Implement unmeta codes

- cited from io.github.izhangzhihao.unmeta

example/build.gradle.kts

@@ -4,5 +4,5 @@ plugins {
 }
 
 unmeta {
-    message.set("Just trying this gradle plugin...")
+    isEnabled.set(true)
 }

gradle/libs.versions.toml

@@ -14,3 +14,5 @@ versionCheck = { id = "com.github.ben-manes.versions", version.ref = "versionChe
 
 [libraries]
 junit = "junit:junit:4.13.2"
+truth = "com.google.truth:truth:1.1.3"
+asm = "org.ow2.asm:asm:9.4"

plugin-build/plugin/build.gradle.kts

@@ -9,8 +9,10 @@ plugins {
 dependencies {
     implementation(kotlin("stdlib"))
     implementation(gradleApi())
+    implementation(libs.asm)
 
     testImplementation(libs.junit)
+    testImplementation(libs.truth)
 }
 
 java {

plugin-build/plugin/src/main/java/com/axzae/unmeta/UnmetaClassVisitor.kt

@@ -0,0 +1,35 @@
+package com.axzae.unmeta
+
+import org.gradle.api.logging.Logger
+import org.objectweb.asm.AnnotationVisitor
+import org.objectweb.asm.ClassVisitor
+import org.objectweb.asm.Opcodes
+
+class UnmetaClassVisitor(
+    private val path: String,
+    classVisitor: ClassVisitor,
+    private val logger: Logger,
+) : ClassVisitor(Opcodes.ASM7, classVisitor), Opcodes {
+
+    var modified = false
+
+    override fun visitAnnotation(desc: String?, visible: Boolean): AnnotationVisitor? {
+        return when (desc) {
+            "Lkotlin/Metadata;" -> {
+                logger.debug("Removed @Metadata annotation from $path")
+                modified = true
+                null
+            }
+
+            "Lkotlin/coroutines/jvm/internal/DebugMetadata;" -> {
+                logger.debug("Removed @DebugMetadata annotation from $path")
+                modified = true
+                null
+            }
+
+            else -> {
+                super.visitAnnotation(desc, visible)
+            }
+        }
+    }
+}

plugin-build/plugin/src/main/java/com/axzae/unmeta/UnmetaExtension.kt

@@ -1,26 +1,16 @@
 package com.axzae.unmeta
 
 import org.gradle.api.Project
-import org.gradle.api.file.RegularFileProperty
 import org.gradle.api.provider.Property
 import javax.inject.Inject
 
-const val DEFAULT_OUTPUT_FILE = "template-example.txt"
+const val DEFAULT_IS_ENABLED = true
 
 @Suppress("UnnecessaryAbstractClass")
 abstract class UnmetaExtension @Inject constructor(project: Project) {
 
     private val objects = project.objects
 
-    // Example of a property that is mandatory. The task will
-    // fail if this property is not set as is annotated with @Optional.
-    val message: Property<String> = objects.property(String::class.java)
-
-    // Example of a property that is optional.
-    val tag: Property<String> = objects.property(String::class.java)
-
-    // Example of a property with a default set with .convention
-    val outputFile: RegularFileProperty = objects.fileProperty().convention(
-        project.layout.buildDirectory.file(DEFAULT_OUTPUT_FILE),
-    )
+    val isEnabled: Property<Boolean> = objects.property(Boolean::class.java)
+        .convention(DEFAULT_IS_ENABLED)
 }

plugin-build/plugin/src/main/java/com/axzae/unmeta/UnmetaPlugin.kt

@@ -8,14 +8,10 @@ const val TASK_NAME = "unmetaTask"
 
 abstract class UnmetaPlugin : Plugin<Project> {
     override fun apply(project: Project) {
-        // Add the 'template' extension object
         val extension = project.extensions.create(EXTENSION_NAME, UnmetaExtension::class.java, project)
 
-        // Add a task that uses configuration from the extension object
         project.tasks.register(TASK_NAME, UnmetaTask::class.java) {
-            it.tag.set(extension.tag)
-            it.message.set(extension.message)
-            it.outputFile.set(extension.outputFile)
+            it.isEnabled = extension.isEnabled.get()
         }
     }
 }

plugin-build/plugin/src/main/java/com/axzae/unmeta/UnmetaTask.kt

@@ -1,14 +1,11 @@
 package com.axzae.unmeta
 
 import org.gradle.api.DefaultTask
-import org.gradle.api.file.RegularFileProperty
 import org.gradle.api.plugins.BasePlugin
-import org.gradle.api.provider.Property
-import org.gradle.api.tasks.Input
-import org.gradle.api.tasks.Optional
-import org.gradle.api.tasks.OutputFile
 import org.gradle.api.tasks.TaskAction
-import org.gradle.api.tasks.options.Option
+import org.objectweb.asm.ClassReader
+import org.objectweb.asm.ClassWriter
+import java.io.File
 
 abstract class UnmetaTask : DefaultTask() {
 
@@ -17,26 +14,29 @@ abstract class UnmetaTask : DefaultTask() {
         group = BasePlugin.BUILD_GROUP
     }
 
