Rewrite minecraft game data handling.

Much faster asset and native validation logic.
Simplfied game metadata model.

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

@@ -59,7 +59,7 @@ public class SetupIntelijRunConfigs {
 		if (extension.ideSync()) {
 			//Ensures the assets are downloaded when idea is syncing a project
 			MinecraftAssetsProvider.provide(extension.getMinecraftProvider(), project);
-			MinecraftNativesProvider.provide(extension.getMinecraftProvider(), project);
+			MinecraftNativesProvider.provide(project);
 		}
 
 		String projectPath = project == rootProject ? "" : project.getPath().replace(':', '_');

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

@@ -64,7 +64,7 @@ public class LaunchProvider extends DependencyProvider {
 				.property("client", "org.lwjgl.librarypath", getExtension().getNativesDirectory().getAbsolutePath())
 
 				.argument("client", "--assetIndex")
-				.argument("client", getExtension().getMinecraftProvider().getVersionInfo().assetIndex.getFabricId(getExtension().getMinecraftProvider().getMinecraftVersion()))
+				.argument("client", getExtension().getMinecraftProvider().getVersionInfo().getAssetIndex().getFabricId(getExtension().getMinecraftProvider().getMinecraftVersion()))
 				.argument("client", "--assetsDir")
 				.argument("client", new File(getExtension().getUserCache(), "assets").getAbsolutePath());
 

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

@@ -43,7 +43,7 @@ import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.configuration.DependencyProvider;
 import net.fabricmc.loom.configuration.providers.minecraft.ManifestVersion;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftLibraryProvider;
-import net.fabricmc.loom.configuration.providers.minecraft.MinecraftVersionInfo;
+import net.fabricmc.loom.configuration.providers.minecraft.MinecraftVersionMeta;
 import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.DownloadUtil;
 import net.fabricmc.loom.util.HashedDownloadUtil;
@@ -52,7 +52,7 @@ import net.fabricmc.stitch.merge.JarMerger;
 public class MinecraftProvider extends DependencyProvider {
 	private String minecraftVersion;
 
-	private MinecraftVersionInfo versionInfo;
+	private MinecraftVersionMeta versionInfo;
 	private MinecraftLibraryProvider libraryProvider;
 
 	private File minecraftJson;
@@ -76,7 +76,7 @@ public class MinecraftProvider extends DependencyProvider {
 		downloadMcJson(offline);
 
 		try (FileReader reader = new FileReader(minecraftJson)) {
-			versionInfo = LoomGradlePlugin.GSON.fromJson(reader, MinecraftVersionInfo.class);
+			versionInfo = LoomGradlePlugin.GSON.fromJson(reader, MinecraftVersionMeta.class);
 		}
 
 		// Add Loom as an annotation processor
@@ -209,11 +209,11 @@ public class MinecraftProvider extends DependencyProvider {
 			return;
 		}
 
-		MinecraftVersionInfo.Downloads client = versionInfo.downloads.get("client");
+		MinecraftVersionMeta.Download client = versionInfo.getDownload("client");
-		MinecraftVersionInfo.Downloads server = versionInfo.downloads.get("server");
+		MinecraftVersionMeta.Download server = versionInfo.getDownload("server");
 
-		HashedDownloadUtil.downloadIfInvalid(new URL(client.url), minecraftClientJar, client.sha1, logger, false);
+		HashedDownloadUtil.downloadIfInvalid(new URL(client.getUrl()), minecraftClientJar, client.getSha1(), logger, false);
-		HashedDownloadUtil.downloadIfInvalid(new URL(server.url), minecraftServerJar, server.sha1, logger, false);
+		HashedDownloadUtil.downloadIfInvalid(new URL(server.getUrl()), minecraftServerJar, server.getSha1(), logger, false);
 	}
 
 	private void mergeJars(Logger logger) throws IOException {
@@ -233,7 +233,7 @@ public class MinecraftProvider extends DependencyProvider {
 		return minecraftVersion;
 	}
 
