Refactor LoomGradleExtension (#431)

* First pass at refactoring the extension

* Fix inital issues.

* Combine some interfaces

* Checkstyle

* Fix years

* Add isShareCaches to api

src/main/java/net/fabricmc/loom/LoomGradleExtension.java

@@ -25,368 +25,86 @@
 package net.fabricmc.loom;
 
 import java.io.File;
-import java.nio.file.Path;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.List;
 import java.util.Set;
-import java.util.function.Function;
 import java.util.function.Supplier;
-import java.util.stream.Collectors;
 
 import org.cadixdev.lorenz.MappingSet;
 import org.cadixdev.mercury.Mercury;
-import org.gradle.api.Action;
+import org.gradle.api.NamedDomainObjectProvider;
-import org.gradle.api.NamedDomainObjectContainer;
 import org.gradle.api.Project;
-import org.gradle.api.artifacts.Dependency;
+import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.file.ConfigurableFileCollection;
-import org.gradle.api.plugins.BasePluginConvention;
-import org.jetbrains.annotations.ApiStatus;
 
-import net.fabricmc.loom.api.decompilers.LoomDecompiler;
+import net.fabricmc.loom.api.LoomGradleExtensionAPI;
 import net.fabricmc.loom.configuration.InstallerData;
 import net.fabricmc.loom.configuration.LoomDependencyManager;
-import net.fabricmc.loom.configuration.LoomProjectData;
-import net.fabricmc.loom.configuration.ide.RunConfigSettings;
-import net.fabricmc.loom.configuration.processors.JarProcessor;
 import net.fabricmc.loom.configuration.processors.JarProcessorManager;
 import net.fabricmc.loom.configuration.providers.MinecraftProviderImpl;
-import net.fabricmc.loom.configuration.providers.minecraft.MinecraftMappedProvider;
-import net.fabricmc.loom.configuration.providers.mappings.GradleMappingContext;
-import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingSpec;
-import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingSpecBuilder;
-import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsDependency;
 import net.fabricmc.loom.configuration.providers.mappings.MappingsProviderImpl;
+import net.fabricmc.loom.configuration.providers.minecraft.MinecraftMappedProvider;
+import net.fabricmc.loom.extension.LoomFiles;
+import net.fabricmc.loom.extension.LoomGradleExtensionImpl;
 
-public class LoomGradleExtension {
+public interface LoomGradleExtension extends LoomGradleExtensionAPI {
-	public String refmapName;
+	static LoomGradleExtension get(Project project) {
-	public String loaderLaunchMethod;
+		return project.getExtensions().getByType(LoomGradleExtensionImpl.class);
-	public boolean remapMod = true;
-	public String customManifest = null;
-	public File accessWidener = null;
-	public Function<String, Object> intermediaryUrl = mcVer -> "https://maven.fabricmc.net/net/fabricmc/intermediary/" + mcVer + "/intermediary-" + mcVer + "-v2.jar";
-	public boolean shareCaches = false;
-
-	private final ConfigurableFileCollection unmappedMods;
-	private final ConfigurableFileCollection log4jConfigs;
-
-	final List<LoomDecompiler> decompilers = new ArrayList<>();
-	private final List<JarProcessor> jarProcessors = new ArrayList<>();
-
-	// Not to be set in the build.gradle
-	private final Project project;
-	private LoomDependencyManager dependencyManager;
-	private JarProcessorManager jarProcessorManager;
-	private InstallerData installerData;
-	private MappingSet[] srcMappingCache = new MappingSet[2];
-	private Mercury[] srcMercuryCache = new Mercury[2];
-	private Set<File> mixinMappings = Collections.synchronizedSet(new HashSet<>());
-
-	@ApiStatus.Internal
-	private final LoomProjectData projectData;
-
-	private NamedDomainObjectContainer<RunConfigSettings> runConfigs;
-
-	/**
-	 * 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);
 	}
 
-	/**
+	LoomFiles getFiles();
-	 * Add a transformation over the mapped mc jar.
-	 * Adding any jar processor will cause mapped mc jars to be stored per-project so that
-	 * different transformation can be applied in different projects.
-	 * This means remapping will need to be done individually per-project, which is slower when developing
-	 * more than one project using the same minecraft version.
-	 */
-	public void addJarProcessor(JarProcessor processor) {
-		jarProcessors.add(processor);
-	}
 
-	public MappingSet getOrCreateSrcMappingCache(int id, Supplier<MappingSet> factory) {
+	NamedDomainObjectProvider<Configuration> createLazyConfiguration(String name);
-		return srcMappingCache[id] != null ? srcMappingCache[id] : (srcMappingCache[id] = factory.get());
-	}
 
-	public Mercury getOrCreateSrcMercuryCache(int id, Supplier<Mercury> factory) {
+	NamedDomainObjectProvider<Configuration> getLazyConfigurationProvider(String name);
-		return srcMercuryCache[id] != null ? srcMercuryCache[id] : (srcMercuryCache[id] = factory.get());
-	}
 
-	public Dependency officialMojangMappings() {
+	MappingSet getOrCreateSrcMappingCache(int id, Supplier<MappingSet> factory);
-		return layered(LayeredMappingSpecBuilder::officialMojangMappings);
-	}
 
-	public Dependency layered(Action<LayeredMappingSpecBuilder> action) {
+	Mercury getOrCreateSrcMercuryCache(int id, Supplier<Mercury> factory);
-		LayeredMappingSpecBuilder builder = new LayeredMappingSpecBuilder();
-		action.execute(builder);
-		LayeredMappingSpec builtSpec = builder.build();
-		return new LayeredMappingsDependency(new GradleMappingContext(project, "layers_" + builtSpec.getVersion().replace("+", "_").replace(".", "_")), builtSpec, builtSpec.getVersion());
-	}
 
-	public LoomGradleExtension(Project project) {
+	ConfigurableFileCollection getUnmappedModCollection();
-		this.project = project;
-		this.unmappedMods = project.files();
-		this.runConfigs = project.container(RunConfigSettings.class,
-				baseName -> new RunConfigSettings(project, baseName));
-		this.log4jConfigs = project.files(getDefaultLog4jConfigFile());
-		projectData = new LoomProjectData(project);
-	}
 
-	/**
+	void setInstallerData(InstallerData data);
-	 * @see ConfigurableFileCollection#from(Object...)
-	 * @deprecated use {@link #getUnmappedModCollection()}{@code .from()} instead
-	 */
-	@Deprecated
-	public void addUnmappedMod(Path file) {
-		getUnmappedModCollection().from(file);
-	}
 
-	/**
+	InstallerData getInstallerData();
-	 * @deprecated use {@link #getUnmappedModCollection()} instead
-	 */
-	@Deprecated
-	public List<Path> getUnmappedMods() {
-		return unmappedMods.getFiles().stream()
-				.map(File::toPath)
-				.collect(Collectors.toList());
-	}
 
-	public ConfigurableFileCollection getUnmappedModCollection() {
+	void setDependencyManager(LoomDependencyManager dependencyManager);
-		return unmappedMods;
-	}
 
-	public void setInstallerData(InstallerData data) {
+	LoomDependencyManager getDependencyManager();
-		this.installerData = data;
-	}
 
-	public InstallerData getInstallerData() {
+	void setJarProcessorManager(JarProcessorManager jarProcessorManager);
-		return installerData;
-	}
 
-	public void accessWidener(Object file) {
+	JarProcessorManager getJarProcessorManager();
-		this.accessWidener = project.file(file);
-	}
 
-	public File getUserCache() {
+	default MinecraftProviderImpl getMinecraftProvider() {
-		File userCache = new File(project.getGradle().getGradleUserHomeDir(), "caches" + File.separator + "fabric-loom");
-
-		if (!userCache.exists()) {
-			userCache.mkdirs();
-		}
-
-		return userCache;
-	}
-
-	public File getRootProjectPersistentCache() {
-		File projectCache = new File(project.getRootProject().file(".gradle"), "loom-cache");
-
-		if (!projectCache.exists()) {
-			projectCache.mkdirs();
-		}
-
-		return projectCache;
-	}
-
-	public File getProjectPersistentCache() {
-		File projectCache = new File(project.file(".gradle"), "loom-cache");
-
-		if (!projectCache.exists()) {
-			projectCache.mkdirs();
-		}
-
-		return projectCache;
-	}
-
-	public File getRootProjectBuildCache() {
-		File projectCache = new File(project.getRootProject().getBuildDir(), "loom-cache");
-
-		if (!projectCache.exists()) {
-			projectCache.mkdirs();
-		}
-
-		return projectCache;
-	}
-
-	public File getProjectBuildCache() {
-		File projectCache = new File(project.getBuildDir(), "loom-cache");
-
-		if (!projectCache.exists()) {
-			projectCache.mkdirs();
-		}
-
-		return projectCache;
-	}
-
-	public File getRemappedModCache() {
-		File remappedModCache = new File(getRootProjectPersistentCache(), "remapped_mods");
-
-		if (!remappedModCache.exists()) {
-			remappedModCache.mkdir();
-		}
-
-		return remappedModCache;
-	}
-
-	public File getNestedModCache() {
-		File nestedModCache = new File(getRootProjectPersistentCache(), "nested_mods");
-
-		if (!nestedModCache.exists()) {
-			nestedModCache.mkdir();
-		}
-
-		return nestedModCache;
-	}
-
-	public File getNativesJarStore() {
-		File natives = new File(getUserCache(), "natives/jars");
-
-		if (!natives.exists()) {
-			natives.mkdirs();
-		}
-
-		return natives;
-	}
-
-	public File getNativesDirectory() {
-		if (project.hasProperty("fabric.loom.natives.dir")) {
-			return new File((String) project.property("fabric.loom.natives.dir"));
-		}
-
-		File natives = new File(getUserCache(), "natives/" + getMinecraftProvider().minecraftVersion());
-
-		if (!natives.exists()) {
-			natives.mkdirs();
-		}
-
-		return natives;
-	}
-
-	public boolean hasCustomNatives() {
-		return project.getProperties().get("fabric.loom.natives.dir") != null;
-	}
-
-	public File getDevLauncherConfig() {
-		return new File(getProjectPersistentCache(), "launch.cfg");
-	}
-
-	public String getLoaderLaunchMethod() {
-		return loaderLaunchMethod != null ? loaderLaunchMethod : "";
-	}
-
-	public LoomDependencyManager getDependencyManager() {
-		return dependencyManager;
-	}
-
-	public MinecraftProviderImpl getMinecraftProvider() {
 		return getDependencyManager().getProvider(MinecraftProviderImpl.class);
 	}
 
