Add a Metro DSL in buildSrc

This DSL allows App Platform modules to enable Metro, e.g. `:renderer:public` will use this DSL. There will be separate PR for the DSL in our published Gradle plugin.

See #109

Author: vRallev

buildSrc/build.gradle

@@ -77,6 +77,7 @@ dependencies {
     implementation libs.kotlin.hierarchy.plugin
     implementation libs.ktfmt.gradle.plugin
     implementation libs.maven.publish.gradle.plugin
+    implementation libs.metro.gradle.plugin
     implementation libs.detekt.gradle.plugin
     implementation "$GROUP:gradle-plugin:$VERSION_NAME"
 }

buildSrc/src/main/kotlin/software/amazon/app/platform/gradle/buildsrc/AppPlatformExtension.kt

@@ -8,6 +8,7 @@ import software.amazon.app.platform.gradle.AppPlatformExtension as AppPlatformEx
 import software.amazon.app.platform.gradle.buildsrc.BaseAndroidPlugin.Companion.enableInstrumentedTests
 import software.amazon.app.platform.gradle.buildsrc.KmpPlugin.Companion.enableCompose
 import software.amazon.app.platform.gradle.buildsrc.KmpPlugin.Companion.enableKotlinInject
+import software.amazon.app.platform.gradle.buildsrc.KmpPlugin.Companion.enableMetro
 import software.amazon.app.platform.gradle.buildsrc.KmpPlugin.Companion.enableMolecule
 import software.amazon.app.platform.gradle.buildsrc.SdkPlugin.publishSdk
 
@@ -43,6 +44,20 @@ constructor(objects: ObjectFactory, private val project: Project) {
 
   internal fun isKotlinInjectEnabled(): Property<Boolean> = enableKotlinInject
 
+  private val enableMetro: Property<Boolean> =
+    objects.property(Boolean::class.java).convention(false)
+
+  public fun enableMetro(enabled: Boolean) {
+    enableMetro.set(enabled)
+    enableMetro.disallowChanges()
+
+    if (enabled) {
+      project.enableMetro()
+    }
+  }
+
+  internal fun isMetroEnabled(): Property<Boolean> = enableMetro
+
   private val enableMolecule: Property<Boolean> =
     objects.property(Boolean::class.java).convention(false)
 

buildSrc/src/main/kotlin/software/amazon/app/platform/gradle/buildsrc/KmpPlugin.kt

@@ -178,7 +178,7 @@ public open class KmpPlugin : Plugin<Project> {
     }
 
     fun Project.enableKotlinInject() {
-      plugins.apply(Plugins.KSP)
+      enableKsp()
 
       val kspExtension = extensions.getByType(KspExtension::class.java)
 
@@ -189,12 +189,6 @@ public open class KmpPlugin : Plugin<Project> {
         "disabled",
       )
 
-      tasks.withType(KspTask::class.java).configureEach { kspTask ->
-        if (kspTask is KotlinCompile) {
-          kspTask.compilerOptions.jvmTarget.set(javaTarget)
-        }
-      }
-
       if (isKmpModule) {
         kmpExtension.sourceSets.getByName("commonMain").dependencies {
           implementation(libs.findLibrary("kotlin.inject.runtime").get().get().toString())
@@ -269,6 +263,47 @@ public open class KmpPlugin : Plugin<Project> {
       }
     }
 
+    fun Project.enableMetro() {
+      plugins.apply(Plugins.METRO)
+
+      // Enable KSP for our custom extensions.
+      enableKsp()
+
+      if (isKmpModule) {
+        kmpExtension.sourceSets.getByName("commonMain").dependencies {
+          implementation(project(":di-common:public"))
+          implementation(project(":metro:public"))
+        }
+      } else {
+        dependencies.add("implementation", project(":metro:public"))
+      }
+
+      fun DependencyHandler.addKspProcessorDependencies(kspConfigurationName: String) {
+        add(kspConfigurationName, project(":metro-extensions:contribute:impl-code-generators"))
+      }
+
+      if (isKmpModule) {
+        kmpExtension.targets.configureEach {
+          if (it.name != "metadata") {
+            dependencies.addKspProcessorDependencies("ksp${it.name.capitalize()}")
+            dependencies.addKspProcessorDependencies("ksp${it.name.capitalize()}Test")
+          }
+        }
+      } else {
+        dependencies.addKspProcessorDependencies("ksp")
+      }
+    }
+
+    private fun Project.enableKsp() {
+      plugins.apply(Plugins.KSP)
+
+      tasks.withType(KspTask::class.java).configureEach { kspTask ->
+        if (kspTask is KotlinCompile) {
+          kspTask.compilerOptions.jvmTarget.set(javaTarget)
+        }
+      }
+    }
+
     fun Project.enableMolecule() {
       plugins.apply(Plugins.COMPOSE_COMPILER)
       kmpExtension.sourceSets.getByName("commonMain").dependencies {

buildSrc/src/main/kotlin/software/amazon/app/platform/gradle/buildsrc/Plugins.kt

@@ -14,4 +14,5 @@ internal object Plugins {
   const val KSP = "com.google.devtools.ksp"
   const val KTFMT = "com.ncorti.ktfmt.gradle"
   const val MAVEN_PUBLISH = "com.vanniktech.maven.publish"
+  const val METRO = "dev.zacsweers.metro"
 }