Refactor some parts of NewLaunch (part 2)

12 files changed, 493 insertions, 578 deletions

diff --git a/libraries/launcher/org/multimc/EntryPoint.java b/libraries/launcher/org/multimc/EntryPoint.java
index b626d095..be06d1b4 100644
--- a/libraries/launcher/org/multimc/EntryPoint.java
+++ b/libraries/launcher/org/multimc/EntryPoint.java
@@ -14,7 +14,8 @@ package org.multimc;/*
  * limitations under the License.
  */
 
-import org.multimc.onesix.OneSixLauncher;
+import org.multimc.exception.ParseException;
+import org.multimc.utils.ParamBucket;
 
 import java.io.BufferedReader;
 import java.io.IOException;
@@ -23,31 +24,27 @@ import java.nio.charset.StandardCharsets;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-public class EntryPoint
-{
+public final class EntryPoint {
 
     private static final Logger LOGGER = Logger.getLogger("EntryPoint");
 
     private final ParamBucket params = new ParamBucket();
 
-    private org.multimc.Launcher launcher;
+    private String launcherType;
 
-    public static void main(String[] args)
-    {
+    public static void main(String[] args) {
         EntryPoint listener = new EntryPoint();
 
         int retCode = listener.listen();
 
-        if (retCode != 0)
-        {
+        if (retCode != 0) {
             LOGGER.info("Exiting with " + retCode);
 
             System.exit(retCode);
         }
     }
 
-    private Action parseLine(String inData) throws ParseException
-    {
+    private Action parseLine(String inData) throws ParseException {
         String[] tokens = inData.split("\\s+", 2);
 
         if (tokens.length == 0)
@@ -66,15 +63,9 @@ public class EntryPoint
                 if (tokens.length != 2)
                     throw new ParseException("Expected 2 tokens, got " + tokens.length);
 
-                if (tokens[1].equals("onesix")) {
-                    launcher = new OneSixLauncher();
+                launcherType = tokens[1];
 
-                    LOGGER.info("Using onesix launcher.");
-
-                    return Action.Proceed;
-                } else {
-                    throw new ParseException("Invalid launcher type: " + tokens[1]);
-                }
+                return Action.Proceed;
             }
 
             default: {
@@ -88,8 +79,7 @@ public class EntryPoint
         }
     }
 
-    public int listen()
-    {
+    public int listen() {
         Action action = Action.Proceed;
 
         try (BufferedReader reader = new BufferedReader(new InputStreamReader(
@@ -112,16 +102,31 @@ public class EntryPoint
         }
 
         // Main loop
-        if (action == Action.Abort)
-        {
+        if (action == Action.Abort) {
             LOGGER.info("Launch aborted by the launcher.");
 
             return 1;
         }
 
-        if (launcher != null)
-        {
-            return launcher.launch(params);
+        if (launcherType != null) {
+            try {
+                Launcher launcher =
+                        LauncherFactory
+                                .getInstance()
+                                .createLauncher(launcherType, params);
+
+                launcher.launch();
+
+                return 0;
+            } catch (IllegalArgumentException e) {
+                LOGGER.log(Level.SEVERE, "Wrong argument.", e);
+
+                return 1;
+            } catch (Exception e) {
+                LOGGER.log(Level.SEVERE, "Exception caught from launcher.", e);
+
+                return 1;
+            }
         }
 
         LOGGER.log(Level.SEVERE, "No valid launcher implementation specified.");
diff --git a/libraries/launcher/org/multimc/Launcher.java b/libraries/launcher/org/multimc/Launcher.java
index c5e8fbc1..bc0b525e 100644
--- a/libraries/launcher/org/multimc/Launcher.java
+++ b/libraries/launcher/org/multimc/Launcher.java
@@ -16,7 +16,8 @@
 
 package org.multimc;
 