-	public MinecraftVersionInfo getVersionInfo() {
+	public MinecraftVersionMeta getVersionInfo() {
 		return versionInfo;
 	}
 

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

@@ -55,7 +55,7 @@ import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
-import net.fabricmc.loom.configuration.providers.minecraft.MinecraftVersionInfo;
+import net.fabricmc.loom.configuration.providers.minecraft.MinecraftVersionMeta;
 import net.fabricmc.loom.util.DownloadUtil;
 import net.fabricmc.lorenztiny.TinyMappingsReader;
 import net.fabricmc.mapping.tree.TinyMappingFactory;
@@ -121,14 +121,14 @@ public class MojangMappingsDependency implements SelfResolvingDependency {
 	}
 
 	private MappingSet getMappingsSet(Path clientMappings, Path serverMappings) throws IOException {
-		MinecraftVersionInfo versionInfo = extension.getMinecraftProvider().getVersionInfo();
+		MinecraftVersionMeta versionInfo = extension.getMinecraftProvider().getVersionInfo();
 
-		if (versionInfo.downloads.get(MANIFEST_CLIENT_MAPPINGS) == null) {
+		if (versionInfo.getDownload(MANIFEST_CLIENT_MAPPINGS) == null) {
 			throw new RuntimeException("Failed to find official mojang mappings for " + getVersion());
 		}
 
-		String clientMappingsUrl = versionInfo.downloads.get(MANIFEST_CLIENT_MAPPINGS).url;
+		String clientMappingsUrl = versionInfo.getDownload(MANIFEST_CLIENT_MAPPINGS).getUrl();
-		String serverMappingsUrl = versionInfo.downloads.get(MANIFEST_SERVER_MAPPINGS).url;
+		String serverMappingsUrl = versionInfo.getDownload(MANIFEST_CLIENT_MAPPINGS).getUrl();
 
 		DownloadUtil.downloadIfChanged(new URL(clientMappingsUrl), clientMappings.toFile(), project.getLogger());
 		DownloadUtil.downloadIfChanged(new URL(serverMappingsUrl), serverMappings.toFile(), project.getLogger());

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

@@ -36,22 +36,13 @@ public class MinecraftLibraryProvider {
 	public File MINECRAFT_LIBS;
 
 	public void provide(MinecraftProvider minecraftProvider, Project project) {
-		MinecraftVersionInfo versionInfo = minecraftProvider.getVersionInfo();
+		MinecraftVersionMeta versionInfo = minecraftProvider.getVersionInfo();
 
 		initFiles(project, minecraftProvider);
 
-		for (MinecraftVersionInfo.Library library : versionInfo.libraries) {
+		for (MinecraftVersionMeta.Library library : versionInfo.getLibraries()) {
-			if (library.allowed() && !library.isNative() && library.getFile(MINECRAFT_LIBS) != null) {
+			if (library.isValidForOS() && !library.hasNatives() && library.getArtifact() != null) {
-				// TODO: Add custom library locations
+				project.getDependencies().add(Constants.Configurations.MINECRAFT_DEPENDENCIES, project.getDependencies().module(library.getName()));
-
-				// By default, they are all available on all sides
-				/* boolean isClientOnly = false;
-
-				if (library.name.contains("java3d") || library.name.contains("paulscode") || library.name.contains("lwjgl") || library.name.contains("twitch") || library.name.contains("jinput") || library.name.contains("text2speech") || library.name.contains("objc")) {
-					isClientOnly = true;
-				} */
-
-				project.getDependencies().add(Constants.Configurations.MINECRAFT_DEPENDENCIES, project.getDependencies().module(library.getArtifactName()));
 			}
 		}
 	}

