Use the MCPC JAR remapper when loading classes. Fixes #11

This will allow plugins to use MinecraftReflection.getMinecraftClass() 
in both CraftBukkit and MCPC.

ProtocolLib/src/main/java/com/comphenix/protocol/utility/CachedPackage.java

@@ -19,6 +19,7 @@ package com.comphenix.protocol.utility;
 
 import java.util.Map;
 
+import com.google.common.base.Strings;
 import com.google.common.collect.Maps;
 
 /**
@@ -27,12 +28,19 @@ import com.google.common.collect.Maps;
  * @author Kristian
  */
 class CachedPackage {
-	private Map<String, Class<?>> cache;
-	private String packageName;
+	private final Map<String, Class<?>> cache;
+	private final String packageName;
+	private final ClassSource source;
 	
-	public CachedPackage(String packageName) {
+	/**
+	 * Construct a new cached package.
+	 * @param packageName - the name of the current package.
+	 * @param source - the class source.
+	 */
+	public CachedPackage(String packageName, ClassSource source) {
 		this.packageName = packageName;
 		this.cache = Maps.newConcurrentMap();
+		this.source = source;
 	}
 	
 	/**
@@ -57,11 +65,9 @@ class CachedPackage {
 			// Concurrency is not a problem - we don't care if we look up a class twice
 			if (result == null) {
 				// Look up the class dynamically
-				result = CachedPackage.class.getClassLoader().
-							loadClass(combine(packageName, className));
+				result = source.loadClass(combine(packageName, className));
 				cache.put(className, result);
 			}	
-
 			return result;
 		
 		} catch (ClassNotFoundException e) {
@@ -75,9 +81,11 @@ class CachedPackage {
 	 * @param className - the class name.
 	 * @return We full class path.
 	 */
-	private String combine(String packageName, String className) {
-		if (packageName.length() == 0)
+	public static String combine(String packageName, String className) {
+		if (Strings.isNullOrEmpty(packageName))
 			return className;
+		if (Strings.isNullOrEmpty(className))
+			return packageName;
 		return packageName + "." + className;
 	}
 }

ProtocolLib/src/main/java/com/comphenix/protocol/utility/ClassSource.java

@@ -0,0 +1,37 @@
+package com.comphenix.protocol.utility;
+
+/**
+ * Represents an abstract class loader that can only retrieve classes by their canonical name.
+ * @author Kristian
+ */
+abstract class ClassSource {
+	/**
+	 * Construct a class source from the current class loader.
+	 * @return A package source.
+	 */
+	public static ClassSource fromClassLoader() {
+		return fromClassLoader(ClassSource.class.getClassLoader());
+	}
+	
+	/**
+	 * Construct a class source from the given class loader.
+	 * @param loader - the class loader.
+	 * @return The corresponding package source.
+	 */
+	public static ClassSource fromClassLoader(final ClassLoader loader) {
+		return new ClassSource() {
+			@Override
+			public Class<?> loadClass(String canonicalName) throws ClassNotFoundException {
+				return loader.loadClass(canonicalName);
+			}
+		};
+	}
+	
+	/**
+	 * Retrieve a class by name.
+	 * @param canonicalName - the full canonical name of the class.
+	 * @return The corresponding class 
+	 * @throws ClassNotFoundException If the class could not be found.
+	 */
+	public abstract Class<?> loadClass(String canonicalName) throws ClassNotFoundException;
+}

ProtocolLib/src/main/java/com/comphenix/protocol/utility/MinecraftReflection.java

@@ -30,6 +30,7 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import javax.annotation.Nonnull;
@@ -42,6 +43,10 @@ import org.bukkit.Bukkit;
 import org.bukkit.Server;
 import org.bukkit.inventory.ItemStack;
 