-public interface Launcher
-{
-    int launch(ParamBucket params);
+public interface Launcher {
+
+    void launch() throws Exception;
+
 }
diff --git a/libraries/launcher/org/multimc/LauncherFactory.java b/libraries/launcher/org/multimc/LauncherFactory.java
new file mode 100644
index 00000000..b5d0dd5b
--- /dev/null
+++ b/libraries/launcher/org/multimc/LauncherFactory.java
@@ -0,0 +1,34 @@
+package org.multimc;
+
+import org.multimc.impl.OneSixLauncher;
+import org.multimc.utils.ParamBucket;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Function;
+
+public final class LauncherFactory {
+
+    private static final LauncherFactory INSTANCE = new LauncherFactory();
+
+    private final Map<String, Function<ParamBucket, Launcher>> launcherRegistry = new HashMap<>();
+
+    private LauncherFactory() {
+        launcherRegistry.put("onesix", OneSixLauncher::new);
+    }
+
+    public Launcher createLauncher(String name, ParamBucket parameters) {
+        Function<ParamBucket, Launcher> launcherCreator =
+                launcherRegistry.get(name);
+
+        if (launcherCreator == null)
+            throw new IllegalArgumentException("Invalid launcher type: " + name);
+
+        return launcherCreator.apply(parameters);
+    }
+
+    public static LauncherFactory getInstance() {
+        return INSTANCE;
+    }
+
+}
diff --git a/libraries/launcher/org/multimc/LegacyFrame.java b/libraries/launcher/org/multimc/LegacyFrame.java
deleted file mode 100644
index 985a10e6..00000000
--- a/libraries/launcher/org/multimc/LegacyFrame.java
+++ /dev/null
@@ -1,176 +0,0 @@
-package org.multimc;/*
- * Copyright 2012-2021 MultiMC Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import net.minecraft.Launcher;
-
-import javax.imageio.ImageIO;
-import java.applet.Applet;
-import java.awt.*;
-import java.awt.event.WindowEvent;
-import java.awt.event.WindowListener;
-import java.awt.image.BufferedImage;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
-import java.io.IOException;
-import java.net.MalformedURLException;
-import java.net.URL;
-import java.util.Scanner;
-
-public class LegacyFrame extends Frame implements WindowListener
-{
-    private Launcher appletWrap = null;
-    public LegacyFrame(String title)
-    {
-        super ( title );
-        BufferedImage image;
-        try {
-            image = ImageIO.read ( new File ( "icon.png" ) );
-            setIconImage ( image );
-        } catch ( IOException e ) {
-            e.printStackTrace();
-        }
-        this.addWindowListener ( this );
-    }
-
-    public void start (
-        Applet mcApplet,
-        String user,
-        String session,
-        int winSizeW,
-        int winSizeH,
-        boolean maximize,
-        String serverAddress,
-        String serverPort
-    )
-    {
-        try {
-            appletWrap = new Launcher( mcApplet, new URL ( "http://www.minecraft.net/game" ) );
-        } catch ( MalformedURLException ignored ) {}
-        
-        // Implements support for launching in to multiplayer on classic servers using a mpticket
-        // file generated by an external program and stored in the instance's root folder.
-        File mpticketFile = null;
-        Scanner fileReader = null;
-        try {
-            mpticketFile = new File(System.getProperty("user.dir") + "/../mpticket").getCanonicalFile();
-            fileReader = new Scanner(new FileInputStream(mpticketFile), "ascii");
-            String[] mpticketParams = new String[3];
-            
-            for(int i=0;i<3;i++) {
-                if(fileReader.hasNextLine()) {
-                    mpticketParams[i] = fileReader.nextLine();
-                } else {
-                    throw new IllegalArgumentException();
-                }
-            }
-            
-            // Assumes parameters are valid and in the correct order
-            appletWrap.setParameter("server", mpticketParams[0]);
-            appletWrap.setParameter("port", mpticketParams[1]);
-            appletWrap.setParameter("mppass", mpticketParams[2]);
-            
-            fileReader.close();
-            mpticketFile.delete();
-        }
-        catch (FileNotFoundException e) {}
-        catch (IllegalArgumentException e) {
-            
-            fileReader.close();
-            File mpticketFileCorrupt = new File(System.getProperty("user.dir") + "/../mpticket.corrupt");
-            if(mpticketFileCorrupt.exists()) {
-                mpticketFileCorrupt.delete();
-            }
-            mpticketFile.renameTo(mpticketFileCorrupt);
-            
-            System.err.println("Malformed mpticket file, missing argument.");
-            e.printStackTrace(System.err);
-            System.exit(-1);
-        }
-        catch (Exception e) {
-            e.printStackTrace(System.err);
-            System.exit(-1);
-        }
-