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

@@ -27,24 +27,39 @@ package net.fabricmc.loom.configuration.providers.minecraft;
 import java.io.File;
 import java.io.IOException;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
+import org.apache.commons.io.FileUtils;
 import org.gradle.api.GradleException;
 import org.gradle.api.Project;
 import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
-import net.fabricmc.loom.configuration.providers.MinecraftProvider;
+import net.fabricmc.loom.LoomGradlePlugin;
-import net.fabricmc.loom.util.DownloadUtil;
+import net.fabricmc.loom.util.HashedDownloadUtil;
 
 public class MinecraftNativesProvider {
-	public static void provide(MinecraftProvider minecraftProvider, Project project) throws IOException {
+	private final Project project;
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+	private final LoomGradleExtension extension;
-		MinecraftVersionInfo versionInfo = minecraftProvider.getVersionInfo();
+	private final File nativesDir;
-		boolean offline = project.getGradle().getStartParameter().isOffline();
+	private final File jarStore;
 
-		File nativesDir = extension.getNativesDirectory();
+	public MinecraftNativesProvider(Project project) {
-		File jarStore = extension.getNativesJarStore();
+		this.project = project;
+		extension = project.getExtensions().getByType(LoomGradleExtension.class);
 
+		nativesDir = extension.getNativesDirectory();
+		jarStore = extension.getNativesJarStore();
+	}
+
+	public static void provide(Project project) throws IOException {
+		new MinecraftNativesProvider(project).provide();
+	}
+
+	private void provide() throws IOException {
 		if (extension.hasCustomNatives()) {
 			if (!nativesDir.exists()) {
 				throw new RuntimeException("Could no find custom natives directory at " + nativesDir.getAbsolutePath());
@@ -53,21 +68,82 @@ public class MinecraftNativesProvider {
 			return;
 		}
 
-		for (MinecraftVersionInfo.Library library : versionInfo.libraries) {
+		if (!LoomGradlePlugin.refreshDeps && !requiresExtract()) {
-			File libJarFile = library.getFile(jarStore);
+			project.getLogger().info("Natives do no need extracting, skipping");
+			return;
+		}
 
-			if (library.allowed() && library.isNative() && libJarFile != null) {
+		extractNatives();
-				if (!offline) {
+	}
-					DownloadUtil.downloadIfChanged(new URL(library.getURL()), libJarFile, project.getLogger());
-				}
 
-				if (!libJarFile.exists()) {
+	private void extractNatives() throws IOException {
-					throw new GradleException("Native jar not found at " + libJarFile.getAbsolutePath());
+		boolean offline = project.getGradle().getStartParameter().isOffline();
-				}
 
-				// TODO possibly find a way to prevent needing to re-extract after each run, doesnt seem too slow
+		if (nativesDir.exists()) {
-				ZipUtil.unpack(libJarFile, nativesDir);
+			try {
+				FileUtils.deleteDirectory(nativesDir);
+			} catch (IOException e) {
+				throw new IOException("Failed to delete the natives directory, is the game running?", e);
 			}
 		}
+
+		nativesDir.mkdirs();
+
+		for (MinecraftVersionMeta.Classifier library : getNatives()) {
+			File libJarFile = library.getRelativeFile(jarStore);
+
+			if (!offline) {
+				HashedDownloadUtil.downloadIfInvalid(new URL(library.getUrl()), libJarFile, library.getSha1(), project.getLogger(), false);
+			}
+
+			if (!libJarFile.exists()) {
+				throw new GradleException("Native jar not found at " + libJarFile.getAbsolutePath());
+			}
+
+			ZipUtil.unpack(libJarFile, nativesDir);
+
+			// Store a file containing the hash of the extracted natives, used on subsequent runs to skip extracting all the natives if they haven't changed
+			File libSha1File = new File(nativesDir, libJarFile.getName() + ".sha1");
+			FileUtils.writeStringToFile(libSha1File, library.getSha1(), StandardCharsets.UTF_8);
+		}
+	}
+
+	private boolean requiresExtract() {
+		List<MinecraftVersionMeta.Classifier> natives = getNatives();
+
+		if (natives.isEmpty()) {
+			throw new IllegalStateException("No natives found for the current system");
+		}
+
+		for (MinecraftVersionMeta.Classifier library : natives) {
+			File libJarFile = library.getRelativeFile(jarStore);
+			File libSha1File = new File(nativesDir, libJarFile.getName() + ".sha1");
+
+			if (!libSha1File.exists()) {
+				return true;
+			}
+
+			try {
+				String sha1 = FileUtils.readFileToString(libSha1File, StandardCharsets.UTF_8);
+
+				if (!sha1.equalsIgnoreCase(library.getSha1())) {
+					return true;
+				}
+			} catch (IOException e) {
+				project.getLogger().error("Failed to read " + libSha1File.getAbsolutePath(), e);
+				return true;
+			}
+		}
+
+		// All looks good, no need to re-extract
+		return false;
+	}
+
+	private List<MinecraftVersionMeta.Classifier> getNatives() {
+		return extension.getMinecraftProvider().getVersionInfo().getLibraries().stream()
+				.filter((MinecraftVersionMeta.Library::hasNativesForOS))
+				.map(MinecraftVersionMeta.Library::getClassifierForOS)
+				.filter(Objects::nonNull)
+				.collect(Collectors.toList());
 	}
 }