-	public MinecraftMappedProvider getMinecraftMappedProvider() {
+	default MappingsProviderImpl getMappingsProvider() {
-		return getMappingsProvider().mappedProvider;
-	}
-
-	public MappingsProviderImpl getMappingsProvider() {
 		return getDependencyManager().getProvider(MappingsProviderImpl.class);
 	}
 
-	public void setDependencyManager(LoomDependencyManager dependencyManager) {
+	default MinecraftMappedProvider getMinecraftMappedProvider() {
-		this.dependencyManager = dependencyManager;
+		return getMappingsProvider().mappedProvider;
 	}
 
-	public JarProcessorManager getJarProcessorManager() {
+	File getNextMixinMappings();
-		return jarProcessorManager;
-	}
 
-	public void setJarProcessorManager(JarProcessorManager jarProcessorManager) {
+	Set<File> getAllMixinMappings();
-		this.jarProcessorManager = jarProcessorManager;
-	}
 
-	public List<JarProcessor> getJarProcessors() {
+	boolean isRootProject();
-		return jarProcessors;
-	}
 
-	public String getRefmapName() {
+	boolean isShareCaches();
-		if (refmapName == null || refmapName.isEmpty()) {
-			String defaultRefmapName = project.getConvention().getPlugin(BasePluginConvention.class).getArchivesBaseName() + "-refmap.json";
-			project.getLogger().info("Could not find refmap definition, will be using default name: " + defaultRefmapName);
-			refmapName = defaultRefmapName;
-		}
 
-		return refmapName;
+	default boolean ideSync() {
-	}
-
-	public boolean ideSync() {
 		return Boolean.parseBoolean(System.getProperty("idea.sync.active", "false"));
 	}
 
-	// Ideally this should use maven, but this is a lot easier
+	default String getCustomManifest() {
-	public Function<String, String> getIntermediaryUrl() {
+		// TODO reimplement
-		// Done like this to work around this possibly not being a java string...
+		return null;
-		return s -> intermediaryUrl.apply(s).toString();
 	}
 
-	public boolean isRootProject() {
+	default String getIntermediaryUrl(String minecraftVersion) {
-		return project.getRootProject() == project;
+		// TODO reimplement a way to change this, was never really supported api anyway
-	}
+		return String.format("https://maven.fabricmc.net/net/fabricmc/intermediary/%1$s/intermediary-%1$s-v2.jar", minecraftVersion);
-
-	public LoomGradleExtension getRootGradleExtension() {
-		if (isRootProject()) {
-			return this;
-		}
-
-		return project.getRootProject().getExtensions().getByType(LoomGradleExtension.class);
-	}
-
-	public LoomGradleExtension getSharedGradleExtension() {
-		return isShareCaches() ? getRootGradleExtension() : this;
-	}
-
-	public boolean isShareCaches() {
-		return shareCaches;
-	}
-
-	// Creates a new file each time its called, this is then held onto later when remapping the output jar
-	// Required as now when using parallel builds the old single file could be written by another sourceset compile task
-	public synchronized File getNextMixinMappings() {
-		File mixinMapping = new File(getProjectBuildCache(), "mixin-map-" + getMinecraftProvider().minecraftVersion() + "-" + getMappingsProvider().mappingsVersion + "." + mixinMappings.size() + ".tiny");
-		mixinMappings.add(mixinMapping);
-		return mixinMapping;
-	}
-
-	public Set<File> getAllMixinMappings() {
-		return Collections.unmodifiableSet(mixinMappings);
-	}
-
-	public List<LoomDecompiler> getDecompilers() {
-		return decompilers;
-	}
-
-	public File getDefaultLog4jConfigFile() {
-		return new File(getProjectPersistentCache(), "log4j.xml");
-	}
-
-	public File getUnpickLoggingConfigFile() {
-		return new File(getProjectPersistentCache(), "unpick-logging.properties");
-	}
-
-	public ConfigurableFileCollection getLog4jConfigs() {
-		return log4jConfigs;
-	}
-
-	public void runs(Action<NamedDomainObjectContainer<RunConfigSettings>> action) {
-		action.execute(runConfigs);
-	}
-
-	public NamedDomainObjectContainer<RunConfigSettings> getRunConfigs() {
-		return runConfigs;
-	}
-
-	@ApiStatus.Internal
-	public LoomProjectData getProjectData() {
-		return projectData;
 	}
 }

src/main/java/net/fabricmc/loom/LoomGradlePlugin.java

@@ -41,6 +41,8 @@ import net.fabricmc.loom.configuration.MavenPublication;
 import net.fabricmc.loom.configuration.ide.IdeConfiguration;
 import net.fabricmc.loom.configuration.providers.mappings.MappingsCache;
 import net.fabricmc.loom.decompilers.DecompilerConfiguration;
+import net.fabricmc.loom.extension.LoomGradleExtensionImpl;
+import net.fabricmc.loom.extension.LoomFilesImpl;
 import net.fabricmc.loom.task.LoomTasks;
 
 public class LoomGradlePlugin implements BootstrappedPlugin {
@@ -74,7 +76,7 @@ public class LoomGradlePlugin implements BootstrappedPlugin {
 		project.apply(ImmutableMap.of("plugin", "idea"));
 
 		// Setup extensions, loom shadows minecraft
-		project.getExtensions().create("minecraft", LoomGradleExtension.class, project);
+		project.getExtensions().create(LoomGradleExtension.class, "minecraft", LoomGradleExtensionImpl.class, project, new LoomFilesImpl(project));
 		project.getExtensions().add("loom", project.getExtensions().getByName("minecraft"));
 		project.getExtensions().create("fabricApi", FabricApiExtension.class, project);
 

src/main/java/net/fabricmc/loom/api/LoomGradleExtensionAPI.java

@@ -0,0 +1,83 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2021 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;
+
+import java.io.File;
+import java.util.List;
+
+import org.gradle.api.Action;
+import org.gradle.api.NamedDomainObjectContainer;
+import org.gradle.api.artifacts.Dependency;
+import org.gradle.api.file.ConfigurableFileCollection;
+
+import net.fabricmc.loom.api.decompilers.LoomDecompiler;
+import net.fabricmc.loom.configuration.ide.RunConfigSettings;
+import net.fabricmc.loom.configuration.processors.JarProcessor;
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingSpecBuilder;
+
+/**
+ * This is the public api available exposed to build scripts.
+ */
+public interface LoomGradleExtensionAPI {
+	File getAccessWidener();
+
+	void setAccessWidener(Object file);
+
+	void setShareCaches(boolean shareCaches);
+
+	boolean isShareCaches();
+
+	default void shareCaches() {
+		setShareCaches(true);
+	}
+
+	List<LoomDecompiler> getDecompilers();
+
+	void addDecompiler(LoomDecompiler decompiler);
+
+	List<JarProcessor> getJarProcessors();
+
+	void addJarProcessor(JarProcessor processor);
+
+	ConfigurableFileCollection getLog4jConfigs();
+
+	default Dependency officialMojangMappings() {
+		return layered(LayeredMappingSpecBuilder::officialMojangMappings);
+	}
+
+	Dependency layered(Action<LayeredMappingSpecBuilder> action);
+
+	String getRefmapName();
+
+	void setRefmapName(String refmapName);
+
+	boolean isRemapMod();
+
+	void setRemapMod(boolean remapMod);
+
+	void runs(Action<NamedDomainObjectContainer<RunConfigSettings>> action);
+
+	NamedDomainObjectContainer<RunConfigSettings> getRunConfigs();
+}

src/main/java/net/fabricmc/loom/build/ModCompileRemapper.java

@@ -51,7 +51,6 @@ import org.jetbrains.annotations.Nullable;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
-import net.fabricmc.loom.configuration.LoomProjectData;
 import net.fabricmc.loom.configuration.RemappedConfigurationEntry;
 import net.fabricmc.loom.configuration.mods.ModProcessor;
 import net.fabricmc.loom.configuration.processors.dependency.ModDependencyInfo;
@@ -76,13 +75,11 @@ public class ModCompileRemapper {
 		DependencyHandler dependencies = project.getDependencies();
 		boolean refreshDeps = LoomGradlePlugin.refreshDeps;
 
