Synchronize selected extension filter (#49)

* Synchronize selected extension filter for the native file choosers

* Try to mimic the native behaviour for the WebFileSavePicker

* Refactor extension filter change listeners for both native and web platforms

* Update the TextEditor sample to accommodate the last changes

* Add javadoc documentation for the newly added methods

* Update changelog

CHANGELOG.md

@@ -1,5 +1,8 @@
 ### 0.4.5 (TBD)
 
+#### Improvements
+* Synchronize selected extension filter for the native file choosers in the `jpro-file` module.
+
 ----------------------
 
 ### 0.4.4 (November 8, 2024)

jpro-file/example/src/main/java/one/jpro/platform/file/example/editor/TextEditorSample.java

@@ -60,7 +60,9 @@ public class TextEditorSample extends Application {
     private static final Logger LOGGER = LoggerFactory.getLogger(TextEditorSample.class);
 
     private static final PseudoClass FILES_DRAG_OVER_PSEUDO_CLASS = PseudoClass.getPseudoClass("files-drag-over");
-    private static final ExtensionFilter TEXT_EXTENSION_FILTER = ExtensionFilter.of("Text files", ".txt", ".srt", ".md", ".csv");
+    private static final ExtensionFilter SUBTITLE_EXTENSION_FILTER = ExtensionFilter.of("Subtitle files", ".srt");
+    private static final ExtensionFilter MARKDOWN_EXTENSION_FILTER = ExtensionFilter.of("Markdown files", ".md");
+    private static final ExtensionFilter CSV_EXTENSION_FILTER = ExtensionFilter.of("CSV files", ".csv");
     private final ObjectProperty<File> lastOpenedFile = new SimpleObjectProperty<>(this, "lastOpenedFile");
 
     @Override
@@ -77,15 +79,15 @@ public void start(Stage stage) {
     }
 
     public Parent createRoot(Stage stage) {
-        Label dropLabel = new Label("Drop " + TEXT_EXTENSION_FILTER.description().toLowerCase() + " here!");
+        Label dropLabel = new Label("Drop " + SUBTITLE_EXTENSION_FILTER.description().toLowerCase() + " here!");
         StackPane dropPane = new StackPane(dropLabel);
         dropPane.getStyleClass().add("drop-pane");
 
         TextArea textArea = new TextArea();
         StackPane contentPane = new StackPane(textArea, dropPane);
 
         FileDropper fileDropper = FileDropper.create(contentPane);
-        fileDropper.setExtensionFilter(TEXT_EXTENSION_FILTER);
+        fileDropper.setExtensionFilter(SUBTITLE_EXTENSION_FILTER);
         fileDropper.setOnDragEntered(event -> {
             dropPane.pseudoClassStateChanged(FILES_DRAG_OVER_PSEUDO_CLASS, true);
             contentPane.getChildren().setAll(textArea, dropPane);
@@ -106,7 +108,8 @@ public Parent createRoot(Stage stage) {
 
         Button openButton = new Button("Open", new FontIcon(Material2AL.FOLDER_OPEN));
         FileOpenPicker fileOpenPicker = FileOpenPicker.create(openButton);
-        fileOpenPicker.setSelectedExtensionFilter(TEXT_EXTENSION_FILTER);
+        fileOpenPicker.getExtensionFilters().addAll(SUBTITLE_EXTENSION_FILTER,
+                MARKDOWN_EXTENSION_FILTER, CSV_EXTENSION_FILTER);
         fileOpenPicker.setOnFilesSelected(fileSources -> {
             openFile(fileSources, textArea);
             contentPane.getChildren().setAll(textArea);
@@ -134,7 +137,8 @@ public Parent createRoot(Stage stage) {
         fileSavePicker.initialFileNameProperty().bind(lastOpenedFile.map(file ->
                 FilenameUtils.getName(file.getName())).orElse("subtitle"));
         fileSavePicker.initialDirectoryProperty().bind(lastOpenedFile.map(File::getParentFile));
-        fileSavePicker.setSelectedExtensionFilter(TEXT_EXTENSION_FILTER);
+        fileSavePicker.getExtensionFilters().addAll(SUBTITLE_EXTENSION_FILTER,
+                MARKDOWN_EXTENSION_FILTER, CSV_EXTENSION_FILTER);
         fileSavePicker.setOnFileSelected(file -> saveToFile(textArea).apply(file));
 
         BorderPane rootPane = new BorderPane(contentPane);

jpro-file/src/main/java/one/jpro/platform/file/ExtensionFilter.java

@@ -1,5 +1,7 @@
 package one.jpro.platform.file;
 
+import javafx.stage.FileChooser;
+
 import java.util.List;
 
