Cleanup launcher classes

Cleanup a bunch of the code in launcher classes
- Migrate the majority of the reflection to ReflectionUtils
- Decrease logic in AbstractLauncher
- Add logging to launcher classes at FINE level
- make mcParams in AbstractLauncher an immutable list to prevent runtime manipulation
  - StandardLauncher instead copies the list to modify it

Signed-off-by: solonovamax <solonovamax@12oclockpoint.com>

8 files changed, 248 insertions, 114 deletions

diff --git a/libraries/launcher/CMakeLists.txt b/libraries/launcher/CMakeLists.txt
index f85c2354..45a43b93 100644
--- a/libraries/launcher/CMakeLists.txt
+++ b/libraries/launcher/CMakeLists.txt
@@ -18,6 +18,7 @@ set(SRC
     org/prismlauncher/exception/ParameterNotFoundException.java
     org/prismlauncher/exception/ParseException.java
     org/prismlauncher/utils/Parameters.java
+    org/prismlauncher/utils/ReflectionUtils.java
     net/minecraft/Launcher.java
 )
 add_jar(NewLaunch ${SRC})
diff --git a/libraries/launcher/org/prismlauncher/exception/ParameterNotFoundException.java b/libraries/launcher/org/prismlauncher/exception/ParameterNotFoundException.java
index c083e02a..3dd6efc3 100644
--- a/libraries/launcher/org/prismlauncher/exception/ParameterNotFoundException.java
+++ b/libraries/launcher/org/prismlauncher/exception/ParameterNotFoundException.java
@@ -54,10 +54,28 @@
 
 package org.prismlauncher.exception;
 
+
+@SuppressWarnings("serial")
 public final class ParameterNotFoundException extends IllegalArgumentException {
 
-    public ParameterNotFoundException(String key) {
-        super("Unknown parameter name: " + key);
+    public ParameterNotFoundException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public ParameterNotFoundException(Throwable cause) {
+        super(cause);
+    }
+
+    public ParameterNotFoundException(String message) {
+        super(message);
+    }
+
+    public ParameterNotFoundException() {
+        super();
+    }
+
+    public static ParameterNotFoundException forParameterName(String parameterName) {
+        return new ParameterNotFoundException(String.format("Unknown parameter name '%s'", parameterName));
     }
 
 }
diff --git a/libraries/launcher/org/prismlauncher/exception/ParseException.java b/libraries/launcher/org/prismlauncher/exception/ParseException.java
index 8904f9ee..2243f23f 100644
--- a/libraries/launcher/org/prismlauncher/exception/ParseException.java
+++ b/libraries/launcher/org/prismlauncher/exception/ParseException.java
@@ -54,10 +54,31 @@
 
 package org.prismlauncher.exception;
 
+
+@SuppressWarnings({ "serial", "unused" })
 public final class ParseException extends IllegalArgumentException {
 
     public ParseException(String message) {
         super(message);
     }
 
+    public ParseException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public ParseException(Throwable cause) {
+        super(cause);
+    }
+
+    public ParseException() {
+        super();
+    }
+
+    public static ParseException forInputString(String inputString) {
+        return new ParseException(String.format("Could not parse input string '%s'", inputString));
+    }
+
+    public static ParseException forInputString(String inputString, Throwable cause) {
+        return new ParseException(String.format("Could not parse input string '%s'", inputString), cause);
+    }
 }
diff --git a/libraries/launcher/org/prismlauncher/launcher/impl/AbstractLauncher.java b/libraries/launcher/org/prismlauncher/launcher/impl/AbstractLauncher.java
index c572db10..9dd7df10 100644
--- a/libraries/launcher/org/prismlauncher/launcher/impl/AbstractLauncher.java
+++ b/libraries/launcher/org/prismlauncher/launcher/impl/AbstractLauncher.java
@@ -55,81 +55,66 @@
 
 package org.prismlauncher.launcher.impl;
 
+
 import org.prismlauncher.exception.ParseException;
 import org.prismlauncher.launcher.Launcher;
 import org.prismlauncher.utils.Parameters;
 import org.prismlauncher.utils.StringUtils;
 