-		final File modStore = extension.getRemappedModCache();
+		final File modStore = extension.getFiles().getRemappedModCache();
 		final RemapData remapData = new RemapData(mappingsSuffix, modStore);
 
-		final LoomProjectData data = extension.getProjectData();
-
 		for (RemappedConfigurationEntry entry : Constants.MOD_COMPILE_ENTRIES) {
-			data.getLazyConfigurationProvider(entry.getRemappedConfiguration()).configure(remappedConfig -> {
+			extension.getLazyConfigurationProvider(entry.getRemappedConfiguration()).configure(remappedConfig -> {
 				Configuration sourceConfig = project.getConfigurations().getByName(entry.sourceConfiguration());
 				Configuration regularConfig = project.getConfigurations().getByName(entry.getTargetConfiguration(project.getConfigurations()));
 

src/main/java/net/fabricmc/loom/build/mixin/AnnotationProcessorInvoker.java

@@ -70,7 +70,7 @@ public abstract class AnnotationProcessorInvoker<T extends Task> {
 
 	private void passMixinArguments(T task) {
 		try {
-			LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+			LoomGradleExtension extension = LoomGradleExtension.get(project);
 			Map<String, String> args = new HashMap<>() {{
 					put(Constants.MixinArguments.IN_MAP_FILE_NAMED_INTERMEDIARY, extension.getMappingsProvider().tinyMappings.getCanonicalPath());
 					put(Constants.MixinArguments.OUT_MAP_FILE_NAMED_INTERMEDIARY, extension.getNextMixinMappings().getCanonicalPath());
@@ -87,7 +87,7 @@ public abstract class AnnotationProcessorInvoker<T extends Task> {
 
 	public void configureMixin() {
 		ConfigurationContainer configs = project.getConfigurations();
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 
 		if (!extension.ideSync()) {
 			for (Configuration processorConfig : annotationProcessorConfigurations) {

src/main/java/net/fabricmc/loom/build/mixin/KaptApInvoker.java

@@ -71,7 +71,7 @@ public class KaptApInvoker extends AnnotationProcessorInvoker<JavaCompile> {
 			// target location for the refmap and then move it to the correct place for each sourceset
 			task.doLast(t -> {
 				try {
-					LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+					LoomGradleExtension extension = LoomGradleExtension.get(project);
 					Path src = Paths.get(getRefmapDestination(task, extension));
 					Path dest = Paths.get(task.getDestinationDir().toString(), extension.getRefmapName());
 

src/main/java/net/fabricmc/loom/build/nesting/NestedDependencyProvider.java

@@ -157,8 +157,8 @@ public final class NestedDependencyProvider implements NestedJarProvider {
 
 			//A lib that doesnt have a mod.json, we turn it into a fake mod
 			if (!ZipUtil.containsEntry(file, "fabric.mod.json")) {
-				LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+				LoomGradleExtension extension = LoomGradleExtension.get(project);
-				File tempDir = new File(extension.getUserCache(), "temp/modprocessing");
+				File tempDir = new File(extension.getFiles().getUserCache(), "temp/modprocessing");
 
 				if (!tempDir.exists()) {
 					tempDir.mkdirs();

src/main/java/net/fabricmc/loom/configuration/CompileConfiguration.java

@@ -49,30 +49,31 @@ public final class CompileConfiguration {
 
 	public static void setupConfigurations(Project project) {
 		final ConfigurationContainer configurations = project.getConfigurations();
-		LoomProjectData data = project.getExtensions().getByType(LoomGradleExtension.class).getProjectData();
 
-		data.createLazyConfiguration(Constants.Configurations.MOD_COMPILE_CLASSPATH).configure(configuration -> configuration.setTransitive(true));
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
-		data.createLazyConfiguration(Constants.Configurations.MOD_COMPILE_CLASSPATH_MAPPED).configure(configuration -> configuration.setTransitive(false));
+
-		data.createLazyConfiguration(Constants.Configurations.MINECRAFT_NAMED).configure(configuration -> configuration.setTransitive(false)); // The launchers do not recurse dependencies
+		extension.createLazyConfiguration(Constants.Configurations.MOD_COMPILE_CLASSPATH).configure(configuration -> configuration.setTransitive(true));
-		data.createLazyConfiguration(Constants.Configurations.MINECRAFT_DEPENDENCIES).configure(configuration -> configuration.setTransitive(false));
+		extension.createLazyConfiguration(Constants.Configurations.MOD_COMPILE_CLASSPATH_MAPPED).configure(configuration -> configuration.setTransitive(false));
-		data.createLazyConfiguration(Constants.Configurations.LOADER_DEPENDENCIES).configure(configuration -> configuration.setTransitive(false));
+		extension.createLazyConfiguration(Constants.Configurations.MINECRAFT_NAMED).configure(configuration -> configuration.setTransitive(false)); // The launchers do not recurse dependencies
-		data.createLazyConfiguration(Constants.Configurations.MINECRAFT).configure(configuration -> configuration.setTransitive(false));
+		extension.createLazyConfiguration(Constants.Configurations.MINECRAFT_DEPENDENCIES).configure(configuration -> configuration.setTransitive(false));
-		data.createLazyConfiguration(Constants.Configurations.INCLUDE).configure(configuration -> configuration.setTransitive(false)); // Dont get transitive deps
+		extension.createLazyConfiguration(Constants.Configurations.LOADER_DEPENDENCIES).configure(configuration -> configuration.setTransitive(false));
-		data.createLazyConfiguration(Constants.Configurations.MAPPING_CONSTANTS);
+		extension.createLazyConfiguration(Constants.Configurations.MINECRAFT).configure(configuration -> configuration.setTransitive(false));
+		extension.createLazyConfiguration(Constants.Configurations.INCLUDE).configure(configuration -> configuration.setTransitive(false)); // Dont get transitive deps
+		extension.createLazyConfiguration(Constants.Configurations.MAPPING_CONSTANTS);
 
 		extendsFrom(JavaPlugin.COMPILE_ONLY_CONFIGURATION_NAME, Constants.Configurations.MAPPING_CONSTANTS, project);
 
-		data.createLazyConfiguration(Constants.Configurations.MAPPINGS);
+		extension.createLazyConfiguration(Constants.Configurations.MAPPINGS);
-		data.createLazyConfiguration(Constants.Configurations.MAPPINGS_FINAL);
+		extension.createLazyConfiguration(Constants.Configurations.MAPPINGS_FINAL);
-		data.createLazyConfiguration(Constants.Configurations.LOOM_DEVELOPMENT_DEPENDENCIES);
+		extension.createLazyConfiguration(Constants.Configurations.LOOM_DEVELOPMENT_DEPENDENCIES);
-		data.createLazyConfiguration(Constants.Configurations.UNPICK_CLASSPATH);
+		extension.createLazyConfiguration(Constants.Configurations.UNPICK_CLASSPATH);
 
 		for (RemappedConfigurationEntry entry : Constants.MOD_COMPILE_ENTRIES) {
-			data.createLazyConfiguration(entry.sourceConfiguration())
+			extension.createLazyConfiguration(entry.sourceConfiguration())
 					.configure(configuration -> configuration.setTransitive(true));
 
 			// Don't get transitive deps of already remapped mods
-			data.createLazyConfiguration(entry.getRemappedConfiguration())
+			extension.createLazyConfiguration(entry.getRemappedConfiguration())
 					.configure(configuration -> configuration.setTransitive(false));
 
 			extendsFrom(entry.getTargetConfiguration(configurations), entry.getRemappedConfiguration(), project);
@@ -111,7 +112,7 @@ public final class CompileConfiguration {
 		});
 
 		p.afterEvaluate(project -> {
-			LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+			LoomGradleExtension extension = LoomGradleExtension.get(project);
 
 			LoomDependencyManager dependencyManager = new LoomDependencyManager();
 			extension.setDependencyManager(dependencyManager);
@@ -129,7 +130,7 @@ public final class CompileConfiguration {
 			SetupIntelijRunConfigs.setup(project);
 
 			// Enables the default mod remapper
-			if (extension.remapMod) {
+			if (extension.isRemapMod()) {
 				RemapConfiguration.setupDefaultRemap(project);
 			} else {
 				Jar jarTask = (Jar) project.getTasks().getByName("jar");

src/main/java/net/fabricmc/loom/configuration/DependencyProvider.java

@@ -49,6 +49,7 @@ import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
+import net.fabricmc.loom.extension.LoomFiles;
 
 public abstract class DependencyProvider {
 	private LoomDependencyManager dependencyManager;
@@ -57,7 +58,7 @@ public abstract class DependencyProvider {
 
 	public DependencyProvider(Project project) {
 		this.project = project;
-		this.extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		this.extension = LoomGradleExtension.get(project);
 	}
 
 	public abstract void provide(DependencyInfo dependency, Consumer<Runnable> postPopulationScheduler) throws Exception;
@@ -88,6 +89,10 @@ public abstract class DependencyProvider {
 		return extension;
 	}
 