+import com.comphenix.protocol.ProtocolLibrary;
+import com.comphenix.protocol.error.ErrorReporter;
+import com.comphenix.protocol.error.Report;
+import com.comphenix.protocol.error.ReportType;
 import com.comphenix.protocol.injector.BukkitUnwrapper;
 import com.comphenix.protocol.injector.packet.PacketRegistry;
 import com.comphenix.protocol.reflect.FuzzyReflection;
@@ -52,6 +57,8 @@ import com.comphenix.protocol.reflect.fuzzy.FuzzyClassContract;
 import com.comphenix.protocol.reflect.fuzzy.FuzzyFieldContract;
 import com.comphenix.protocol.reflect.fuzzy.FuzzyMatchers;
 import com.comphenix.protocol.reflect.fuzzy.FuzzyMethodContract;
+import com.comphenix.protocol.utility.RemappedClassSource.RemapperUnavaibleException;
+import com.comphenix.protocol.utility.RemappedClassSource.RemapperUnavaibleException.Reason;
 import com.comphenix.protocol.wrappers.WrappedDataWatcher;
 import com.comphenix.protocol.wrappers.nbt.NbtFactory;
 import com.comphenix.protocol.wrappers.nbt.NbtType;
@@ -63,6 +70,9 @@ import com.google.common.base.Joiner;
  * @author Kristian
  */
 public class MinecraftReflection {
+	public static final ReportType REPORT_CANNOT_FIND_MCPC_REMAPPER = new ReportType("Cannot find MCPC remapper.");
+	public static final ReportType REPORT_CANNOT_LOAD_CPC_REMAPPER = new ReportType("Unable to load MCPC remapper.");
+	
 	/**
 	 * Regular expression that matches a Minecraft object.
 	 * <p>
@@ -76,11 +86,22 @@ public class MinecraftReflection {
 	 */
 	private static String DYNAMIC_PACKAGE_MATCHER = null;
 	
+	/**
+	 * The Entity package in Forge 1.5.2
+	 */
+	private static final String FORGE_ENTITY_PACKAGE = "net.minecraft.entity";
+	
 	/**
 	 * The package name of all the classes that belongs to the native code in Minecraft.
 	 */
 	private static String MINECRAFT_PREFIX_PACKAGE = "net.minecraft.server";
 
+	/**
+	 * Represents a regular expression that will match the version string in a package:
+	 *    org.bukkit.craftbukkit.v1_6_R2      ->      v1_6_R2
+	 */
+	private static final Pattern PACKAGE_VERSION_MATCHER = Pattern.compile(".*\\.(v\\d+_\\d+_\\w*\\d+)");
+	
 	private static String MINECRAFT_FULL_PACKAGE = null;
 	private static String CRAFTBUKKIT_PACKAGE = null;
 
@@ -99,9 +120,15 @@ public class MinecraftReflection {
 	private static Method craftBukkitMethod;
 	private static boolean craftItemStackFailed;
 
+	// The NMS version
+	private static String packageVersion;
+	
 	// net.minecraft.server
 	private static Class<?> itemStackArrayClass;
 	
+	// The current class source
+	private static ClassSource classSource;
+	
 	/**
 	 * Whether or not we're currently initializing the reflection handler.
 	 */
@@ -152,6 +179,12 @@ public class MinecraftReflection {
 				Class<?> craftClass = craftServer.getClass();
 				CRAFTBUKKIT_PACKAGE = getPackage(craftClass.getCanonicalName());
 				
+				// Parse the package version
+				Matcher packageMatcher = PACKAGE_VERSION_MATCHER.matcher(CRAFTBUKKIT_PACKAGE);
+				if (packageMatcher.matches()) {
+					packageVersion = packageMatcher.group(1);
+				}
+				
 				// Libigot patch
 				handleLibigot();
 				
@@ -161,12 +194,18 @@ public class MinecraftReflection {
 				
 				MINECRAFT_FULL_PACKAGE = getPackage(getHandle.getReturnType().getCanonicalName());
 				
-				// Pretty important invariant
+				// Pretty important invariantt
 				if (!MINECRAFT_FULL_PACKAGE.startsWith(MINECRAFT_PREFIX_PACKAGE)) {
-					// Assume they're the same instead
-					MINECRAFT_PREFIX_PACKAGE = MINECRAFT_FULL_PACKAGE;
+					// See if we got the Forge entity package
+					if (MINECRAFT_FULL_PACKAGE.equals(FORGE_ENTITY_PACKAGE)) {
+						// USe the standard NMS versioned package
+						MINECRAFT_FULL_PACKAGE = CachedPackage.combine(MINECRAFT_PREFIX_PACKAGE, packageVersion);
+					} else {
+						// Assume they're the same instead
+						MINECRAFT_PREFIX_PACKAGE = MINECRAFT_FULL_PACKAGE;
+					}
 
