Avoid creating fake PSI for default imports

#KT-13860 Fixed

compiler/psi/src/org/jetbrains/kotlin/psi/KtImportDirective.java

@@ -27,7 +27,7 @@ import org.jetbrains.kotlin.psi.stubs.KotlinImportDirectiveStub;
 import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes;
 import org.jetbrains.kotlin.resolve.ImportPath;
 
-public class KtImportDirective extends KtElementImplStub<KotlinImportDirectiveStub> {
+public class KtImportDirective extends KtElementImplStub<KotlinImportDirectiveStub> implements KtImportInfo {
 
     public KtImportDirective(@NotNull ASTNode node) {
         super(node);
@@ -59,12 +59,14 @@ public class KtImportDirective extends KtElementImplStub<KotlinImportDirectiveSt
         return getStubOrPsiChild(KtStubElementTypes.IMPORT_ALIAS);
     }
 
+    @Override
     @Nullable
     public String getAliasName() {
         KtImportAlias alias = getAlias();
         return alias != null ? alias.getName() : null;
     }
 
+    @Override
     public boolean isAllUnder() {
         KotlinImportDirectiveStub stub = getStub();
         if (stub != null) {
@@ -73,6 +75,21 @@ public class KtImportDirective extends KtElementImplStub<KotlinImportDirectiveSt
         return getNode().findChildByType(KtTokens.MUL) != null;
     }
 
+    @Nullable
+    @Override
+    public ImportContent getImportContent() {
+        KtExpression reference = getImportedReference();
+        if (reference == null) return null;
+        return new ImportContent.ExpressionBased(reference);
+    }
+
+    @Nullable
+    @Override
+    public Name getImportedName() {
+        return KtImportInfo.DefaultImpls.getImportedName(this);
+    }
+
+    @Override
     @Nullable
     @IfNotParsed
     public FqName getImportedFqName() {

compiler/psi/src/org/jetbrains/kotlin/psi/KtImportInfo.kt

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.psi
+
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+
+interface KtImportInfo {
+    sealed class ImportContent {
+        class ExpressionBased(val expression: KtExpression) : ImportContent()
+        class FqNameBased(val fqName: FqName) : ImportContent()
+    }
+
+    val isAllUnder: Boolean
+    val importContent: ImportContent?
+    val importedFqName: FqName?
+    val aliasName: String?
+
+    val importedName: Name?
+        get() {
+            return computeNameAsString()?.takeIf(CharSequence::isNotEmpty)?.let(Name::identifier)
+        }
+
+    private fun computeNameAsString(): String? {
+        if (isAllUnder) return null
+        aliasName?.let { return it }
+        val importContent = importContent
+        return when (importContent) {
+            is ImportContent.ExpressionBased -> KtPsiUtil.getLastReference(importContent.expression)?.getReferencedName()
+            is ImportContent.FqNameBased -> importContent.fqName.takeUnless(FqName::isRoot)?.shortName()?.asString()
+            null -> null
+        }
+    }
+}

compiler/psi/src/org/jetbrains/kotlin/psi/KtPsiUtil.java

@@ -30,7 +30,6 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.KtNodeTypes;
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
-import org.jetbrains.kotlin.descriptors.DeclarationDescriptor;
 import org.jetbrains.kotlin.kdoc.psi.api.KDocElement;
 import org.jetbrains.kotlin.lexer.KtToken;
 import org.jetbrains.kotlin.lexer.KtTokens;
@@ -224,24 +223,6 @@ public class KtPsiUtil {
         return null;
     }
 
-    @Nullable
-    public static Name getAliasName(@NotNull KtImportDirective importDirective) {
-        if (importDirective.isAllUnder()) {
-            return null;
-        }
-        String aliasName = importDirective.getAliasName();
-        KtExpression importedReference = importDirective.getImportedReference();
-        if (importedReference == null) {
-            return null;
-        }
-        KtSimpleNameExpression referenceExpression = getLastReference(importedReference);
-        if (aliasName == null) {
-            aliasName = referenceExpression != null ? referenceExpression.getReferencedName() : null;
-        }
-
-        return aliasName != null && !aliasName.isEmpty() ? Name.identifier(aliasName) : null;
-    }
-
     @Nullable
     public static KtSimpleNameExpression getLastReference(@NotNull KtExpression importedReference) {
         KtElement selector = KtPsiUtilKt.getQualifiedElementSelector(importedReference);