Enhanced asset download support (#25)

- Add support for copying Assets from an existing Launcher
- Add support for writing the Neoform asset JSON reference format
- Add support for specifying the asset download directory

README.md

@@ -69,13 +69,13 @@ NFRT helps with this by downloading the assets required to run a particular vers
 
 ```
 # Download Assets for a specific version of Minecraft
-nfrt download-assets --minecraft-version 1.20.6 --output-properties-to assets.properties
+nfrt download-assets --minecraft-version 1.20.6 --write-properties assets.properties
 
 # Download Assets for the Minecraft version used by the given NeoForm version
-nfrt download-assets --neoform net.neoforged:neoform:1.20.6-20240429.153634@zip --output-properties-to assets.properties
+nfrt download-assets --neoform net.neoforged:neoform:1.20.6-20240429.153634@zip --write-properties assets.properties
 
 # Download Assets for the Minecraft version used by the given NeoForge version
-nfrt download-assets --neoforge net.neoforged:neoforge:20.6.72-beta:userdev --output-properties-to assets.properties
+nfrt download-assets --neoforge net.neoforged:neoforge:20.6.72-beta:userdev --write-properties assets.properties
 
 # In all three cases, a properties file will be written to assets.properties containing the following,
 # which can be used to pass the required command line arguments for starting a Minecraft client.
@@ -86,6 +86,15 @@ assets_root=...path to assets...
 While it may seem odd that NFRT supports passing NeoForm or NeoForge versions to this command, this is in service
 of potential Gradle plugins never having to actually read and parse the NeoForm configuration file.
 
+| Option                         | Description                                                                                                                                                                      |
+|--------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `--asets-dir`                  | Where to store the downloaded assets. Optional. Defaults to `<nfrt_home>/assets`, or a detected Launcher installation.                                                           |
+| `--no-copy-launcher-assets`    | Disables copying of local Minecraft Launcher assets, if using the asset root directly is disabled.                                                                               |
+| `--no-use-launcher-asset-root` | Disables using a detected Minecraft Launcher installation directly to store the required assets.                                                                                 |
+| `--concurrent-downloads`       | Limits the maximum number of concurrent downloads. Default is 25.                                                                                                                |
+| `--write-properties`         | Writes a property file to the given path that contains the asset index id (`asset_index`) and asset root path (`assets_root`) suitable for passing to Minecraft.                 |
+| `--write-json`               | Writes a JSON file to the given path that contains the asset index id (`asset_index`) and asset root path (`assets`) suitable for passing to Minecraft via a Neoform entrypoint. |
+
 ## Common Options
 
 These options affect all NFRT subcommands.

build.gradle

@@ -101,8 +101,12 @@ dependencies {
     annotationProcessor 'info.picocli:picocli-codegen:4.7.6'
 
     testImplementation platform('org.junit:junit-bom:5.10.0')
+    testImplementation platform('org.mockito:mockito-bom:5.12.0')
+    testImplementation platform('org.assertj:assertj-bom:3.26.3')
     testImplementation 'org.junit.jupiter:junit-jupiter'
     testImplementation 'org.junit.jupiter:junit-jupiter-params'
+    testImplementation 'org.mockito:mockito-junit-jupiter'
+    testImplementation 'org.assertj:assertj-core'
 }
 
 // Add dependencies to external tools
@@ -203,7 +207,7 @@ idea {
                 }
                 "Download assets 1.20.6"(Application) {
                     mainClass = mainClassName
-                    programParameters = "download-assets --neoforge net.neoforged:neoforge:20.6.72-beta:userdev --output-properties-to build/assets.properties"
+                    programParameters = "download-assets --neoforge net.neoforged:neoforge:20.6.72-beta:userdev --write-properties build/assets.properties --write-json build/assets.json"
                     moduleRef(project, sourceSets.main)
                 }
             }

src/main/java/net/neoforged/neoform/runtime/actions/CreateLibrariesOptionsFileAction.java

@@ -2,8 +2,8 @@
 
 import net.neoforged.neoform.runtime.cache.CacheKeyBuilder;
 import net.neoforged.neoform.runtime.engine.ProcessingEnvironment;
-import net.neoforged.neoform.runtime.graph.ResultRepresentation;
 import net.neoforged.neoform.runtime.graph.ExecutionNodeAction;
+import net.neoforged.neoform.runtime.graph.ResultRepresentation;
 
 import java.io.IOException;
 import java.nio.file.Files;

src/main/java/net/neoforged/neoform/runtime/actions/DownloadFromVersionManifestAction.java

@@ -1,7 +1,7 @@
 package net.neoforged.neoform.runtime.actions;
 
-import net.neoforged.neoform.runtime.cache.CacheKeyBuilder;
 import net.neoforged.neoform.runtime.artifacts.ArtifactManager;
+import net.neoforged.neoform.runtime.cache.CacheKeyBuilder;
 import net.neoforged.neoform.runtime.engine.ProcessingEnvironment;
 import net.neoforged.neoform.runtime.graph.ResultRepresentation;
 

src/main/java/net/neoforged/neoform/runtime/actions/PatchActionFactory.java