-					// The package is usualy flat, so go with that assumtion
+					// The package is usualy flat, so go with that assumption
 					String matcher = 
 							(MINECRAFT_PREFIX_PACKAGE.length() > 0 ? 
 									Pattern.quote(MINECRAFT_PREFIX_PACKAGE + ".") : "") + "\\w+";
@@ -195,6 +234,15 @@ public class MinecraftReflection {
 		}
 	}
 	
+	/**
+	 * Retrieve the package version of the underlying CraftBukkit server.
+	 * @return The package version, or NULL if not applicable (before 1.4.6).
+	 */
+	public static String getPackageVersion() {
+		getMinecraftPackage();
+		return packageVersion;
+	}
+	
 	/**
 	 * Update the dynamic package matcher.
 	 * @param regex - the Minecraft package regex.
@@ -1260,7 +1308,7 @@ public class MinecraftReflection {
 	@SuppressWarnings("rawtypes")
 	public static Class getCraftBukkitClass(String className) {
 		if (craftbukkitPackage == null)
-			craftbukkitPackage = new CachedPackage(getCraftBukkitPackage());
+			craftbukkitPackage = new CachedPackage(getCraftBukkitPackage(), getClassSource());
 		return craftbukkitPackage.getPackageClass(className);
 	}
 	
@@ -1272,7 +1320,7 @@ public class MinecraftReflection {
 	 */
 	public static Class<?> getMinecraftClass(String className) {
 		if (minecraftPackage == null)
-			minecraftPackage = new CachedPackage(getMinecraftPackage());
+			minecraftPackage = new CachedPackage(getMinecraftPackage(), getClassSource());
 		return minecraftPackage.getPackageClass(className);
 	}
 	
@@ -1284,11 +1332,36 @@ public class MinecraftReflection {
 	 */
 	private static Class<?> setMinecraftClass(String className, Class<?> clazz) {
 		if (minecraftPackage == null)
-			minecraftPackage = new CachedPackage(getMinecraftPackage());
+			minecraftPackage = new CachedPackage(getMinecraftPackage(), getClassSource());
 		minecraftPackage.setPackageClass(className, clazz);
 		return clazz;
 	}
 	
+	/**
+	 * Retrieve the current class source.
+	 * @return The class source.
+	 */
+	private static ClassSource getClassSource() {
+		ErrorReporter reporter = ProtocolLibrary.getErrorReporter();
+		
+		// Lazy pattern again
+		if (classSource == null) {
+			// Attempt to use MCPC
+			try {
+				return classSource = new RemappedClassSource().initialize();
+			} catch (RemapperUnavaibleException e) {
+				if (e.getReason() != Reason.MCPC_NOT_PRESENT)
+					reporter.reportWarning(MinecraftReflection.class, Report.newBuilder(REPORT_CANNOT_FIND_MCPC_REMAPPER));
+			} catch (Exception e) {
+				reporter.reportWarning(MinecraftReflection.class, Report.newBuilder(REPORT_CANNOT_LOAD_CPC_REMAPPER));
+			} 
+			
+			// Just use the default class loader
+			classSource = ClassSource.fromClassLoader();
+		}
+		return classSource;
+	}
+	
 	/**
 	 * Retrieve the first class that matches a specified Minecraft name.
 	 * @param className - the specific Minecraft class.

