Merge remote-tracking branch 'upstream/dev/0.4' into dev/0.4

15 files changed, 308 insertions, 297 deletions

diff --git a/src/main/java/net/fabricmc/loom/LoomGradleExtension.java b/src/main/java/net/fabricmc/loom/LoomGradleExtension.java
index 72b3c61f..f44755d5 100644
--- a/src/main/java/net/fabricmc/loom/LoomGradleExtension.java
+++ b/src/main/java/net/fabricmc/loom/LoomGradleExtension.java
@@ -45,6 +45,7 @@ import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.Dependency;
 import org.gradle.api.plugins.BasePluginConvention;
 
+import net.fabricmc.loom.api.decompilers.LoomDecompiler;
 import net.fabricmc.loom.processors.JarProcessorManager;
 import net.fabricmc.loom.providers.MappingsProvider;
 import net.fabricmc.loom.providers.MinecraftMappedProvider;
@@ -63,6 +64,8 @@ public class LoomGradleExtension {
 
 	private List<Path> unmappedModsBuilt = new ArrayList<>();
 
+	final List<LoomDecompiler> decompilers = new ArrayList<>();
+
 	//Not to be set in the build.gradle
 	private Project project;
 	private LoomDependencyManager dependencyManager;
@@ -71,6 +74,14 @@ public class LoomGradleExtension {
 	private MappingSet[] srcMappingCache = new MappingSet[2];
 	private Mercury[] srcMercuryCache = new Mercury[2];
 
+	/**
+	 * Loom will generate a new genSources task (with a new name, based off of {@link LoomDecompiler#name()})
+	 * that uses the specified decompiler instead.
+	 */
+	public void addDecompiler(LoomDecompiler decompiler) {
+		decompilers.add(decompiler);
+	}
+
 	public MappingSet getOrCreateSrcMappingCache(int id, Supplier<MappingSet> factory) {
 		return srcMappingCache[id] != null ? srcMappingCache[id] : (srcMappingCache[id] = factory.get());
 	}
diff --git a/src/main/java/net/fabricmc/loom/LoomGradlePlugin.java b/src/main/java/net/fabricmc/loom/LoomGradlePlugin.java
index c4a47b75..575efb70 100644
--- a/src/main/java/net/fabricmc/loom/LoomGradlePlugin.java
+++ b/src/main/java/net/fabricmc/loom/LoomGradlePlugin.java
@@ -25,18 +25,14 @@
 package net.fabricmc.loom;
 
 import java.io.File;
-import java.io.IOException;
-import java.nio.file.Files;
-import java.nio.file.Path;
 import java.util.Locale;
 
 import org.gradle.api.Project;
-import org.gradle.api.Task;
 import org.gradle.api.tasks.TaskContainer;
 
+import net.fabricmc.loom.api.decompilers.LoomDecompiler;
+import net.fabricmc.loom.decompilers.fernflower.FabricFernFlowerDecompiler;
 import net.fabricmc.loom.providers.MappingsProvider;
-import net.fabricmc.loom.providers.MinecraftLibraryProvider;
-import net.fabricmc.loom.task.AbstractDecompileTask;
 import net.fabricmc.loom.task.CleanEclipseRunsTask;
 import net.fabricmc.loom.task.CleanLoomBinaries;
 import net.fabricmc.loom.task.CleanLoomMappings;
@@ -44,13 +40,12 @@ import net.fabricmc.loom.task.DownloadAssetsTask;
 import net.fabricmc.loom.task.GenEclipseRunsTask;
 import net.fabricmc.loom.task.GenIdeaProjectTask;
 import net.fabricmc.loom.task.GenVsCodeProjectTask;
+import net.fabricmc.loom.task.GenerateSourcesTask;
 import net.fabricmc.loom.task.MigrateMappingsTask;
 import net.fabricmc.loom.task.RemapJarTask;
-import net.fabricmc.loom.task.RemapLineNumbersTask;
 import net.fabricmc.loom.task.RemapSourcesJarTask;
 import net.fabricmc.loom.task.RunClientTask;
 import net.fabricmc.loom.task.RunServerTask;
-import net.fabricmc.loom.task.fernflower.FernFlowerTask;
 
 public class LoomGradlePlugin extends AbstractPlugin {
 	public static File getMappedByproduct(Project project, String suffix) {
@@ -92,63 +87,6 @@ public class LoomGradlePlugin extends AbstractPlugin {
 			t.setGroup("fabric");
 		});
 
