[K/JS] Rework ES modules part with squashed JsImport and right renaming strategy inside import/export statements

js/js.ast/src/org/jetbrains/kotlin/js/backend/JsToStringGenerationVisitor.java

@@ -1342,7 +1342,7 @@ public class JsToStringGenerationVisitor extends JsVisitor {
             blockOpen();
             List<JsExport.Element> elements = ((JsExport.Subject.Elements) subject).getElements();
             for (JsExport.Element element : elements) {
-                nameDef(element.getName());
+                visitNameRef(element.getName());
                 JsName alias = element.getAlias();
                 if (alias != null) {
                     p.print(" as ");
@@ -1369,10 +1369,10 @@ public class JsToStringGenerationVisitor extends JsVisitor {
         p.print("import ");
 
         if (target instanceof JsImport.Target.Default) {
-            nameDef(((JsImport.Target.Default) target).getName());
+            visitNameRef(((JsImport.Target.Default) target).getName());
         } else if (target instanceof JsImport.Target.All) {
             p.print("* as ");
-            nameDef(((JsImport.Target.All) target).getAlias());
+            visitNameRef(((JsImport.Target.All) target).getAlias());
         } else if (target instanceof JsImport.Target.Elements) {
             List<JsImport.Element> elements = ((JsImport.Target.Elements) target).getElements();
 
@@ -1386,10 +1386,10 @@ public class JsToStringGenerationVisitor extends JsVisitor {
 
             for (JsImport.Element element : elements) {
                 nameDef(element.getName());
-                JsName alias = element.getAlias();
+                JsNameRef alias = element.getAlias();
                 if (alias != null) {
                     p.print(" as ");
-                    nameDef(alias);
+                    visitNameRef(alias);
                 }
 
                 if (isMultiline) {

js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsExport.kt

@@ -11,7 +11,7 @@ class JsExport(
 ) : SourceInfoAwareJsNode(), JsStatement {
 
     constructor(element: Element) : this(Subject.Elements(listOf(element)))
-    constructor(name: JsName, alias: JsName? = null) : this(Element(name, alias))
+    constructor(name: JsNameRef, alias: JsName? = null) : this(Element(name, alias))
 
     sealed class Subject {
         class Elements(val elements: List<Element>) : Subject()
@@ -19,7 +19,7 @@ class JsExport(
     }
 
     class Element(
-        val name: JsName,
+        val name: JsNameRef,
         val alias: JsName?
     )
 
@@ -28,6 +28,11 @@ class JsExport(
     }
 
     override fun acceptChildren(visitor: JsVisitor) {
+        if (subject is Subject.Elements) {
+            subject.elements.forEach {
+                visitor.accept(it.name)
+            }
+        }
     }
 
     override fun deepCopy(): JsStatement =

js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsImport.kt

@@ -9,34 +9,39 @@ class JsImport(
     val module: String,
     val target: Target,
 ) : SourceInfoAwareJsNode(), JsStatement {
-    constructor(module: String, elements: MutableList<Element> = mutableListOf()) : this(module, Target.Elements(elements))
+    constructor(module: String, vararg elements: Element) : this(module, Target.Elements(elements.toMutableList()))
 
     val elements: MutableList<Element>
         get() = (target as Target.Elements).elements
 
     sealed class Target {
         class Elements(val elements: MutableList<Element>) : Target()
-        class Default(val name: JsName) : Target() {
-            constructor(name: String) : this(JsName(name, false))
+        class Default(val name: JsNameRef) : Target() {
+            constructor(name: String) : this(JsNameRef(name))
         }
 
-        class All(val alias: JsName) : Target() {
-            constructor(alias: String) : this(JsName(alias, false))
+        class All(val alias: JsNameRef) : Target() {
+            constructor(alias: String) : this(JsNameRef(alias))
         }
     }
 
     class Element(
         val name: JsName,
-        val alias: JsName?
-    ) {
-        constructor(name: String, alias: String?) : this(JsName(name, false), alias?.let { JsName(it, false) })
-    }
+        val alias: JsNameRef?
+    )
 
     override fun accept(visitor: JsVisitor) {
         visitor.visitImport(this)
     }
 
     override fun acceptChildren(visitor: JsVisitor) {
+        when (target) {
+            is Target.All -> visitor.accept(target.alias)
+            is Target.Default -> visitor.accept(target.name)
+            is Target.Elements -> target.elements.forEach {
+                it.alias?.let(visitor::accept)
+            }
+        }
     }
 
     override fun deepCopy(): JsStatement =

js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsImportedModule.kt

@@ -26,7 +26,14 @@ class JsImportedModule @JvmOverloads constructor(
     val key = JsImportedModuleKey(externalName, plainReference?.toString())
 }
 
-val JsImportedModule.requireName: String
-    get() = relativeRequirePath?.let { "$it.js" } ?: externalName
+const val REGULAR_EXTENSION = ".js"
+const val ESM_EXTENSION = ".mjs"
+
+fun JsImportedModule.getRequireName(isEsm: Boolean = false): String {
+    return relativeRequirePath?.let {
+        val extension = if (isEsm) ESM_EXTENSION else REGULAR_EXTENSION
+        "$it$extension"
+    } ?: externalName
+}
 
 data class JsImportedModuleKey(val baseName: String, val plainName: String?)