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

@@ -1,198 +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.configuration.providers.minecraft;
-
-import java.io.File;
-import java.util.List;
-import java.util.Map;
-
-import com.google.gson.JsonElement;
-import com.google.gson.JsonObject;
-
-import net.fabricmc.loom.util.Constants;
-import net.fabricmc.loom.util.OperatingSystem;
-
-public class MinecraftVersionInfo {
-	public List<Library> libraries;
-	public Map<String, Downloads> downloads;
-	public AssetIndex assetIndex;
-
-	public class Downloads {
-		public String url;
-		public String sha1;
-	}
-
-	public class AssetIndex {
-		private String id;
-		public String sha1;
-		public String url;
-
-		public String getId() {
-			return id;
-		}
-
-		public String getFabricId(String version) {
-			return id.equals(version) ? version : version + "-" + id;
-		}
-	}
-
-	public class Library {
-		public String name;
-		public JsonObject natives;
-		public JsonObject downloads;
-		private Artifact artifact;
-		public Rule[] rules;
-
-		public String getURL() {
-			String path;
-			String[] parts = this.name.split(":", 3);
-			path = parts[0].replace(".", "/") + "/" + parts[1] + "/" + parts[2] + "/" + parts[1] + "-" + parts[2] + getClassifier() + ".jar";
-			return Constants.LIBRARIES_BASE + path;
-		}
-
-		public File getFile(File baseDir) {
-			String[] parts = this.name.split(":", 3);
-			return new File(baseDir, parts[0].replace(".", File.separator) + File.separator + parts[1] + File.separator + parts[2] + File.separator + parts[1] + "-" + parts[2] + getClassifier() + ".jar");
-		}
-
-		public String getSha1() {
-			if (this.downloads == null) {
-				return "";
-			} else if (this.downloads.getAsJsonObject("artifact") == null) {
-				return "";
-			} else if (this.downloads.getAsJsonObject("artifact").get("sha1") == null) {
-				return "";
-			} else {
-				return this.downloads.getAsJsonObject("artifact").get("sha1").getAsString();
-			}
-		}
-
-		public String getClassifier() {
-			if (natives == null) {
-				return "";
-			} else {
-				JsonElement element = natives.get(OperatingSystem.getOS().replace("${arch}", OperatingSystem.getArch()));
-
-				if (element == null) {
-					return "";
-				}
-
-				return "-" + element.getAsString().replace("\"", "").replace("${arch}", OperatingSystem.getArch());
-			}
-		}
-
-		public boolean isNative() {
-			return getClassifier().contains("natives");
-		}
-
-		public boolean allowed() {
-			if (this.rules == null || this.rules.length <= 0) {
-				return true;
-			}
-
-			boolean success = false;
-
-			for (Rule rule : this.rules) {
-				if (rule.os != null && rule.os.name != null) {
-					if (rule.os.name.equalsIgnoreCase(OperatingSystem.getOS())) {
-						return rule.action.equalsIgnoreCase("allow");
-					}
-				} else {
-					success = rule.action.equalsIgnoreCase("allow");
-				}
-			}
-
-			return success;
-		}
-
-		public String getArtifactName() {
-			if (artifact == null) {
-				artifact = new Artifact(name);
-			}
-
-			if (natives != null) {
-				JsonElement jsonElement = natives.get(OperatingSystem.getOS());
-
-				if (jsonElement != null) {
-					return artifact.getArtifact(jsonElement.getAsString());
-				}
-			}
-
-			return artifact.getArtifact(artifact.classifier);
-		}
-
-		private class Artifact {
-			private final String domain, name, version, classifier, ext;
-
-			Artifact(String name) {
-				String[] splitedArtifact = name.split(":");
-				int idx = splitedArtifact[splitedArtifact.length - 1].indexOf('@');
-
-				if (idx != -1) {
-					ext = splitedArtifact[splitedArtifact.length - 1].substring(idx + 1);
-					splitedArtifact[splitedArtifact.length - 1] = splitedArtifact[splitedArtifact.length - 1].substring(0, idx);
-				} else {
-					ext = "jar";
-				}
-
-				this.domain = splitedArtifact[0];
-				this.name = splitedArtifact[1];
-				this.version = splitedArtifact[2];
-				this.classifier = splitedArtifact.length > 3 ? splitedArtifact[3] : null;
-			}
-
-			public String getArtifact(String classifier) {
-				String ret = domain + ":" + name + ":" + version;
-
-				if (classifier != null && classifier.indexOf('$') > -1) {
-					classifier = classifier.replace("${arch}", Constants.SYSTEM_ARCH);
-				}
-
-				if (classifier != null) {
-					ret += ":" + classifier;
-				}
-
-				if (!"jar".equals(ext)) {
-					ret += "@" + ext;
-				}
-
-				return ret;
-			}
-
-			public String getClassifier() {
-				return classifier;
-			}
-		}
-	}
-
-	private class Rule {
-		public String action;
-		public OS os;
-
-		private class OS {
-			String name;
-		}
-	}
-}

