Add Fabric loader version pinning

build.gradle

@@ -13,7 +13,7 @@ apply plugin: 'net.minecraftforge.gradle'
 apply plugin: 'eclipse'
 apply plugin: 'maven-publish'
 
-version = '2.0.1'
+version = '2.1.0'
 group = 'link.infra.jumploader' // http://maven.apache.org/guides/mini/guide-naming-conventions.html
 archivesBaseName = 'jumploader'
 

gradle.properties

@@ -1,3 +1,3 @@
 modGroup=link.infra.jumploader
-modVersion=2.0.1
+modVersion=2.1.0
 modBaseName=jumploader

src/main/java/link/infra/jumploader/ConfigFile.java

@@ -48,6 +48,13 @@ public class ConfigFile {
 	// Call this main class instead of the class determined by the source list
 	@Expose
 	public String overrideMainClass = null;
+	// TODO: Rewrite everything according to https://medium.com/@sdboyer/so-you-want-to-write-a-package-manager-4ae9c17d9527
+	// TODO: - all the metadata can be supplied with modpacks - as long as it's ensured that the files are downloaded from fabricmc/mojang
+	// Use this Fabric loader version, if possible, instead of the latest one
+	// This should be automatically set on first load to the version that is loaded, if it does not already exist
+	// Then, updating the Fabric loader version in a modpack is an explicit action - and is set by the modpack
+	@Expose
+	public String pinFabricLoaderVersion = null;
 
 	// Legacy config file detection
 	@Expose(serialize = false)

src/main/java/link/infra/jumploader/Jumploader.java

@@ -34,7 +34,7 @@
 import java.util.Set;
 
 public class Jumploader implements ITransformationService {
-	public static final String VERSION = "2.0.1";
+	public static final String VERSION = "2.1.0";
 	public static final String USER_AGENT = "Jumploader/" + VERSION;
 
 	private final Logger LOGGER = LogManager.getLogger();

src/main/java/link/infra/jumploader/resolution/sources/FabricJarSource.java

@@ -20,29 +20,32 @@ public class FabricJarSource implements ResolvableJarSource<FabricJarSource.Fabr
 	public static class FabricInvalidationKey implements MetadataCacheHelper.InvalidationKey<FabricInvalidationKey> {
 		public final String gameVersion;
 		public final Side side;
+		public final String pinnedFabricVersion;
 
-		protected FabricInvalidationKey(String gameVersion, Side side) {
+		protected FabricInvalidationKey(String gameVersion, Side side, String pinnedFabricVersion) {
 			this.gameVersion = gameVersion;
 			this.side = side;
+			this.pinnedFabricVersion = pinnedFabricVersion;
 		}
 
 		@Override
 		public boolean isValid(FabricInvalidationKey key) {
-			return equals(key);
+			return equals(key) && key.pinnedFabricVersion != null;
 		}
 
 		@Override
 		public boolean equals(Object o) {
 			if (this == o) return true;
 			if (o == null || getClass() != o.getClass()) return false;
 			FabricInvalidationKey that = (FabricInvalidationKey) o;
-			return gameVersion.equals(that.gameVersion) &&
-				side == that.side;
+			return Objects.equals(gameVersion, that.gameVersion) &&
+				side == that.side &&
+				Objects.equals(pinnedFabricVersion, that.pinnedFabricVersion);
 		}
 
 		@Override
 		public int hashCode() {
-			return Objects.hash(gameVersion, side);
+			return Objects.hash(gameVersion, side, pinnedFabricVersion);
 		}
 	}
 
@@ -84,13 +87,24 @@ public MetadataResolutionResult resolve(MetadataCacheHelper.MetadataCacheView ca
 		FabricMetadata meta;
 		meta = cacheView.getObject("fabric.json", FabricMetadata.class, () -> {
 			try {
-				URL loaderJsonUrl = new URI("https", "meta.fabricmc.net", "/v2/versions/loader/" + gameVersion, null).toURL();
-				JsonArray manifestData = RequestUtils.getJson(loaderJsonUrl).getAsJsonArray();
-				if (manifestData.size() == 0) {
-					throw new IOException("Failed to update configuration: no Fabric versions available!");
+				JsonObject latestLoaderData;
+				if (ctx.getConfigFile().pinFabricLoaderVersion != null) {
+					URL loaderJsonUrl = new URI("https", "meta.fabricmc.net", "/v2/versions/loader/" + gameVersion + "/" + ctx.getConfigFile().pinFabricLoaderVersion, null).toURL();
+					latestLoaderData = RequestUtils.getJson(loaderJsonUrl).getAsJsonObject();
+				} else {
+					URL loaderJsonUrl = new URI("https", "meta.fabricmc.net", "/v2/versions/loader/" + gameVersion, null).toURL();
+					JsonArray manifestData = RequestUtils.getJson(loaderJsonUrl).getAsJsonArray();
+					if (manifestData.size() == 0) {
+						throw new IOException("Failed to update configuration: no Fabric versions available!");
+					}
+					latestLoaderData = manifestData.get(0).getAsJsonObject();
+				}
+
+				if (ctx.getConfigFile().pinFabricLoaderVersion == null) {
+					ctx.getConfigFile().pinFabricLoaderVersion = latestLoaderData.getAsJsonObject("loader").get("version").getAsString();
+					ctx.getConfigFile().save();
 				}
 
-				JsonObject latestLoaderData = manifestData.get(0).getAsJsonObject();
 				JsonObject launcherMeta = latestLoaderData.getAsJsonObject("launcherMeta");
 				JsonObject mainClass = launcherMeta.getAsJsonObject("mainClass");
 
@@ -152,6 +166,6 @@ public Class<FabricInvalidationKey> getInvalidationKeyType() {
 
 	@Override
 	public FabricInvalidationKey getInvalidationKey(ResolutionContext ctx) {
-		return new FabricInvalidationKey(ctx.getLoadingVersion(), ctx.getLoadingSide());
+		return new FabricInvalidationKey(ctx.getLoadingVersion(), ctx.getLoadingSide(), ctx.getConfigFile().pinFabricLoaderVersion);
 	}
 }

src/main/resources/fabric.mod.json

@@ -1,7 +1,7 @@
 {
   "schemaVersion": 1,
   "id": "jumploader",
-  "version": "2.0.1",
+  "version": "2.1.0",
 
   "name": "Jumploader",
   "description": "Allows the use of Fabric mods in Twitch modpacks, by loading Fabric as if it were a Forge mod.",