Golang: Display Go external libraries based on importpath structure (…

…bazelbuild/intellij PR import #2973)

This is a modified version of the original change by Brandon Lico with a few modifications:
 * read from the fileToImportPathMap directly when modifying the structure
 * add unit tests.

## Design choices:
 * We don't inherit from BlazeExternalSyntheticLibrary since that contains irrelevant logic. Also we can't logically fulfill the "Only supports one instance per value of presentableText." condition that's outlined in the class javadoc since we could have nodes with identical presentableText properties in the tree in different positions.

## Discussion thread for this change

Issue number: #1744 #2365

## Description of this change

Modifies the structure of the external "Go Libraries" project view to be based on importpath rather than a flat list of files. See my comment within #2365 for an example of how the new structure looks.

Closes #2973

## Tests
Unit tests added.

PiperOrigin-RevId: 401216309

base/src/com/google/idea/blaze/base/sync/libraries/BlazeExternalSyntheticLibrary.java

@@ -49,7 +49,7 @@ public final class BlazeExternalSyntheticLibrary extends SyntheticLibrary
    *     equals, hashcode -- there must only be one instance per value of this text
    * @param files collection of files that this synthetic library is responsible for.
    */
-  BlazeExternalSyntheticLibrary(String presentableText, Collection<File> files) {
+  public BlazeExternalSyntheticLibrary(String presentableText, Collection<File> files) {
     this.presentableText = presentableText;
     this.files = ImmutableSet.copyOf(files);
     this.validFiles =

golang/BUILD

@@ -71,10 +71,12 @@ intellij_unit_test_suite(
         ":golang",
         "//base",
         "//base:unit_test_utils",
+        "//common/experiments",
+        "//common/experiments:unit_test_utils",
         "//intellij_platform_sdk:jsr305",
         "//intellij_platform_sdk:plugin_api_for_tests",
         "//intellij_platform_sdk:test_libs",
-        "//sdkcompat",
+        "//testing:lib",
         "//third_party/go:go_for_tests",
         "@junit//jar",
     ],

golang/src/META-INF/go-contents.xml

@@ -44,5 +44,6 @@
     <documentationProvider implementation="com.google.idea.blaze.golang.resolve.BlazeGoImportResolver$GoPackageDocumentationProvider"/>
     <additionalLibraryRootsProvider implementation="com.google.idea.blaze.golang.sync.BlazeGoAdditionalLibraryRootsProvider"/>
     <postStartupActivity implementation="com.google.idea.blaze.golang.run.producers.NonBlazeProducerSuppressor"/>
+    <treeStructureProvider implementation="com.google.idea.blaze.golang.treeview.BlazeGoTreeStructureProvider" order="last"/>
   </extensions>
 </idea-plugin>

golang/src/com/google/idea/blaze/golang/resolve/BlazeGoPackageFactory.java

@@ -36,7 +36,8 @@
 import java.util.concurrent.ConcurrentMap;
 import javax.annotation.Nullable;
 
-class BlazeGoPackageFactory implements GoPackageFactory {
+/** Updates and exposes a map of import paths to files. */
+public class BlazeGoPackageFactory implements GoPackageFactory {
   @Nullable
   @Override
   public GoPackage createPackage(GoFile goFile) {
@@ -54,7 +55,7 @@ public GoPackage createPackage(GoFile goFile) {
   }
 
   @Nullable
-  static ConcurrentMap<File, String> getFileToImportPathMap(Project project) {
+  public static ConcurrentMap<File, String> getFileToImportPathMap(Project project) {
     return SyncCache.getInstance(project)
         .get(BlazeGoPackageFactory.class, BlazeGoPackageFactory::buildFileToImportPathMap);
   }

golang/src/com/google/idea/blaze/golang/sync/BlazeGoAdditionalLibraryRootsProvider.java

@@ -32,9 +32,11 @@
 /** Provides out-of-project go sources for indexing. */
 public final class BlazeGoAdditionalLibraryRootsProvider extends BlazeExternalLibraryProvider {
 
+  public static final String GO_EXTERNAL_LIBRARY_ROOT_NAME = "Go Libraries";
+
   @Override
   protected String getLibraryName() {
-    return "Go Libraries";
+    return GO_EXTERNAL_LIBRARY_ROOT_NAME;
   }
 