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

@@ -0,0 +1,277 @@
+/*
+ * 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.configuration.providers.minecraft;
+
+import java.io.File;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
+import com.google.gson.JsonObject;
+
+import net.fabricmc.loom.util.OperatingSystem;
+
+@SuppressWarnings("unused")
+public final class MinecraftVersionMeta {
+	private JsonObject arguments;
+	private AssetIndex assetIndex;
+	private String assets;
+	private int complianceLevel;
+	private Map<String, Download> downloads;
+	private String id;
+	private List<Library> libraries;
+	private JsonObject logging;
+	private String mainClass;
+	private int minimumLauncherVersion;
+	private String releaseTime;
+	private String time;
+	private String type;
+
+	public Download getDownload(String key) {
+		return getDownloads().get(key);
+	}
+
+	public JsonObject getArguments() {
+		return arguments;
+	}
+
+	public AssetIndex getAssetIndex() {
+		return assetIndex;
+	}
+
+	public String getAssets() {
+		return assets;
+	}
+
+	public int getComplianceLevel() {
+		return complianceLevel;
+	}
+
+	public Map<String, Download> getDownloads() {
+		return downloads;
+	}
+
+	public String getId() {
+		return id;
+	}
+
+	public List<Library> getLibraries() {
+		return libraries;
+	}
+
+	public JsonObject getLogging() {
+		return logging;
+	}
+
+	public String getMainClass() {
+		return mainClass;
+	}
+
+	public int getMinimumLauncherVersion() {
+		return minimumLauncherVersion;
+	}
+
+	public String getReleaseTime() {
+		return releaseTime;
+	}
+
+	public String getTime() {
+		return time;
+	}
+
+	public String getType() {
+		return type;
+	}
+
+	public final class AssetIndex extends Downloadable {
+		private String id;
+		private long totalSize;
+
+		public String getFabricId(String version) {
+			return id.equals(version) ? version : version + "-" + id;
+		}
+
+		public String getId() {
+			return id;
+		}
+
+		public long getTotalSize() {
+			return totalSize;
+		}
+	}
+
+	public final class Download extends Downloadable {
+	}
+
+	public final class Library {
+		private Downloads downloads;
+		private String name;
+		private Map<String, String> natives;
+		private List<Rule> rules;
+
+		public boolean isValidForOS() {
+			if (rules == null || rules.isEmpty()) {
+				return true;
+			}
+
+			for (Rule rule : rules) {
+				if (rule.appliesToOS() && !rule.isAllowed()) {
+					return false;
+				}
+			}
+
+			return true;
+		}
+
+		public boolean hasNatives() {
+			return this.natives != null;
+		}
+
+		public boolean hasNativesForOS() {
+			if (!hasNatives()) {
+				return false;
+			}
+
+			if (natives.get(OperatingSystem.getOS()) == null) {
+				return false;
+			}
+
+			return isValidForOS();
+		}
+
+		public Classifier getClassifierForOS() {
+			return getDownloads().getClassifier(natives.get(OperatingSystem.getOS()));
+		}
+
+		public Downloads getDownloads() {
+			return downloads;
+		}
+
+		public Artifact getArtifact() {
+			if (getDownloads() == null) {
+				return null;
+			}
+
+			return getDownloads().getArtifact();
+		}
+
+		public String getName() {
+			return name;
+		}
+