-		tasks.register("genSourcesDecompile", FernFlowerTask.class, t -> {
-			t.setDescription("Decompiles sources for the genSources task.");
-			t.getOutputs().upToDateWhen((o) -> false);
-		});
-
-		tasks.register("genSourcesRemapLineNumbers", RemapLineNumbersTask.class, t -> {
-			t.setDescription("Remaps line numbers for the genSources task.");
-			t.getOutputs().upToDateWhen((o) -> false);
-		});
-
-		tasks.register("genSources", t -> {
-			t.setDescription("Generates a human-readable version of the Minecraft source.");
-			t.getOutputs().upToDateWhen((o) -> false);
-			t.setGroup("fabric");
-		});
-
-		project.afterEvaluate((p) -> {
-			AbstractDecompileTask decompileTask = (AbstractDecompileTask) p.getTasks().getByName("genSourcesDecompile");
-			RemapLineNumbersTask remapLineNumbersTask = (RemapLineNumbersTask) p.getTasks().getByName("genSourcesRemapLineNumbers");
-			Task genSourcesTask = p.getTasks().getByName("genSources");
-
-			genSourcesTask.dependsOn(remapLineNumbersTask);
-			remapLineNumbersTask.dependsOn(decompileTask);
-
-			Project project = this.getProject();
-			LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
-			MinecraftLibraryProvider libraryProvider = extension.getMinecraftProvider().getLibraryProvider();
-			MappingsProvider mappingsProvider = extension.getMappingsProvider();
-			File mappedJar = mappingsProvider.mappedProvider.getMappedJar();
-			File linemappedJar = getMappedByproduct(project, "-linemapped.jar");
-			File sourcesJar = getMappedByproduct(project, "-sources.jar");
-			File linemapFile = getMappedByproduct(project, "-sources.lmap");
-
-			decompileTask.setInput(mappedJar);
-			decompileTask.setOutput(sourcesJar);
-			decompileTask.setLineMapFile(linemapFile);
-			decompileTask.setLibraries(libraryProvider.getLibraries());
-
-			remapLineNumbersTask.setInput(mappedJar);
-			remapLineNumbersTask.setLineMapFile(linemapFile);
-			remapLineNumbersTask.setOutput(linemappedJar);
-
-			Path mappedJarPath = mappedJar.toPath();
-			Path linemappedJarPath = linemappedJar.toPath();
-
-			genSourcesTask.doLast((tt) -> {
-				if (Files.exists(linemappedJarPath)) {
-					try {
-						Files.deleteIfExists(mappedJarPath);
-						Files.copy(linemappedJarPath, mappedJarPath);
-					} catch (IOException e) {
-						throw new RuntimeException(e);
-					}
-				}
-			});
-		});
-
 		tasks.register("downloadAssets", DownloadAssetsTask.class, t -> t.setDescription("Downloads required assets for Fabric."));
 
 		tasks.register("genIdeaWorkspace", GenIdeaProjectTask.class, t -> {
@@ -187,5 +125,16 @@ public class LoomGradlePlugin extends AbstractPlugin {
 			t.dependsOn("jar");
 			t.setGroup("fabric");
 		});
+
+		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		extension.addDecompiler(new FabricFernFlowerDecompiler(project));
+
+		project.afterEvaluate((p) -> {
+			for (LoomDecompiler decompiler : extension.decompilers) {
+				String taskName = (decompiler instanceof FabricFernFlowerDecompiler) ? "genSources" : "genSourcesWith" + decompiler.name();
+				// decompiler will be passed to the constructor of GenerateSourcesTask
+				tasks.register(taskName, GenerateSourcesTask.class, decompiler);
+			}
+		});
 	}
 }
diff --git a/src/main/java/net/fabricmc/loom/task/AbstractDecompileTask.java b/src/main/java/net/fabricmc/loom/api/decompilers/DecompilationMetadata.java
index c7403a92..35dcbfa6 100644
--- a/src/main/java/net/fabricmc/loom/task/AbstractDecompileTask.java
+++ b/src/main/java/net/fabricmc/loom/api/decompilers/DecompilationMetadata.java
@@ -22,54 +22,19 @@
  * SOFTWARE.
  */
 
-package net.fabricmc.loom.task;
+package net.fabricmc.loom.api.decompilers;
 
-import java.io.File;
+import java.nio.file.Path;
+import java.util.Collection;
 