-        if (serverAddress != null)
-        {
-            appletWrap.setParameter("server", serverAddress);
-            appletWrap.setParameter("port", serverPort);
-        }
-
-        appletWrap.setParameter ( "username", user );
-        appletWrap.setParameter ( "sessionid", session );
-        appletWrap.setParameter ( "stand-alone", "true" ); // Show the quit button.
-        appletWrap.setParameter ( "haspaid", "true" ); // Some old versions need this for world saves to work.
-        appletWrap.setParameter ( "demo", "false" );
-        appletWrap.setParameter ( "fullscreen", "false" );
-        mcApplet.setStub(appletWrap);
-        this.add ( appletWrap );
-        appletWrap.setPreferredSize ( new Dimension (winSizeW, winSizeH) );
-        this.pack();
-        this.setLocationRelativeTo ( null );
-        this.setResizable ( true );
-        if ( maximize ) {
-            this.setExtendedState ( MAXIMIZED_BOTH );
-        }
-        validate();
-        appletWrap.init();
-        appletWrap.start();
-        setVisible ( true );
-    }
-
-    @Override
-    public void windowActivated ( WindowEvent e ) {}
-
-    @Override
-    public void windowClosed ( WindowEvent e ) {}
-
-    @Override
-    public void windowClosing ( WindowEvent e )
-    {
-        new Thread() {
-            public void run() {
-                try {
-                    Thread.sleep ( 30000L );
-                } catch ( InterruptedException localInterruptedException ) {
-                    localInterruptedException.printStackTrace();
-                }
-                System.out.println ( "FORCING EXIT!" );
-                System.exit ( 0 );
-            }
-        }
-        .start();
-
-        if ( appletWrap != null ) {
-            appletWrap.stop();
-            appletWrap.destroy();
-        }
-        // old minecraft versions can hang without this >_<
-        System.exit ( 0 );
-    }
-
-    @Override
-    public void windowDeactivated ( WindowEvent e ) {}
-
-    @Override
-    public void windowDeiconified ( WindowEvent e ) {}
-
-    @Override
-    public void windowIconified ( WindowEvent e ) {}
-
-    @Override
-    public void windowOpened ( WindowEvent e ) {}
-}
diff --git a/libraries/launcher/org/multimc/Utils.java b/libraries/launcher/org/multimc/Utils.java
deleted file mode 100644
index e48029c2..00000000
--- a/libraries/launcher/org/multimc/Utils.java
+++ /dev/null
@@ -1,86 +0,0 @@
-/*
- * Copyright 2012-2021 MultiMC Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.multimc;
-
-import java.io.File;
-import java.lang.reflect.Field;
-import java.lang.reflect.Modifier;
-import java.util.List;
-
-public class Utils
-{
-    /**
-     * Combine two parts of a path.
-     *
-     * @param path1
-     * @param path2
-     * @return the paths, combined
-     */
-    public static String combine(String path1, String path2)
-    {
-        File file1 = new File(path1);
-        File file2 = new File(file1, path2);
-        return file2.getPath();
-    }
-
-    /**
-     * Join a list of strings into a string using a separator!
-     *
-     * @param strings   the string list to join
-     * @param separator the glue
-     * @return the result.
-     */
-    public static String join(List<String> strings, String separator)
-    {
-        StringBuilder sb = new StringBuilder();
-        String sep = "";
-        for (String s : strings)
-        {
-            sb.append(sep).append(s);
-            sep = separator;
-        }
-        return sb.toString();
-    }
-
-    /**
-     * Finds a field that looks like a Minecraft base folder in a supplied class
-     *
-     * @param mc the class to scan
-     */
-    public static Field getMCPathField(Class<?> mc)
-    {
-        Field[] fields = mc.getDeclaredFields();
-
-        for (Field f : fields)
-        {
-            if (f.getType() != File.class)
-            {
-                // Has to be File
-                continue;
-            }
-            if (f.getModifiers() != (Modifier.PRIVATE + Modifier.STATIC))
-            {
-                // And Private Static.
-                continue;
-            }
-            return f;
-        }
-        return null;
-    }
-
-}
-
diff --git a/libraries/launcher/org/multimc/applet/LegacyFrame.java b/libraries/launcher/org/multimc/applet/LegacyFrame.java
new file mode 100644
index 00000000..a5e6c170
--- /dev/null
+++ b/libraries/launcher/org/multimc/applet/LegacyFrame.java
@@ -0,0 +1,167 @@
+package org.multimc.applet;/*
+ * Copyright 2012-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import net.minecraft.Launcher;
+
+import javax.imageio.ImageIO;
+import java.applet.Applet;
+import java.awt.*;
+import java.awt.event.WindowAdapter;
+import java.awt.event.WindowEvent;
+import java.io.File;
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardCopyOption;