+		public Map<String, String> getNatives() {
+			return natives;
+		}
+
+		public List<Rule> getRules() {
+			return rules;
+		}
+	}
+
+	public final class Downloads {
+		private Artifact artifact;
+		private Map<String, Classifier> classifiers;
+
+		public Classifier getClassifier(String os) {
+			return classifiers.get(os);
+		}
+
+		public Artifact getArtifact() {
+			return artifact;
+		}
+
+		public Map<String, Classifier> getClassifiers() {
+			return classifiers;
+		}
+	}
+
+	public final class Artifact extends Downloadable {
+	}
+
+	public final class Classifier extends Downloadable {
+	}
+
+	public final class Rule {
+		private String action;
+		private OS os;
+
+		public boolean appliesToOS() {
+			return getOS() == null || getOS().isValidForOS();
+		}
+
+		public boolean isAllowed() {
+			return getAction().equals("allow");
+		}
+
+		public String getAction() {
+			return action;
+		}
+
+		public OS getOS() {
+			return os;
+		}
+	}
+
+	public final class OS {
+		private String name;
+
+		public boolean isValidForOS() {
+			return getName() == null || getName().equalsIgnoreCase(OperatingSystem.getOS());
+		}
+
+		public String getName() {
+			return name;
+		}
+	}
+
+	// A base class for everything that can be downloaded
+	public abstract class Downloadable {
+		private String path;
+		private String sha1;
+		private long size;
+		private String url;
+
+		public File getRelativeFile(File baseDirectory) {
+			Objects.requireNonNull(getPath(), "Cannot get relative file from a null path");
+			return new File(baseDirectory, getPath());
+		}
+
+		public String getPath() {
+			return path;
+		}
+
+		public String getSha1() {
+			return sha1;
+		}
+
+		public long getSize() {
+			return size;
+		}
+
+		public String getUrl() {
+			return url;
+		}
+	}
+}

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

@@ -26,32 +26,25 @@ package net.fabricmc.loom.configuration.providers.minecraft.assets;
 
 import java.io.File;
 import java.io.FileReader;
-import java.io.FileWriter;
 import java.io.IOException;
 import java.net.URL;
 import java.util.Deque;
 import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentLinkedDeque;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 
 import com.google.common.base.Stopwatch;
-import com.google.common.hash.Hashing;
-import com.google.common.io.Files;
-import com.google.gson.Gson;
-import com.google.gson.reflect.TypeToken;
 import org.gradle.api.GradleException;
 import org.gradle.api.Project;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.configuration.providers.MinecraftProvider;
-import net.fabricmc.loom.configuration.providers.minecraft.MinecraftVersionInfo;
+import net.fabricmc.loom.configuration.providers.minecraft.MinecraftVersionMeta;
-import net.fabricmc.loom.util.Checksum;
 import net.fabricmc.loom.util.Constants;
-import net.fabricmc.loom.util.DownloadUtil;
+import net.fabricmc.loom.util.HashedDownloadUtil;
 import net.fabricmc.loom.util.gradle.ProgressLogger;
 
 public class MinecraftAssetsProvider {
@@ -59,8 +52,8 @@ public class MinecraftAssetsProvider {
 		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
 		boolean offline = project.getGradle().getStartParameter().isOffline();
 