+	public LoomFiles getDirectories() {
+		return getExtension().getFiles();
+	}
+
 	public boolean isRefreshDeps() {
 		return LoomGradlePlugin.refreshDeps;
 	}

src/main/java/net/fabricmc/loom/configuration/FabricApiExtension.java

@@ -103,9 +103,9 @@ public class FabricApiExtension {
 	}
 
 	private File getApiMavenPom(String fabricApiVersion) {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 
-		File mavenPom = new File(extension.getUserCache(), "fabric-api/" + fabricApiVersion + ".pom");
+		File mavenPom = new File(extension.getFiles().getUserCache(), "fabric-api/" + fabricApiVersion + ".pom");
 
 		try {
 			URL url = new URL(String.format("https://maven.fabricmc.net/net/fabricmc/fabric-api/fabric-api/%1$s/fabric-api-%1$s.pom", fabricApiVersion));

src/main/java/net/fabricmc/loom/configuration/JarManifestConfiguration.java

@@ -43,7 +43,7 @@ public final record JarManifestConfiguration(Project project) {
 			return;
 		}
 
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 
 		Attributes attributes = manifest.getMainAttributes();
 		var tinyRemapperVersion = Optional.ofNullable(TinyRemapper.class.getPackage().getImplementationVersion());
@@ -79,7 +79,7 @@ public final record JarManifestConfiguration(Project project) {
 	}
 
 	private Optional<String> getLoaderVersion() {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 
 		if (extension.getInstallerData() == null) {
 			project.getLogger().warn("Could not determine fabric loader version for jar manifest");

src/main/java/net/fabricmc/loom/configuration/LoomDependencyManager.java

@@ -89,7 +89,7 @@ public class LoomDependencyManager {
 		MappingsProviderImpl mappingsProvider = null;
 
 		project.getLogger().info(":setting up loom dependencies");
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 		Map<String, ProviderList> providerListMap = new HashMap<>();
 		List<ProviderList> targetProviders = new ArrayList<>();
 
@@ -177,7 +177,7 @@ public class LoomDependencyManager {
 	}
 
 	private static void handleInstallerJson(JsonObject jsonObject, Project project) {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 
 		JsonObject libraries = jsonObject.get("libraries").getAsJsonObject();
 		Configuration loaderDepsConfig = project.getConfigurations().getByName(Constants.Configurations.LOADER_DEPENDENCIES);

src/main/java/net/fabricmc/loom/configuration/LoomProjectData.java

@@ -1,70 +0,0 @@
-/*
- * This file is part of fabric-loom, licensed under the MIT License (MIT).
- *
- * Copyright (c) 2016-2021 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.configuration;
-
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Objects;
-
-import org.gradle.api.NamedDomainObjectProvider;
-import org.gradle.api.Project;
-import org.gradle.api.artifacts.Configuration;
-import org.jetbrains.annotations.ApiStatus;
-
-@ApiStatus.Internal
-/**
- * This class is stored in the gradle extension, and should not be used outside of loom.
- * It contains data/info related to the current project
- */
-public final class LoomProjectData {
-	private final Project project;
-	private final Map<String, NamedDomainObjectProvider<Configuration>> lazyConfigurations = new HashMap<>();
-
-	public LoomProjectData(Project project) {
-		this.project = Objects.requireNonNull(project);
-	}
-
-	public NamedDomainObjectProvider<Configuration> createLazyConfiguration(String name) {
-		NamedDomainObjectProvider<Configuration> provider = project.getConfigurations().register(name);
-
-		if (lazyConfigurations.containsKey(name)) {
-			throw new IllegalStateException("Duplicate configuration name" + name);
-		}
-
-		lazyConfigurations.put(name, provider);
-
-		return provider;
-	}
-
-	public NamedDomainObjectProvider<Configuration> getLazyConfigurationProvider(String name) {
-		NamedDomainObjectProvider<Configuration> provider = lazyConfigurations.get(name);
-
-		if (provider == null) {
-			throw new NullPointerException("Could not find provider with name: " + name);
-		}
-
-		return provider;
-	}
-}

src/main/java/net/fabricmc/loom/configuration/RemapConfiguration.java

@@ -63,7 +63,7 @@ public class RemapConfiguration {
 
 	// isDefaultRemap is set to true for the standard remap task, some defaults are left out when this is false.
 	private static void setupRemap(Project project, boolean isDefaultRemap, String jarTaskName, String sourcesJarTaskName, String remapJarTaskName, String remapSourcesJarTaskName, String remapAllJarsTaskName, String remapAllSourcesTaskName) {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 		AbstractArchiveTask jarTask = (AbstractArchiveTask) project.getTasks().getByName(jarTaskName);
 		RemapJarTask remapJarTask = (RemapJarTask) project.getTasks().findByName(remapJarTaskName);
 

src/main/java/net/fabricmc/loom/configuration/accesswidener/AccessWidenerJarProcessor.java

@@ -71,15 +71,15 @@ public class AccessWidenerJarProcessor implements JarProcessor {
 
 	@Override
 	public void setup() {
-		LoomGradleExtension loomGradleExtension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension loomGradleExtension = LoomGradleExtension.get(project);
 
-		if (!loomGradleExtension.accessWidener.exists()) {
+		if (!loomGradleExtension.getAccessWidener().exists()) {
-			throw new RuntimeException("Could not find access widener file @ " + loomGradleExtension.accessWidener.getAbsolutePath());
+			throw new RuntimeException("Could not find access widener file @ " + loomGradleExtension.getAccessWidener().getAbsolutePath());
 		}
 
-		inputHash = Checksum.sha256(loomGradleExtension.accessWidener);
+		inputHash = Checksum.sha256(loomGradleExtension.getAccessWidener());
 
-		try (BufferedReader reader = new BufferedReader(new FileReader(loomGradleExtension.accessWidener))) {
+		try (BufferedReader reader = new BufferedReader(new FileReader(loomGradleExtension.getAccessWidener()))) {
 			accessWidenerReader.read(reader);
 		} catch (IOException e) {
 			throw new RuntimeException("Failed to read project access widener file");

src/main/java/net/fabricmc/loom/configuration/ide/RunConfig.java

@@ -27,12 +27,10 @@ package net.fabricmc.loom.configuration.ide;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.charset.StandardCharsets;
-import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
 import com.google.common.base.Strings;
-import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
@@ -44,7 +42,6 @@ import org.w3c.dom.Element;
 import org.w3c.dom.Node;
 
 import net.fabricmc.loom.LoomGradleExtension;
-import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.OperatingSystem;
 
 public class RunConfig {
@@ -110,42 +107,8 @@ public class RunConfig {
 		runConfig.vmArgs = "";
 		runConfig.programArgs = "";
 
-		if ("launchwrapper".equals(extension.getLoaderLaunchMethod())) {
+		runConfig.mainClass = "net.fabricmc.devlaunchinjector.Main";
-			runConfig.mainClass = "net.minecraft.launchwrapper.Launch"; // TODO What about custom tweakers for run configs?
+		runConfig.vmArgs = "-XX:+ShowCodeDetailsInExceptionMessages -Dfabric.dli.config=" + encodeEscaped(extension.getFiles().getDevLauncherConfig().getAbsolutePath()) + " -Dfabric.dli.env=" + environment.toLowerCase();
-			runConfig.programArgs += "--tweakClass " + ("client".equals(environment) ? Constants.LaunchWrapper.DEFAULT_FABRIC_CLIENT_TWEAKER : Constants.LaunchWrapper.DEFAULT_FABRIC_SERVER_TWEAKER);
-		} else {
-			runConfig.mainClass = "net.fabricmc.devlaunchinjector.Main";
-			runConfig.vmArgs = "-XX:+ShowCodeDetailsInExceptionMessages -Dfabric.dli.config=" + encodeEscaped(extension.getDevLauncherConfig().getAbsolutePath()) + " -Dfabric.dli.env=" + environment.toLowerCase();
-		}
-
-		if (extension.getLoaderLaunchMethod().equals("launchwrapper")) {
-			// if installer.json found...
-			JsonObject installerJson = extension.getInstallerData().installerJson();
-
-			if (installerJson != null) {
-				List<String> sideKeys = ImmutableList.of(environment, "common");
-
-				// copy launchwrapper tweakers
-				if (installerJson.has("launchwrapper")) {
-					JsonObject launchwrapperJson = installerJson.getAsJsonObject("launchwrapper");
-
-					if (launchwrapperJson.has("tweakers")) {
-						JsonObject tweakersJson = launchwrapperJson.getAsJsonObject("tweakers");
-						StringBuilder builder = new StringBuilder();
-
-						for (String s : sideKeys) {
-							if (tweakersJson.has(s)) {
-								for (JsonElement element : tweakersJson.getAsJsonArray(s)) {
-									builder.append(" --tweakClass ").append(element.getAsString());
-								}
-							}
-						}
-
-						runConfig.programArgs += builder.toString();
-					}
-				}
-			}
-		}
 	}
 
 	// Turns camelCase/PascalCase into Capital Case
@@ -159,7 +122,7 @@ public class RunConfig {
 	}
 
 	public static RunConfig runConfig(Project project, RunConfigSettings settings) {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 		String name = settings.getName();
 
 		String configName = settings.getConfigName();
@@ -264,11 +227,6 @@ public class RunConfig {
 			return mainClassName;
 		}
 