+import java.util.Scanner;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public final class LegacyFrame extends Frame {
+
+    private static final Logger LOGGER = Logger.getLogger("LegacyFrame");
+
+    private Launcher appletWrap;
+
+    public LegacyFrame(String title) {
+        super(title);
+
+        try {
+            setIconImage(ImageIO.read(new File("icon.png")));
+        } catch (IOException e) {
+            LOGGER.log(Level.WARNING, "Unable to read Minecraft icon!", e);
+        }
+
+        this.addWindowListener(new ForceExitHandler());
+    }
+
+    public void start (
+        Applet mcApplet,
+        String user,
+        String session,
+        int winSizeW,
+        int winSizeH,
+        boolean maximize,
+        String serverAddress,
+        String serverPort
+    ) {
+        try {
+            appletWrap = new Launcher(mcApplet, new URL("http://www.minecraft.net/game"));
+        } catch (MalformedURLException ignored) {}
+        
+        // Implements support for launching in to multiplayer on classic servers using a mpticket
+        // file generated by an external program and stored in the instance's root folder.
+        Path mpticketFile = Paths.get(System.getProperty("user.dir") + "/../mpticket");
+        Path mpticketFileCorrupt = Paths.get(System.getProperty("user.dir") + "/../mpticket.corrupt");
+
+        if (Files.exists(mpticketFile)) {
+            try (Scanner fileScanner = new Scanner(
+                    Files.newInputStream(mpticketFile),
+                    StandardCharsets.US_ASCII.name()
+            )) {
+                String[] mpticketParams = new String[3];
+
+                for (int i = 0; i < mpticketParams.length; i++) {
+                    if (fileScanner.hasNextLine()) {
+                        mpticketParams[i] = fileScanner.nextLine();
+                    } else {
+                        Files.move(
+                                mpticketFile,
+                                mpticketFileCorrupt,
+                                StandardCopyOption.REPLACE_EXISTING
+                        );
+
+                        throw new IllegalArgumentException("Mpticket file is corrupted!");
+                    }
+                }
+
+                Files.delete(mpticketFile);
+
+                // Assumes parameters are valid and in the correct order
+                appletWrap.setParameter("server", mpticketParams[0]);
+                appletWrap.setParameter("port", mpticketParams[1]);
+                appletWrap.setParameter("mppass", mpticketParams[2]);
+            } catch (IOException e) {
+                LOGGER.log(Level.WARNING, "Unable to read mpticket file!", e);
+            }
+        }
+
+        if (serverAddress != null) {
+            appletWrap.setParameter("server", serverAddress);
+            appletWrap.setParameter("port", serverPort);
+        }
+
+        appletWrap.setParameter("username", user);
+        appletWrap.setParameter("sessionid", session);
+        appletWrap.setParameter("stand-alone", "true"); // Show the quit button.
+        appletWrap.setParameter("haspaid", "true"); // Some old versions need this for world saves to work.
+        appletWrap.setParameter("demo", "false");
+        appletWrap.setParameter("fullscreen", "false");
+
+        mcApplet.setStub(appletWrap);
+
+        add(appletWrap);
+
+        appletWrap.setPreferredSize(new Dimension(winSizeW, winSizeH));
+
+        pack();
+
+        setLocationRelativeTo(null);
+        setResizable(true);
+
+        if (maximize)
+            this.setExtendedState(MAXIMIZED_BOTH);
+
+        validate();
+
+        appletWrap.init();
+        appletWrap.start();
+
+        setVisible(true);
+    }
+
+    private final class ForceExitHandler extends WindowAdapter {
+
+        @Override
+        public void windowClosing(WindowEvent e) {
+            new Thread(() -> {
+                try {
+                    Thread.sleep(30000L);
+                } catch (InterruptedException localInterruptedException) {
+                    localInterruptedException.printStackTrace();
+                }
+
+                LOGGER.info("Forcing exit!");
+
+                System.exit(0);
+            }).start();
+
+            if (appletWrap != null) {
+                appletWrap.stop();
+                appletWrap.destroy();
+            }
+
+            // old minecraft versions can hang without this >_<
+            System.exit(0);
+        }
+
+    }
+
+}
diff --git a/libraries/launcher/org/multimc/NotFoundException.java b/libraries/launcher/org/multimc/exception/ParameterNotFoundException.java
index ba12951d..9edbb826 100644
--- a/libraries/launcher/org/multimc/NotFoundException.java
+++ b/libraries/launcher/org/multimc/exception/ParameterNotFoundException.java
@@ -14,8 +14,12 @@
  * limitations under the License.
  */
 