-import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
-import java.lang.invoke.MethodType;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
+
 public abstract class AbstractLauncher implements Launcher {
 
     private static final int DEFAULT_WINDOW_WIDTH = 854;
+
     private static final int DEFAULT_WINDOW_HEIGHT = 480;
 
     // parameters, separated from ParamBucket
     protected final List<String> mcParams;
-    private final String mainClass;
 
     // secondary parameters
     protected final int width;
+
     protected final int height;
+
     protected final boolean maximize;
 
-    protected final String serverAddress, serverPort;
+    protected final String serverAddress;
 
-    protected final ClassLoader classLoader;
+    protected final String serverPort;
 
-    protected AbstractLauncher(Parameters params) {
-        classLoader = ClassLoader.getSystemClassLoader();
+    protected final String mainClassName;
 
-        mcParams = params.getList("param", new ArrayList<String>());
-        mainClass = params.getString("mainClass", "net.minecraft.client.Minecraft");
+    protected AbstractLauncher(Parameters params) {
+        this.mcParams = Collections.unmodifiableList(params.getList("param", new ArrayList<String>()));
+        this.mainClassName = params.getString("mainClass", "net.minecraft.client.Minecraft");
 
-        serverAddress = params.getString("serverAddress", null);
-        serverPort = params.getString("serverPort", null);
+        this.serverAddress = params.getString("serverAddress", null);
+        this.serverPort = params.getString("serverPort", null);
 
         String windowParams = params.getString("windowParams", null);
 
-        if ("max".equals(windowParams) || windowParams == null) {
-            maximize = windowParams != null;
+        this.maximize = "max".equalsIgnoreCase(windowParams);
 
-            width = DEFAULT_WINDOW_WIDTH;
-            height = DEFAULT_WINDOW_HEIGHT;
-        } else {
-            maximize = false;
-    
+        if (windowParams != null && !"max".equalsIgnoreCase(windowParams)) {
             String[] sizePair = StringUtils.splitStringPair('x', windowParams);
-    
+
             if (sizePair != null) {
                 try {
-                    width = Integer.parseInt(sizePair[0]);
-                    height = Integer.parseInt(sizePair[1]);
-                    return;
-                } catch (NumberFormatException ignored) {
+                    this.width = Integer.parseInt(sizePair[0]);
+                    this.height = Integer.parseInt(sizePair[1]);
+                } catch (NumberFormatException e) {
+                    throw new ParseException(String.format("Could not parse window parameters from '%s'", windowParams), e);
                 }
+            } else {
+                throw new ParseException(String.format("Invalid window size parameters '%s'. Format: [height]x[width]", windowParams));
             }
-
-            throw new ParseException("Invalid window size parameter value: " + windowParams);
+        } else {
+            this.width = DEFAULT_WINDOW_WIDTH;
+            this.height = DEFAULT_WINDOW_HEIGHT;
         }
     }
-
-    protected Class<?> loadMain() throws ClassNotFoundException {
-        return classLoader.loadClass(mainClass);
-    }
-
-    protected void loadAndInvokeMain() throws Throwable {
-        invokeMain(loadMain());
-    }
-
-    protected void invokeMain(Class<?> mainClass) throws Throwable {
-        MethodHandle method = MethodHandles.lookup().findStatic(mainClass, "main", MethodType.methodType(void.class, String[].class));
-
-        method.invokeExact(mcParams.toArray(new String[0]));
-    }
-
 }
diff --git a/libraries/launcher/org/prismlauncher/launcher/impl/StandardLauncher.java b/libraries/launcher/org/prismlauncher/launcher/impl/StandardLauncher.java
index 24b12c95..fc0c9823 100644
--- a/libraries/launcher/org/prismlauncher/launcher/impl/StandardLauncher.java
+++ b/libraries/launcher/org/prismlauncher/launcher/impl/StandardLauncher.java
@@ -58,9 +58,17 @@ package org.prismlauncher.launcher.impl;
 import org.prismlauncher.launcher.Launcher;
 import org.prismlauncher.launcher.LauncherProvider;
 import org.prismlauncher.utils.Parameters;
+import org.prismlauncher.utils.ReflectionUtils;
+
+import java.lang.invoke.MethodHandle;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.logging.Logger;
 
 
 public final class StandardLauncher extends AbstractLauncher {
+    private static final Logger LOGGER = Logger.getLogger("LegacyLauncher");
+
 
     public StandardLauncher(Parameters params) {
         super(params);
@@ -78,21 +86,27 @@ public final class StandardLauncher extends AbstractLauncher {
         // the following often breaks linux screen setups
         // mcparams.add("--fullscreen");
 