 /**
@@ -10,7 +12,7 @@
  * format.
  *
  * @param description the textual description for the filter
- * @param extensions a list of the accepted file name extensions
+ * @param extensions  a list of the accepted file name extensions
  * @author Besmir Beqiri
  */
 public record ExtensionFilter(String description, List<String> extensions) {
@@ -20,7 +22,7 @@ public record ExtensionFilter(String description, List<String> extensions) {
     /**
      * Compact constructor for {@code ExtensionFilter}.
      *
-     * @throws NullPointerException if the description or the extensions are {@code null}
+     * @throws NullPointerException     if the description or the extensions are {@code null}
      * @throws IllegalArgumentException if the description or the extensions are empty
      */
     public ExtensionFilter {
@@ -32,7 +34,6 @@ public record ExtensionFilter(String description, List<String> extensions) {
      *
      * @param description the description of the filter
      * @param extension   the extension to filter
-     *
      * @throws NullPointerException     if the description or the extension are {@code null}
      * @throws IllegalArgumentException if the description or the extension are empty
      */
@@ -47,10 +48,10 @@ public ExtensionFilter(String description, String extension) {
      * File name extension should be specified in the {@code *.<extension>} format.
      *
      * @param description the textual description for the filter
-     * @param extensions an array of the accepted file name extensions
-     * @throws NullPointerException if the description or the extensions are {@code null}
-     * @throws IllegalArgumentException if the description or the extensions are empty
+     * @param extensions  an array of the accepted file name extensions
      * @return the created {@code ExtensionFilter}
+     * @throws NullPointerException     if the description or the extensions are {@code null}
+     * @throws IllegalArgumentException if the description or the extensions are empty
      */
     public static ExtensionFilter of(String description, String... extensions) {
         return new ExtensionFilter(description, List.of(extensions));
@@ -63,21 +64,46 @@ public static ExtensionFilter of(String description, String... extensions) {
      * File name extension should be specified in the {@code *.<extension>} format.
      *
      * @param description the textual description for the filter
-     * @param extension the accepted file name extension
-     * @throws NullPointerException if the description or the extension is {@code null}
-     * @throws IllegalArgumentException if the description or the extension is empty
+     * @param extension   the accepted file name extension
      * @return the created {@code ExtensionFilter}
+     * @throws NullPointerException     if the description or the extension is {@code null}
+     * @throws IllegalArgumentException if the description or the extension is empty
      */
     public static ExtensionFilter of(String description, String extension) {
         return new ExtensionFilter(description, extension);
     }
 
+    /**
+     * Converts this {@code ExtensionFilter} to a JavaFX {@link FileChooser.ExtensionFilter}.
+     *
+     * @return a corresponding {@link FileChooser.ExtensionFilter} instance
+     */
+    public static FileChooser.ExtensionFilter toJavaFXExtensionFilter(ExtensionFilter extensionFilter) {
+        if (extensionFilter == null) return null;
+        return new FileChooser.ExtensionFilter(extensionFilter.description(),
+                extensionFilter.extensions().stream().map(ext -> "*" + ext).toList());
+    }
+
+    /**
+     * Converts a JavaFX {@link FileChooser.ExtensionFilter} to an {@code ExtensionFilter}.
+     *
+     * @param extensionFilter the JavaFX {@link FileChooser.ExtensionFilter} to convert
+     * @return the corresponding {@code ExtensionFilter} instance
+     */
+    public static ExtensionFilter fromJavaFXExtensionFilter(FileChooser.ExtensionFilter extensionFilter) {
+        if (extensionFilter == null) return null;
+        return new ExtensionFilter(extensionFilter.getDescription(),
+                extensionFilter.getExtensions().stream()
+                        .filter(ext -> ext.startsWith("*"))
+                        .map(ext -> ext.substring(1)).toList());
+    }
+
     /**
      * Validates the arguments.
      *
      * @param description the textual description for the filter
-     * @param extensions the accepted file name extensions
-     * @throws NullPointerException if the description or the extensions are {@code null}
+     * @param extensions  the accepted file name extensions
+     * @throws NullPointerException     if the description or the extensions are {@code null}
      * @throws IllegalArgumentException if the description or the extensions are empty
      */
     private static void validateArgs(final String description, final List<String> extensions) {

jpro-file/src/main/java/one/jpro/platform/file/picker/BaseFilePicker.java

@@ -1,14 +1,23 @@
 package one.jpro.platform.file.picker;
 