-import org.gradle.api.file.FileCollection;
-import org.gradle.api.tasks.InputFile;
-import org.gradle.api.tasks.InputFiles;
-import org.gradle.api.tasks.OutputFile;
+public class DecompilationMetadata {
+	public final int numberOfThreads;
+	public final Path javaDocs;
+	public final Collection<Path> libraries;
 
-public abstract class AbstractDecompileTask extends AbstractLoomTask {
-	private Object input;
-	private Object output;
-	private Object lineMapFile;
-	private Object libraries;
-
-	@InputFile
-	public File getInput() {
-		return getProject().file(input);
-	}
-
-	@OutputFile
-	public File getOutput() {
-		return getProject().file(output);
-	}
-
-	@OutputFile
-	public File getLineMapFile() {
-		return getProject().file(lineMapFile);
-	}
-
-	@InputFiles
-	public FileCollection getLibraries() {
-		return getProject().files(libraries);
-	}
-
-	public void setInput(Object input) {
-		this.input = input;
-	}
-
-	public void setOutput(Object output) {
-		this.output = output;
-	}
-
-	public void setLineMapFile(Object lineMapFile) {
-		this.lineMapFile = lineMapFile;
-	}
-
-	public void setLibraries(Object libraries) {
+	public DecompilationMetadata(int numberOfThreads, Path javaDocs, Collection<Path> libraries) {
+		this.numberOfThreads = numberOfThreads;
+		this.javaDocs = javaDocs;
 		this.libraries = libraries;
 	}
 }
diff --git a/src/main/java/net/fabricmc/loom/api/decompilers/LoomDecompiler.java b/src/main/java/net/fabricmc/loom/api/decompilers/LoomDecompiler.java
new file mode 100644
index 00000000..c19a4a8c
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/api/decompilers/LoomDecompiler.java
@@ -0,0 +1,40 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * 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.
+ */
+
+package net.fabricmc.loom.api.decompilers;
+
+import java.nio.file.Path;
+
+public interface LoomDecompiler {
+	String name();
+
+	/**
+	 * @param sourcesDestination Decompiled sources jar
+	 * @param linemapDestination A byproduct of decompilation that lines up the compiled jar's line numbers with the decompiled
+	 *                           sources jar for debugging.
+	 *                           A decompiler may not produce a linemap at all.
+	 * @param metaData Additional information that may or may not be needed while decompiling
+	 */
+	void decompile(Path compiledJar, Path sourcesDestination, Path linemapDestination, DecompilationMetadata metaData);
+}
diff --git a/src/main/java/net/fabricmc/loom/task/fernflower/FernFlowerTask.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/AbstractFernFlowerDecompiler.java
index d2881d75..71146d24 100644
--- a/src/main/java/net/fabricmc/loom/task/fernflower/FernFlowerTask.java
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/AbstractFernFlowerDecompiler.java
@@ -22,10 +22,11 @@
  * SOFTWARE.
  */
 
-package net.fabricmc.loom.task.fernflower;
+package net.fabricmc.loom.decompilers.fernflower;
 
 import static java.text.MessageFormat.format;
 
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -33,58 +34,59 @@ import java.util.Map;
 import java.util.Stack;
 import java.util.function.Supplier;
 
-import org.jetbrains.java.decompiler.main.extern.IFernflowerPreferences;
+import org.gradle.api.Project;
 import org.gradle.api.internal.project.ProjectInternal;
 import org.gradle.api.logging.LogLevel;
-import org.gradle.api.tasks.Input;
-import org.gradle.api.tasks.TaskAction;
 import org.gradle.internal.logging.progress.ProgressLogger;
 import org.gradle.internal.logging.progress.ProgressLoggerFactory;
 import org.gradle.internal.service.ServiceRegistry;
 import org.gradle.process.ExecResult;
+import org.jetbrains.java.decompiler.main.extern.IFernflowerPreferences;
 
-import net.fabricmc.loom.task.AbstractDecompileTask;
-import net.fabricmc.loom.task.ForkingJavaExecTask;
+import net.fabricmc.loom.api.decompilers.DecompilationMetadata;
+import net.fabricmc.loom.api.decompilers.LoomDecompiler;
 import net.fabricmc.loom.util.ConsumingOutputStream;
 import net.fabricmc.loom.util.OperatingSystem;
 
-/**
- * Created by covers1624 on 9/02/19.
- */
-public class FernFlowerTask extends AbstractDecompileTask implements ForkingJavaExecTask {
-	private boolean noFork = false;
-	private int numThreads = Runtime.getRuntime().availableProcessors();
+public abstract class AbstractFernFlowerDecompiler implements LoomDecompiler {
+	private final Project project;
+
+	protected AbstractFernFlowerDecompiler(Project project) {
+		this.project = project;
+	}
 