-        if (!maximize) {
-            mcParams.add("--width");
-            mcParams.add(Integer.toString(width));
-            mcParams.add("--height");
-            mcParams.add(Integer.toString(height));
+        List<String> launchParameters = new ArrayList<>(this.mcParams);
+
+        if (!this.maximize) {
+            launchParameters.add("--width");
+            launchParameters.add(Integer.toString(width));
+            launchParameters.add("--height");
+            launchParameters.add(Integer.toString(height));
         }
 
-        if (serverAddress != null) {
-            mcParams.add("--server");
-            mcParams.add(serverAddress);
-            mcParams.add("--port");
-            mcParams.add(serverPort);
+        if (this.serverAddress != null) {
+            launchParameters.add("--server");
+            launchParameters.add(serverAddress);
+            launchParameters.add("--port");
+            launchParameters.add(serverPort);
         }
 
-        loadAndInvokeMain();
+        LOGGER.info("Launching minecraft using the main class entrypoint");
+
+        MethodHandle method = ReflectionUtils.findMainEntrypoint(this.mainClassName);
+
+        method.invokeExact((Object[]) launchParameters.toArray(new String[0]));
     }
 
 
diff --git a/libraries/launcher/org/prismlauncher/launcher/impl/legacy/LegacyLauncher.java b/libraries/launcher/org/prismlauncher/launcher/impl/legacy/LegacyLauncher.java
index e342e788..0ce3c57b 100644
--- a/libraries/launcher/org/prismlauncher/launcher/impl/legacy/LegacyLauncher.java
+++ b/libraries/launcher/org/prismlauncher/launcher/impl/legacy/LegacyLauncher.java
@@ -60,14 +60,11 @@ import org.prismlauncher.launcher.Launcher;
 import org.prismlauncher.launcher.LauncherProvider;
 import org.prismlauncher.launcher.impl.AbstractLauncher;
 import org.prismlauncher.utils.Parameters;
+import org.prismlauncher.utils.ReflectionUtils;
 
-import java.applet.Applet;
 import java.io.File;
 import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
-import java.lang.invoke.MethodType;
 import java.lang.reflect.Field;
-import java.lang.reflect.Modifier;
 import java.util.Collections;
 import java.util.List;
 import java.util.logging.Level;
@@ -87,7 +84,7 @@ public final class LegacyLauncher extends AbstractLauncher {
 
     private final String appletClass;
 
-    private final boolean noApplet;
+    private final boolean usesApplet;
 
     private final String cwd;
 
@@ -100,8 +97,9 @@ public final class LegacyLauncher extends AbstractLauncher {
         appletClass = params.getString("appletClass", "net.minecraft.client.MinecraftApplet");
 
         List<String> traits = params.getList("traits", Collections.<String>emptyList());
-        noApplet = traits.contains("noapplet");
+        usesApplet = !traits.contains("noapplet");
 
+        //noinspection AccessOfSystemProperties
         cwd = System.getProperty("user.dir");
     }
 
@@ -109,74 +107,40 @@ public final class LegacyLauncher extends AbstractLauncher {
         return new LegacyLauncherProvider();
     }
 