   @Override

golang/src/com/google/idea/blaze/golang/treeview/BlazeGoExternalSyntheticLibrary.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2022 The Bazel Authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.idea.blaze.golang.treeview;
+
+import com.google.common.collect.ImmutableSet;
+import com.intellij.navigation.ItemPresentation;
+import com.intellij.openapi.roots.SyntheticLibrary;
+import com.intellij.openapi.vfs.VirtualFile;
+import icons.BlazeIcons;
+import java.util.Comparator;
+import java.util.SortedSet;
+import java.util.TreeSet;
+import javax.swing.Icon;
+
+/** Represents a {@link SyntheticLibrary} with a mutable set of child files. */
+final class BlazeGoExternalSyntheticLibrary extends SyntheticLibrary implements ItemPresentation {
+
+  private final SortedSet<VirtualFile> childFiles;
+  private final String presentableText;
+
+  BlazeGoExternalSyntheticLibrary(String presentableText, ImmutableSet<VirtualFile> childFiles) {
+    this.childFiles = new TreeSet<>(Comparator.comparing(VirtualFile::toString));
+    this.childFiles.addAll(childFiles);
+    this.presentableText = presentableText;
+  }
+
+  void addFiles(ImmutableSet<VirtualFile> files) {
+    childFiles.addAll(files);
+  }
+
+  @Override
+  public String getPresentableText() {
+    return presentableText;
+  }
+
+  @Override
+  public Icon getIcon(boolean unused) {
+    return BlazeIcons.Logo;
+  }
+
+  @Override
+  public SortedSet<VirtualFile> getSourceRoots() {
+    return childFiles;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    return o instanceof BlazeGoExternalSyntheticLibrary
+        && ((BlazeGoExternalSyntheticLibrary) o).presentableText.equals(presentableText)
+        && ((BlazeGoExternalSyntheticLibrary) o).getSourceRoots().equals(getSourceRoots());
+  }
+
+  @Override
+  public int hashCode() {
+    return presentableText.hashCode();
+  }
+}

golang/src/com/google/idea/blaze/golang/treeview/BlazeGoTreeStructureProvider.java

