Add Modrinth project files support

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

@@ -9,6 +9,7 @@
 import java.net.URI;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
@@ -46,10 +47,17 @@ public class ModrinthCommand implements Callable<Integer> {
 
     @Option(
         names = "--projects",
-        description = "Project ID or Slug. Prefix with loader: e.g. fabric:project-id",
+        description = "Project ID or Slug. Can be <project ID>|<slug>,"
+            + " <loader>:<project ID>|<slug>,"
+            + " <loader>:<project ID>|<slug>:<version ID|version number|release type>,"
+            + " '@'<filename with ref per line (supports # comments)>"
+            + "%nExamples: fabric-api, fabric:fabric-api, fabric:fabric-api:0.76.1+1.19.2,"
+            + " datapack:terralith, @/path/to/modrinth-mods.txt"
+            + "%nValid release types: release, beta, alpha"
+            + "%nValid loaders: fabric, forge, paper, datapack, etc.",
         split = SPLIT_COMMA_NL,
         splitSynopsisLabel = SPLIT_SYNOPSIS_COMMA_NL,
-        paramLabel = "[loader:]id|slug"
+        paramLabel = "[loader:]id|slug[:version]"
     )
     List<String> projects;
 
@@ -124,7 +132,7 @@ private List<Path> processProjects(List<String> projects) {
             //noinspection DataFlowIssue since it thinks block() may return null
             return
                 modrinthApiClient.bulkGetProjects(
-                    projects.stream()
+                    expandProjectListings(projects).stream()
                         .filter(s -> !s.trim().isEmpty())
                         .map(ProjectRef::parse)
                 )
@@ -142,6 +150,30 @@ private List<Path> processProjects(List<String> projects) {
         }
     }
 
+    private List<String> expandProjectListings(List<String> projects) {
+        return projects.stream()
+            .distinct()
+            // handle @-file containing refs
+            .flatMap(ref -> {
+                if (ref.startsWith("@")) {
+                    try {
+                        return Files.readAllLines(Paths.get(ref.substring(1))).stream()
+                            .map(s -> s
+                                .replaceFirst("#.*", "")
+                                .trim()
+                            )
+                            .filter(s -> !s.isEmpty());
+                    } catch (IOException e) {
+                        throw new GenericException("Reading project refs from file: " + ref.substring(1), e);
+                    }
+                }
+                else {
+                    return Stream.of(ref);
+                }
+            })
+            .collect(Collectors.toList());
+    }
+
     private ModrinthManifest loadManifest() throws IOException {
         final Path legacyManifestPath = outputDirectory.resolve(LegacyModrinthManifest.FILENAME);
 

src/test/java/me/itzg/helpers/modrinth/ModrinthCommandTest.java

@@ -15,6 +15,8 @@
 import com.github.tomakehurst.wiremock.junit5.WireMockExtension;
 import com.github.tomakehurst.wiremock.matching.RequestPatternBuilder;
 import java.nio.file.Path;
+import java.nio.file.Files;
+import java.util.Arrays;
 import java.util.function.Consumer;
 import me.itzg.helpers.LatchingExecutionExceptionHandler;
 import me.itzg.helpers.errors.InvalidParameterException;
@@ -378,6 +380,37 @@ void handlesDatapacksLatestVersion(@TempDir Path tempDir) {
             .hasContent("content of zip");
     }
 
+    @Test
+    void usingListingFile(@TempDir Path tempDir) throws Exception {
+        setupStubs();
+
+        final Path listingFile = Files.write(tempDir.resolve("listing.txt"),
+            Arrays.asList(
+                "fabric-api",
+                "# This is a comment",
+                "cloth-config",
+                "",
+                "# Another comment"
+            )
+        );
+
+        final int exitCode = new CommandLine(
+            new ModrinthCommand()
+        )
+            .execute(
+                "--api-base-url", wm.getRuntimeInfo().getHttpBaseUrl(),
+                "--output-directory", tempDir.toString(),
+                "--game-version", "1.19.2",
+                "--loader", "fabric",
+                "--projects=@" + listingFile
+            );
+
+        assertThat(exitCode).isEqualTo(ExitCode.OK);
+
+        assertThat(tempDir.resolve("mods/fabric-api-0.76.1+1.19.2.jar")).exists();
+        assertThat(tempDir.resolve("mods/cloth-config-8.3.103-fabric.jar")).exists();
+    }
+
     @NotNull
     private static RequestPatternBuilder projectVersionsRequest(String projectId) {
         return getRequestedFor(urlPathEqualTo("/v2/project/" + projectId + "/version"));