-    /**
-     * Finds a field that looks like a Minecraft base folder in a supplied class
-     *
-     * @param clazz the class to scan
-     *
-     * @return The found field.
-     */
-    private static Field getMinecraftGameDirField(Class<?> clazz) {
-        // Field we're looking for is always
-        // private static File obfuscatedName = null;
-        for (Field field : clazz.getDeclaredFields()) {
-            // Has to be File
-            if (field.getType() != File.class)
-                continue;
-
-            // And Private Static.
-            if (!Modifier.isStatic(field.getModifiers()) || !Modifier.isPrivate(field.getModifiers()))
-                continue;
-
-            return field;
-        }
-
-        return null;
-    }
-
     @Override
     public void launch() throws Throwable {
-        Class<?> main = loadMain();
-        Field gameDirField = getMinecraftGameDirField(main);
+        Class<?> main = ClassLoader.getSystemClassLoader().loadClass(this.mainClassName);
+        Field gameDirField = ReflectionUtils.getMinecraftGameDirField(main);
 
         if (gameDirField == null) {
-            LOGGER.warning("Could not find Mineraft path field.");
+            LOGGER.warning("Could not find Minecraft path field");
         } else {
             gameDirField.setAccessible(true);
-            gameDirField.set(null, new File(cwd));
+            gameDirField.set(null /* field is static, so instance is null */, new File(cwd));
         }
 
-        if (!noApplet) {
-            LOGGER.info("Launching with applet wrapper...");
+        if (this.usesApplet) {
+            LOGGER.info("Launching legacy minecraft using applet wrapper...");
 
             try {
-                Class<?> appletClass = classLoader.loadClass(this.appletClass);
-
-                MethodHandle constructor = MethodHandles.lookup().findConstructor(appletClass, MethodType.methodType(void.class));
-                Applet applet = (Applet) constructor.invoke();
-
-                LegacyFrame window = new LegacyFrame(title, applet);
+                LegacyFrame window = new LegacyFrame(title, ReflectionUtils.createAppletClass(this.appletClass));
 
                 window.start(
-                        user,
-                        session,
-                        width,
-                        height,
-                        maximize,
-                        serverAddress,
-                        serverPort,
-                        mcParams.contains("--demo")
+                        this.user,
+                        this.session,
+                        this.width, this.height, this.maximize,
+                        this.serverAddress, this.serverPort,
+                        this.mcParams.contains("--demo")
                             );
-
-                return;
             } catch (Throwable e) {
-                LOGGER.log(Level.SEVERE, "Applet wrapper failed:", e);
-
-                LOGGER.warning("Falling back to using main class.");
+                LOGGER.log(Level.SEVERE, "Running applet wrapper failed with exception", e);
             }
-        }
+        } else {
+            LOGGER.info("Launching legacy minecraft using the main class entrypoint");
+            MethodHandle method = ReflectionUtils.findMainEntrypoint(main);
 
-        invokeMain(main);
+            method.invokeExact((Object[]) mcParams.toArray(new String[0]));
+        }
     }
 
 
diff --git a/libraries/launcher/org/prismlauncher/utils/Parameters.java b/libraries/launcher/org/prismlauncher/utils/Parameters.java
index 5596e88a..6fbd0ef1 100644
--- a/libraries/launcher/org/prismlauncher/utils/Parameters.java
+++ b/libraries/launcher/org/prismlauncher/utils/Parameters.java
@@ -83,7 +83,7 @@ public final class Parameters {
         List<String> params = map.get(key);
 
         if (params == null)
-            throw new ParameterNotFoundException(key);
+            throw ParameterNotFoundException.forParameterName(key);
 
         return params;
     }
@@ -101,7 +101,7 @@ public final class Parameters {
         List<String> list = getList(key);
 
         if (list.isEmpty())
-            throw new ParameterNotFoundException(key);
+            throw ParameterNotFoundException.forParameterName(key);
 