-		// Fallback to default class names, happens when in a loader dev env
-		if ("launchwrapper".equals(extension.getLoaderLaunchMethod())) {
-			return "net.minecraft.launchwrapper.Launch";
-		}
-
 		return defaultMainClass;
 	}
 

src/main/java/net/fabricmc/loom/configuration/ide/RunConfigSettings.java

@@ -100,7 +100,7 @@ public final class RunConfigSettings implements Named {
 	public RunConfigSettings(Project project, String baseName) {
 		this.baseName = baseName;
 		this.project = project;
-		this.extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		this.extension = LoomGradleExtension.get(project);
 		this.ideConfigGenerated = extension.isRootProject();
 
 		source("main");

src/main/java/net/fabricmc/loom/configuration/ide/SetupIntelijRunConfigs.java

@@ -37,7 +37,7 @@ import net.fabricmc.loom.configuration.providers.minecraft.assets.MinecraftAsset
 
 public class SetupIntelijRunConfigs {
 	public static void setup(Project project) {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 
 		File projectDir = project.getRootProject().file(".idea");
 
@@ -54,7 +54,7 @@ public class SetupIntelijRunConfigs {
 
 	private static void generate(Project project) throws IOException {
 		Project rootProject = project.getRootProject();
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 
 		if (extension.ideSync()) {
 			//Ensures the assets are downloaded when idea is syncing a project

src/main/java/net/fabricmc/loom/configuration/mods/ModProcessor.java

@@ -127,7 +127,7 @@ public class ModProcessor {
 	}
 
 	private static void remapJars(Project project, List<ModDependencyInfo> processList) throws IOException {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 		String fromM = "intermediary";
 		String toM = "named";
 
@@ -210,28 +210,15 @@ public class ModProcessor {
 
 	public static JsonObject readInstallerJson(File file, Project project) {
 		try {
-			LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+			LoomGradleExtension extension = LoomGradleExtension.get(project);
-			String launchMethod = extension.getLoaderLaunchMethod();
 
 			String jsonStr;
 
 			try (JarFile jarFile = new JarFile(file)) {
-				ZipEntry entry = null;
+				ZipEntry entry = jarFile.getEntry("fabric-installer.json");
-
-				if (!launchMethod.isEmpty()) {
-					entry = jarFile.getEntry("fabric-installer." + launchMethod + ".json");
-
-					if (entry == null) {
-						project.getLogger().warn("Could not find loader launch method '" + launchMethod + "', falling back");
-					}
-				}
 
 				if (entry == null) {
-					entry = jarFile.getEntry("fabric-installer.json");
+					return null;
-
-					if (entry == null) {
-						return null;
-					}
 				}
 
 				try (InputStream inputstream = jarFile.getInputStream(entry)) {

src/main/java/net/fabricmc/loom/configuration/processors/MinecraftProcessedProvider.java

@@ -70,7 +70,7 @@ public class MinecraftProcessedProvider extends MinecraftMappedProvider {
 	}
 
 	private void invalidateJars() {
-		File dir = getJarDirectory(getExtension().getUserCache(), projectMappedClassifier);
+		File dir = getJarDirectory(getExtension().getFiles().getUserCache(), projectMappedClassifier);
 
 		if (dir.exists()) {
 			getProject().getLogger().warn("Invalidating project jars");
@@ -87,7 +87,7 @@ public class MinecraftProcessedProvider extends MinecraftMappedProvider {
 	public void initFiles(MinecraftProviderImpl minecraftProvider, MappingsProviderImpl mappingsProvider) {
 		super.initFiles(minecraftProvider, mappingsProvider);
 
-		projectMappedJar = new File(getJarDirectory(getExtension().getRootProjectPersistentCache(), projectMappedClassifier), "minecraft-" + getJarVersionString(projectMappedClassifier) + ".jar");
+		projectMappedJar = new File(getJarDirectory(getExtension().getFiles().getRootProjectPersistentCache(), projectMappedClassifier), "minecraft-" + getJarVersionString(projectMappedClassifier) + ".jar");
 	}
 
 	@Override

src/main/java/net/fabricmc/loom/configuration/providers/LaunchProvider.java

@@ -58,13 +58,13 @@ public class LaunchProvider extends DependencyProvider {
 				.property("fabric.remapClasspathFile", getRemapClasspathFile().getAbsolutePath())
 				.property("log4j.configurationFile", getAllLog4JConfigFiles())
 
-				.property("client", "java.library.path", getExtension().getNativesDirectory().getAbsolutePath())
+				.property("client", "java.library.path", getDirectories().getNativesDirectory(getExtension().getMinecraftProvider()).getAbsolutePath())
-				.property("client", "org.lwjgl.librarypath", getExtension().getNativesDirectory().getAbsolutePath())
+				.property("client", "org.lwjgl.librarypath", getDirectories().getNativesDirectory(getExtension().getMinecraftProvider()).getAbsolutePath())
 
 				.argument("client", "--assetIndex")
 				.argument("client", getExtension().getMinecraftProvider().getVersionInfo().assetIndex().fabricId(getExtension().getMinecraftProvider().minecraftVersion()))
 				.argument("client", "--assetsDir")
-				.argument("client", new File(getExtension().getUserCache(), "assets").getAbsolutePath());
+				.argument("client", new File(getDirectories().getUserCache(), "assets").getAbsolutePath());
 
 		//Enable ansi by default for idea and vscode
 		if (new File(getProject().getRootDir(), ".vscode").exists()
@@ -74,7 +74,7 @@ public class LaunchProvider extends DependencyProvider {
 		}
 
 		writeLog4jConfig();
-		FileUtils.writeStringToFile(getExtension().getDevLauncherConfig(), launchConfig.asString(), StandardCharsets.UTF_8);
+		FileUtils.writeStringToFile(getDirectories().getDevLauncherConfig(), launchConfig.asString(), StandardCharsets.UTF_8);
 
 		addDependency(Constants.Dependencies.DEV_LAUNCH_INJECTOR + Constants.Dependencies.Versions.DEV_LAUNCH_INJECTOR, Constants.Configurations.LOOM_DEVELOPMENT_DEPENDENCIES);
 		addDependency(Constants.Dependencies.TERMINAL_CONSOLE_APPENDER + Constants.Dependencies.Versions.TERMINAL_CONSOLE_APPENDER, Constants.Configurations.LOOM_DEVELOPMENT_DEPENDENCIES);
@@ -84,7 +84,7 @@ public class LaunchProvider extends DependencyProvider {
 	}
 
 	private File getLog4jConfigFile() {
-		return getExtension().getDefaultLog4jConfigFile();
+		return getDirectories().getDefaultLog4jConfigFile();
 	}
 
 	private String getAllLog4JConfigFiles() {
@@ -94,7 +94,7 @@ public class LaunchProvider extends DependencyProvider {
 	}
 
 	private File getRemapClasspathFile() {
-		return new File(getExtension().getDevLauncherConfig().getParentFile(), "remapClasspath.txt");
+		return new File(getDirectories().getDevLauncherConfig().getParentFile(), "remapClasspath.txt");
 	}
 
 	private void writeLog4jConfig() {

src/main/java/net/fabricmc/loom/configuration/providers/MinecraftProviderImpl.java

@@ -111,11 +111,11 @@ public class MinecraftProviderImpl extends DependencyProvider implements Minecra
 	}
 
 	private void initFiles() {
-		minecraftJson = new File(getExtension().getUserCache(), "minecraft-" + minecraftVersion + "-info.json");
+		minecraftJson = new File(getDirectories().getUserCache(), "minecraft-" + minecraftVersion + "-info.json");
-		minecraftClientJar = new File(getExtension().getUserCache(), "minecraft-" + minecraftVersion + "-client.jar");
+		minecraftClientJar = new File(getDirectories().getUserCache(), "minecraft-" + minecraftVersion + "-client.jar");
-		minecraftServerJar = new File(getExtension().getUserCache(), "minecraft-" + minecraftVersion + "-server.jar");
+		minecraftServerJar = new File(getDirectories().getUserCache(), "minecraft-" + minecraftVersion + "-server.jar");
-		minecraftMergedJar = new File(getExtension().getUserCache(), "minecraft-" + minecraftVersion + "-merged.jar");
+		minecraftMergedJar = new File(getDirectories().getUserCache(), "minecraft-" + minecraftVersion + "-merged.jar");
-		versionManifestJson = new File(getExtension().getUserCache(), "version_manifest.json");
+		versionManifestJson = new File(getDirectories().getUserCache(), "version_manifest.json");
 	}
 
 	private void downloadMcJson(boolean offline) throws IOException {
@@ -143,10 +143,10 @@ public class MinecraftProviderImpl extends DependencyProvider implements Minecra
 
 		Optional<ManifestVersion.Versions> optionalVersion = Optional.empty();
 
-		if (getExtension().customManifest != null) {
+		if (getExtension().getCustomManifest() != null) {
 			ManifestVersion.Versions customVersion = new ManifestVersion.Versions();
 			customVersion.id = minecraftVersion;
-			customVersion.url = getExtension().customManifest;
+			customVersion.url = getExtension().getCustomManifest();
 			optionalVersion = Optional.of(customVersion);
 			getProject().getLogger().lifecycle("Using custom minecraft manifest");
 		}
@@ -183,7 +183,7 @@ public class MinecraftProviderImpl extends DependencyProvider implements Minecra
 	}
 
 	private boolean hasRecentValidManifest() throws IOException {
-		if (getExtension().customManifest != null) {
+		if (getExtension().getCustomManifest() != null) {
 			return false;
 		}
 

src/main/java/net/fabricmc/loom/configuration/providers/mappings/GradleMappingContext.java