@@ -3,7 +3,6 @@
 import net.neoforged.neoform.runtime.graph.ExecutionNodeBuilder;
 import net.neoforged.neoform.runtime.graph.NodeOutput;
 import net.neoforged.neoform.runtime.graph.NodeOutputType;
-import net.neoforged.neoform.runtime.utils.MavenCoordinate;
 import net.neoforged.neoform.runtime.utils.ToolCoordinate;
 
 import java.nio.file.Path;

src/main/java/net/neoforged/neoform/runtime/artifacts/Artifact.java

@@ -1,6 +1,13 @@
 package net.neoforged.neoform.runtime.artifacts;
 
+import java.io.IOException;
+import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.attribute.BasicFileAttributes;
 
 public record Artifact(Path path, long lastModified, long size) {
+    public static Artifact ofPath(Path path) throws IOException {
+        var attributes = Files.readAttributes(path, BasicFileAttributes.class);
+        return new Artifact(path, attributes.lastModifiedTime().toMillis(), attributes.size());
+    }
 }

src/main/java/net/neoforged/neoform/runtime/artifacts/ArtifactManager.java

@@ -82,7 +82,7 @@ public Artifact get(MinecraftLibrary library) throws IOException {
                 // Ensure the file matches before using it
                 var fileHash = HashingUtil.hashFile(localPath, artifact.checksumAlgorithm());
                 if (Objects.equals(fileHash, artifact.checksum())) {
-                    return getArtifactFromPath(localPath);
+                    return Artifact.ofPath(localPath);
                 }
             } catch (IOException ignored) {
                 // Ignore if it doesn't exist or is otherwise fails to be read
@@ -175,7 +175,7 @@ public Artifact getVersionManifest(String minecraftVersion) throws IOException {
         for (var root : launcherInstallations.getInstallationRoots()) {
             var localPath = root.resolve("versions").resolve(minecraftVersion).resolve(minecraftVersion + ".json");
             if (Files.isReadable(localPath)) {
-                return getArtifactFromPath(localPath);
+                return Artifact.ofPath(localPath);
             }
         }
 
@@ -250,15 +250,7 @@ public void loadArtifactManifest(Path artifactManifestPath) throws IOException {
     }
 
     private Artifact getArtifactFromPath(String path) throws IOException {
-        return getArtifactFromPath(Paths.get(path));
-    }
-
-    private Artifact getArtifactFromPath(Path path) throws IOException {
-        if (!Files.isRegularFile(path)) {
-            throw new NoSuchFileException(path.toString());
-        }
-        var attrView = Files.getFileAttributeView(path, BasicFileAttributeView.class).readAttributes();
-        return new Artifact(path, attrView.lastModifiedTime().toMillis(), attrView.size());
+        return Artifact.ofPath(Paths.get(path));
     }
 
     @FunctionalInterface

src/main/java/net/neoforged/neoform/runtime/cache/CacheManager.java

@@ -73,12 +73,12 @@ public class CacheManager implements AutoCloseable {
     private boolean analyzeMisses;
     private boolean verbose;
 
-    public CacheManager(Path homeDir, Path workspacesDir) throws IOException {
+    public CacheManager(Path homeDir, @Nullable Path assetsDir, Path workspacesDir) throws IOException {
         this.homeDir = homeDir;
         Files.createDirectories(homeDir);
         this.artifactCacheDir = homeDir.resolve("artifacts");
         this.intermediateResultsDir = homeDir.resolve("intermediate_results");
-        this.assetsDir = homeDir.resolve("assets");
+        this.assetsDir = Objects.requireNonNullElse(assetsDir, homeDir.resolve("assets"));
         this.workspacesDir = workspacesDir;
     }
 

src/main/java/net/neoforged/neoform/runtime/cache/LauncherInstallations.java

@@ -4,11 +4,16 @@
 import net.neoforged.neoform.runtime.utils.Logger;
 import org.jetbrains.annotations.Nullable;
 
+import java.io.IOException;
 import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -39,19 +44,23 @@ public class LauncherInstallations {
     };
     private static final Pattern PLACEHOLDER_PATTERN = Pattern.compile("\\$\\{([^}]+)}");
 
+    // Sort launcher directories in descending order by the number of asset indices they contain
+    private static final Comparator<LauncherDirectory> ASSET_INDEX_COUNT_DESCENDING = Comparator.<LauncherDirectory>comparingInt(d -> d.assetIndices.size()).reversed();
+
     private final List<LauncherDirectory> launcherDirectories = new ArrayList<>();
 
-    /** If true, the scan was already performed and launcherDirectories is up-to-date */
+    /** If true, the scan was already performed and launcherDirectories is up to date */
     private boolean scanned;
 
     private boolean verbose;
 
-    public LauncherInstallations(List<Path> additionalLauncherDirs) {
+    public LauncherInstallations(List<Path> additionalLauncherDirs) throws IOException {
         for (var dir : additionalLauncherDirs) {
             var launcherDir = analyzeLauncherDirectory(dir);
-            if (launcherDir != null) {
-                launcherDirectories.add(launcherDir);
+            if (launcherDir == null) {
+                throw new NoSuchFileException(dir.toString());
             }
+            launcherDirectories.add(launcherDir);
         }
     }
 
@@ -70,6 +79,51 @@ public List<Path> getInstallationRoots() {
         return launcherDirectories.stream().map(LauncherDirectory::directory).toList();
     }
 
+    /**
+     * Try finding an asset root in any of the known launcher installations that already has
+     * an asset index with the given id.