-package org.multimc;
+package org.multimc.exception;
+
+public final class ParameterNotFoundException extends IllegalArgumentException {
+
+    public ParameterNotFoundException(String key) {
+        super("Unknown parameter name: " + key);
+    }
 
-public class NotFoundException extends Exception
-{
 }
diff --git a/libraries/launcher/org/multimc/ParseException.java b/libraries/launcher/org/multimc/exception/ParseException.java
index 7ea44c1f..c9a4c856 100644
--- a/libraries/launcher/org/multimc/ParseException.java
+++ b/libraries/launcher/org/multimc/exception/ParseException.java
@@ -14,12 +14,16 @@
  * limitations under the License.
  */
 
-package org.multimc;
+package org.multimc.exception;
+
+public final class ParseException extends IllegalArgumentException {
+
+    public ParseException() {
+        super();
+    }
 
-public class ParseException extends java.lang.Exception
-{
-    public ParseException() { super(); }
     public ParseException(String message) {
         super(message);
     }
+
 }
diff --git a/libraries/launcher/org/multimc/impl/OneSixLauncher.java b/libraries/launcher/org/multimc/impl/OneSixLauncher.java
new file mode 100644
index 00000000..d2596a69
--- /dev/null
+++ b/libraries/launcher/org/multimc/impl/OneSixLauncher.java
@@ -0,0 +1,183 @@
+/* Copyright 2012-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.multimc.impl;
+
+import org.multimc.Launcher;
+import org.multimc.applet.LegacyFrame;
+import org.multimc.utils.ParamBucket;
+import org.multimc.utils.Utils;
+
+import java.applet.Applet;
+import java.io.File;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Collections;
+import java.util.List;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public final class OneSixLauncher implements Launcher {
+
+    private static final int DEFAULT_WINDOW_WIDTH = 854;
+    private static final int DEFAULT_WINDOW_HEIGHT = 480;
+
+    private static final Logger LOGGER = Logger.getLogger("OneSixLauncher");
+
+    // parameters, separated from ParamBucket
+    private final List<String> mcParams;
+    private final List<String> traits;
+    private final String appletClass;
+    private final String mainClass;
+    private final String userName, sessionId;
+    private final String windowTitle;
+
+    // secondary parameters
+    private final int winSizeW;
+    private final int winSizeH;
+    private final boolean maximize;
+    private final String cwd;
+
+    private final String serverAddress;
+    private final String serverPort;
+
+    private final ClassLoader classLoader;
+
+    public OneSixLauncher(ParamBucket params) {
+        classLoader = ClassLoader.getSystemClassLoader();
+
+        mcParams = params.allSafe("param", Collections.emptyList());
+        mainClass = params.firstSafe("mainClass", "net.minecraft.client.Minecraft");
+        appletClass = params.firstSafe("appletClass", "net.minecraft.client.MinecraftApplet");
+        traits = params.allSafe("traits", Collections.emptyList());
+
+        userName = params.first("userName");
+        sessionId = params.first("sessionId");
+        windowTitle = params.firstSafe("windowTitle", "Minecraft");
+
+        serverAddress = params.firstSafe("serverAddress", null);
+        serverPort = params.firstSafe("serverPort", null);
+
+        cwd = System.getProperty("user.dir");
+
+        String windowParams = params.firstSafe("windowParams", "854x480");
+
+        String[] dimStrings = windowParams.split("x");
+
+        if (windowParams.equalsIgnoreCase("max")) {
+            maximize = true;
+
+            winSizeW = DEFAULT_WINDOW_WIDTH;
+            winSizeH = DEFAULT_WINDOW_HEIGHT;
+        } else if (dimStrings.length == 2) {
+            maximize = false;
+
+            winSizeW = Integer.parseInt(dimStrings[0]);
+            winSizeH = Integer.parseInt(dimStrings[1]);
+        } else {
+            throw new IllegalArgumentException("Unexpected window size parameter value: " + windowParams);
+        }
+    }
+
+    private void invokeMain(Class<?> mainClass) throws Exception {
+        Method method = mainClass.getMethod("main", String[].class);
+
+        method.invoke(null, (Object) mcParams.toArray(new String[0]));
+    }
+
+    private void legacyLaunch() throws Exception {
+        // Get the Minecraft Class and set the base folder
+        Class<?> minecraftClass = classLoader.loadClass(mainClass);
+
+        Field baseDirField = Utils.getMinecraftBaseDirField(minecraftClass);
+
+        if (baseDirField == null) {
+            LOGGER.warning("Could not find Minecraft path field.");
+        } else {
+            baseDirField.setAccessible(true);
+
+            baseDirField.set(null, new File(cwd));
+        }
+
+        System.setProperty("minecraft.applet.TargetDirectory", cwd);
+
+        if (!traits.contains("noapplet")) {
+            LOGGER.info("Launching with applet wrapper...");
+
+            try {