@@ -40,7 +40,7 @@ public class GradleMappingContext implements MappingContext {
 
 	public GradleMappingContext(Project project, String workingDirName) {
 		this.project = project;
-		this.extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		this.extension = LoomGradleExtension.get(project);
 		this.workingDirName = workingDirName;
 	}
 

src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProviderImpl.java

@@ -86,7 +86,7 @@ public class MappingsProviderImpl extends DependencyProvider implements Mappings
 
 	public MappingsProviderImpl(Project project) {
 		super(project);
-		mappingsDir = getExtension().getUserCache().toPath().resolve("mappings");
+		mappingsDir = getDirectories().getUserCache().toPath().resolve("mappings");
 		mappingsStepsDir = mappingsDir.resolve("steps");
 	}
 
@@ -148,7 +148,7 @@ public class MappingsProviderImpl extends DependencyProvider implements Mappings
 
 		tinyMappings = mappingsDir.resolve(StringUtils.removeSuffix(mappingsJar.getName(), ".jar") + ".tiny").toFile();
 		unpickDefinitionsFile = mappingsDir.resolve(StringUtils.removeSuffix(mappingsJar.getName(), ".jar") + ".unpick").toFile();
-		tinyMappingsJar = new File(getExtension().getUserCache(), mappingsJar.getName().replace(".jar", "-" + jarClassifier + ".jar"));
+		tinyMappingsJar = new File(getDirectories().getUserCache(), mappingsJar.getName().replace(".jar", "-" + jarClassifier + ".jar"));
 
 		if (!tinyMappings.exists() || isRefreshDeps()) {
 			storeMappings(getProject(), minecraftProvider, mappingsJar.toPath());
@@ -177,7 +177,7 @@ public class MappingsProviderImpl extends DependencyProvider implements Mappings
 
 		LoomGradleExtension extension = getExtension();
 
-		if (extension.accessWidener != null) {
+		if (extension.getAccessWidener() != null) {
 			extension.addJarProcessor(new AccessWidenerJarProcessor(getProject()));
 		}
 
@@ -386,7 +386,7 @@ public class MappingsProviderImpl extends DependencyProvider implements Mappings
 
 				// Download and extract intermediary
 				String encodedMinecraftVersion = UrlEscapers.urlFragmentEscaper().escape(minecraftVersion);
-				String intermediaryArtifactUrl = getExtension().getIntermediaryUrl().apply(encodedMinecraftVersion);
+				String intermediaryArtifactUrl = getExtension().getIntermediaryUrl(encodedMinecraftVersion);
 				Path intermediaryJar = mappingsDir.resolve("v2-intermediary-" + minecraftVersion + ".jar");
 				DownloadUtil.downloadIfChanged(new URL(intermediaryArtifactUrl), intermediaryJar.toFile(), getProject().getLogger());
 

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MinecraftLibraryProvider.java

@@ -48,7 +48,7 @@ public class MinecraftLibraryProvider {
 	}
 
 	private void initFiles(Project project, MinecraftProviderImpl minecraftProvider) {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
-		MINECRAFT_LIBS = new File(extension.getUserCache(), "libraries");
+		MINECRAFT_LIBS = new File(extension.getFiles().getUserCache(), "libraries");
 	}
 }

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MinecraftMappedProvider.java

@@ -150,8 +150,8 @@ public class MinecraftMappedProvider extends DependencyProvider {
 
 	public void initFiles(MinecraftProviderImpl minecraftProvider, MappingsProviderImpl mappingsProvider) {
 		this.minecraftProvider = minecraftProvider;
-		minecraftIntermediaryJar = new File(getExtension().getUserCache(), "minecraft-" + getJarVersionString("intermediary") + ".jar");
+		minecraftIntermediaryJar = new File(getDirectories().getUserCache(), "minecraft-" + getJarVersionString("intermediary") + ".jar");
-		minecraftMappedJar = new File(getJarDirectory(getExtension().getUserCache(), "mapped"), "minecraft-" + getJarVersionString("mapped") + ".jar");
+		minecraftMappedJar = new File(getJarDirectory(getDirectories().getUserCache(), "mapped"), "minecraft-" + getJarVersionString("mapped") + ".jar");
 	}
 
 	protected File getJarDirectory(File parentDirectory, String type) {
@@ -171,7 +171,7 @@ public class MinecraftMappedProvider extends DependencyProvider {
 	}
 
 	public File getUnpickedJar() {
-		return new File(getJarDirectory(getExtension().getUserCache(), "mapped"), "minecraft-" + getJarVersionString("unpicked") + ".jar");
+		return new File(getJarDirectory(getDirectories().getUserCache(), "mapped"), "minecraft-" + getJarVersionString("unpicked") + ".jar");
 	}
 
 	@Override

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MinecraftNativesProvider.java

@@ -49,10 +49,10 @@ public class MinecraftNativesProvider {
 
 	public MinecraftNativesProvider(Project project) {
 		this.project = project;
-		extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		extension = LoomGradleExtension.get(project);
 
-		nativesDir = extension.getNativesDirectory();
+		nativesDir = extension.getFiles().getNativesDirectory(extension.getMinecraftProvider());
-		jarStore = extension.getNativesJarStore();
+		jarStore = extension.getFiles().getNativesJarStore();
 	}
 
 	public static void provide(Project project) throws IOException {
@@ -60,7 +60,7 @@ public class MinecraftNativesProvider {
 	}
 
 	private void provide() throws IOException {
-		if (extension.hasCustomNatives()) {
+		if (extension.getFiles().hasCustomNatives()) {
 			if (!nativesDir.exists()) {
 				throw new RuntimeException("Could no find custom natives directory at " + nativesDir.getAbsolutePath());
 			}

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/assets/MinecraftAssetsProvider.java

@@ -49,14 +49,14 @@ import net.fabricmc.loom.util.gradle.ProgressLogger;
 
 public class MinecraftAssetsProvider {
 	public static void provide(MinecraftProviderImpl minecraftProvider, Project project) throws IOException {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 		boolean offline = project.getGradle().getStartParameter().isOffline();
 
 		MinecraftVersionMeta versionInfo = minecraftProvider.getVersionInfo();
 		MinecraftVersionMeta.AssetIndex assetIndex = versionInfo.assetIndex();
 
 		// get existing cache files
-		File assets = new File(extension.getUserCache(), "assets");
+		File assets = new File(extension.getFiles().getUserCache(), "assets");
 
 		if (!assets.exists()) {
 			assets.mkdirs();

src/main/java/net/fabricmc/loom/decompilers/DecompilerConfiguration.java

@@ -35,7 +35,7 @@ public final class DecompilerConfiguration {
 	}
 
 	public static void setup(Project project) {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 		extension.addDecompiler(new FabricFernFlowerDecompiler(project));
 		extension.addDecompiler(new FabricCFRDecompiler(project));
 	}

src/main/java/net/fabricmc/loom/extension/LoomFiles.java

@@ -0,0 +1,43 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2021 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.extension;
+
+import java.io.File;
+
+import net.fabricmc.loom.configuration.providers.MinecraftProvider;
+
+public interface LoomFiles {
+	File getUserCache();
+	File getRootProjectPersistentCache();
+	File getProjectPersistentCache();
+	File getProjectBuildCache();
+	File getRemappedModCache();
+	File getNativesJarStore();
+	boolean hasCustomNatives();
+	File getNativesDirectory(MinecraftProvider minecraftProvider);
+	File getDefaultLog4jConfigFile();
+	File getDevLauncherConfig();
+	File getUnpickLoggingConfigFile();
+}

src/main/java/net/fabricmc/loom/extension/LoomFilesImpl.java

@@ -0,0 +1,128 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2021 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.extension;
+
+import java.io.File;
+
+import org.gradle.api.Project;
+
+import net.fabricmc.loom.configuration.providers.MinecraftProvider;
+
+public final class LoomFilesImpl implements LoomFiles {
+	private final Project project;
+
+	private final File userCache;
+	private final File rootProjectPersistentCache;
+	private final File projectPersistentCache;
+	private final File projectBuildCache;
+	private final File remappedModCache;
+	private final File nativesJarStore;
+
+	public LoomFilesImpl(Project project) {
+		this.project = project;
+
+		this.userCache = createFile(project.getGradle().getGradleUserHomeDir(), "caches" + File.separator + "fabric-loom");
+		this.rootProjectPersistentCache = createFile(project.getRootProject().file(".gradle"), "loom-cache");
+		this.projectPersistentCache = createFile(project.file(".gradle"), "loom-cache");
+		this.projectBuildCache = createFile(project.getBuildDir(), "loom-cache");
+		this.remappedModCache = createFile(getRootProjectPersistentCache(), "remapped_mods");
+		this.nativesJarStore = createFile(getUserCache(), "natives/jars");
+	}
+
+	private File createFile(File parent, String child) {
+		File file = new File(parent, child);
+
+		if (!file.exists()) {
+			file.mkdirs();
+		}
+
+		return file;
+	}
+
+	@Override
+	public File getUserCache() {
+		return userCache;
+	}
+
+	@Override
+	public File getRootProjectPersistentCache() {
+		return rootProjectPersistentCache;
+	}
+
+	@Override
+	public File getProjectPersistentCache() {
+		return projectPersistentCache;
+	}
+
+	@Override
+	public File getProjectBuildCache() {
+		return projectBuildCache;
+	}
+
+	@Override
+	public File getRemappedModCache() {
+		return remappedModCache;
+	}
+
+	@Override
+	public File getNativesJarStore() {
+		return nativesJarStore;
+	}
+
+	@Override
+	public boolean hasCustomNatives() {
+		return project.getProperties().get("fabric.loom.natives.dir") != null;
+	}
+
+	@Override
+	public File getNativesDirectory(MinecraftProvider minecraftProvider) {
+		if (hasCustomNatives()) {
+			return new File((String) project.property("fabric.loom.natives.dir"));
+		}
+
+		File natives = new File(getUserCache(), "natives/" + minecraftProvider.minecraftVersion());
+
+		if (!natives.exists()) {
+			natives.mkdirs();
+		}
+
+		return natives;
+	}
+
+	@Override
+	public File getDefaultLog4jConfigFile() {
+		return new File(getProjectPersistentCache(), "log4j.xml");
+	}
+
+	@Override
+	public File getDevLauncherConfig() {
+		return new File(getProjectPersistentCache(), "launch.cfg");
+	}
+
+	@Override
+	public File getUnpickLoggingConfigFile() {
+		return new File(getProjectPersistentCache(), "unpick-logging.properties");
+	}
+}

