From 447362e3021efe94ef9210f6a62a38083a09cff5 Mon Sep 17 00:00:00 2001
From: Michael <mquindt@yahoo.com>
Date: Tue, 4 Jul 2023 16:08:29 -0500
Subject: [PATCH] Add reflective checks on plugin enable to prevent script
 errors later

---
 .../java/dev/magicmq/pyspigot/PySpigot.java   | 19 +++++++++++++++++++
 .../manager/script/ScriptManager.java         |  7 ++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/src/main/java/dev/magicmq/pyspigot/PySpigot.java b/src/main/java/dev/magicmq/pyspigot/PySpigot.java
index 1b498f8..48866f5 100644
--- a/src/main/java/dev/magicmq/pyspigot/PySpigot.java
+++ b/src/main/java/dev/magicmq/pyspigot/PySpigot.java
@@ -26,8 +26,13 @@
 import dev.magicmq.pyspigot.manager.script.ScriptManager;
 import dev.magicmq.pyspigot.manager.task.TaskManager;
 import org.bukkit.Bukkit;
+import org.bukkit.command.PluginCommand;
+import org.bukkit.command.SimpleCommandMap;
+import org.bukkit.plugin.Plugin;
 import org.bukkit.plugin.java.JavaPlugin;
 
+import java.util.logging.Level;
+
 /**
  * Main class of the plugin.
  */
@@ -81,6 +86,13 @@ public void onEnable() {
 
         if (isPlaceholderApiAvailable())
             placeholder = PlaceholderManager.get();
+
+        try {
+            checkReflection();
+        } catch (NoSuchMethodException | NoSuchFieldException e) {
+            getLogger().log(Level.SEVERE, "Error when accessing CraftBukkit (Are you on a supported MC version?), PySpigot will not work correctly.");
+            Bukkit.getPluginManager().disablePlugin(this);
+        }
     }
 
     @Override
@@ -112,6 +124,13 @@ public boolean isPlaceholderApiAvailable() {
         return Bukkit.getPluginManager().getPlugin("PlaceholderAPI") != null;
     }
 
+    private void checkReflection() throws NoSuchMethodException, NoSuchFieldException {
+        //Check reflection for commands
+        PluginCommand.class.getDeclaredConstructor(String.class, Plugin.class);
+        Bukkit.getServer().getClass().getDeclaredField("commandMap");
+        SimpleCommandMap.class.getDeclaredField("knownCommands");
+    }
+
     /**
      * Get the instance of this plugin.
      * @return The instance
diff --git a/src/main/java/dev/magicmq/pyspigot/manager/script/ScriptManager.java b/src/main/java/dev/magicmq/pyspigot/manager/script/ScriptManager.java
index 12351a9..d28ec28 100644
--- a/src/main/java/dev/magicmq/pyspigot/manager/script/ScriptManager.java
+++ b/src/main/java/dev/magicmq/pyspigot/manager/script/ScriptManager.java
@@ -29,6 +29,7 @@
 import dev.magicmq.pyspigot.manager.protocol.ProtocolManager;
 import dev.magicmq.pyspigot.manager.task.TaskManager;
 import org.bukkit.Bukkit;
+import org.bukkit.scheduler.BukkitTask;
 import org.python.core.*;
 import org.python.util.PythonInterpreter;
 
@@ -56,6 +57,8 @@ public class ScriptManager {
     private final List<Script> scripts;
     private final HashMap<String, PyObject> globalVariables;
 
+    private final BukkitTask startScriptTask;
+
     private ScriptManager() {
         this.systemState = new PySystemState();
         systemState.setClassLoader(LibraryManager.get().getClassLoader());
@@ -71,13 +74,15 @@ private ScriptManager() {
         if (!logs.exists())
             logs.mkdir();
 
-        Bukkit.getScheduler().runTaskLater(PySpigot.get(), this::loadScripts, PluginConfig.getLoadScriptDelay());
+        startScriptTask = Bukkit.getScheduler().runTaskLater(PySpigot.get(), this::loadScripts, PluginConfig.getLoadScriptDelay());
     }
 
     /**
      * Called on plugin unload or server shutdown. Gracefully stops and unloads all loaded and running scripts.
      */
     public void shutdown() {
+        startScriptTask.cancel();
+
         for (Script script : scripts) {
             ScriptUnloadEvent event = new ScriptUnloadEvent(script, false);
             Bukkit.getPluginManager().callEvent(event);