-		MinecraftVersionInfo versionInfo = minecraftProvider.getVersionInfo();
+		MinecraftVersionMeta versionInfo = minecraftProvider.getVersionInfo();
-		MinecraftVersionInfo.AssetIndex assetIndex = versionInfo.assetIndex;
+		MinecraftVersionMeta.AssetIndex assetIndex = versionInfo.getAssetIndex();
 
 		// get existing cache files
 		File assets = new File(extension.getUserCache(), "assets");
@@ -70,42 +63,28 @@ public class MinecraftAssetsProvider {
 		}
 
 		File assetsInfo = new File(assets, "indexes" + File.separator + assetIndex.getFabricId(minecraftProvider.getMinecraftVersion()) + ".json");
-		File checksumInfo = new File(assets, "checksum" + File.separator + minecraftProvider.getMinecraftVersion() + ".json");
 
-		if (!assetsInfo.exists() || !Checksum.equals(assetsInfo, assetIndex.sha1)) {
+		project.getLogger().info(":downloading asset index");
-			project.getLogger().info(":downloading asset index");
 
-			if (offline) {
+		if (offline) {
-				if (assetsInfo.exists()) {
+			if (assetsInfo.exists()) {
-					//We know it's outdated but can't do anything about it, oh well
+				//We know it's outdated but can't do anything about it, oh well
-					project.getLogger().warn("Asset index outdated");
+				project.getLogger().warn("Asset index outdated");
-				} else {
-					//We don't know what assets we need, just that we don't have any
-					throw new GradleException("Asset index not found at " + assetsInfo.getAbsolutePath());
-				}
 			} else {
-				DownloadUtil.downloadIfChanged(new URL(assetIndex.url), assetsInfo, project.getLogger());
+				//We don't know what assets we need, just that we don't have any
-			}
+				throw new GradleException("Asset index not found at " + assetsInfo.getAbsolutePath());
-		}
-
-		Gson gson = new Gson();
-		Map<String, String> checksumInfos = new ConcurrentHashMap<>();
-
-		if (checksumInfo.exists()) {
-			try (FileReader reader = new FileReader(checksumInfo)) {
-				checksumInfos.putAll(gson.fromJson(reader, new TypeToken<Map<String, String>>() {
-				}.getType()));
 			}
+		} else {
+			HashedDownloadUtil.downloadIfInvalid(new URL(assetIndex.getUrl()), assetsInfo, assetIndex.getSha1(), project.getLogger(), false);
 		}
 
 		Deque<ProgressLogger> loggers = new ConcurrentLinkedDeque<>();
 		ExecutorService executor = Executors.newFixedThreadPool(Math.min(10, Math.max(Runtime.getRuntime().availableProcessors() / 2, 1)));
-		int toDownload = 0;
 
 		AssetIndex index;
 
 		try (FileReader fileReader = new FileReader(assetsInfo)) {
-			index = gson.fromJson(fileReader, AssetIndex.class);
+			index = LoomGradlePlugin.GSON.fromJson(fileReader, AssetIndex.class);
 		}
 
 		Stopwatch stopwatch = Stopwatch.createStarted();
@@ -118,75 +97,49 @@ public class MinecraftAssetsProvider {
 			String filename = "objects" + File.separator + sha1.substring(0, 2) + File.separator + sha1;
 			File file = new File(assets, filename);
 
