GH-481 Add Quilt loader support

... with a caveat that it may break in future due to Quilt's broken
metadata

launcher-builder/src/main/java/com/skcraft/launcher/builder/PackageBuilder.java

@@ -168,7 +168,9 @@ public class PackageBuilder {
                     processor = new ModernForgeLoaderProcessor();
                 }
             } else if (BuilderUtils.getZipEntry(jarFile, "fabric-installer.json") != null) {
-            	processor = new FabricLoaderProcessor();
+            	processor = new FabricLoaderProcessor(FabricLoaderProcessor.Variant.FABRIC);
+            } else if (BuilderUtils.getZipEntry(jarFile, "quilt_installer.json") != null) {
+                processor = new FabricLoaderProcessor(FabricLoaderProcessor.Variant.QUILT);
             }
         } finally {
             closer.close();
@@ -205,8 +207,8 @@ public class PackageBuilder {
                     Files.createParentDirs(outputPath);
                     boolean found = false;
 
-                    // Try just the URL, it might be a full URL to the file
-                    if (!artifact.getUrl().isEmpty()) {
+                    // If URL doesn't end with a /, it might be the direct file
+                    if (!artifact.getUrl().endsWith("/")) {
                         found = tryDownloadLibrary(library, artifact, artifact.getUrl(), outputPath);
                     }
 
@@ -261,7 +263,9 @@ public class PackageBuilder {
 
         try {
             log.info("Downloading library " + library.getName() + " from " + url + "...");
-            HttpRequest.get(url).execute().expectResponseCode(200).saveContent(tempFile);
+            HttpRequest.get(url).execute().expectResponseCode(200)
+                    .expectContentType("application/java-archive", "application/octet-stream")
+                    .saveContent(tempFile);
         } catch (IOException e) {
             log.info("Could not get file from " + url + ": " + e.getMessage());
             return false;

launcher-builder/src/main/java/com/skcraft/launcher/builder/loaders/FabricLoaderProcessor.java

@@ -4,10 +4,13 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.io.Closer;
 import com.skcraft.launcher.builder.BuilderUtils;
 import com.skcraft.launcher.model.loader.FabricMod;
+import com.skcraft.launcher.model.loader.QuiltMod;
+import com.skcraft.launcher.model.loader.Versionable;
 import com.skcraft.launcher.model.minecraft.Library;
 import com.skcraft.launcher.model.minecraft.VersionManifest;
 import com.skcraft.launcher.model.modpack.Manifest;
 import com.skcraft.launcher.util.HttpRequest;
+import lombok.RequiredArgsConstructor;
 import lombok.extern.java.Log;
 
 import java.io.File;
@@ -18,7 +21,10 @@ import java.util.jar.JarFile;
 import java.util.zip.ZipEntry;
 
 @Log
+@RequiredArgsConstructor
 public class FabricLoaderProcessor implements ILoaderProcessor {
+	private final Variant variant;
+
 	@Override
 	public LoaderResult process(File loaderJar, Manifest manifest, ObjectMapper mapper, File baseDir) throws IOException {
 		JarFile jarFile = new JarFile(loaderJar);
@@ -26,24 +32,23 @@ public class FabricLoaderProcessor implements ILoaderProcessor {
 		Closer closer = Closer.create();
 
 		try {
-			String loaderVersion;
+			Versionable loaderMod;
 
-			ZipEntry modEntry = BuilderUtils.getZipEntry(jarFile, "fabric.mod.json");
+			ZipEntry modEntry = BuilderUtils.getZipEntry(jarFile, variant.modJsonName);
 			if (modEntry != null) {
 				InputStreamReader reader = new InputStreamReader(jarFile.getInputStream(modEntry));
-				FabricMod loaderMod = mapper.readValue(
-						BuilderUtils.readStringFromStream(closer.register(reader)), FabricMod.class);
 
-				loaderVersion = loaderMod.getVersion();
+				loaderMod = mapper.readValue(
+						BuilderUtils.readStringFromStream(closer.register(reader)), variant.mappedClass);
 			} else {
-				log.warning("Fabric loader has no 'fabric.mod.json' file, is it really a Fabric Loader jar?");
+				log.warning(String.format("%s loader has no '%s' file, is it really a %s Loader jar?",
+						variant.friendlyName, variant.modJsonName, variant.friendlyName));
 				return null;
 			}
 