+                Class<?> mcAppletClass = classLoader.loadClass(appletClass);
+
+                Applet mcApplet = (Applet) mcAppletClass.getConstructor().newInstance();
+
+                LegacyFrame mcWindow = new LegacyFrame(windowTitle);
+
+                mcWindow.start(
+                        mcApplet,
+                        userName,
+                        sessionId,
+                        winSizeW,
+                        winSizeH,
+                        maximize,
+                        serverAddress,
+                        serverPort
+                );
+
+                return;
+            } catch (Exception e) {
+                LOGGER.log(Level.SEVERE, "Applet wrapper failed: ", e);
+
+                LOGGER.warning("Falling back to using main class.");
+            }
+        }
+
+        invokeMain(minecraftClass);
+    }
+
+    void launchWithMainClass() throws Exception {
+        // window size, title and state, onesix
+
+        // FIXME: there is no good way to maximize the minecraft window in onesix.
+        // the following often breaks linux screen setups
+        // mcparams.add("--fullscreen");
+
+        if (!maximize) {
+            mcParams.add("--width");
+            mcParams.add(Integer.toString(winSizeW));
+            mcParams.add("--height");
+            mcParams.add(Integer.toString(winSizeH));
+        }
+
+        if (serverAddress != null) {
+            mcParams.add("--server");
+            mcParams.add(serverAddress);
+            mcParams.add("--port");
+            mcParams.add(serverPort);
+        }
+
+        invokeMain(classLoader.loadClass(mainClass));
+    }
+
+    @Override
+    public void launch() throws Exception {
+        if (traits.contains("legacyLaunch") || traits.contains("alphaLaunch")) {
+            // legacy launch uses the applet wrapper
+            legacyLaunch();
+        } else {
+            // normal launch just calls main()
+            launchWithMainClass();
+        }
+    }
+
+}
diff --git a/libraries/launcher/org/multimc/onesix/OneSixLauncher.java b/libraries/launcher/org/multimc/onesix/OneSixLauncher.java
deleted file mode 100644
index 0058bd43..00000000
--- a/libraries/launcher/org/multimc/onesix/OneSixLauncher.java
+++ /dev/null
@@ -1,256 +0,0 @@
-/* Copyright 2012-2021 MultiMC Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.multimc.onesix;
-
-import org.multimc.*;
-
-import java.applet.Applet;
-import java.io.File;
-import java.lang.reflect.Field;
-import java.lang.reflect.Method;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
-public class OneSixLauncher implements Launcher
-{
-
-    private static final Logger LOGGER = Logger.getLogger("OneSixLauncher");
-
-    // parameters, separated from ParamBucket
-    private List<String> libraries;
-    private List<String> mcparams;
-    private List<String> mods;
-    private List<String> jarmods;
-    private List<String> coremods;
-    private List<String> traits;
-    private String appletClass;
-    private String mainClass;
-    private String nativePath;
-    private String userName, sessionId;
-    private String windowTitle;
-    private String windowParams;
-
-    // secondary parameters
-    private int winSizeW;
-    private int winSizeH;
-    private boolean maximize;
-    private String cwd;
-
-    private String serverAddress;
-    private String serverPort;
-
-    // the much abused system classloader, for convenience (for further abuse)
-    private ClassLoader cl;
-
-    private void processParams(ParamBucket params) throws NotFoundException
-    {
-        libraries = params.all("cp");
-        mcparams = params.allSafe("param", new ArrayList<String>() );
-        mainClass = params.firstSafe("mainClass", "net.minecraft.client.Minecraft");
-        appletClass = params.firstSafe("appletClass", "net.minecraft.client.MinecraftApplet");
-        traits = params.allSafe("traits", new ArrayList<String>());
-        nativePath = params.first("natives");
-
-        userName = params.first("userName");
-        sessionId = params.first("sessionId");
-        windowTitle = params.firstSafe("windowTitle", "Minecraft");
-        windowParams = params.firstSafe("windowParams", "854x480");
-
-        serverAddress = params.firstSafe("serverAddress", null);
-        serverPort = params.firstSafe("serverPort", null);
-
-        cwd = System.getProperty("user.dir");
-
-        winSizeW = 854;
-        winSizeH = 480;
-        maximize = false;
-
-        String[] dimStrings = windowParams.split("x");
-
-        if (windowParams.equalsIgnoreCase("max"))
-        {
-            maximize = true;
-        }
-        else if (dimStrings.length == 2)
-        {
-            try
-            {
-                winSizeW = Integer.parseInt(dimStrings[0]);
-                winSizeH = Integer.parseInt(dimStrings[1]);
-            } catch (NumberFormatException ignored) {}
-        }
-    }
-
