modrinth: prioritize target loader when resolving project versions

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

@@ -7,6 +7,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
@@ -181,31 +182,56 @@ public Mono<Path> downloadMrPack(VersionFile versionFile) {
     public Mono<List<Version>> getVersionsForProject(String projectIdOrSlug,
                                                      @Nullable Loader loader, String gameVersion
     ) {
-        return sharedFetch.fetch(
-                uriBuilder.resolve("/v2/project/{id|slug}/version",
-                    queryParameters()
-                        .addStringArray("loaders", expandCompatibleLoaders(loader))
-                        .addStringArray("game_versions", gameVersion),
-                    projectIdOrSlug
+        return getJustVersionsForProject(projectIdOrSlug, gameVersion,
+            loader != null ? Collections.singletonList(loader.toString()) : null,
+            false
+        )
+            .switchIfEmpty(
+                getJustVersionsForProject(projectIdOrSlug, gameVersion,
+                    expandCompatibleLoaders(loader),
+                    true
                 )
             )
-            .toObjectList(Version.class)
-            .assemble()
-            .flatMap(versions ->
-                versions.isEmpty() ?
-                    getProject(projectIdOrSlug)
-                        .flatMap(project -> Mono.error(new NoFilesAvailableException(project, loader, gameVersion)))
-                    : Mono.just(versions)
-                );
+            .switchIfEmpty(
+                getProject(projectIdOrSlug)
+                    .flatMap(project -> Mono.error(new NoFilesAvailableException(project, loader, gameVersion)))
+            );
+    }
+
+    /**
+     * @return the non-empty list of versions or an empty mono
+     */
+    private Mono<List<Version>> getJustVersionsForProject(
+        String projectIdOrSlug, String gameVersion,
+        Collection<String> loaderNames,
+        boolean skipEmptyLoaders
+    ) {
+        return
+            skipEmptyLoaders && (loaderNames == null || loaderNames.isEmpty()) ?
+                Mono.empty() :
+                sharedFetch.fetch(
+                        uriBuilder.resolve("/v2/project/{id|slug}/version",
+                            queryParameters()
+                                .addStringArray("loaders", loaderNames)
+                                .addStringArray("game_versions", gameVersion),
+                            projectIdOrSlug
+                        )
+                    )
+                    .toObjectList(Version.class)
+                    .assemble()
+                    .filter(versions -> !versions.isEmpty());
     }
 
+    /**
+     * @param loader the target loader
+     * @return a list of the compatible loaders
+     */
     private List<String> expandCompatibleLoaders(@Nullable Loader loader) {
         if (loader == null) {
             return null;
         }
 
         final ArrayList<String> expanded = new ArrayList<>();
-        expanded.add(loader.toString());
         Loader compatibleWith = loader;
         while ((compatibleWith = compatibleWith.getCompatibleWith()) != null) {
             expanded.add(compatibleWith.toString());

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

@@ -45,33 +45,75 @@ void getBulkProjectsWithUnknownServerSide(WireMockRuntimeInfo wmInfo) {
         }
     }
 
-    @Test
-    void getVersionsForProject(WireMockRuntimeInfo wmInfo) {
-
-        stubFor(get(urlPathMatching("/v2/project/(BITzwT7B|clickvillagers)/version"))
-            .withQueryParam("loaders", equalTo("[\"purpur\",\"paper\",\"spigot\"]"))
-            .withQueryParam("game_versions", equalTo("[\"1.20.1\"]"))
-            .willReturn(aResponse()
-                .withHeader("Content-Type", "application/json")
-                .withBodyFile("modrinth/project-BITzwT7B-version-resp.json")
-            )
-        );
+    @Nested
+    class getVersionsForProject {
+        @Test
+        void exactLoader(WireMockRuntimeInfo wmInfo) {
 
