Loader prefix system for Modrinth

src/main/java/me/itzg/helpers/modrinth/ModrinthApiClient.java

@@ -130,10 +130,8 @@ public Mono<Version> resolveProjectVersion(Project project, ProjectRef projectRe
                                                @Nullable Loader loader, String gameVersion,
                                                VersionType defaultVersionType) {
 
-        final Loader loaderToQuery = projectRef.isDatapack() ? Loader.datapack : loader;
-
         if (projectRef.hasVersionName()) {
-            return getVersionsForProject(project.getId(), loaderToQuery, gameVersion)
+            return getVersionsForProject(project.getId(), loader, gameVersion)
                 .flatMap(versions ->
                     Mono.justOrEmpty(versions.stream()
                         .filter(version ->
@@ -144,7 +142,7 @@ public Mono<Version> resolveProjectVersion(Project project, ProjectRef projectRe
                     ));
         }
         if (projectRef.hasVersionType()) {
-            return getVersionsForProject(project.getId(), loaderToQuery, gameVersion)
+            return getVersionsForProject(project.getId(), loader, gameVersion)
                 .mapNotNull(versions -> pickVersion(project, versions, projectRef.getVersionType()));
         } else if (projectRef.hasVersionId()) {
             return getVersionFromId(projectRef.getVersionId())
@@ -153,7 +151,7 @@ public Mono<Version> resolveProjectVersion(Project project, ProjectRef projectRe
                         projectRef.getVersionId(), project.getSlug()))
                 );
         } else {
-            return getVersionsForProject(project.getId(), loaderToQuery, gameVersion)
+            return getVersionsForProject(project.getId(), loader, gameVersion)
                     .mapNotNull(versions -> pickVersion(project, versions, defaultVersionType));
         }
     }

src/main/java/me/itzg/helpers/modrinth/ModrinthCommand.java

@@ -26,7 +26,6 @@
 import me.itzg.helpers.http.Fetch;
 import me.itzg.helpers.http.SharedFetchArgs;
 import me.itzg.helpers.json.ObjectMappers;
-import me.itzg.helpers.modrinth.model.Constants;
 import me.itzg.helpers.modrinth.model.DependencyType;
 import me.itzg.helpers.modrinth.model.Project;
 import me.itzg.helpers.modrinth.model.ProjectType;
@@ -44,9 +43,13 @@
 public class ModrinthCommand implements Callable<Integer> {
 
     public static final String DATAPACKS_SUBDIR = "datapacks";
-    @Option(names = "--projects", description = "Project ID or Slug",
-        split = SPLIT_COMMA_NL, splitSynopsisLabel = SPLIT_SYNOPSIS_COMMA_NL,
-        paramLabel = "id|slug"
+
+    @Option(
+        names = "--projects",
+        description = "Project ID or Slug. Prefix with loader: e.g. fabric:project-id",
+        split = SPLIT_COMMA_NL,
+        splitSynopsisLabel = SPLIT_SYNOPSIS_COMMA_NL,
+        paramLabel = "[loader:]id|slug"
     )
     List<String> projects;
 
@@ -75,7 +78,7 @@ public enum DownloadDependencies {
         /**
          * Implies {@link #REQUIRED}
          */
-        OPTIONAL
+        OPTIONAL,
     }
 
     @Option(names = "--allowed-version-type", defaultValue = "release", description = "Valid values: ${COMPLETION-CANDIDATES}")
@@ -128,9 +131,13 @@ private List<Path> processProjects(List<String> projects) {
                 .defaultIfEmpty(Collections.emptyList())
                 .block()
                 .stream()
-                .flatMap(resolvedProject -> processProject(
-                    modrinthApiClient, resolvedProject.getProjectRef(), resolvedProject.getProject()
-                ))
+                .flatMap(resolvedProject ->
+                    processProject(
+                        modrinthApiClient,
+                        resolvedProject.getProjectRef(),
+                        resolvedProject.getProject()
+                    )
+                )
                 .collect(Collectors.toList());
         }
     }
@@ -142,9 +149,9 @@ private ModrinthManifest loadManifest() throws IOException {
             final ObjectMapper objectMapper = ObjectMappers.defaultMapper();
 
             final LegacyModrinthManifest legacyManifest = objectMapper.readValue(
-                legacyManifestPath.toFile(),
-                LegacyModrinthManifest.class
-            );
+                    legacyManifestPath.toFile(),
+                    LegacyModrinthManifest.class
+                );
 
             Files.delete(legacyManifestPath);
 
@@ -157,7 +164,13 @@ private ModrinthManifest loadManifest() throws IOException {
         return Manifests.load(outputDirectory, ModrinthManifest.ID, ModrinthManifest.class);
     }
 
-    private Stream<Version> expandDependencies(ModrinthApiClient modrinthApiClient, Project project, Version version) {
+    private Stream<Version> expandDependencies(
+        ModrinthApiClient modrinthApiClient,
+        Loader loader,
+        String gameVersion,
+        Project project,
+        Version version
+    ) {
         log.debug("Expanding dependencies of version={}", version);
         return version.getDependencies().stream()
             .filter(this::filterDependency)
@@ -170,7 +183,7 @@ private Stream<Version> expandDependencies(ModrinthApiClient modrinthApiClient,
                     if (dep.getVersionId() == null) {
                         log.debug("Fetching versions of dep={} and picking", dep);
                         depVersion = pickVersion(
-                            getVersionsForProject(modrinthApiClient, dep.getProjectId())
+                            getVersionsForProject(modrinthApiClient, dep.getProjectId(), loader, gameVersion)
                         );
                     }
                     else {
@@ -192,8 +205,8 @@ private Stream<Version> expandDependencies(ModrinthApiClient modrinthApiClient,
                 if (depVersion != null) {
                     log.debug("Resolved version={} for dep={}", depVersion.getVersionNumber(), dep);
                     return Stream.concat(
-                            Stream.of(depVersion),
-                            expandDependencies(modrinthApiClient, project, depVersion)
+                        Stream.of(depVersion),
+                            expandDependencies(modrinthApiClient, loader, gameVersion, project, depVersion)
                         )
                         .peek(expandedVer -> log.debug("Expanded dependency={} into version={}", dep, expandedVer));
                 }
@@ -229,16 +242,14 @@ private Version pickVersion(List<Version> versions, VersionType versionType) {
         return null;
     }
 
