Support Kotlin JS targets in Compose Gradle plugin

gradle-plugins/buildSrc/src/main/kotlin/BuildProperties.kt

@@ -17,4 +17,6 @@ object BuildProperties {
     fun deployVersion(project: Project): String =
         System.getenv("COMPOSE_GRADLE_PLUGIN_VERSION")
             ?: project.findProperty("deploy.version") as String
+    fun isComposeWithWeb(project: Project): Boolean =
+        project.findProperty("compose.with.web") == "true"
 }

gradle-plugins/compose/build.gradle.kts

@@ -25,6 +25,7 @@ buildConfig {
     packageName = "org.jetbrains.compose"
     clsName = "ComposeBuildConfig"
     buildConfigField("String", "composeVersion", BuildProperties.composeVersion(project))
+    buildConfigField("Boolean", "isComposeWithWeb", BuildProperties.isComposeWithWeb(project).toString())
 }
 
 val embedded by configurations.creating

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/ComposeCompilerKotlinSupportPlugin.kt

@@ -6,23 +6,48 @@
 package org.jetbrains.compose
 
 import org.gradle.api.provider.Provider
+import org.jetbrains.compose.internal.webExt
 import org.jetbrains.kotlin.gradle.plugin.*
+import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsIrTarget
 
 class ComposeCompilerKotlinSupportPlugin : KotlinCompilerPluginSupportPlugin {
     override fun getCompilerPluginId(): String =
-        "org.jetbrains.compose"
+        "androidx.compose.compiler.plugins.kotlin"
 
-    override fun isApplicable(kotlinCompilation: KotlinCompilation<*>): Boolean {
-        val targetPlatform = kotlinCompilation.target.platformType
-        return targetPlatform != KotlinPlatformType.js
-                && targetPlatform != KotlinPlatformType.native
-    }
+    override fun isApplicable(kotlinCompilation: KotlinCompilation<*>): Boolean =
+        when (kotlinCompilation.target.platformType) {
+            KotlinPlatformType.common -> true
+            KotlinPlatformType.jvm -> true
+            KotlinPlatformType.js -> isApplicableJsTarget(kotlinCompilation.target)
+            KotlinPlatformType.androidJvm -> true
+            KotlinPlatformType.native -> false
+        }
 
-    override fun applyToCompilation(kotlinCompilation: KotlinCompilation<*>): Provider<List<SubpluginOption>> =
-        kotlinCompilation.target.project.provider { emptyList() }
+    override fun applyToCompilation(kotlinCompilation: KotlinCompilation<*>): Provider<List<SubpluginOption>> {
+        val target = kotlinCompilation.target
+        return target.project.provider {
+            platformPluginOptions[target.platformType] ?: emptyList()
+        }
+    }
 
     override fun getPluginArtifact(): SubpluginArtifact =
         SubpluginArtifact(
             groupId = "org.jetbrains.compose.compiler", artifactId = "compiler", version = composeVersion
         )
+
+    private fun isApplicableJsTarget(kotlinTarget: KotlinTarget): Boolean {
+        if (kotlinTarget !is KotlinJsIrTarget) return false
+
+        val project = kotlinTarget.project
+        val webExt = project.webExt ?: return false
+
+        return kotlinTarget in webExt.targetsToConfigure(project)
+    }
+
+    private val platformPluginOptions = mapOf(
+        KotlinPlatformType.js to options("generateDecoys" to "true")
+    )
+
+    private fun options(vararg options: Pair<String, String>): List<SubpluginOption> =
+        options.map { SubpluginOption(it.first, it.second) }
 }

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/ComposePlugin.kt

@@ -16,6 +16,7 @@ import org.jetbrains.compose.desktop.DesktopExtension
 import org.jetbrains.compose.desktop.application.internal.configureApplicationImpl
 import org.jetbrains.compose.desktop.application.internal.currentTarget
 import org.jetbrains.compose.desktop.preview.internal.initializePreview
+import org.jetbrains.compose.web.internal.initializeWeb
 import org.jetbrains.kotlin.gradle.plugin.KotlinDependencyHandler
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
@@ -37,8 +38,11 @@ class ComposePlugin : Plugin<Project> {
         }
 
         project.initializePreview()
+        if (ComposeBuildConfig.isComposeWithWeb) {
+            project.initializeWeb(composeExtension)
+        }
 