-			log.info("Downloading fabric metadata...");
+			log.info(String.format("Downloading %s metadata...", variant.friendlyName));
 			URL metaUrl = HttpRequest.url(
-					String.format("https://meta.fabricmc.net/v2/versions/loader/%s/%s/profile/json",
-							manifest.getGameVersion(), loaderVersion));
+					String.format(variant.metaUrl, manifest.getGameVersion(), loaderMod.getVersion()));
 			VersionManifest fabricManifest = HttpRequest.get(metaUrl)
 					.execute()
 					.expectResponseCode(200)
@@ -51,6 +56,20 @@ public class FabricLoaderProcessor implements ILoaderProcessor {
 					.asJson(VersionManifest.class);
 
 			for (Library library : fabricManifest.getLibraries()) {
+				// To quote a famous comment: "And here we come upon a sad state of affairs."
+				// Quilt's meta API returns broken data about how to launch the game. It specifies its own incomplete
+				// and ultimately broken set of intermediary mappings called "hashed". If the loader finds "hashed" in
+				// the classpath it tries to use it and blows up because it doesn't work.
+				// We work around this here by just throwing the hashed library out - they do now at least specify
+				// fabric's intermediary mappings in the library list, which DO work.
+				// Historical note: previously they didn't do this! Every launcher that added Quilt support had to add
+				// a hack that replaced hashed with intermediary! This is a lot of technical debt that is gonna come
+				// back to bite them in the ass later, because it's all still there!
+				// TODO pester Quilt again about fixing this....
+				if (library.getName().startsWith("org.quiltmc:hashed") && loaderMod instanceof QuiltMod) {
+					continue;
+				}
+
 				result.getLoaderLibraries().add(library);
 				log.info("Adding loader library " + library.getName());
 			}
@@ -61,7 +80,8 @@ public class FabricLoaderProcessor implements ILoaderProcessor {
 				log.info("Using main class " + mainClass);
 			}
 		} catch (InterruptedException e) {
-			log.warning("HTTP request to fabric metadata API was interrupted, this will probably not work!");
+			log.warning(String.format("HTTP request to %s metadata API was interrupted!", variant.friendlyName));
+			throw new IOException(e);
 		} finally {
 			closer.close();
 			jarFile.close();
@@ -69,4 +89,15 @@ public class FabricLoaderProcessor implements ILoaderProcessor {
 
 		return result;
 	}
+
+	@RequiredArgsConstructor
+	public enum Variant {
+		FABRIC("Fabric", "fabric.mod.json", "https://meta.fabricmc.net/v2/versions/loader/%s/%s/profile/json", FabricMod.class),
+		QUILT("Quilt", "quilt.mod.json", "https://meta.quiltmc.org/v3/versions/loader/%s/%s/profile/json", QuiltMod.class);
+
+		private final String friendlyName;
+		private final String modJsonName;
+		private final String metaUrl;
+		private final Class<? extends Versionable> mappedClass;
+	}
 }

launcher/src/main/java/com/skcraft/launcher/model/loader/FabricMod.java

@@ -5,7 +5,7 @@ import lombok.Data;
 
 @Data
 @JsonIgnoreProperties(ignoreUnknown = true)
-public class FabricMod {
+public class FabricMod implements Versionable {
 	private String id;
 	private String name;
 	private String version;

launcher/src/main/java/com/skcraft/launcher/model/loader/QuiltMod.java

@@ -0,0 +1,29 @@
+package com.skcraft.launcher.model.loader;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import lombok.Data;
+
+@Data
+@JsonIgnoreProperties(ignoreUnknown = true)
+public class QuiltMod implements Versionable {
+	@JsonProperty("schema_version")
+	private int schemaVersion;
+
+	@JsonProperty("quilt_loader")
+	private Mod meta;
+
+	@Override
+	public String getVersion() {
+		return meta.getVersion();
+	}
+
+	@Data
+	@JsonIgnoreProperties(ignoreUnknown = true)
+	public static class Mod {
+		private String version;
+
+		@JsonProperty("intermediate_mappings")
+		private String intermediateMappings;
+	}
+}

launcher/src/main/java/com/skcraft/launcher/model/loader/Versionable.java

@@ -0,0 +1,5 @@
+package com.skcraft.launcher.model.loader;
+
+public interface Versionable {
+	String getVersion();
+}

launcher/src/main/java/com/skcraft/launcher/util/HttpRequest.java

@@ -232,6 +232,28 @@ public class HttpRequest implements Closeable, ProgressObservable {
         throw exc;
     }
 
+    /**
+     * Continue if the content type matches, otherwise throw an exception
+     *
+     * @param expectedTypes Expected content-type(s)
+     * @return this object
+     * @throws IOException Unexpected content-type or other error
+     */
+    public HttpRequest expectContentType(String... expectedTypes) throws IOException {
+        if (conn == null) throw new IllegalArgumentException("No connection has been made!");
+
+        String contentType = conn.getHeaderField("Content-Type");
+        for (String expectedType : expectedTypes) {
+            if (expectedType.equals(contentType)) {
+                return this;
+            }
+        }
+
+        close();
+        throw new IOException(String.format("Did not get expected content type '%s', instead got '%s'.",
+                String.join(" | ", expectedTypes), contentType));
+    }
+
     /**
      * Get the response code.
      *