-        try (ModrinthApiClient client = new ModrinthApiClient(wmInfo.getHttpBaseUrl(), "modrinth", Options.builder().build())) {
-            final List<Version> result = client.getVersionsForProject("BITzwT7B", Loader.purpur, "1.20.1")
-                .block();
+            stubFor(get(urlPathMatching("/v2/project/(BITzwT7B|clickvillagers)/version"))
+                .withQueryParam("loaders", equalTo("[\"purpur\"]"))
+                .withQueryParam("game_versions", equalTo("[\"1.20.1\"]"))
+                .willReturn(aResponse()
+                    .withHeader("Content-Type", "application/json")
+                    .withBodyFile("modrinth/project-BITzwT7B-version-resp.json")
+                )
+            );
+
+            try (ModrinthApiClient client = new ModrinthApiClient(wmInfo.getHttpBaseUrl(), "modrinth", Options.builder().build())) {
+                final List<Version> result = client.getVersionsForProject("BITzwT7B", Loader.purpur, "1.20.1")
+                    .block();
+
+                assertThat(result)
+                    .hasSize(3)
+                    .extracting(Version::getId)
+                    .containsExactly(
+                        "O9nndrTu",
+                        "DfUyEmsH",
+                        "oUJMLDhz"
+                    );
+            }
+        }
+
+        @Test
+        void fallbackToCompatibleLoader(WireMockRuntimeInfo wmInfo) {
+            stubFor(get(urlPathMatching("/v2/project/entityculling/version"))
+                .withQueryParam("loaders", equalTo("[\"neoforge\"]"))
+                .withQueryParam("game_versions", equalTo("[\"1.12.2\"]"))
+                .willReturn(aResponse()
+                    .withHeader("Content-Type", "application/json")
+                    .withBodyFile("modrinth/versions-entityculling-neoforge-not-forge.json")
+                )
+            );
+            stubFor(get(urlPathMatching("/v2/project/entityculling/version"))
+                .withQueryParam("loaders", equalTo("[\"forge\"]"))
+                .withQueryParam("game_versions", equalTo("[\"1.12.2\"]"))
+                .willReturn(aResponse()
+                    .withHeader("Content-Type", "application/json")
+                    .withBodyFile("modrinth/versions-entityculling-forge.json")
+                )
+            );
 
-            assertThat(result)
-                .hasSize(3)
-                .extracting(Version::getId)
-                .containsExactly(
-                    "O9nndrTu",
-                    "DfUyEmsH",
-                    "oUJMLDhz"
-                );
+            try (ModrinthApiClient client = new ModrinthApiClient(wmInfo.getHttpBaseUrl(), "modrinth",
+                Options.builder().build()
+            )) {
+                final List<Version> result = client.getVersionsForProject(
+                        "entityculling",
+                        Loader.neoforge,
+                        "1.12.2"
+                    )
+                    .block();
+
+                assertThat(result)
+                    .extracting(Version::getId)
+                    .containsExactly(
+                        "knltv3Vh"
+                    );
+            }
         }
     }
 
+
+
     @Nested
     class resolveProjectVersion {
 
@@ -142,7 +184,7 @@ void noFiles(WireMockRuntimeInfo wmInfo) {
         @Test
         void noApplicableVersionsOfType(WireMockRuntimeInfo wmInfo) {
             stubFor(get(urlPathMatching("/v2/project/(3wmN97b8|multiverse-core)/version"))
-                .withQueryParam("loaders", equalTo("[\"purpur\",\"paper\",\"spigot\"]"))
+                .withQueryParam("loaders", equalTo("[\"purpur\"]"))
                 .withQueryParam("game_versions", equalTo("[\"1.21.1\"]"))
                 .willReturn(aResponse()
                     .withHeader("Content-Type", "application/json")

