)) {
+            event.setCancelled(true);
+            plugin.getCommand("sellgui").execute(event.getPlayer(), "sellgui", new String[0]);
+        }
+    }
+}

src/main/java/net/mackenziemolloy/shopguiplus/sellgui/utility/CommandRegistrar.java

@@ -0,0 +1,94 @@
+package net.mackenziemolloy.shopguiplus.sellgui.utility;
+
+import net.mackenziemolloy.shopguiplus.sellgui.SellGUI;
+import org.bukkit.Bukkit;
+
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandMap;
+import org.bukkit.command.PluginCommand;
+import org.bukkit.plugin.Plugin;
+import org.bukkit.plugin.SimplePluginManager;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.util.List;
+import java.util.logging.Level;
+
+public class CommandRegistrar {
+
+    private final SellGUI plugin;
+
+    public CommandRegistrar(SellGUI plugin) {
+        this.plugin = plugin;
+    }
+
+    public void registerAliases() {
+        List<String> aliases = plugin.getConfiguration().getStringList("options.commands.aliases");
+        if (aliases == null || aliases.isEmpty()) {
+            return;
+        }
+
+        CommandMap commandMap = getCommandMap();
+        if (commandMap == null) {
+            plugin.getLogger().severe("Could not retrieve CommandMap. Custom aliases will not work.");
+            return;
+        }
+
+        PluginCommand sellGuiCommand = plugin.getCommand("sellgui");
+        if (sellGuiCommand == null) {
+            plugin.getLogger().severe("The main 'sellgui' command is not registered!");
+            return;
+        }
+
+        for (String alias : aliases) {
+            Command command = commandMap.getCommand(alias);
+            if (command != null && !command.getLabel().equalsIgnoreCase(alias)) {
+                // If the command exists but under a fallback prefix (plugin:cmd), we might
+                // still want to register ours?
+                // Bukkit's getCommand returns the first match.
+                // If Essentials has 'sell', getCommand('sell') returns it.
+            }
+
+            // We only skip if there is a command that directly matches the alias
+            if (command != null
+                    && (command.getLabel().equalsIgnoreCase(alias) || command.getAliases().contains(alias))) {
+                // plugin.getLogger().info("Skipping registration of alias '" + alias + "' as it
+                // is already registered.");
+                continue;
+            }
+
+            PluginCommand aliasCommand = createPluginCommand(alias, plugin);
+            if (aliasCommand != null) {
+                aliasCommand.setExecutor(sellGuiCommand.getExecutor());
+                aliasCommand.setTabCompleter(sellGuiCommand.getTabCompleter());
+                aliasCommand.setDescription(sellGuiCommand.getDescription());
+
+                commandMap.register(plugin.getDescription().getName(), aliasCommand);
+            }
+        }
+    }
+
+    private CommandMap getCommandMap() {
+        try {
+            if (Bukkit.getPluginManager() instanceof SimplePluginManager) {
+                Field f = SimplePluginManager.class.getDeclaredField("commandMap");
+                f.setAccessible(true);
+                return (CommandMap) f.get(Bukkit.getPluginManager());
+            }
+        } catch (Exception e) {
+            plugin.getLogger().log(Level.SEVERE, "Failed to get command map", e);
+        }
+        return null;
+    }
+
+    private PluginCommand createPluginCommand(String name, Plugin plugin) {
+        try {
+            Constructor<PluginCommand> c = PluginCommand.class.getDeclaredConstructor(String.class, Plugin.class);
+            c.setAccessible(true);
+            return c.newInstance(name, plugin);
+        } catch (Exception e) {
+            plugin.getLogger().log(Level.SEVERE, "Failed to create PluginCommand for alias: " + name, e);
+            return null;
+        }
+    }
+}

src/main/resources/config.yml

@@ -17,6 +17,18 @@
 #
 
 options:
+  #
+  # Command Configuration
+  #
+  commands:
+    #
+    # Custom aliases for /sellgui
+    #
+    aliases:
+      - "sell"
+      - "sg"
+      - "sellg"
+
   #
   # 0 - None
   # 1 - Hover message (Adds "receipt_text" to the end of the message)