-    private Path download(boolean isDatapack, VersionFile versionFile) {
+    private Path download(Loader loader, VersionFile versionFile) {
         final Path outPath;
         try {
-            if (!isDatapack) {
-                outPath = Files.createDirectories(outputDirectory
-                        .resolve(loader.getType())
-                    )
-                    .resolve(versionFile.getFilename());
-            }
-            else {
+            final Loader effectiveLoader = loader != null ? loader : this.loader;
+            final String outputType = effectiveLoader.getType();
+
+            if (outputType == null) {
+                // Datapack case
                 if (worldDirectory.isAbsolute()) {
                     outPath = Files.createDirectories(worldDirectory
                             .resolve(DATAPACKS_SUBDIR)
@@ -253,9 +264,15 @@ private Path download(boolean isDatapack, VersionFile versionFile) {
                         .resolve(versionFile.getFilename());
                 }
             }
+            else {
+                outPath = Files.createDirectories(outputDirectory
+                        .resolve(outputType)
+                    )
+                    .resolve(versionFile.getFilename());
+            }
 
         } catch (IOException e) {
-            throw new RuntimeException("Creating mods directory", e);
+            throw new RuntimeException("Creating output directory", e);
         }
 
         try {
@@ -267,11 +284,11 @@ private Path download(boolean isDatapack, VersionFile versionFile) {
                 .handleStatus(Fetch.loggingDownloadStatusHandler(log))
                 .execute();
         } catch (IOException e) {
-            throw new RuntimeException("Downloading mod file", e);
+            throw new RuntimeException("Downloading file", e);
         }
     }
 
-    private List<Version> getVersionsForProject(ModrinthApiClient modrinthApiClient, String project) {
+    private List<Version> getVersionsForProject(ModrinthApiClient modrinthApiClient, String project, Loader loader, String gameVersion) {
         final List<Version> versions = modrinthApiClient.getVersionsForProject(
                 project, loader, gameVersion
             )
@@ -294,10 +311,19 @@ private Stream<Path> processProject(ModrinthApiClient modrinthApiClient, Project
         log.debug("Starting with project='{}' slug={}", project.getTitle(), project.getSlug());
 
         if (projectsProcessed.add(project.getId())) {
+            final Loader effectiveLoader = projectRef.getLoader() != null
+                ? projectRef.getLoader()
+                : this.loader;
+
             final Version version;
             try {
-                version = modrinthApiClient.resolveProjectVersion(
-                        project, projectRef, loader, gameVersion, defaultVersionType
+                version = modrinthApiClient
+                    .resolveProjectVersion(
+                        project,
+                        projectRef,
+                        effectiveLoader,
+                        gameVersion,
+                        defaultVersionType
                     )
                     .block();
             } catch (NoApplicableVersionsException | NoFilesAvailableException e) {
@@ -306,36 +332,46 @@ private Stream<Path> processProject(ModrinthApiClient modrinthApiClient, Project
 
             if (version != null) {
                 if (version.getFiles().isEmpty()) {
-                    throw new GenericException(String.format("Project %s has no files declared", project.getSlug()));
+                    throw new GenericException(
+                        String.format(
+                            "Project %s has no files declared",
+                            project.getSlug()
+                        )
+                    );
                 }
 
-                final boolean isDatapack = isDatapack(version);
-
                 return Stream.concat(
-                        Stream.of(version),
-                        expandDependencies(modrinthApiClient, project, version)
+                    Stream.of(version),
+                    expandDependencies(
+                        modrinthApiClient,
+                        effectiveLoader,
+                        gameVersion,
+                        project,
+                        version
                     )
+                )
                     .map(ModrinthApiClient::pickVersionFile)
-                    .map(versionFile -> download(isDatapack, versionFile))
-                    .flatMap(downloadedFile -> !isDatapack ? expandIfZip(downloadedFile) : Stream.empty());
-            }
-            else {
+                    .map(versionFile -> download(effectiveLoader, versionFile))
+                    .flatMap(downloadedFile -> {
+                        // Only expand ZIPs for non-datapack loaders
+                        return effectiveLoader == Loader.datapack
+                            ? Stream.of(downloadedFile)
+                            : expandIfZip(downloadedFile);
+                    });
+            } else {
                 throw new InvalidParameterException(
-                    String.format("Project %s does not have any matching versions for loader %s, game version %s",
-                        projectRef, loader, gameVersion
-                    ));
+                    String.format(
+                        "Project %s does not have any matching versions for loader %s, game version %s",
+                        projectRef,
+                        effectiveLoader,
+                        gameVersion
+                    )
+                );
             }
         }
         return Stream.empty();
     }
 
-    private boolean isDatapack(Version version) {
-        return
-            version.getLoaders() != null
-            && version.getLoaders().size() == 1
-            && version.getLoaders().get(0).equals(Constants.LOADER_DATAPACK);
-    }
-
     /**
      * If downloadedFile ends in .zip, then expand it, return its files and given file.
      *