-	@TaskAction
-	public void doTask() throws Throwable {
+	public abstract Class<? extends AbstractForkedFFExecutor> fernFlowerExecutor();
+
+	@Override
+	public void decompile(Path compiledJar, Path sourcesDestination, Path linemapDestination, DecompilationMetadata metaData) {
 		if (!OperatingSystem.is64Bit()) {
-			throw new UnsupportedOperationException("FernFlowerTask requires a 64bit JVM to run due to the memory requirements");
+			throw new UnsupportedOperationException("FernFlower decompiler requires a 64bit JVM to run due to the memory requirements");
 		}
 
-		Map<String, Object> options = new HashMap<>();
-		options.put(IFernflowerPreferences.DECOMPILE_GENERIC_SIGNATURES, "1");
-		options.put(IFernflowerPreferences.BYTECODE_SOURCE_MAPPING, "1");
-		options.put(IFernflowerPreferences.REMOVE_SYNTHETIC, "1");
-		options.put(IFernflowerPreferences.LOG_LEVEL, "trace");
-		options.put(IFernflowerPreferences.THREADS, getNumThreads());
-		getLogging().captureStandardOutput(LogLevel.LIFECYCLE);
+		project.getLogging().captureStandardOutput(LogLevel.LIFECYCLE);
+
+		Map<String, Object> options = new HashMap<String, Object>() {{
+				put(IFernflowerPreferences.DECOMPILE_GENERIC_SIGNATURES, "1");
+				put(IFernflowerPreferences.BYTECODE_SOURCE_MAPPING, "1");
+				put(IFernflowerPreferences.REMOVE_SYNTHETIC, "1");
+				put(IFernflowerPreferences.LOG_LEVEL, "trace");
+				put(IFernflowerPreferences.THREADS, metaData.numberOfThreads);
+			}};
 
 		List<String> args = new ArrayList<>();
 
 		options.forEach((k, v) -> args.add(format("-{0}={1}", k, v)));
-		args.add(getInput().getAbsolutePath());
-		args.add("-o=" + getOutput().getAbsolutePath());
-
-		if (getLineMapFile() != null) {
-			args.add("-l=" + getLineMapFile().getAbsolutePath());
-		}
-
-		args.add("-m=" + getExtension().getMappingsProvider().tinyMappings.getAbsolutePath());
+		args.add(absolutePathOf(compiledJar));
+		args.add("-o=" + absolutePathOf(sourcesDestination));
+		args.add("-l=" + absolutePathOf(linemapDestination));
+		args.add("-m=" + absolutePathOf(metaData.javaDocs));
 
 		//TODO, Decompiler breaks on jemalloc, J9 module-info.class?
-		getLibraries().forEach(f -> args.add("-e=" + f.getAbsolutePath()));
+		for (Path library : metaData.libraries) {
+			args.add("-e=" + absolutePathOf(library));
+		}
 
-		ServiceRegistry registry = ((ProjectInternal) getProject()).getServices();
+		ServiceRegistry registry = ((ProjectInternal) project).getServices();
 		ProgressLoggerFactory factory = registry.get(ProgressLoggerFactory.class);
 		ProgressLogger progressGroup = factory.newOperation(getClass()).setDescription("Decompile");
 		Supplier<ProgressLogger> loggerFactory = () -> {
@@ -97,8 +99,8 @@ public class FernFlowerTask extends AbstractDecompileTask implements ForkingJava
 		Map<String, ProgressLogger> inUseLoggers = new HashMap<>();
 
 		progressGroup.started();
-		ExecResult result = javaexec(spec -> {
-			spec.setMain(ForkedFFExecutor.class.getName());
+		ExecResult result = ForkingJavaExec.javaexec(project, spec -> {
+			spec.setMain(fernFlowerExecutor().getName());
 			spec.jvmArgs("-Xms200m", "-Xmx3G");
 			spec.setArgs(args);
 			spec.setErrorOutput(System.err);
@@ -145,21 +147,7 @@ public class FernFlowerTask extends AbstractDecompileTask implements ForkingJava
 		result.assertNormalExitValue();
 	}
 