-			String localFileChecksum = !file.exists() ? null : checksumInfos.computeIfAbsent(entry.getKey(), path -> {
+			if (offline) {
-				try {
+				if (file.exists()) {
-					return Files.asByteSource(file).hash(Hashing.sha1()).toString();
+					project.getLogger().warn("Outdated asset " + entry.getKey());
-				} catch (IOException e) {
-					e.printStackTrace();
-					return null;
-				}
-			});
-
-			if (LoomGradlePlugin.refreshDeps || localFileChecksum == null || !localFileChecksum.equals(sha1)) {
-				if (offline) {
-					if (file.exists()) {
-						project.getLogger().warn("Outdated asset " + entry.getKey());
-					} else {
-						throw new GradleException("Asset " + entry.getKey() + " not found at " + file.getAbsolutePath());
-					}
 				} else {
-					toDownload++;
+					throw new GradleException("Asset " + entry.getKey() + " not found at " + file.getAbsolutePath());
-					executor.execute(() -> {
-						ProgressLogger progressLogger;
-
-						if (loggers.isEmpty()) {
-							//Create a new logger if we need one
-							progressLogger = ProgressLogger.getProgressFactory(project, MinecraftAssetsProvider.class.getName());
-							progressLogger.start("Downloading assets...", "assets");
-						} else {
-							// use a free logger if we can
-							progressLogger = loggers.pop();
-						}
-
-						String assetName = entry.getKey();
-						int end = assetName.lastIndexOf("/") + 1;
-
-						if (end > 0) {
-							assetName = assetName.substring(end);
-						}
-
-						project.getLogger().debug(":downloading asset " + assetName);
-						progressLogger.progress(String.format("%-30.30s", assetName) + " - " + sha1);
-
-						try {
-							DownloadUtil.downloadIfChanged(new URL(Constants.RESOURCES_BASE + sha1.substring(0, 2) + "/" + sha1), file, project.getLogger(), true);
-						} catch (IOException e) {
-							throw new RuntimeException("Failed to download: " + assetName, e);
-						}
-
-						if (localFileChecksum == null) {
-							checksumInfos.put(entry.getKey(), sha1);
-						}
-
-						//Give this logger back
-						loggers.add(progressLogger);
-					});
 				}
+			} else {
+				executor.execute(() -> {
+					ProgressLogger progressLogger;
+
+					if (loggers.isEmpty()) {
+						//Create a new logger if we need one
+						progressLogger = ProgressLogger.getProgressFactory(project, MinecraftAssetsProvider.class.getName());
+						progressLogger.start("Downloading assets...", "assets");
+					} else {
+						// use a free logger if we can
+						progressLogger = loggers.pop();
+					}
+
+					String assetName = entry.getKey();
+					int end = assetName.lastIndexOf("/") + 1;
+
+					if (end > 0) {
+						assetName = assetName.substring(end);
+					}
+
+					project.getLogger().debug(":downloading asset " + assetName);
+					progressLogger.progress(String.format("%-30.30s", assetName) + " - " + sha1);
+
+					try {
+						HashedDownloadUtil.downloadIfInvalid(new URL(Constants.RESOURCES_BASE + sha1.substring(0, 2) + "/" + sha1), file, sha1, project.getLogger(), true);
+					} catch (IOException e) {
+						throw new RuntimeException("Failed to download: " + assetName, e);
+					}
+
+					//Give this logger back
+					loggers.add(progressLogger);
+				});
 			}
 		}
 
 		project.getLogger().info("Took " + stopwatch.stop() + " to iterate " + parent.size() + " asset index.");
 
-		if (toDownload > 0) {
-			project.getLogger().lifecycle(":downloading " + toDownload + " asset" + (toDownload == 1 ? "" : "s") + "...");
-		}
-
-		checksumInfo.getParentFile().mkdirs();
-
-		try (FileWriter writer = new FileWriter(checksumInfo)) {
-			gson.toJson(checksumInfos, writer);
-		}
-
 		//Wait for the assets to all download
 		executor.shutdown();
 

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

@@ -40,6 +40,6 @@ public class DownloadAssetsTask extends AbstractLoomTask {
 		LoomGradleExtension extension = getExtension();
 
 		MinecraftAssetsProvider.provide(extension.getMinecraftProvider(), project);
-		MinecraftNativesProvider.provide(extension.getMinecraftProvider(), project);
+		MinecraftNativesProvider.provide(project);
 	}
 }