-    @get:Input
-    @get:Option(option = "message", description = "A message to be printed in the output file")
-    abstract val message: Property<String>
-
-    @get:Input
-    @get:Option(option = "tag", description = "A Tag to be used for debug and in the output file")
-    @get:Optional
-    abstract val tag: Property<String>
-
-    @get:OutputFile
-    abstract val outputFile: RegularFileProperty
-
     @TaskAction
     fun unmetaAction() {
-        val prettyTag = tag.orNull?.let { "[$it]" } ?: ""
+        if (!isEnabled) {
+            logger.warn("unmeta is disabled")
+            return
+        }
 
-        logger.lifecycle("$prettyTag message is: ${message.orNull}")
-        logger.lifecycle("$prettyTag tag is: ${tag.orNull}")
-        logger.lifecycle("$prettyTag outputFile is: ${outputFile.orNull}")
+        logger.info("Start dropping @Metadata & @DebugMetadata from kotlin classes")
+        project.buildDir.listFiles()?.forEach { file -> if (file.isDirectory) dropMetadata(file) }
+    }
 
-        outputFile.get().asFile.writeText("$prettyTag ${message.get()}")
+    private fun dropMetadata(directory: File) {
+        directory.walk()
+            .filter { it.path.contains("classes") && it.path.endsWith(".class") && it.isFile }
+            .forEach {
+                val sourceClassBytes = it.readBytes()
+                val classReader = ClassReader(sourceClassBytes)
+                val classWriter = ClassWriter(classReader, ClassWriter.COMPUTE_MAXS)
+                val unmetaClassVisitor = UnmetaClassVisitor(it.absolutePath, classWriter, logger)
+                classReader.accept(unmetaClassVisitor, ClassReader.SKIP_DEBUG)
+                if (unmetaClassVisitor.modified) {
+                    it.writeBytes(classWriter.toByteArray())
+                }
+            }
     }
 }

plugin-build/plugin/src/test/java/com/axzae/unmeta/UnmetaPluginTest.kt

@@ -1,10 +1,8 @@
 package com.axzae.unmeta
 
+import com.google.common.truth.Truth.assertThat
 import org.gradle.testfixtures.ProjectBuilder
-import org.junit.Assert.assertEquals
-import org.junit.Assert.assertNotNull
 import org.junit.Test
-import java.io.File
 
 class UnmetaPluginTest {
 
@@ -13,7 +11,7 @@ class UnmetaPluginTest {
         val project = ProjectBuilder.builder().build()
         project.pluginManager.apply("com.axzae.unmeta")
 
-        assert(project.tasks.getByName("unmetaTask") is UnmetaTask)
+        assertThat(project.tasks.getByName("unmetaTask")).isInstanceOf(UnmetaTask::class.java)
     }
 
     @Test
@@ -21,24 +19,18 @@ class UnmetaPluginTest {
         val project = ProjectBuilder.builder().build()
         project.pluginManager.apply("com.axzae.unmeta")
 
-        assertNotNull(project.extensions.getByName("unmeta"))
+        assertThat(project.extensions.getByName("unmeta")).isNotNull()
     }
 
     @Test
     fun `parameters are passed correctly from extension to task`() {
         val project = ProjectBuilder.builder().build()
         project.pluginManager.apply("com.axzae.unmeta")
-        val aFile = File(project.projectDir, ".tmp")
         (project.extensions.getByName("unmeta") as UnmetaExtension).apply {
-            tag.set("a-sample-tag")
-            message.set("just-a-message")
-            outputFile.set(aFile)
+            isEnabled.set(false)
         }
 
         val task = project.tasks.getByName("unmetaTask") as UnmetaTask
-
-        assertEquals("a-sample-tag", task.tag.get())
-        assertEquals("just-a-message", task.message.get())
-        assertEquals(aFile, task.outputFile.get().asFile)
+        assertThat(task.isEnabled).isFalse()
     }
 }