1 files changed, 104 insertions, 0 deletions
diff --git a/idea_plugin/src/main/java/com/google/googlejavaformat/intellij/JreConfigurationChecker.java b/idea_plugin/src/main/java/com/google/googlejavaformat/intellij/JreConfigurationChecker.java
new file mode 100644
index 0000000..5084b6a
--- /dev/null
+++ b/idea_plugin/src/main/java/com/google/googlejavaformat/intellij/JreConfigurationChecker.java
@@ -0,0 +1,104 @@
+/*
+ * Copyright 2023 Google Inc. 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.googlejavaformat.intellij;
+
+import com.google.common.base.Suppliers;
+import com.intellij.ide.ui.IdeUiService;
+import com.intellij.notification.Notification;
+import com.intellij.notification.NotificationType;
+import com.intellij.openapi.diagnostic.Logger;
+import com.intellij.openapi.project.Project;
+import java.util.function.Supplier;
+
+class JreConfigurationChecker {
+
+  private static final Supplier<Boolean> hasAccess =
+      Suppliers.memoize(JreConfigurationChecker::checkJreConfiguration);
+  private static final Logger logger = Logger.getInstance(JreConfigurationChecker.class);
+
+  private final Project project;
+
+  public JreConfigurationChecker(Project project) {
+    this.project = project;
+  }
+
+  static boolean checkJreConfiguration(Project project) {
+    var success = hasAccess.get();
+    if (!success) {
+      project.getService(JreConfigurationChecker.class).displayConfigurationErrorNotification();
+    }
+    return success;
+  }
+
+  /**
+   * Determine whether the JRE is configured to work with the google-java-format plugin. If not,
+   * display a notification with instructions and return false.
+   */
+  private static boolean checkJreConfiguration() {
+    try {
+      return testClassAccess(
+          "com.sun.tools.javac.api.JavacTrees",
+          "com.sun.tools.javac.code.Flags",
+          "com.sun.tools.javac.file.JavacFileManager",
+          "com.sun.tools.javac.parser.JavacParser",
+          "com.sun.tools.javac.tree.JCTree",
+          "com.sun.tools.javac.util.Log");
+    } catch (ClassNotFoundException e) {
+      logger.error("Error checking jre configuration for google-java-format", e);
+      return false;
+    }
+  }
+
+  private static boolean testClassAccess(String... classNames) throws ClassNotFoundException {
+    for (String className : classNames) {
+      if (!testClassAccess(className)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  private static boolean testClassAccess(String className) throws ClassNotFoundException {
+    Class<?> klass = Class.forName(className);
+    return klass
+        .getModule()
+        // isExported returns true if the package is either open or exported. Either one is
+        // sufficient
+        // to run the google-java-format code (even though the documentation specifies --add-opens).
+        .isExported(
+            klass.getPackageName(),
+            JreConfigurationChecker.class.getClassLoader().getUnnamedModule());
+  }
+
+  private void displayConfigurationErrorNotification() {
+    Notification notification =
+        new Notification(
+            "Configure JRE for google-java-format",
+            "Configure the JRE for google-java-format",
+            "The google-java-format plugin needs additional configuration before it can be used. "
+                + "<a href=\"instructions\">Follow the instructions here</a>.",
+            NotificationType.INFORMATION);
+    notification.setListener(
+        (n, e) -> {
+          IdeUiService.getInstance()
+              .browse(
+                  "https://github.com/google/google-java-format/blob/master/README.md#intellij-jre-config");
+          n.expire();
+        });
+    notification.notify(project);
+  }
+}