fix(spigot): unregister commands on shutdown

spigot/src/main/kotlin/su/plo/slib/spigot/SpigotServerLib.kt

@@ -92,7 +92,7 @@ class SpigotServerLib(
     }
 
     fun onShutdown() {
-        commandManager.clear()
+        commandManager.clear(loader)
         permissionManager.clear()
         adventure.close()
     }

spigot/src/main/kotlin/su/plo/slib/spigot/command/SpigotCommand.kt

@@ -14,6 +14,10 @@ class SpigotCommand(
 ) : Command(name) {
 
     override fun execute(sender: CommandSender, commandLabel: String, args: Array<String>): Boolean {
+        if (!isRegistered) {
+            return false
+        }
+
         val source = commandManager.getCommandSource(sender)
         if (!command.hasPermission(source, args)) {
             source.sendMessage(minecraftServer.permissionManager.noPermissionMessage)
@@ -30,9 +34,19 @@ class SpigotCommand(
         alias: String,
         args: Array<String>,
         location: Location?
-    ): List<String> =
-        command.suggest(commandManager.getCommandSource(sender), args)
+    ): List<String> {
+        if (!isRegistered) {
+            return super.tabComplete(sender, alias, args)
+        }
+
+        return command.suggest(commandManager.getCommandSource(sender), args)
+    }
+
+    override fun testPermissionSilent(target: CommandSender): Boolean {
+        if (!isRegistered) {
+            return super.testPermissionSilent(target)
+        }
 
-    override fun testPermissionSilent(target: CommandSender): Boolean =
-        command.hasPermission(commandManager.getCommandSource(target), null)
+        return command.hasPermission(commandManager.getCommandSource(target), null)
+    }
 }

spigot/src/main/kotlin/su/plo/slib/spigot/command/SpigotCommandManager.kt

@@ -1,42 +1,73 @@
 package su.plo.slib.spigot.command
 
+import org.bukkit.command.Command
 import org.bukkit.command.CommandSender
 import org.bukkit.command.SimpleCommandMap
 import org.bukkit.entity.Player
 import org.bukkit.plugin.java.JavaPlugin
 import su.plo.slib.api.command.McCommand
 import su.plo.slib.api.command.McCommandManager
 import su.plo.slib.api.command.McCommandSource
+import su.plo.slib.api.logging.McLoggerFactory
 import su.plo.slib.api.server.event.command.McServerCommandsRegisterEvent
 import su.plo.slib.spigot.SpigotServerLib
 
 class SpigotCommandManager(
     private val minecraftServer: SpigotServerLib
 ) : McCommandManager<McCommand>() {
 
+    private val logger = McLoggerFactory.createLogger("SpigotCommandManager")
+
     @Synchronized
     fun registerCommands(loader: JavaPlugin) {
         McServerCommandsRegisterEvent.invoker.onCommandsRegister(this, minecraftServer)
 
         commandByName.forEach { (name, command) ->
             val spigotCommand = SpigotCommand(minecraftServer, this, command, name)
-
-            val commandMap = loader.server.javaClass
-                .getDeclaredField("commandMap").also {
-                    it.isAccessible = true
-                }
-                .get(loader.server) as SimpleCommandMap
+            val commandMap = loader.commandMap()
 
             commandMap.register("plasmovoice", spigotCommand)
         }
 
         registered = true
     }
 
+    @Synchronized
+    fun clear(loader: JavaPlugin) {
+        val commandMap = loader.commandMap()
+
+        commandByName.keys
+            .mapNotNull { commandMap.getCommand(it) }
+            .forEach { commandMap.unregister(it) }
+
+        super.clear()
+    }
+
     override fun getCommandSource(source: Any): McCommandSource  {
         require(source is CommandSender) { "source is not ${CommandSender::class.java}" }
 
         return if (source is Player) minecraftServer.getPlayerByInstance(source)
         else SpigotDefaultCommandSource(minecraftServer, source)
     }
+
+    @Suppress("UNCHECKED_CAST")
+    private fun SimpleCommandMap.unregister(command: Command) {
+        try {
+            command.unregister(this)
+
+            val knownCommandsField = SimpleCommandMap::class.java.getDeclaredField("knownCommands")
+            knownCommandsField.isAccessible = true
+
+            val knownCommands = knownCommandsField.get(this) as MutableMap<String, Command>
+            knownCommands.remove(command.name)
+        } catch (e: Throwable) {
+            logger.error("Failed to unregister command ${command.name}", e)
+        }
+    }
+
+    private fun JavaPlugin.commandMap(): SimpleCommandMap =
+        server.javaClass
+            .getDeclaredField("commandMap")
+            .also { it.isAccessible = true }
+            .get(server) as SimpleCommandMap
 }