-    int legacyLaunch()
-    {
-        // Get the Minecraft Class and set the base folder
-        Class<?> mc;
-        try
-        {
-            mc = cl.loadClass(mainClass);
-
-            Field f = Utils.getMCPathField(mc);
-
-            if (f == null)
-            {
-                LOGGER.warning("Could not find Minecraft path field.");
-            }
-            else
-            {
-                f.setAccessible(true);
-                f.set(null, new File(cwd));
-            }
-        } catch (Exception e)
-        {
-            LOGGER.log(
-                    Level.SEVERE,
-                    "Could not set base folder. Failed to find/access Minecraft main class:",
-                    e
-            );
-
-            return -1;
-        }
-
-        System.setProperty("minecraft.applet.TargetDirectory", cwd);
-
-        if(!traits.contains("noapplet"))
-        {
-            LOGGER.info("Launching with applet wrapper...");
-            try
-            {
-                Class<?> MCAppletClass = cl.loadClass(appletClass);
-                Applet mcappl = (Applet) MCAppletClass.newInstance();
-                LegacyFrame mcWindow = new LegacyFrame(windowTitle);
-                mcWindow.start(mcappl, userName, sessionId, winSizeW, winSizeH, maximize, serverAddress, serverPort);
-                return 0;
-            } catch (Exception e)
-            {
-                LOGGER.log(Level.SEVERE, "Applet wrapper failed:", e);
-
-                LOGGER.warning("Falling back to using main class.");
-            }
-        }
-
-        // init params for the main method to chomp on.
-        String[] paramsArray = mcparams.toArray(new String[mcparams.size()]);
-        try
-        {
-            mc.getMethod("main", String[].class).invoke(null, (Object) paramsArray);
-            return 0;
-        } catch (Exception e)
-        {
-            LOGGER.log(Level.SEVERE, "Failed to invoke the Minecraft main class:", e);
-
-            return -1;
-        }
-    }
-
-    int launchWithMainClass()
-    {
-        // window size, title and state, onesix
-        if (maximize)
-        {
-            // FIXME: there is no good way to maximize the minecraft window in onesix.
-            // the following often breaks linux screen setups
-            // mcparams.add("--fullscreen");
-        }
-        else
-        {
-            mcparams.add("--width");
-            mcparams.add(Integer.toString(winSizeW));
-            mcparams.add("--height");
-            mcparams.add(Integer.toString(winSizeH));
-        }
-
-        if (serverAddress != null)
-        {
-            mcparams.add("--server");
-            mcparams.add(serverAddress);
-            mcparams.add("--port");
-            mcparams.add(serverPort);
-        }
-
-        // Get the Minecraft Class.
-        Class<?> mc;
-        try
-        {
-            mc = cl.loadClass(mainClass);
-        } catch (ClassNotFoundException e)
-        {
-            LOGGER.log(Level.SEVERE, "Failed to find Minecraft main class:", e);
-
-            return -1;
-        }
-
-        // get the main method.
-        Method meth;
-        try
-        {
-            meth = mc.getMethod("main", String[].class);
-        } catch (NoSuchMethodException e)
-        {
-            LOGGER.log(Level.SEVERE, "Failed to acquire the main method:", e);
-
-            return -1;
-        }
-
-        // init params for the main method to chomp on.
-        String[] paramsArray = mcparams.toArray(new String[mcparams.size()]);
-        try
-        {
-            // static method doesn't have an instance
-            meth.invoke(null, (Object) paramsArray);
-        } catch (Exception e)
-        {
-            LOGGER.log(Level.SEVERE, "Failed to start Minecraft:", e);
-
-            return -1;
-        }
-        return 0;
-    }
-
-    @Override
-    public int launch(ParamBucket params)
-    {
-        // get and process the launch script params
-        try
-        {
-            processParams(params);
-        } catch (NotFoundException e)
-        {
-            LOGGER.log(Level.SEVERE, "Not enough arguments!");
-
-            return -1;
-        }
-
-        // grab the system classloader and ...
-        cl = ClassLoader.getSystemClassLoader();
-
-        if (traits.contains("legacyLaunch") || traits.contains("alphaLaunch") )
-        {
-            // legacy launch uses the applet wrapper
-            return legacyLaunch();
-        }
-        else
-        {
-            // normal launch just calls main()
-            return launchWithMainClass();
-        }
-    }
-
-}
diff --git a/libraries/launcher/org/multimc/ParamBucket.java b/libraries/launcher/org/multimc/utils/ParamBucket.java
index 8ff03ddc..26ff8eef 100644
--- a/libraries/launcher/org/multimc/ParamBucket.java
+++ b/libraries/launcher/org/multimc/utils/ParamBucket.java
@@ -14,36 +14,34 @@
  * limitations under the License.
  */
 
