Copy over WriteManifest task (unused for now)

Author: Jonathing

src/main/groovy/net/minecraftforge/gradleutils/WriteManifest.java

@@ -0,0 +1,75 @@
+package net.minecraftforge.gradleutils;
+
+import org.gradle.api.DefaultTask;
+import org.gradle.api.file.DuplicatesStrategy;
+import org.gradle.api.file.ProjectLayout;
+import org.gradle.api.file.RegularFileProperty;
+import org.gradle.api.java.archives.internal.ManifestInternal;
+import org.gradle.api.plugins.JavaPluginExtension;
+import org.gradle.api.provider.Property;
+import org.gradle.api.tasks.Input;
+import org.gradle.api.tasks.OutputFile;
+import org.gradle.api.tasks.SourceSet;
+import org.gradle.api.tasks.TaskAction;
+import org.gradle.api.tasks.TaskProvider;
+import org.gradle.jvm.tasks.Jar;
+import org.gradle.language.jvm.tasks.ProcessResources;
+import org.jetbrains.annotations.ApiStatus;
+
+import javax.inject.Inject;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.file.Files;
+
+@ApiStatus.Internal
+@ApiStatus.Experimental
+public abstract class WriteManifest extends DefaultTask implements GradleUtilsTask {
+    protected abstract @Input Property<byte[]> getInputBytes();
+    protected abstract @OutputFile RegularFileProperty getOutput();
+
+    protected abstract @Inject ProjectLayout getLayout();
+
+    @Inject
+    public WriteManifest(TaskProvider<? extends Jar> jar) {
+        // The output name is ALWAYS "MANIFEST.MF", and output cannot be changed
+        this.getOutput().value(getLayout().getBuildDirectory().file(this.getName() + "/MANIFEST.MF")).disallowChanges();
+
+        var tasks = getProject().getTasks();
+        var sourceSet = findSourceSet(jar.getName());
+
+        tasks.named(sourceSet.getProcessResourcesTaskName(), ProcessResources.class, processResources -> {
+            processResources.dependsOn(this);
+            processResources.from(this, copy -> {
+                copy.into("META-INF");
+                copy.setDuplicatesStrategy(DuplicatesStrategy.INCLUDE);
+            });
+        });
+
+        afterEvaluate(project -> {
+            try (var os = new ByteArrayOutputStream()) {
+                // RATIONALE: ManifestInternal has not changed since Gradle 2.14
+                // Due to the hacky nature of needing the proper manifest in the resources, this is the only good way of doing this
+                // The DefaultManifest object cannot be serialized into the Gradle cache, and the normal Manifest interface does not have this method
+                // This should be the only Gradle internals we need to use in all of ForgeDev, thankfully
+                ((ManifestInternal) jar.get().getManifest()).writeTo(os);
+                this.getInputBytes().value(os.toByteArray()).finalizeValue();
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+        });
+    }
+
+    @TaskAction
+    protected void exec() throws IOException {
+        Files.write(
+            this.getOutput().getAsFile().get().toPath(),
+            this.getInputBytes().get()
+        );
+    }
+
+    private SourceSet findSourceSet(String jarTaskName) {
+        var java = getProject().getExtensions().getByType(JavaPluginExtension.class);
+        var candidates = java.getSourceSets().matching(sourceSet -> sourceSet.getJarTaskName().equals(jarTaskName)).iterator();
+        return candidates.hasNext() ? candidates.next() : java.getSourceSets().getByName(SourceSet.MAIN_SOURCE_SET_NAME);
+    }
+}