src/main/java/net/fabricmc/loom/extension/LoomGradleExtensionApiImpl.java

@@ -0,0 +1,182 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2021 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.extension;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+import org.gradle.api.Action;
+import org.gradle.api.NamedDomainObjectContainer;
+import org.gradle.api.Project;
+import org.gradle.api.artifacts.Dependency;
+import org.gradle.api.file.ConfigurableFileCollection;
+import org.gradle.api.plugins.BasePluginConvention;
+
+import net.fabricmc.loom.api.decompilers.LoomDecompiler;
+import net.fabricmc.loom.api.LoomGradleExtensionAPI;
+import net.fabricmc.loom.configuration.ide.RunConfigSettings;
+import net.fabricmc.loom.configuration.processors.JarProcessor;
+import net.fabricmc.loom.configuration.providers.mappings.GradleMappingContext;
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingSpec;
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingSpecBuilder;
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsDependency;
+
+/**
+ * This class implements the public extension api.
+ */
+public abstract class LoomGradleExtensionApiImpl implements LoomGradleExtensionAPI {
+	protected final List<LoomDecompiler> decompilers = new ArrayList<>();
+	protected final List<JarProcessor> jarProcessors = new ArrayList<>();
+	protected final ConfigurableFileCollection log4jConfigs;
+
+	protected File accessWidener = null;
+	protected boolean shareCaches = false;
+	protected String refmapName = null;
+	protected boolean remapMod = true;
+
+	private NamedDomainObjectContainer<RunConfigSettings> runConfigs;
+
+	protected LoomGradleExtensionApiImpl(Project project, LoomFiles directories) {
+		this.runConfigs = project.container(RunConfigSettings.class,
+				baseName -> new RunConfigSettings(project, baseName));
+		this.log4jConfigs = project.files(directories.getDefaultLog4jConfigFile());
+	}
+
+	@Override
+	public File getAccessWidener() {
+		return accessWidener;
+	}
+
+	@Override
+	public void setAccessWidener(Object file) {
+		Objects.requireNonNull(file, "Access widener file cannot be null");
+		this.accessWidener = getProject().file(file);
+	}
+
+	@Override
+	public void setShareCaches(boolean shareCaches) {
+		this.shareCaches = shareCaches;
+	}
+
+	@Override
+	public boolean isShareCaches() {
+		return shareCaches;
+	}
+
+	@Override
+	public List<LoomDecompiler> getDecompilers() {
+		return decompilers;
+	}
+
+	@Override
+	public void addDecompiler(LoomDecompiler decompiler) {
+		Objects.requireNonNull(decompiler, "Decompiler cannot be null");
+		decompilers.add(decompiler);
+	}
+
+	@Override
+	public List<JarProcessor> getJarProcessors() {
+		return jarProcessors;
+	}
+
+	@Override
+	public void addJarProcessor(JarProcessor processor) {
+		Objects.requireNonNull(processor, "Jar processor cannot be null");
+		jarProcessors.add(processor);
+	}
+
+	@Override
+	public Dependency layered(Action<LayeredMappingSpecBuilder> action) {
+		LayeredMappingSpecBuilder builder = new LayeredMappingSpecBuilder();
+		action.execute(builder);
+		LayeredMappingSpec builtSpec = builder.build();
+		return new LayeredMappingsDependency(new GradleMappingContext(getProject(), "layers_" + builtSpec.getVersion().replace("+", "_").replace(".", "_")), builtSpec, builtSpec.getVersion());
+	}
+
+	@Override
+	public String getRefmapName() {
+		if (refmapName == null || refmapName.isEmpty()) {
+			String defaultRefmapName = getProject().getConvention().getPlugin(BasePluginConvention.class).getArchivesBaseName() + "-refmap.json";
+			getProject().getLogger().info("Could not find refmap definition, will be using default name: " + defaultRefmapName);
+			refmapName = defaultRefmapName;
+		}
+
+		return refmapName;
+	}
+
+	@Override
+	public void setRefmapName(String refmapName) {
+		this.refmapName = refmapName;
+	}
+
+	@Override
+	public void setRemapMod(boolean remapMod) {
+		this.remapMod = remapMod;
+	}
+
+	@Override
+	public void runs(Action<NamedDomainObjectContainer<RunConfigSettings>> action) {
+		action.execute(runConfigs);
+	}
+
+	@Override
+	public NamedDomainObjectContainer<RunConfigSettings> getRunConfigs() {
+		return runConfigs;
+	}
+
+	@Override
+	public ConfigurableFileCollection getLog4jConfigs() {
+		return log4jConfigs;
+	}
+
+	@Override
+	public boolean isRemapMod() {
+		return remapMod;
+	}
+
+	protected abstract Project getProject();
+
+	protected abstract LoomFiles getFiles();
+
+	// This is here to ensure that LoomGradleExtensionApiImpl compiles without any unimplemented methods
+	private final class EnsureCompile extends LoomGradleExtensionApiImpl {
+		private EnsureCompile() {
+			super(null, null);
+			throw new RuntimeException();
+		}
+
+		@Override
+		protected Project getProject() {
+			throw new RuntimeException("Yeah... something is really wrong");
+		}
+
+		@Override
+		protected LoomFiles getFiles() {
+			throw new RuntimeException("Yeah... something is really wrong");
+		}
+	}
+}

src/main/java/net/fabricmc/loom/extension/LoomGradleExtensionImpl.java

@@ -0,0 +1,163 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2021 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.extension;
+
+import java.io.File;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.function.Supplier;
+
+import org.cadixdev.lorenz.MappingSet;
+import org.cadixdev.mercury.Mercury;
+import org.gradle.api.NamedDomainObjectProvider;
+import org.gradle.api.Project;
+import org.gradle.api.artifacts.Configuration;
+import org.gradle.api.file.ConfigurableFileCollection;
+
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.configuration.InstallerData;
+import net.fabricmc.loom.configuration.LoomDependencyManager;
+import net.fabricmc.loom.configuration.processors.JarProcessorManager;
+
+public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implements LoomGradleExtension {
+	private final Project project;
+	private final LoomFiles loomFiles;
+	private final ConfigurableFileCollection unmappedMods;
+
+	private final Set<File> mixinMappings = Collections.synchronizedSet(new HashSet<>());
+	private final MappingSet[] srcMappingCache = new MappingSet[2];
+	private final Mercury[] srcMercuryCache = new Mercury[2];
+	private final Map<String, NamedDomainObjectProvider<Configuration>> lazyConfigurations = new HashMap<>();
+
+	private LoomDependencyManager dependencyManager;
+	private JarProcessorManager jarProcessorManager;
+	private InstallerData installerData;
+
+	public LoomGradleExtensionImpl(Project project, LoomFiles files) {
+		super(project, files);
+		this.project = project;
+		this.loomFiles = files;
+		this.unmappedMods = project.files();
+	}
+
+	@Override
+	protected Project getProject() {
+		return project;
+	}
+
+	@Override
+	public LoomFiles getFiles() {
+		return loomFiles;
+	}
+
+	@Override
+	public synchronized File getNextMixinMappings() {
+		File mixinMapping = new File(getFiles().getProjectBuildCache(), "mixin-map-" + getMinecraftProvider().minecraftVersion() + "-" + getMappingsProvider().mappingsVersion + "." + mixinMappings.size() + ".tiny");
+		mixinMappings.add(mixinMapping);
+		return mixinMapping;
+	}
+
+	@Override
+	public Set<File> getAllMixinMappings() {
+		return mixinMappings;
+	}
+
+	@Override
+	public void setDependencyManager(LoomDependencyManager dependencyManager) {
+		this.dependencyManager = dependencyManager;
+	}
+
+	@Override
+	public LoomDependencyManager getDependencyManager() {
+		return Objects.requireNonNull(dependencyManager, "Cannot get LoomDependencyManager before it has been setup");
+	}
+
+	@Override
+	public void setJarProcessorManager(JarProcessorManager jarProcessorManager) {
+		this.jarProcessorManager = jarProcessorManager;
+	}
+
+	@Override
+	public JarProcessorManager getJarProcessorManager() {
+		return Objects.requireNonNull(jarProcessorManager, "Cannot get JarProcessorManager before it has been setup");
+	}
+
+	@Override
+	public MappingSet getOrCreateSrcMappingCache(int id, Supplier<MappingSet> factory) {
+		return srcMappingCache[id] != null ? srcMappingCache[id] : (srcMappingCache[id] = factory.get());
+	}
+
+	@Override
+	public Mercury getOrCreateSrcMercuryCache(int id, Supplier<Mercury> factory) {
+		return srcMercuryCache[id] != null ? srcMercuryCache[id] : (srcMercuryCache[id] = factory.get());
+	}
+
+	@Override
+	public ConfigurableFileCollection getUnmappedModCollection() {
+		return unmappedMods;
+	}
+
+	public void setInstallerData(InstallerData object) {
+		this.installerData = object;
+	}
+
+	@Override
+	public InstallerData getInstallerData() {
+		return installerData;
+	}
+
+	@Override
+	public boolean isRootProject() {
+		return project.getRootProject() == project;
+	}
+
+	@Override
+	public NamedDomainObjectProvider<Configuration> createLazyConfiguration(String name) {
+		NamedDomainObjectProvider<Configuration> provider = project.getConfigurations().register(name);
+
+		if (lazyConfigurations.containsKey(name)) {
+			throw new IllegalStateException("Duplicate configuration name" + name);
+		}
+
+		lazyConfigurations.put(name, provider);
+
+		return provider;
+	}
+
+	@Override
+	public NamedDomainObjectProvider<Configuration> getLazyConfigurationProvider(String name) {
+		NamedDomainObjectProvider<Configuration> provider = lazyConfigurations.get(name);
+
+		if (provider == null) {
+			throw new NullPointerException("Could not find provider with name: " + name);
+		}
+
+		return provider;
+	}
+}

