New J2K: suggest user to configure Kotlin in a project before nj2k conversion

idea/idea-j2k/src/org/jetbrains/kotlin/idea/j2k/JavaToKotlinConverterFactory.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.idea.j2k
 
+import com.intellij.openapi.module.Module
 import com.intellij.openapi.project.Project
 import org.jetbrains.kotlin.j2k.*
 
@@ -18,4 +19,7 @@ object JavaToKotlinConverterFactory {
 
     fun createPostProcessor(formatCode: Boolean): PostProcessor =
         J2kConverterExtension.extension.createPostProcessor(formatCode)
+
+    fun doCheckBeforeConversion(project: Project, module: Module): Boolean =
+        J2kConverterExtension.extension.doCheckBeforeConversion(project, module)
 }

idea/src/org/jetbrains/kotlin/idea/actions/JavaToKotlinAction.kt

@@ -21,9 +21,7 @@ import com.intellij.ide.highlighter.ArchiveFileType
 import com.intellij.ide.highlighter.JavaFileType
 import com.intellij.ide.scratch.ScratchFileService
 import com.intellij.ide.scratch.ScratchRootType
-import com.intellij.openapi.actionSystem.AnAction
+import com.intellij.openapi.actionSystem.*
-import com.intellij.openapi.actionSystem.AnActionEvent
-import com.intellij.openapi.actionSystem.CommonDataKeys
 import com.intellij.openapi.command.CommandProcessor
 import com.intellij.openapi.fileEditor.FileDocumentManager
 import com.intellij.openapi.fileEditor.FileEditorManager
@@ -182,6 +180,10 @@ class JavaToKotlinAction : AnAction() {
                 .showInCenterOf(statusBar.component)
         }
 
+
+        val module = e.getData(LangDataKeys.MODULE)!!
+        if (!JavaToKotlinConverterFactory.doCheckBeforeConversion(project, module)) return
+
         val firstSyntaxError = javaFiles.asSequence().map { PsiTreeUtil.findChildOfType(it, PsiErrorElement::class.java) }.firstOrNull()
 
         if (firstSyntaxError != null) {

j2k/src/org/jetbrains/kotlin/j2k/J2KConverterExtension.kt

@@ -2,6 +2,7 @@ package org.jetbrains.kotlin.j2k
 
 import com.intellij.openapi.extensions.AbstractExtensionPointBean
 import com.intellij.openapi.extensions.ExtensionPointName
+import com.intellij.openapi.module.Module
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.util.registry.Registry
 
@@ -16,6 +17,8 @@ abstract class J2kConverterExtension : AbstractExtensionPointBean() {
 
     abstract fun createPostProcessor(formatCode: Boolean): PostProcessor
 
+    open fun doCheckBeforeConversion(project: Project, module: Module): Boolean =
+        true
 
     companion object {
         private fun useNewJ2k() = Registry.`is`("kotlin.use.new.j2k", false)

nj2k/nj2k-services/build.gradle.kts

@@ -31,6 +31,7 @@ dependencies {
     compile(project(":idea:fir-view"))
     compile(project(":idea:idea-core"))
     compile(project(":idea:ide-common"))
+    compile(project(":idea:idea-jvm"))
     compile(project(":idea:idea-jps-common"))
     compile(project(":idea:kotlin-gradle-tooling"))
     compile(project(":plugins:uast-kotlin"))

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/NewJ2kConveterExtension.kt

@@ -1,8 +1,15 @@
 package org.jetbrains.kotlin.nj2k
 
+import com.intellij.openapi.module.Module
 import com.intellij.openapi.project.Project
+import com.intellij.openapi.ui.Messages
+import org.jetbrains.kotlin.idea.configuration.getAbleToRunConfigurators
+import org.jetbrains.kotlin.idea.configuration.hasAnyKotlinRuntimeInScope
+import org.jetbrains.kotlin.idea.configuration.isModuleConfigured
+import org.jetbrains.kotlin.idea.configuration.toModuleGroup
 import org.jetbrains.kotlin.j2k.*
 import org.jetbrains.kotlin.nj2k.postProcessing.NewJ2kPostProcessor
+import org.jetbrains.kotlin.platform.jvm.isJvm
 
 class NewJ2kConverterExtension : J2kConverterExtension() {
     override val isNewJ2k = true
@@ -16,4 +23,43 @@ class NewJ2kConverterExtension : J2kConverterExtension() {
 
     override fun createPostProcessor(formatCode: Boolean): PostProcessor =
         NewJ2kPostProcessor()
+
+    override fun doCheckBeforeConversion(project: Project, module: Module): Boolean =
+        checkKotlinIsConfigured(project, module)
+
+    private fun checkKotlinIsConfigured(project: Project, module: Module): Boolean {
+        val kotlinIsConfigured =
+            hasAnyKotlinRuntimeInScope(module) || isModuleConfigured(module.toModuleGroup())
+        if (kotlinIsConfigured) return true
+
+        val title = "Kotlin is not configured in the project"
+        if (Messages.showOkCancelDialog(
+                project,
+                "You will have to configure Kotlin in project before performing a conversion.",
+                title,
+                "OK, configure Kotlin in the project",
+                "No, cancel conversion",
+                Messages.getWarningIcon()
+            ) == Messages.OK
+        ) {
+            val configurators = getAbleToRunConfigurators(module).filter { it.targetPlatform.isJvm() }
+            when {
+                configurators.isEmpty() -> Messages.showErrorDialog("There aren't configurators available", title)
+                configurators.size == 1 -> configurators.single().configure(project, emptyList())
+                else -> {
+                    val resultIndex = Messages.showChooseDialog(//TODO a better dialog?
+                        project,
+                        "Choose Configurator",
+                        title,
+                        null,
+                        configurators.map { it.presentableText }.toTypedArray(),
+                        configurators.first().presentableText
+                    )
+                    configurators.getOrNull(resultIndex)?.configure(project, emptyList())
+                }
+            }
+        }
+
+        return false
+    }
 }