Add mechanism for alerting the user when they try to do something wrong (#693)

Author: SamCarlberg

core/src/main/java/edu/wpi/grip/core/events/WarningEvent.java

@@ -0,0 +1,46 @@
+package edu.wpi.grip.core.events;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * An event fired when the user should be warned they tried to do something unsupported, such as
+ * trying to generate code with an operation that does not support code gen.
+ *
+ * <p>The event contains a short header text describing the warning and a detailed body text
+ * that lets the user know why what they attempted was not allowed.</p>
+ */
+public class WarningEvent {
+
+  private final String header;
+  private final String body;
+
+  /**
+   * Creates a new warning event.
+   *
+   * @param header the header or title of the warning (e.g. "Cannot generate code").
+   *               This should be short and descriptive.
+   * @param body   the body of the warning.
+   *               This should go into detail about what the user did wrong.
+   */
+  public WarningEvent(String header, String body) {
+    checkNotNull(header, "Header text cannot be null");
+    checkNotNull(body, "Body text cannot be null");
+    this.header = header;
+    this.body = body;
+  }
+
+  /**
+   * Gets the warning header.
+   */
+  public String getHeader() {
+    return header;
+  }
+
+  /**
+   * Gets the warning body.
+   */
+  public String getBody() {
+    return body;
+  }
+
+}

ui/src/main/java/edu/wpi/grip/ui/MainWindowController.java

@@ -8,6 +8,7 @@
 import edu.wpi.grip.core.events.ProjectSettingsChangedEvent;
 import edu.wpi.grip.core.events.TimerEvent;
 import edu.wpi.grip.core.events.UnexpectedThrowableEvent;
+import edu.wpi.grip.core.events.WarningEvent;
 import edu.wpi.grip.core.serialization.Project;
 import edu.wpi.grip.core.settings.AppSettings;
 import edu.wpi.grip.core.settings.ProjectSettings;
@@ -31,7 +32,6 @@
 import java.util.logging.Logger;
 
 import javafx.application.Platform;
-import javafx.event.ActionEvent;
 import javafx.fxml.FXML;
 import javafx.scene.Parent;
 import javafx.scene.Scene;
@@ -275,9 +275,9 @@ protected void quit() {
   /**
    * Controls the export button in the main menu. Opens a filechooser with language selection.
    * The user can select the language to export to, save location and file name.
-   * @param actionEvent Unused event passed by the controller.
    */
-  public void generate(ActionEvent actionEvent) {
+  @FXML
+  public void generate() {
     final FileChooser fileChooser = new FileChooser();
     fileChooser.setTitle("Export to");
     fileChooser.getExtensionFilters().add(new ExtensionFilter(Language.JAVA.name, "*.java"));
@@ -290,13 +290,15 @@ public void generate(ActionEvent actionEvent) {
     }
     Language lang = Language.get(fileChooser.getSelectedExtensionFilter().getDescription());
     Exporter exporter = new Exporter(pipeline.getSteps(), lang, file);
-    final Set<String> nonExportableSteps = exporter.getNonExportableSteps();
+    final Set<String> nonExportableSteps = exporter.getNonExportableStepNames();
     if (!nonExportableSteps.isEmpty()) {
-      StringBuilder b = new StringBuilder("The following steps cannot be exported:\n");
-      nonExportableSteps.forEach(n -> b.append("  ").append(n).append('\n'));
-      Alert alert = new Alert(Alert.AlertType.WARNING);
-      alert.setContentText(b.toString());
-      alert.showAndWait();
+      StringBuilder b = new StringBuilder(
+          "The following steps do not support code generation:\n\n"
+      );
+      nonExportableSteps.stream()
+          .sorted()
+          .forEach(n -> b.append(" - ").append(n).append("\n"));
+      eventBus.post(new WarningEvent("Cannot generate code", b.toString()));
       return;
     }
     Thread exportRunner = new Thread(exporter);
@@ -325,7 +327,20 @@ protected void deploy() {
   }
 
   @Subscribe
-  @SuppressWarnings( {"PMD.UnusedPrivateMethod", "PMD.UnusedFormalParameter"})
+  public void onWarningEvent(WarningEvent e) {
+    if (Platform.isFxApplicationThread()) {
+      showWarningAlert(e);
+    } else {
+      Platform.runLater(() -> showWarningAlert(e));
+    }
+  }
+
+  private void showWarningAlert(WarningEvent e) {
+    Alert alert = new WarningAlert(e.getHeader(), e.getBody(), root.getScene().getWindow());
+    alert.showAndWait();
+  }
+
+  @SuppressWarnings({"PMD.UnusedPrivateMethod", "PMD.UnusedFormalParameter"})
   private void runStopped(TimerEvent event) {
     if (event.getTarget() instanceof PipelineRunner) {
       Platform.runLater(() -> updateElapsedTimeLabel(event.getElapsedTime()));

ui/src/main/java/edu/wpi/grip/ui/WarningAlert.java

@@ -0,0 +1,42 @@
+package edu.wpi.grip.ui;
+
+import javafx.scene.control.Alert;
+import javafx.scene.layout.Region;
+import javafx.stage.StageStyle;
+import javafx.stage.Window;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * An alert that warns the user when they try to do something unsupported, such as trying to
+ * generate code with an operation that does not support code gen.
+ */
+public class WarningAlert extends Alert {
+
+  /**
+   * Creates a new warning alert.
+   *
+   * @param header the header text of the alert. This should be short and descriptive.
+   * @param body   the body text of the alert. This should go into detail about the warning
+   *               and what prompted it.
+   * @param owner  the owner window of this alert
+   *
+   * @throws NullPointerException if any of the parameters are null
+   */
+  public WarningAlert(String header, String body, Window owner) {
+    super(AlertType.WARNING);
+    checkNotNull(header, "The header text cannot be null");
+    checkNotNull(body, "The body text cannot be null");
+    checkNotNull(owner, "The owner window cannot be null");
+
+    initStyle(StageStyle.UTILITY);
+    initOwner(owner);
+    getDialogPane().setMinHeight(Region.USE_PREF_SIZE); // expand to fit content
+    getDialogPane().setMinWidth(Region.USE_PREF_SIZE);
+
+    setTitle("Warning | " + header);
+    setHeaderText(header);
+    setContentText(body);
+  }
+
+}

ui/src/main/java/edu/wpi/grip/ui/codegeneration/Exporter.java

@@ -99,7 +99,7 @@ public void run() {
    *
    * @return a set of the names of the non-exportable operations in the pipeline
    */
-  public Set<String> getNonExportableSteps() {
+  public Set<String> getNonExportableStepNames() {
     return steps.stream()
         .filter(s -> {
           return s.getOperationDescription().category() != OperationDescription.Category.NETWORK;