-	@Input
-	public int getNumThreads() {
-		return numThreads;
-	}
-
-	@Input
-	public boolean isNoFork() {
-		return noFork;
-	}
-
-	public void setNoFork(boolean noFork) {
-		this.noFork = noFork;
-	}
-
-	public void setNumThreads(int numThreads) {
-		this.numThreads = numThreads;
+	private static String absolutePathOf(Path path) {
+		return path.toAbsolutePath().toString();
 	}
 }
diff --git a/src/main/java/net/fabricmc/loom/task/fernflower/ForkedFFExecutor.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/AbstractForkedFFExecutor.java
index 10b5ccf8..d42bf7ff 100644
--- a/src/main/java/net/fabricmc/loom/task/fernflower/ForkedFFExecutor.java
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/AbstractForkedFFExecutor.java
@@ -22,31 +22,27 @@
  * SOFTWARE.
  */
 
-package net.fabricmc.loom.task.fernflower;
+package net.fabricmc.loom.decompilers.fernflower;
 
 import java.io.File;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
-import org.jetbrains.java.decompiler.main.Fernflower;
-import org.jetbrains.java.decompiler.main.extern.IFernflowerLogger;
-import org.jetbrains.java.decompiler.main.extern.IResultSaver;
-
-import net.fabricmc.fernflower.api.IFabricJavadocProvider;
-
 /**
  * Entry point for Forked FernFlower task.
  * Takes one parameter, a single file, each line is treated as command line input.
  * Forces one input file.
  * Forces one output file using '-o=/path/to/output'
  * Created by covers1624 on 11/02/19.
+ * <p>Extending classes MUST have a standard "public static void main(args)".
+ * They may then call AbstractForkedFFExecutor#decompile for it to use the overridden AbstractForkedFFExecutor#runFF
+ * </p>
  */
-public class ForkedFFExecutor {
-	public static void main(String[] args) throws IOException {
+public abstract class AbstractForkedFFExecutor {
+	public static void decompile(String[] args, AbstractForkedFFExecutor ffExecutor) {
 		Map<String, Object> options = new HashMap<>();
 		File input = null;
 		File output = null;
@@ -104,20 +100,8 @@ public class ForkedFFExecutor {
 		Objects.requireNonNull(output, "Output not set.");
 		Objects.requireNonNull(mappings, "Mappings not set.");
 
-		options.put(IFabricJavadocProvider.PROPERTY_NAME, new TinyJavadocProvider(mappings));
-		runFF(options, libraries, input, output, lineMap);
+		ffExecutor.runFF(options, libraries, input, output, lineMap, mappings);
 	}
 
-	public static void runFF(Map<String, Object> options, List<File> libraries, File input, File output, File lineMap) {
-		IResultSaver saver = new ThreadSafeResultSaver(() -> output, () -> lineMap);
-		IFernflowerLogger logger = new ThreadIDFFLogger();
-		Fernflower ff = new Fernflower(FernFlowerUtils::getBytecode, saver, options, logger);
-
-		for (File library : libraries) {
-			ff.addLibrary(library);
-		}
-
-		ff.addSource(input);
-		ff.decompileContext();
-	}
+	public abstract void runFF(Map<String, Object> options, List<File> libraries, File input, File output, File lineMap, File mappings);
 }
diff --git a/src/main/java/net/fabricmc/loom/task/fernflower/NoopFFLogger.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/FabricFernFlowerDecompiler.java
index 6e03a1cd..7fc98ab2 100644
--- a/src/main/java/net/fabricmc/loom/task/fernflower/NoopFFLogger.java
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/FabricFernFlowerDecompiler.java
@@ -22,18 +22,22 @@
  * SOFTWARE.
  */
 
-package net.fabricmc.loom.task.fernflower;
+package net.fabricmc.loom.decompilers.fernflower;
 
-import org.jetbrains.java.decompiler.main.extern.IFernflowerLogger;
+import org.gradle.api.Project;
+
+public class FabricFernFlowerDecompiler extends AbstractFernFlowerDecompiler {
+	public FabricFernFlowerDecompiler(Project project) {
+		super(project);
+	}
 
-/**
- * Literally does nothing.
- * Created by covers1624 on 11/02/19.
- */
-public class NoopFFLogger extends IFernflowerLogger {
 	@Override
-	public void writeMessage(String message, Severity severity) { }
+	public String name() {
+		return "FabricFlower"; // Or something else?
+	}
 