-package org.multimc;
+package org.multimc.utils;
+
+import org.multimc.exception.ParameterNotFoundException;
 
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
-public class ParamBucket
-{
+public final class ParamBucket {
 
     private final Map<String, List<String>> paramsMap = new HashMap<>();
 
-    public void add(String key, String value)
-    {
+    public void add(String key, String value) {
         paramsMap.computeIfAbsent(key, k -> new ArrayList<>())
                 .add(value);
     }
 
-    public List<String> all(String key) throws NotFoundException
-    {
+    public List<String> all(String key) throws ParameterNotFoundException {
         List<String> params = paramsMap.get(key);
 
         if (params == null)
-            throw new NotFoundException();
+            throw new ParameterNotFoundException(key);
 
         return params;
     }
 
-    public List<String> allSafe(String key, List<String> def)
-    {
+    public List<String> allSafe(String key, List<String> def) {
         List<String> params = paramsMap.get(key);
 
         if (params == null || params.isEmpty())
@@ -52,23 +50,16 @@ public class ParamBucket
         return params;
     }
 
-    public List<String> allSafe(String key)
-    {
-        return allSafe(key, new ArrayList<>());
-    }
-
-    public String first(String key) throws NotFoundException
-    {
+    public String first(String key) throws ParameterNotFoundException {
         List<String> list = all(key);
 
         if (list.isEmpty())
-            throw new NotFoundException();
+            throw new ParameterNotFoundException(key);
 
         return list.get(0);
     }
 
-    public String firstSafe(String key, String def)
-    {
+    public String firstSafe(String key, String def) {
         List<String> params = paramsMap.get(key);
 
         if (params == null || params.isEmpty())
@@ -77,9 +68,4 @@ public class ParamBucket
         return params.get(0);
     }
 
-    public String firstSafe(String key)
-    {
-        return firstSafe(key, "");
-    }
-
 }
diff --git a/libraries/launcher/org/multimc/utils/Utils.java b/libraries/launcher/org/multimc/utils/Utils.java
new file mode 100644
index 00000000..416eff26
--- /dev/null
+++ b/libraries/launcher/org/multimc/utils/Utils.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2012-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.multimc.utils;
+
+import java.io.File;
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+
+public final class Utils {
+
+    private Utils() {}
+
+    /**
+     * Finds a field that looks like a Minecraft base folder in a supplied class
+     *
+     * @param clazz the class to scan
+     */
+    public static Field getMinecraftBaseDirField(Class<?> clazz) {
+        for (Field f : clazz.getDeclaredFields()) {
+            // Has to be File
+            if (f.getType() != File.class)
+                continue;
+
+            // And Private Static.
+            if (!Modifier.isStatic(f.getModifiers()) || !Modifier.isPrivate(f.getModifiers()))
+                continue;
+
+            return f;
+        }
+
+        return null;
+    }
+
+}
+