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

@@ -14,8 +14,8 @@
 import com.github.tomakehurst.wiremock.extension.responsetemplating.ResponseTemplateTransformer;
 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.nio.file.Path;
 import java.util.Arrays;
 import java.util.function.Consumer;
 import me.itzg.helpers.LatchingExecutionExceptionHandler;
@@ -167,7 +167,8 @@ void failsWhenNoDependenciesForModLoader(@TempDir Path tempDir) throws JsonProce
                 .put("project_id", requiredDepProjectId)
                 .put("dependency_type", "required");
         });
-        stubVersionRequestEmptyResponse(requiredDepProjectId);
+        stubVersionRequestEmptyResponse(requiredDepProjectId, "paper");
+        stubVersionRequestEmptyResponse(requiredDepProjectId, "spigot");
         stubGetProject(requiredDepProjectId, new Project().setProjectType(ProjectType.resourcepack));
 
         stubDownload();
@@ -462,7 +463,7 @@ private void stubVersionRequest(String projectId, String versionId, Consumer<Arr
         depsAdder.accept(dependenciesArray);
 
         stubFor(get(urlPathEqualTo("/v2/project/" + projectId + "/version"))
-            .withQueryParam("loaders", equalTo("[\"paper\",\"spigot\"]"))
+            .withQueryParam("loaders", equalTo("[\"paper\"]"))
             .withQueryParam("game_versions", equalTo("[\"1.21.1\"]"))
             .willReturn(aResponse()
                 .withHeader("Content-Type", "application/json")
@@ -471,11 +472,11 @@ private void stubVersionRequest(String projectId, String versionId, Consumer<Arr
         );
     }
 
-    private void stubVersionRequestEmptyResponse(String projectId) {
+    private void stubVersionRequestEmptyResponse(String projectId, String loader) {
         final ArrayNode versionResp = objectMapper.createArrayNode();
 
         stubFor(get(urlPathEqualTo("/v2/project/" + projectId + "/version"))
-            .withQueryParam("loaders", equalTo("[\"paper\",\"spigot\"]"))
+            .withQueryParam("loaders", equalTo("[\"" + loader + "\"]"))
             .withQueryParam("game_versions", equalTo("[\"1.21.1\"]"))
             .willReturn(aResponse()
                 .withHeader("Content-Type", "application/json")

src/test/resources/__files/modrinth/versions-entityculling-forge.json

@@ -0,0 +1,44 @@
+[
+  {
+    "game_versions": [
+      "1.12.2"
+    ],
+    "loaders": [
+      "forge"
+    ],
+    "id": "knltv3Vh",
+    "project_id": "NNAgCjsB",
+    "author_id": "Qnt13hO8",
+    "featured": false,
+    "name": "1.6.3-1.12.2 - Forge",
+    "version_number": "1.6.3-1.12.2",
+    "changelog": "Initial backport to 1.12.2.",
+    "changelog_url": null,
+    "date_published": "2024-03-09T20:04:35.562295Z",
+    "downloads": 293074,
+    "version_type": "release",
+    "status": "listed",
+    "requested_status": null,
+    "files": [
+      {
+        "hashes": {
+          "sha512": "97c4def2a2979a0ba61c0fb016762756cf8361cdff651558dbb91cbe3d8627c388436d31ec2b93ff62df99a7ff589033184db4e6f298f4b8fdd4acf4c83ba202",
+          "sha1": "fb22f03b297ca7b1bb7c6d5948e46c12e0a24446"
+        },
+        "url": "https://cdn.modrinth.com/data/NNAgCjsB/versions/knltv3Vh/entityculling-1.12.2-1.6.3.jar",
+        "filename": "entityculling-1.12.2-1.6.3.jar",
+        "primary": true,
+        "size": 41478,
+        "file_type": null
+      }
+    ],
+    "dependencies": [
+      {
+        "version_id": null,
+        "project_id": "G1ckZuWK",
+        "file_name": null,
+        "dependency_type": "required"
+      }
+    ]
+  }
+]

src/test/resources/__files/modrinth/versions-entityculling-neoforge-not-forge.json

@@ -0,0 +1 @@
+[]