 	@Override
-	public void writeMessage(String message, Severity severity, Throwable t) { }
+	public Class<? extends AbstractForkedFFExecutor> fernFlowerExecutor() {
+		return FabricForkedFFExecutor.class;
+	}
 }
diff --git a/src/main/java/net/fabricmc/loom/decompilers/fernflower/FabricForkedFFExecutor.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/FabricForkedFFExecutor.java
new file mode 100644
index 00000000..708acab2
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/FabricForkedFFExecutor.java
@@ -0,0 +1,57 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * 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.
+ */
+
+package net.fabricmc.loom.decompilers.fernflower;
+
+import java.io.File;
+import java.util.List;
+import java.util.Map;
+
+import org.jetbrains.java.decompiler.main.Fernflower;
+import org.jetbrains.java.decompiler.main.extern.IFernflowerLogger;
+import org.jetbrains.java.decompiler.main.extern.IResultSaver;
+
+import net.fabricmc.fernflower.api.IFabricJavadocProvider;
+
+public class FabricForkedFFExecutor extends AbstractForkedFFExecutor {
+	public static void main(String[] args) {
+		AbstractForkedFFExecutor.decompile(args, new FabricForkedFFExecutor());
+	}
+
+	@Override
+	public void runFF(Map<String, Object> options, List<File> libraries, File input, File output, File lineMap, File mappings) {
+		options.put(IFabricJavadocProvider.PROPERTY_NAME, new TinyJavadocProvider(mappings));
+
+		IResultSaver saver = new ThreadSafeResultSaver(() -> output, () -> lineMap);
+		IFernflowerLogger logger = new ThreadIDFFLogger();
+		Fernflower ff = new Fernflower(FernFlowerUtils::getBytecode, saver, options, logger);
+
+		for (File library : libraries) {
+			ff.addLibrary(library);
+		}
+
+		ff.addSource(input);
+		ff.decompileContext();
+	}
+}
diff --git a/src/main/java/net/fabricmc/loom/task/fernflower/FernFlowerUtils.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/FernFlowerUtils.java
index 69c0e703..2f999b32 100644
--- a/src/main/java/net/fabricmc/loom/task/fernflower/FernFlowerUtils.java
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/FernFlowerUtils.java
@@ -22,7 +22,7 @@
  * SOFTWARE.
  */
 
-package net.fabricmc.loom.task.fernflower;
+package net.fabricmc.loom.decompilers.fernflower;
 
 import java.io.File;
 import java.io.IOException;
diff --git a/src/main/java/net/fabricmc/loom/task/ForkingJavaExecTask.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/ForkingJavaExec.java
index ab5619ab..8b5f5f60 100644
--- a/src/main/java/net/fabricmc/loom/task/ForkingJavaExecTask.java
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/ForkingJavaExec.java
@@ -22,10 +22,10 @@
  * SOFTWARE.
  */
 
-package net.fabricmc.loom.task;
+package net.fabricmc.loom.decompilers.fernflower;
 
 import org.gradle.api.Action;
-import org.gradle.api.Task;
+import org.gradle.api.Project;
 import org.gradle.api.artifacts.ConfigurationContainer;
 import org.gradle.api.artifacts.dsl.DependencyHandler;
 import org.gradle.api.file.FileCollection;
@@ -33,19 +33,19 @@ import org.gradle.process.ExecResult;
 import org.gradle.process.JavaExecSpec;
 
 /**
- * Simple trait like interface for a Task that wishes to execute a java process
+ * Simple utility class for a Task that wishes to execute a java process
  * with the classpath of the gradle plugin plus groovy.
  *
  * <p>Created by covers1624 on 11/02/19.
  */
-public interface ForkingJavaExecTask extends Task {
-	default ExecResult javaexec(Action<? super JavaExecSpec> action) {
-		ConfigurationContainer configurations = getProject().getBuildscript().getConfigurations();
-		DependencyHandler handler = getProject().getDependencies();
+public class ForkingJavaExec {
+	public static ExecResult javaexec(Project project, Action<? super JavaExecSpec> action) {
+		ConfigurationContainer configurations = project.getBuildscript().getConfigurations();
+		DependencyHandler handler = project.getDependencies();
 		FileCollection classpath = configurations.getByName("classpath")//
-				.plus(configurations.detachedConfiguration(handler.localGroovy()));
+						.plus(configurations.detachedConfiguration(handler.localGroovy()));
 
