Added .eval command

src/main/java/net/dv8tion/discord/Yui.java

@@ -109,6 +109,7 @@ private static void setupBot()
             jdaBuilder.addListener(help.registerCommand(new ReloadCommand()));
             jdaBuilder.addListener(help.registerCommand(new UpdateCommand()));
             jdaBuilder.addListener(help.registerCommand(new PermissionsCommand()));
+            jdaBuilder.addListener(help.registerCommand(new EvalCommand()));
 
             for (IrcConnectInfo info  : settings.getIrcConnectInfos())
             {

src/main/java/net/dv8tion/discord/commands/EvalCommand.java

@@ -0,0 +1,84 @@
+package net.dv8tion.discord.commands;
+
+import net.dv8tion.discord.Permissions;
+import net.dv8tion.jda.events.message.MessageReceivedEvent;
+
+import javax.script.ScriptEngine;
+import javax.script.ScriptEngineManager;
+import javax.script.ScriptException;
+import java.util.Collections;
+import java.util.List;
+
+public class EvalCommand extends Command
+{
+    private ScriptEngine engine;
+
+    public EvalCommand()
+    {
+        engine = new ScriptEngineManager().getEngineByName("nashorn");
+        try
+        {
+            engine.eval("var imports = new JavaImporter(java.io, java.lang, java.util);");
+        }
+        catch (ScriptException e)
+        {
+            e.printStackTrace();
+        }
+    }
+
+    @Override
+    public void onCommand(MessageReceivedEvent e, String[] args)
+    {
+        if (!Permissions.getPermissions().isOp(e.getAuthor()))
+        {
+            sendMessage(e, "Sorry, this command is OP only!");
+            return;
+        }
+
+        try
+        {
+            engine.put("event", e);
+            engine.put("channel", e.getChannel());
+            engine.put("args", args);
+            engine.put("api", e.getJDA());
+            Object out = engine.eval(
+                    "(function() {" +
+                        "with (imports) {" +
+                            e.getMessage().getContent().substring(args[0].length()) +
+                        "}" +
+                    "})();");
+            sendMessage(e, out == null ? "Executed without error." : out.toString());
+        }
+        catch (ScriptException e1)
+        {
+            sendMessage(e, e1.getMessage());
+        }
+    }
+
+    @Override
+    public List<String> getAliases()
+    {
+        return Collections.singletonList(".eval");
+    }
+
+    @Override
+    public String getDescription()
+    {
+        return "Takes Java or Javascript and executes it.";
+    }
+
+    @Override
+    public String getName()
+    {
+        return "Evaluate";
+    }
+
+    @Override
+    public List<String> getUsageInstructions()
+    {
+        return Collections.singletonList(
+                ".eval <Java code>\n" +
+                "    Example: `.eval return \"5 + 5 is: \" + (5 + 5);\n" +
+                "    This will print: 5 + 5 is: 10");
+    }
+}