ProtocolLib/src/main/java/com/comphenix/protocol/utility/RemappedClassSource.java

@@ -0,0 +1,147 @@
+package com.comphenix.protocol.utility;
+
+// Thanks to Bergerkiller for his excellent hack. :D
+
+// Copyright (C) 2013 bergerkiller
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of 
+// this software and associated documentation files (the "Software"), to deal in 
+// the Software without restriction, including without limitation the rights to use,
+// copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the 
+// Software, and to permit persons to whom the Software is furnished to do so, 
+// subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+import java.lang.reflect.Method;
+import org.bukkit.Bukkit;
+
+import com.comphenix.protocol.reflect.FieldUtils;
+import com.comphenix.protocol.reflect.MethodUtils;
+import com.comphenix.protocol.utility.RemappedClassSource.RemapperUnavaibleException.Reason;
+
+class RemappedClassSource extends ClassSource {
+	private Object classRemapper;
+	private Method mapType;
+	private ClassLoader loader;
+	
+	/**
+	 * Construct a new remapped class source using the default class loader.
+	 */
+	public RemappedClassSource() {
+		this(RemappedClassSource.class.getClassLoader());
+	}
+
+	/**
+	 * Construct a new renampped class source with the provided class loader.
+	 * @param loader - the class loader.
+	 */
+	public RemappedClassSource(ClassLoader loader) {
+		this.loader = loader;
+	}
+	
+	/**
+	 * Attempt to load the MCPC remapper.
+	 * @return TRUE if we succeeded, FALSE otherwise.
+	 * @throws RemapperUnavaibleException If the remapper is not present.
+	 */
+	public RemappedClassSource initialize() {
+		try {
+			if (Bukkit.getServer() == null || !Bukkit.getServer().getVersion().contains("MCPC-Plus")) {
+				throw new RemapperUnavaibleException(Reason.MCPC_NOT_PRESENT);
+			}
+			
+			// Obtain the Class remapper used by MCPC+
+			this.classRemapper = FieldUtils.readField(getClass().getClassLoader(), "remapper", true);
+			
+			if (this.classRemapper == null) {
+				throw new RemapperUnavaibleException(Reason.REMAPPER_DISABLED);
+			}
+			
+			// Initialize some fields and methods used by the Jar Remapper
+			Class<?> renamerClazz = classRemapper.getClass();
+	
+			this.mapType = MethodUtils.getAccessibleMethod(renamerClazz, "map", 
+				new Class<?>[] { String.class });
+			
+			return this;
+			
+		} catch (RemapperUnavaibleException e) {
+			throw e;
+		} catch (Exception e) {
+			// Damn it
+			throw new RuntimeException("Cannot access MCPC remapper.", e);
+		}
+	}
+
+	@Override
+	public Class<?> loadClass(String canonicalName) throws ClassNotFoundException {
+		final String remapped = getClassName(canonicalName);
+		
+		try {
+			return loader.loadClass(remapped);
+		} catch (ClassNotFoundException e) {
+			throw new ClassNotFoundException("Cannot find " + canonicalName + "(Remapped: " + remapped + ")"); 
+		}
+	}
+	
+	/**
+	 * Retrieve the obfuscated class name given an unobfuscated canonical class name.
+	 * @param path - the canonical class name.
+	 * @return The obfuscated class name.
+	 */
+	private String getClassName(String path) {
+		try {
+			String remapped = (String) mapType.invoke(classRemapper, path.replace('.', '/'));
+			return remapped.replace('/', '.');
+		} catch (Exception e) {
+			throw new RuntimeException("Cannot remap class name.", e);
+		}
+	}
+
+	public static class RemapperUnavaibleException extends RuntimeException {
+		private static final long serialVersionUID = 1L;
+
+		public enum Reason {
+			MCPC_NOT_PRESENT("The server is not running MCPC+"),
+			REMAPPER_DISABLED("Running an MCPC+ server but the remapper is unavailable. Please turn it on!");
+			
+			private final String message;
+			
+			private Reason(String message) {
+				this.message = message;
+			}
+			
+			/**
+			 * Retrieve a human-readable version of this reason.
+			 * @return The human-readable verison.
+			 */
+			public String getMessage() {
+				return message;
+			}
+		}
+		
+		private final Reason reason;
+		
+		public RemapperUnavaibleException(Reason reason) {
+			super(reason.getMessage());
+			this.reason = reason;
+		}
+		
+		/**
+		 * Retrieve the reasont he remapper is unavailable.
+		 * @return The reason.
+		 */
+		public Reason getReason() {
+			return reason;
+		}
+	}
+}