-		return getProject().javaexec(spec -> {
+		return project.javaexec(spec -> {
 			spec.classpath(classpath);
 			action.execute(spec);
 		});
diff --git a/src/main/java/net/fabricmc/loom/task/fernflower/ThreadIDFFLogger.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/ThreadIDFFLogger.java
index 0d69a4b1..fac5a794 100644
--- a/src/main/java/net/fabricmc/loom/task/fernflower/ThreadIDFFLogger.java
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/ThreadIDFFLogger.java
@@ -22,7 +22,7 @@
  * SOFTWARE.
  */
 
-package net.fabricmc.loom.task.fernflower;
+package net.fabricmc.loom.decompilers.fernflower;
 
 import java.io.PrintStream;
 import java.text.MessageFormat;
diff --git a/src/main/java/net/fabricmc/loom/task/fernflower/ThreadSafeResultSaver.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/ThreadSafeResultSaver.java
index 87a8d21e..66598749 100644
--- a/src/main/java/net/fabricmc/loom/task/fernflower/ThreadSafeResultSaver.java
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/ThreadSafeResultSaver.java
@@ -22,7 +22,7 @@
  * SOFTWARE.
  */
 
-package net.fabricmc.loom.task.fernflower;
+package net.fabricmc.loom.decompilers.fernflower;
 
 import java.io.File;
 import java.io.FileOutputStream;
diff --git a/src/main/java/net/fabricmc/loom/task/fernflower/TinyJavadocProvider.java b/src/main/java/net/fabricmc/loom/decompilers/fernflower/TinyJavadocProvider.java
index 0e49d01d..15cf3bf8 100644
--- a/src/main/java/net/fabricmc/loom/task/fernflower/TinyJavadocProvider.java
+++ b/src/main/java/net/fabricmc/loom/decompilers/fernflower/TinyJavadocProvider.java
@@ -22,7 +22,7 @@
  * SOFTWARE.
  */
 
-package net.fabricmc.loom.task.fernflower;
+package net.fabricmc.loom.decompilers.fernflower;
 