-        project.pluginManager.apply(ComposeCompilerKotlinSupportPlugin::class.java)
+        project.plugins.apply(ComposeCompilerKotlinSupportPlugin::class.java)
 
         project.afterEvaluate {
             if (desktopExtension._isApplicationInitialized) {
@@ -112,6 +116,9 @@ class ComposePlugin : Plugin<Project> {
         val runtime get() = composeDependency("org.jetbrains.compose.runtime:runtime")
         val ui get() = composeDependency("org.jetbrains.compose.ui:ui")
         val materialIconsExtended get() = composeDependency("org.jetbrains.compose.material:material-icons-extended")
+        val web: WebDependencies =
+            if (ComposeBuildConfig.isComposeWithWeb) WebDependencies
+            else error("This version of Compose plugin does not support 'compose.web.*' dependencies")
     }
 
     object DesktopDependencies {
@@ -141,6 +148,12 @@ class ComposePlugin : Plugin<Project> {
             composeDependency("org.jetbrains.compose.desktop:desktop-jvm-${currentTarget.id}")
         }
     }
+
+    object WebDependencies {
+        val web by lazy {
+            composeDependency("org.jetbrains.compose.web:web")
+        }
+    }
 }
 
 fun KotlinDependencyHandler.compose(groupWithArtifact: String) = composeDependency(groupWithArtifact)

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/internal/projectExtensions.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2020-2021 JetBrains s.r.o. and respective authors and developers.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE.txt file.
+ */
+
+package org.jetbrains.compose.internal
+
+import org.gradle.api.Project
+import org.jetbrains.compose.ComposeExtension
+import org.jetbrains.compose.web.WebExtension
+import org.jetbrains.kotlin.gradle.dsl.KotlinMultiplatformExtension
+
+internal val Project.composeExt: ComposeExtension?
+    get() = extensions.findByType(ComposeExtension::class.java)
+
+internal val Project.webExt: WebExtension?
+    get() = composeExt?.extensions?.findByType(WebExtension::class.java)
+
+internal val Project.mppExt: KotlinMultiplatformExtension?
+    get() = extensions.findByType(KotlinMultiplatformExtension::class.java)

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/web/WebExtension.kt

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2020-2021 JetBrains s.r.o. and respective authors and developers.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE.txt file.
+ */
+
+package org.jetbrains.compose.web
+
+import org.gradle.api.Project
+import org.gradle.api.plugins.ExtensionAware
+import org.jetbrains.compose.internal.mppExt
+import org.jetbrains.kotlin.gradle.plugin.KotlinTarget
+import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsIrTarget
+
+abstract class WebExtension : ExtensionAware {
+    private var requestedTargets: Set<KotlinJsIrTarget>? = null
+    private var targetsToConfigure: Set<KotlinJsIrTarget>? = null
+
+    // public api
+    @Suppress("unused")
+    fun targets(vararg targets: KotlinTarget) {
+        check(requestedTargets == null) {
+            "compose.web.targets() was already set!"
+        }
+
+        val jsIrTargets = linkedSetOf<KotlinJsIrTarget>()
+        for (target in targets) {
+            check(target is KotlinJsIrTarget) {
+                """|'${target.name}' is not a JS(IR) target:
+                |* add `kotlin.js.compiler=ir` to gradle properties;
+                |* define target as `kotlin { js(IR) { ... } }`
+            """.trimMargin()
+            }
+            jsIrTargets.add(target)
+        }
+        requestedTargets = jsIrTargets
+    }
+
+    internal fun targetsToConfigure(project: Project): Set<KotlinJsIrTarget> {
+        targetsToConfigure =
+            targetsToConfigure
+                ?: requestedTargets
+                ?: defaultJsTargetsToConfigure(project)
+
+        return targetsToConfigure!!
+    }
+
+    private fun defaultJsTargetsToConfigure(project: Project): Set<KotlinJsIrTarget> {
+        val mppTargets = project.mppExt?.targets?.asMap?.values ?: emptySet()
+        val jsIRTargets = mppTargets.filterIsInstanceTo(LinkedHashSet<KotlinJsIrTarget>())
+
+        return if (jsIRTargets.size > 1) {
+            project.logger.error(
+                "w: Default configuration for Compose Web is disabled: " +
+                        "multiple Kotlin JS IR targets are defined. " +
+                        "Specify Compose Web Kotlin targets by using `compose.web.targets()`"
+            )
+            emptySet()
+        } else jsIRTargets
+    }
+}

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/web/internal/configureWeb.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2020-2021 JetBrains s.r.o. and respective authors and developers.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE.txt file.
+ */
+
+package org.jetbrains.compose.web.internal
+
+import org.gradle.api.Project
+import org.jetbrains.compose.ComposeExtension
+import org.jetbrains.compose.web.WebExtension
+
+internal fun Project.initializeWeb(composeExtension: ComposeExtension) {
+    project.plugins.withId("org.jetbrains.kotlin.multiplatform") {
+        composeExtension.extensions.create("web", WebExtension::class.java)
+    }
+}

gradle-plugins/gradle.properties

@@ -7,6 +7,7 @@ kotlin.code.style=official
 #
 # __LATEST_COMPOSE_RELEASE_VERSION__
 compose.version=0.4.0-build182
+compose.with.web=false
 
 # A version of Gradle plugin, that will be published,
 # unless overridden by COMPOSE_GRADLE_PLUGIN_VERSION env var.