src/main/java/net/fabricmc/loom/task/AbstractLoomTask.java

@@ -36,6 +36,6 @@ public abstract class AbstractLoomTask extends DefaultTask {
 
 	@Internal
 	protected LoomGradleExtension getExtension() {
-		return getProject().getExtensions().getByType(LoomGradleExtension.class);
+		return LoomGradleExtension.get(getProject());
 	}
 }

src/main/java/net/fabricmc/loom/task/GenerateSourcesTask.java

@@ -101,7 +101,7 @@ public class GenerateSourcesTask extends AbstractLoomTask {
 	}
 
 	private File getMappedJarFileWithSuffix(String suffix) {
-		LoomGradleExtension extension = getProject().getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(getProject());
 		MappingsProviderImpl mappingsProvider = extension.getMappingsProvider();
 		File mappedJar = mappingsProvider.mappedProvider.getMappedJar();
 		String path = mappedJar.getAbsolutePath();

src/main/java/net/fabricmc/loom/task/LoomTasks.java

@@ -87,7 +87,7 @@ public final class LoomTasks {
 	}
 
 	private static void registerRunTasks(TaskContainer tasks, Project project) {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 
 		Preconditions.checkArgument(extension.getRunConfigs().size() == 0, "Run configurations must not be registered before loom");
 
@@ -110,7 +110,7 @@ public final class LoomTasks {
 	}
 
 	private static void registerDecompileTasks(TaskContainer tasks, Project project) {
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 
 		project.afterEvaluate(p -> {
 			MappingsProviderImpl mappingsProvider = extension.getMappingsProvider();

src/main/java/net/fabricmc/loom/task/MigrateMappingsTask.java

@@ -120,7 +120,7 @@ public class MigrateMappingsTask extends AbstractLoomTask {
 
 		try {
 			if (mappings.startsWith("net.minecraft:mappings:") || mappings.startsWith("net.mojang.minecraft:mappings:")) {
-				if (!mappings.endsWith(":" + project.getExtensions().getByType(LoomGradleExtension.class).getMinecraftProvider().minecraftVersion())) {
+				if (!mappings.endsWith(":" + LoomGradleExtension.get(project).getMinecraftProvider().minecraftVersion())) {
 					throw new UnsupportedOperationException("Migrating Mojang mappings is currently only supported for the specified minecraft version");
 				}
 

src/main/java/net/fabricmc/loom/task/RemapJarTask.java

@@ -105,7 +105,7 @@ public class RemapJarTask extends Jar {
 			jarRemapper = new JarRemapper();
 		}
 
-		scheduleRemap(singleRemap || getProject().getExtensions().getByType(LoomGradleExtension.class).isRootProject());
+		scheduleRemap(singleRemap || LoomGradleExtension.get(getProject()).isRootProject());
 
 		if (singleRemap) {
 			jarRemapper.remap();
@@ -114,7 +114,7 @@ public class RemapJarTask extends Jar {
 
 	public void scheduleRemap(boolean isMainRemapTask) throws Throwable {
 		Project project = getProject();
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(getProject());
 		Path input = this.getInput().getAsFile().get().toPath();
 		Path output = this.getArchivePath().toPath();
 
@@ -147,7 +147,7 @@ public class RemapJarTask extends Jar {
 
 		jarRemapper.scheduleRemap(input, output)
 				.supplyAccessWidener((remapData, remapper) -> {
-					if (getRemapAccessWidener().getOrElse(false) && extension.accessWidener != null) {
+					if (getRemapAccessWidener().getOrElse(false) && extension.getAccessWidener() != null) {
 						AccessWidenerJarProcessor accessWidenerJarProcessor = extension.getJarProcessorManager().getByType(AccessWidenerJarProcessor.class);
 						byte[] data;
 

src/main/java/net/fabricmc/loom/task/RunClientTask.java

@@ -31,7 +31,7 @@ import net.fabricmc.loom.configuration.ide.RunConfig;
 public class RunClientTask extends AbstractRunTask {
 	public RunClientTask() {
 		super(project -> {
-			LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+			LoomGradleExtension extension = LoomGradleExtension.get(project);
 			return RunConfig.runConfig(project, extension.getRunConfigs().getByName("client"));
 		});
 	}

src/main/java/net/fabricmc/loom/task/RunServerTask.java

@@ -31,7 +31,7 @@ import net.fabricmc.loom.configuration.ide.RunConfig;
 public class RunServerTask extends AbstractRunTask {
 	public RunServerTask() {
 		super(project -> {
-			LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+			LoomGradleExtension extension = LoomGradleExtension.get(project);
 			return RunConfig.runConfig(project, extension.getRunConfigs().getByName("client"));
 		});
 	}

src/main/java/net/fabricmc/loom/task/UnpickJarTask.java

@@ -36,6 +36,7 @@ import org.gradle.api.tasks.OutputFile;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.providers.LaunchProvider;
+import net.fabricmc.loom.extension.LoomFiles;
 import net.fabricmc.loom.util.Constants;
 
 public class UnpickJarTask extends JavaExec {
@@ -60,15 +61,15 @@ public class UnpickJarTask extends JavaExec {
 		fileArg(getMinecraftDependencies());
 
 		writeUnpickLogConfig();
-		systemProperty("java.util.logging.config.file", getExtension().getUnpickLoggingConfigFile().getAbsolutePath());
+		systemProperty("java.util.logging.config.file", getDirectories().getUnpickLoggingConfigFile().getAbsolutePath());
 
 		super.exec();
 	}
 
 	private void writeUnpickLogConfig() {
 		try (InputStream is = LaunchProvider.class.getClassLoader().getResourceAsStream("unpick-logging.properties")) {
-			Files.deleteIfExists(getExtension().getUnpickLoggingConfigFile().toPath());
+			Files.deleteIfExists(getDirectories().getUnpickLoggingConfigFile().toPath());
-			Files.copy(is, getExtension().getUnpickLoggingConfigFile().toPath());
+			Files.copy(is, getDirectories().getUnpickLoggingConfigFile().toPath());
 		} catch (IOException e) {
 			throw new RuntimeException("Failed to copy unpick logging config", e);
 		}
@@ -121,6 +122,10 @@ public class UnpickJarTask extends JavaExec {
 
 	@Internal
 	protected LoomGradleExtension getExtension() {
-		return getProject().getExtensions().getByType(LoomGradleExtension.class);
+		return LoomGradleExtension.get(getProject());
+	}
+
+	private LoomFiles getDirectories() {
+		return getExtension().getFiles();
 	}
 }

src/main/java/net/fabricmc/loom/util/Constants.java

@@ -109,14 +109,6 @@ public class Constants {
 		}
 	}
 
-	public static final class LaunchWrapper {
-		public static final String DEFAULT_FABRIC_CLIENT_TWEAKER = "net.fabricmc.loader.launch.FabricClientTweaker";
-		public static final String DEFAULT_FABRIC_SERVER_TWEAKER = "net.fabricmc.loader.launch.FabricServerTweaker";
-
-		private LaunchWrapper() {
-		}
-	}
-
 	public static final class Knot {
 		public static final String KNOT_CLIENT = "net.fabricmc.loader.launch.knot.KnotClient";
 		public static final String KNOT_SERVER = "net.fabricmc.loader.launch.knot.KnotServer";

src/main/java/net/fabricmc/loom/util/SourceRemapper.java

@@ -159,7 +159,7 @@ public class SourceRemapper {
 			return this.mercury;
 		}
 
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
 		MappingsProviderImpl mappingsProvider = extension.getMappingsProvider();
 
 		MappingSet mappings = extension.getOrCreateSrcMappingCache(toNamed ? 1 : 0, () -> {