 import java.io.BufferedReader;
 import java.io.File;
diff --git a/src/main/java/net/fabricmc/loom/task/GenerateSourcesTask.java b/src/main/java/net/fabricmc/loom/task/GenerateSourcesTask.java
new file mode 100644
index 00000000..8f449d45
--- /dev/null
+++ b/src/main/java/net/fabricmc/loom/task/GenerateSourcesTask.java
@@ -0,0 +1,104 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * 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.
+ */
+
+package net.fabricmc.loom.task;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.util.Collection;
+import java.util.stream.Collectors;
+
+import javax.inject.Inject;
+
+import org.gradle.api.tasks.TaskAction;
+
+import net.fabricmc.loom.LoomGradlePlugin;
+import net.fabricmc.loom.api.decompilers.DecompilationMetadata;
+import net.fabricmc.loom.api.decompilers.LoomDecompiler;
+import net.fabricmc.loom.util.LineNumberRemapper;
+import net.fabricmc.loom.util.progress.ProgressLogger;
+import net.fabricmc.stitch.util.StitchUtil;
+
+public class GenerateSourcesTask extends AbstractLoomTask {
+	public final LoomDecompiler decompiler;
+
+	@Inject
+	public GenerateSourcesTask(LoomDecompiler decompiler) {
+		this.decompiler = decompiler;
+
+		setGroup("fabric");
+		getOutputs().upToDateWhen((o) -> false);
+	}
+
+	@TaskAction
+	public void doTask() throws Throwable {
+		int threads = Runtime.getRuntime().availableProcessors();
+		Path javaDocs = getExtension().getMappingsProvider().tinyMappings.toPath();
+		Collection<Path> libraries = getExtension().getMinecraftProvider().getLibraryProvider().getLibraries()
+						.stream().map(File::toPath).collect(Collectors.toSet());
+
+		DecompilationMetadata metadata = new DecompilationMetadata(threads, javaDocs, libraries);
+		Path compiledJar = getExtension().getMappingsProvider().mappedProvider.getMappedJar().toPath();
+		Path sourcesDestination = LoomGradlePlugin.getMappedByproduct(getProject(), "-sources.jar").toPath();
+		Path linemap = LoomGradlePlugin.getMappedByproduct(getProject(), "-sources.lmap").toPath();
+		decompiler.decompile(compiledJar, sourcesDestination, linemap, metadata);
+
+		if (Files.exists(linemap)) {
+			Path linemappedJarDestination = LoomGradlePlugin.getMappedByproduct(getProject(), "-linemapped.jar").toPath();
+
+			remapLineNumbers(compiledJar, linemap, linemappedJarDestination);
+
+			// In order for IDEs to recognize the new line mappings, we need to overwrite the existing compiled jar
+			// with the linemapped one. In the name of not destroying the existing jar, we will copy it to somewhere else.
+			Path unlinemappedJar = LoomGradlePlugin.getMappedByproduct(getProject(), "-unlinemapped.jar").toPath();
+
+			// The second time genSources is ran, we want to keep the existing unlinemapped jar.
+			if (!Files.exists(unlinemappedJar)) {
+				Files.copy(compiledJar, unlinemappedJar);
+			}
+
+			Files.copy(linemappedJarDestination, compiledJar, StandardCopyOption.REPLACE_EXISTING);
+			Files.delete(linemappedJarDestination);
+		}
+	}
+
+	private void remapLineNumbers(Path oldCompiledJar, Path linemap, Path linemappedJarDestination) throws IOException {
+		getProject().getLogger().info(":adjusting line numbers");
+		LineNumberRemapper remapper = new LineNumberRemapper();
+		remapper.readMappings(linemap.toFile());
+
+		ProgressLogger progressLogger = net.fabricmc.loom.util.progress.ProgressLogger.getProgressFactory(getProject(), getClass().getName());
+		progressLogger.start("Adjusting line numbers", "linemap");
+
+		try (StitchUtil.FileSystemDelegate inFs = StitchUtil.getJarFileSystem(oldCompiledJar.toFile(), true);
+			StitchUtil.FileSystemDelegate outFs = StitchUtil.getJarFileSystem(linemappedJarDestination.toFile(), true)) {
+			remapper.process(progressLogger, inFs.get().getPath("/"), outFs.get().getPath("/"));
+		}
+
+		progressLogger.completed();
+	}
+}
diff --git a/src/main/java/net/fabricmc/loom/task/RemapLineNumbersTask.java b/src/main/java/net/fabricmc/loom/task/RemapLineNumbersTask.java
deleted file mode 100644
index e229de10..00000000
--- a/src/main/java/net/fabricmc/loom/task/RemapLineNumbersTask.java
+++ /dev/null
@@ -1,91 +0,0 @@
-/*
- * This file is part of fabric-loom, licensed under the MIT License (MIT).
- *
- * Copyright (c) 2016, 2017, 2018 FabricMC
- *
- * 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.
- */
-
-package net.fabricmc.loom.task;
-
-import java.io.File;
-import java.io.IOException;
-
-import org.gradle.api.Project;
-import org.gradle.api.tasks.InputFile;
-import org.gradle.api.tasks.OutputFile;
-import org.gradle.api.tasks.TaskAction;
-
-import net.fabricmc.loom.task.fernflower.FernFlowerTask;
-import net.fabricmc.loom.util.LineNumberRemapper;
-import net.fabricmc.loom.util.progress.ProgressLogger;
-import net.fabricmc.stitch.util.StitchUtil;
-
-public class RemapLineNumbersTask extends AbstractLoomTask {
-	private Object input;
-	private Object output;
-	private Object lineMapFile;
-
-	@TaskAction
-	public void doTask() throws Throwable {
-		Project project = getProject();
-
-		project.getLogger().info(":adjusting line numbers");
-		LineNumberRemapper remapper = new LineNumberRemapper();
-		remapper.readMappings(getLineMapFile());
-
-		ProgressLogger progressLogger = ProgressLogger.getProgressFactory(project, FernFlowerTask.class.getName());
-		progressLogger.start("Adjusting line numbers", "linemap");
-
-		try (StitchUtil.FileSystemDelegate inFs = StitchUtil.getJarFileSystem(getInput(), true); StitchUtil.FileSystemDelegate outFs = StitchUtil.getJarFileSystem(getOutput(), true)) {
-			remapper.process(progressLogger, inFs.get().getPath("/"), outFs.get().getPath("/"));
-		} catch (IOException e) {
-			throw new RuntimeException(e);
-		}
-
-		progressLogger.completed();
-	}
-
-	@InputFile
-	public File getInput() {
-		return getProject().file(input);
-	}
-
-	@InputFile
-	public File getLineMapFile() {
-		return getProject().file(lineMapFile);
-	}
-
-	@OutputFile
-	public File getOutput() {
-		return getProject().file(output);
-	}
-
-	public void setInput(Object input) {
-		this.input = input;
-	}
-
-	public void setLineMapFile(Object lineMapFile) {
-		this.lineMapFile = lineMapFile;
-	}
-
-	public void setOutput(Object output) {
-		this.output = output;
-	}
-}