qualified module names: don't show module name in Project View if it matches directory structure (IDEA-166061)

If module name can be composed by appending its directory name to a module name for the parent directory it makes no sense to show the full module name on the directory node in Project View.

java/java-tests/testSrc/com/intellij/projectView/ProjectTreeStructureTest.java

@@ -15,14 +15,21 @@
  */
 package com.intellij.projectView;
 
+import com.intellij.ide.projectView.PresentationData;
+import com.intellij.ide.util.treeView.AbstractTreeNode;
+import com.intellij.ide.util.treeView.PresentableNodeDescriptor;
+import com.intellij.module.ModuleGroupTestsKt;
 import com.intellij.openapi.module.Module;
 import com.intellij.openapi.module.impl.ModuleManagerImpl;
 import com.intellij.openapi.roots.ModuleRootManager;
 import com.intellij.openapi.ui.Queryable;
+import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.testFramework.PlatformTestUtil;
 import com.intellij.testFramework.PsiTestUtil;
-import org.junit.Assert;
+
+import java.util.List;
+import java.util.function.Function;
 
 public class ProjectTreeStructureTest extends BaseProjectViewTestCase {
 
@@ -182,4 +189,48 @@ public class ProjectTreeStructureTest extends BaseProjectViewTestCase {
                          "   A.java\n" +
                          " testContentRootUnderExcluded.iml\n");
   }
+
+  public void testQualifiedModuleNames() throws Exception {
+    VirtualFile testDataRoot = ModuleRootManager.getInstance(myModule).getContentRoots()[0];
+    Module a = createModule("a");
+    PsiTestUtil.addContentRoot(a, testDataRoot.findFileByRelativePath("a"));
+
+    Module main = createModule("a.main");
+    PsiTestUtil.addContentRoot(main, testDataRoot.findFileByRelativePath("a/main"));
+
+    Module util = createModule("util");
+    PsiTestUtil.addContentRoot(util, testDataRoot.findFileByRelativePath("a/util"));
+
+    Module b = createModule("x.b");
+    PsiTestUtil.addContentRoot(b, testDataRoot.findFileByRelativePath("a/b"));
+    myStructure.setShowLibraryContents(false);
+
+    //todo[nik] this function is generic enough, it can be moved to testFramework
+    Function<Object, String> nodePresenter = o -> {
+      AbstractTreeNode node = (AbstractTreeNode)o;
+      node.update();
+      PresentationData presentation = node.getPresentation();
+      List<PresentableNodeDescriptor.ColoredFragment> fragments = presentation.getColoredText();
+      if (fragments.isEmpty()) {
+        return presentation.getPresentableText();
+      }
+      return StringUtil.join(fragments, PresentableNodeDescriptor.ColoredFragment::getText, "");
+    };
+    String treeStructure = ModuleGroupTestsKt.runWithQualifiedModuleNamesEnabled(() -> PlatformTestUtil.print(myStructure, myStructure.getRootElement(), nodePresenter));
+    assertEquals("testQualifiedModuleNames\n" +
+                 " a.iml\n" +
+                 " a.main.iml\n" +
+                 " qualifiedModuleNames [testQualifiedModuleNames]\n" +
+                 "  a\n" +
+                 "   b [x.b]\n" +
+                 "    b.txt\n" +
+                 "   main\n" +
+                 "    main.txt\n" +
+                 "   util\n" +
+                 "    util.txt\n" +
+                 " testQualifiedModuleNames.iml\n" +
+                 " util.iml\n" +
+                 " x.b.iml\n",
+                 treeStructure);
+  }
 }

platform/lang-impl/src/com/intellij/ide/projectView/impl/nodes/PsiDirectoryNode.java

@@ -26,6 +26,7 @@ import com.intellij.idea.ActionsBundle;
 import com.intellij.openapi.extensions.Extensions;
 import com.intellij.openapi.fileTypes.FileTypeRegistry;
 import com.intellij.openapi.module.Module;
+import com.intellij.openapi.module.ModuleGrouperKt;
 import com.intellij.openapi.module.ModuleUtil;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.roots.OrderEntry;
@@ -99,7 +100,7 @@ public class PsiDirectoryNode extends BasePsiNode<PsiDirectory> implements Navig
           if (!shouldShowModuleName()) {
             data.addText(directoryFile.getName() + " ", SimpleTextAttributes.REGULAR_ATTRIBUTES);
           }
-          else if (Comparing.equal(module.getName(), directoryFile.getName())) {
+          else if (moduleNameMatchesDirectoryName(module, directoryFile, fi)) {
             data.addText(directoryFile.getName(), SimpleTextAttributes.REGULAR_BOLD_ATTRIBUTES);
           }
           else {
@@ -135,6 +136,28 @@ public class PsiDirectoryNode extends BasePsiNode<PsiDirectory> implements Navig
     setupIcon(data, psiDirectory);
   }
 
+  private static boolean moduleNameMatchesDirectoryName(Module module, VirtualFile directoryFile, ProjectFileIndex fileIndex) {
+    String moduleName = module.getName();
+    String directoryName = directoryFile.getName();
+    if (moduleName.equals(directoryName)) {
+      return true;
+    }
+    if (ModuleGrouperKt.isQualifiedModuleNamesEnabled() && moduleName.endsWith(directoryName)) {
+      int parentPrefixLength = moduleName.length() - directoryName.length() - 1;
+      if (parentPrefixLength > 0 && moduleName.charAt(parentPrefixLength) == '.') {
+        VirtualFile parentDirectory = directoryFile.getParent();
+        if (ProjectRootsUtil.isModuleContentRoot(parentDirectory, module.getProject())) {
+          Module parentModule = fileIndex.getModuleForFile(parentDirectory);
+          if (parentModule != null && parentModule.getName().length() == parentPrefixLength
+              && moduleName.startsWith(parentModule.getName())) {
+            return true;
+          }
+        }
+      }
+    }
+    return false;
+  }
+
   protected void setupIcon(PresentationData data, PsiDirectory psiDirectory) {
     final VirtualFile virtualFile = psiDirectory.getVirtualFile();
     if (PlatformUtils.isAppCode()) {

platform/testFramework/src/com/intellij/module/moduleGroupTests.kt

@@ -26,15 +26,18 @@ import com.intellij.openapi.util.registry.Registry
  * @author nik
  */
 fun getQualifiedNameModuleGrouper(project: Project): ModuleGrouper {
+  return runWithQualifiedModuleNamesEnabled { ModuleGrouper.instanceFor(project) }
+}
+
+fun <T> runWithQualifiedModuleNamesEnabled(action: () -> T): T {
   val property = Registry.get("project.qualified.module.names")
   return try {
     property.setValue(true)
-    ModuleGrouper.instanceFor(project)
+    action()
   }
   finally {
     property.setValue(false)
   }
-
 }
 
 fun renameModule(module: Module, newName: String) {