         return list.get(0);
     }
diff --git a/libraries/launcher/org/prismlauncher/utils/ReflectionUtils.java b/libraries/launcher/org/prismlauncher/utils/ReflectionUtils.java
new file mode 100644
index 00000000..484e0d8a
--- /dev/null
+++ b/libraries/launcher/org/prismlauncher/utils/ReflectionUtils.java
@@ -0,0 +1,131 @@
+package org.prismlauncher.utils;
+
+
+import java.applet.Applet;
+import java.io.File;
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+
+public final class ReflectionUtils {
+    private static final Logger LOGGER = Logger.getLogger("ReflectionUtils");
+
+    private ReflectionUtils() {
+    }
+
+    /**
+     * Instantiate an applet class by name
+     *
+     * @param appletClassName The name of the applet class to resolve
+     *
+     * @return The instantiated applet class
+     *
+     * @throws ClassNotFoundException if the provided class name cannot be found
+     * @throws NoSuchMethodException  if the no-args constructor cannot be found
+     * @throws IllegalAccessException if the constructor cannot be accessed via method handles
+     * @throws Throwable              any exceptions from the class's constructor
+     */
+    public static Applet createAppletClass(String appletClassName) throws Throwable {
+        Class<?> appletClass = ClassLoader.getSystemClassLoader().loadClass(appletClassName);
+
+        MethodHandle appletConstructor = MethodHandles.lookup().findConstructor(appletClass, MethodType.methodType(void.class));
+        return (Applet) appletConstructor.invoke();
+    }
+
+    /**
+     * Finds a field that looks like a Minecraft base folder in a supplied class
+     *
+     * @param minecraftMainClass the class to scan
+     *
+     * @return The found field.
+     */
+    public static Field getMinecraftGameDirField(Class<?> minecraftMainClass) {
+        LOGGER.fine("Resolving minecraft game directory field");
+        // Field we're looking for is always
+        // private static File obfuscatedName = null;
+        for (Field field : minecraftMainClass.getDeclaredFields()) {
+            // Has to be File
+            if (field.getType() != File.class) {
+                continue;
+            }
+
+            int fieldModifiers = field.getModifiers();
+
+
+            // Must be static
+            if (!Modifier.isStatic(fieldModifiers)) {
+                LOGGER.log(Level.FINE, "Rejecting field {0} because it is not static", field.getName());
+                continue;
+            }
+
+            // Must be private
+            if (!Modifier.isPrivate(fieldModifiers)) {
+                LOGGER.log(Level.FINE, "Rejecting field {0} because it is not private", field.getName());
+                continue;
+            }
+
+            // Must not be final
+            if (Modifier.isFinal(fieldModifiers)) {
+                LOGGER.log(Level.FINE, "Rejecting field {0} because it is final", field.getName());
+                continue;
+            }
+
+            LOGGER.log(Level.FINE, "Identified field {0} to match conditions for minecraft game directory field", field.getName());
+
+            return field;
+        }
+
+        return null;
+    }
+
+    /**
+     * Resolve main entrypoint and returns method handle for it.
+     * <p>
+     * Resolves a method that matches the following signature
+     * <code>
+     * public static void main(String[] args) {
+     * <p>
+     * }
+     * </code>
+     *
+     * @param entrypointClass The entrypoint class to resolve the method from
+     *
+     * @return The method handle for the resolved entrypoint
+     *
+     * @throws NoSuchMethodException  If no method matching the correct signature can be found
+     * @throws IllegalAccessException If method handles cannot access the entrypoint
+     */
+    public static MethodHandle findMainEntrypoint(Class<?> entrypointClass) throws NoSuchMethodException, IllegalAccessException {
+        return MethodHandles.lookup().findStatic(entrypointClass, "main", MethodType.methodType(void.class, String[].class));
+    }
+
+    /**
+     * Resolve main entrypoint and returns method handle for it.
+     * <p>
+     * Resolves a method that matches the following signature
+     * <code>
+     * public static void main(String[] args) {
+     * <p>
+     * }
+     * </code>
+     *
+     * @param entrypointClassName The name of the entrypoint class to resolve the method from
+     *
+     * @return The method handle for the resolved entrypoint
+     *
+     * @throws ClassNotFoundException If a class cannot be found with the provided name
+     * @throws NoSuchMethodException  If no method matching the correct signature can be found
+     * @throws IllegalAccessException If method handles cannot access the entrypoint
+     */
+    public static MethodHandle findMainEntrypoint(String entrypointClassName) throws
+                                                                              ClassNotFoundException,
+                                                                              NoSuchMethodException,
+                                                                              IllegalAccessException {
+        return findMainEntrypoint(ClassLoader.getSystemClassLoader().loadClass(entrypointClassName));
+    }
+}