@@ -0,0 +1,187 @@
+/*
+ * Copyright 2022 The Bazel Authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.idea.blaze.golang.treeview;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.common.collect.ImmutableMap.toImmutableMap;
+import static com.google.idea.blaze.golang.sync.BlazeGoAdditionalLibraryRootsProvider.GO_EXTERNAL_LIBRARY_ROOT_NAME;
+
+import com.google.common.base.Functions;
+import com.google.common.collect.ImmutableListMultimap;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Streams;
+import com.google.idea.blaze.base.settings.Blaze;
+import com.google.idea.blaze.golang.resolve.BlazeGoPackageFactory;
+import com.google.idea.common.experiments.FeatureRolloutExperiment;
+import com.intellij.ide.projectView.TreeStructureProvider;
+import com.intellij.ide.projectView.ViewSettings;
+import com.intellij.ide.projectView.impl.nodes.PsiFileNode;
+import com.intellij.ide.util.treeView.AbstractTreeNode;
+import com.intellij.openapi.project.DumbAware;
+import com.intellij.openapi.project.Project;
+import com.intellij.openapi.vfs.VfsUtil;
+import com.intellij.openapi.vfs.VirtualFile;
+import java.io.File;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.SortedMap;
+import java.util.TreeMap;
+import java.util.function.Function;
+
+/**
+ * Modifies the project view by replacing the External Go Libraries root node (containing a flat
+ * list of sources) with a root node that structures sources based on their import paths.
+ */
+public final class BlazeGoTreeStructureProvider implements TreeStructureProvider, DumbAware {
+
+  public static final FeatureRolloutExperiment experiment =
+      new FeatureRolloutExperiment("go.import.treestructure");
+
+  @Override
+  public Collection<AbstractTreeNode<?>> modify(
+      AbstractTreeNode<?> parent, Collection<AbstractTreeNode<?>> children, ViewSettings settings) {
+    Project project = parent.getProject();
+    if (!Blaze.isBlazeProject(project)
+        || !experiment.isEnabled()
+        || !isGoBlazeExternalLibraryRoot(parent)) {
+      return children;
+    }
+    ImmutableMap<VirtualFile, AbstractTreeNode<?>> originalFileNodes =
+        getOriginalFileNodesMap(children);
+
+    Map<File, String> fileToImportPathMap = BlazeGoPackageFactory.getFileToImportPathMap(project);
+    if (fileToImportPathMap == null) {
+      return children;
+    }
+
+    SortedMap<String, AbstractTreeNode<?>> newChildren = new TreeMap<>();
+
+    ImmutableListMultimap<String, VirtualFile> importPathToFilesMap =
+        originalFileNodes.keySet().stream()
+            .collect(
+                ImmutableListMultimap.toImmutableListMultimap(
+                    // Some nodes may, for some reason, not be in importPathMap, use the empty
+                    // String as a guard character.
+                    virtualFile ->
+                        fileToImportPathMap.getOrDefault(VfsUtil.virtualToIoFile(virtualFile), ""),
+                    Function.identity()));
+
+    for (String importPath : importPathToFilesMap.keySet()) {
+      if (importPath.isEmpty()) {
+        continue;
+      }
+      generateTree(
+          settings,
+          project,
+          newChildren,
+          importPath,
+          ImmutableSet.copyOf(importPathToFilesMap.get(importPath)),
+          originalFileNodes);
+    }
+    return Streams.concat(
+            newChildren.values().stream(),
+            // Put nodes without an importPath as direct children.
+            importPathToFilesMap.get("").stream().map(originalFileNodes::get))
+        .collect(toImmutableList());
+  }
+
+  private static void generateTree(
+      ViewSettings settings,
+      Project project,
+      SortedMap<String, AbstractTreeNode<?>> newChildren,
+      String importPath,
+      ImmutableSet<VirtualFile> availableFiles,
+      Map<VirtualFile, AbstractTreeNode<?>> originalFileNodes) {
+    Iterator<Path> pathIter = Paths.get(importPath).iterator();
+    if (!pathIter.hasNext()) {
+      return;
+    }
+    // Root nodes (e.g., src) have to be added directly to newChildren.
+    String rootName = pathIter.next().toString();
+    GoSyntheticLibraryElementNode root =
+        (GoSyntheticLibraryElementNode)
+            newChildren.computeIfAbsent(
+                rootName,
+                (unused) ->
+                    new GoSyntheticLibraryElementNode(
+                        project,
+                        new BlazeGoExternalSyntheticLibrary(rootName, availableFiles),
+                        rootName,
+                        settings,
+                        new TreeMap<>()));
+
+    // Child nodes (e.g., package_name under src) are added under root nodes recursively.
+    GoSyntheticLibraryElementNode leaf =
+        buildChildTree(settings, project, availableFiles, pathIter, root);
+
+    // Required for files to actually show up in the Project View.
+    availableFiles.forEach((file) -> leaf.addChild(file.getName(), originalFileNodes.get(file)));
+  }
+
+  /**
+   * Recurse down the import path tree and add elements as children.
+   *
+   * <p>Fills previously created nodes with source files from the current import path.
+   */
+  private static GoSyntheticLibraryElementNode buildChildTree(
+      ViewSettings settings,
+      Project project,
+      ImmutableSet<VirtualFile> files,
+      Iterator<Path> pathIter,
+      GoSyntheticLibraryElementNode parent) {
+    while (pathIter.hasNext()) {
+      parent.addFiles(files);
+      String dirName = pathIter.next().toString();
+
+      // current path already was created, no need to re-create
+      if (parent.hasChild(dirName)) {
+        parent = parent.getChildNode(dirName);
+        continue;
+      }
+      GoSyntheticLibraryElementNode libraryNode =
+          new GoSyntheticLibraryElementNode(
+              project,
+              new BlazeGoExternalSyntheticLibrary(dirName, files),
+              dirName,
+              settings,
+              new TreeMap<>());
+      parent.addChild(dirName, libraryNode);
+      parent = libraryNode;
+    }
+    return parent;
+  }
+
+  private static boolean isGoBlazeExternalLibraryRoot(AbstractTreeNode<?> parent) {
+    if (parent.getName() == null) {
+      return false;
+    }
+    return parent.getName().equals(GO_EXTERNAL_LIBRARY_ROOT_NAME);
+  }
+
+  private static ImmutableMap<VirtualFile, AbstractTreeNode<?>> getOriginalFileNodesMap(
+      Collection<AbstractTreeNode<?>> children) {
+
+    return children.stream()
+        .filter(child -> (child instanceof PsiFileNode))
+        .filter(child -> ((PsiFileNode) child).getVirtualFile() != null)
+        .collect(
+            toImmutableMap(child -> ((PsiFileNode) child).getVirtualFile(), Functions.identity()));
+  }
+}