+     *
+     * @return Null if no such launcher installation could be found.
+     */
+    @Nullable
+    public Path getAssetDirectoryForIndex(String assetIndexId) {
+        scanIfNecessary();
+
+        var haveIndex = new ArrayList<LauncherDirectory>();
+        for (var launcherDirectory : launcherDirectories) {
+            if (launcherDirectory.assetIndices.contains(assetIndexId)) {
+                haveIndex.add(launcherDirectory);
+            }
+        }
+
+        // Sort by count of other indices descending
+        haveIndex.sort(ASSET_INDEX_COUNT_DESCENDING);
+
+        if (!haveIndex.isEmpty()) {
+            return haveIndex.getFirst().assetDirectory();
+        }
+
+        return null;
+    }
+
+    /**
+     * Returns the list of asset directories found among the known launcher installations.
+     */
+    public List<Path> getAssetRoots() {
+        scanIfNecessary();
+
+        var launcherDirsWithAssets = new ArrayList<LauncherDirectory>();
+        for (var launcherDirectory : launcherDirectories) {
+            if (launcherDirectory.assetDirectory() != null) {
+                launcherDirsWithAssets.add(launcherDirectory);
+            }
+        }
+
+        launcherDirsWithAssets.sort(ASSET_INDEX_COUNT_DESCENDING);
+
+        return launcherDirsWithAssets.stream().map(LauncherDirectory::assetDirectory).toList();
+    }
+
     private void scanIfNecessary() {
         if (scanned) {
             return;
@@ -112,8 +166,15 @@ private void scanIfNecessary() {
         if (verbose) {
             LOG.println("Launcher directories found:");
             for (var launcherDirectory : launcherDirectories) {
+                String details;
+                if (launcherDirectory.assetDirectory == null || launcherDirectory.assetIndices().isEmpty()) {
+                    details = "no assets";
+                } else {
+                    details = "asset indices: " + String.join(" ", launcherDirectory.assetIndices());
+                }
+
                 LOG.println(AnsiColor.MUTED + "  " + launcherDirectory.directory
-                            + AnsiColor.RESET);
+                            + " (" + details + ")" + AnsiColor.RESET);
             }
         }
     }
@@ -148,17 +209,34 @@ private String resolvePlaceholders(String candidate) {
     }
 
     @Nullable
-    private LauncherDirectory analyzeLauncherDirectory(Path installDir) {
+    private LauncherDirectory analyzeLauncherDirectory(Path installDir) throws IOException {
         if (!Files.isDirectory(installDir)) {
             if (verbose) {
                 LOG.println(AnsiColor.MUTED + " Not found: " + installDir + AnsiColor.RESET);
             }
             return null;
         }
 
-        return new LauncherDirectory(installDir);
+        var assetIndices = new HashSet<String>();
+        var assetRoot = installDir.resolve("assets");
+        var assetIndicesDir = assetRoot.resolve("indexes");
+        var assetObjectsDir = assetRoot.resolve("objects");
+        if (Files.isDirectory(assetIndicesDir) && Files.isDirectory(assetObjectsDir)) {
+            // Count the number of asset indices present to judge how viable this directory is
+            try (var stream = Files.list(assetIndicesDir)) {
+                stream.map(f -> f.getFileName().toString())
+                        .filter(f -> f.endsWith(".json"))
+                        .map(f -> f.substring(0, f.length() - 5))
+                        .forEach(assetIndices::add);
+            }
+        }
+        if (assetIndices.isEmpty()) {
+            assetRoot = null; // Do not use an asset root, when it is empty
+        }
+
+        return new LauncherDirectory(installDir, assetRoot, assetIndices);
     }
 
-    private record LauncherDirectory(Path directory) {
+    private record LauncherDirectory(Path directory, @Nullable Path assetDirectory, Set<String> assetIndices) {
     }
 }