+import com.jpro.webapi.WebAPI;
 import javafx.beans.property.ObjectProperty;
+import javafx.beans.property.SimpleObjectProperty;
 import javafx.beans.property.StringProperty;
+import javafx.beans.value.ChangeListener;
+import javafx.beans.value.WeakChangeListener;
 import javafx.collections.FXCollections;
+import javafx.collections.ListChangeListener;
 import javafx.collections.ObservableList;
 import javafx.scene.Node;
+import javafx.stage.FileChooser;
 import one.jpro.platform.file.ExtensionFilter;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.Objects;
 
+import static one.jpro.platform.file.ExtensionFilter.toJavaFXExtensionFilter;
+
 /**
  * Base file picker implementation.
  *
@@ -18,6 +27,10 @@ abstract class BaseFilePicker implements FilePicker {
 
     private final Node node;
 
+    // Flags to prevent infinite synchronization loops
+    private boolean updatingFromFileChooser = false;
+    private boolean updatingFromProperty = false;
+
     /**
      * Constructs a new instance with the specified Node.
      *
@@ -64,4 +77,159 @@ public final ExtensionFilter getSelectedExtensionFilter() {
     public final void setSelectedExtensionFilter(final ExtensionFilter filter) {
         selectedExtensionFilterProperty().setValue(filter);
     }
+
+    @Override
+    public final ObjectProperty<ExtensionFilter> selectedExtensionFilterProperty() {
+        if (selectedExtensionFilter == null) {
+            selectedExtensionFilter = new SimpleObjectProperty<>(this, "selectedExtensionFilter");
+        }
+        return selectedExtensionFilter;
+    }
+
+    /**
+     * Finds and returns the currently selected {@link ExtensionFilter}. If no filter is selected
+     * or the selected filter is not present in the list, the first filter in the list is returned.
+     * If the list is empty, {@code null} is returned.
+     *
+     * @return the selected extension filter or a default filter, or {@code null} if no filters are available
+     */
+    final ExtensionFilter findSelectedFilter() {
+        ExtensionFilter selectedFilter = getSelectedExtensionFilter();
+        if (selectedFilter == null || !extensionFilters.contains(selectedFilter)) {
+            return extensionFilters.isEmpty() ? null : extensionFilters.get(0);
+        } else {
+            return selectedFilter;
+        }
+    }
+
+    /**
+     * Synchronizes the selected {@link ExtensionFilter} between this file picker and the native {@link FileChooser}.
+     * This ensures that changes in one are reflected in the other without causing infinite update loops.
+     *
+     * @param fileChooser the native file chooser to synchronize with; must not be {@code null}
+     */
+    final void synchronizeSelectedExtensionFilter(FileChooser fileChooser) {
+        fileChooser.selectedExtensionFilterProperty()
+                .addListener(new WeakChangeListener<>(getNativeSelectedExtensionFilterChangeListener()));
+        selectedExtensionFilterProperty()
+                .addListener(new WeakChangeListener<>(getSelectedExtensionFilterChangeListener(fileChooser)));
+    }
+
+    /**
+     * Creates a {@link ChangeListener} that listens for changes in the native {@link FileChooser}'s
+     * selected extension filter and updates the corresponding property in this file picker.
+     *
+     * @return a change listener for the native file chooser's selected extension filter
+     */
+    @NotNull
+    private ChangeListener<FileChooser.ExtensionFilter> getNativeSelectedExtensionFilterChangeListener() {
+        return (observable, oldFilter, newFilter) -> {
+            if (updatingFromProperty) {
+                return;
+            }
+            updatingFromFileChooser = true;
+            try {
+                ExtensionFilter extensionFilter = null;
+                if (newFilter != null) {
+                    for (ExtensionFilter ef : extensionFilters) {
+                        if (newFilter.getDescription().equals(ef.description())) {
+                            extensionFilter = ef;
+                            break;
+                        }
+                    }
+                }
+                setSelectedExtensionFilter(extensionFilter);
+            } finally {
+                updatingFromFileChooser = false;
+            }
+        };
+    }
+
+    /**
+     * Creates a {@link ChangeListener} that listens for changes in the native {@link FileChooser}'s
+     * selected extension filter and updates the corresponding property in this file picker.
+     *
+     * @return a change listener for the native file chooser's selected extension filter
+     */
+    @NotNull
+    private ChangeListener<ExtensionFilter> getSelectedExtensionFilterChangeListener(FileChooser fileChooser) {
+        return (observable, oldFilter, newFilter) -> {
+            if (updatingFromFileChooser) {
+                return;
+            }
+
+            updatingFromProperty = true;
+            try {
+                FileChooser.ExtensionFilter extensionFilter = null;
+                if (newFilter != null) {
+                    for (FileChooser.ExtensionFilter ef : fileChooser.getExtensionFilters()) {
+                        if (newFilter.description().equals(ef.getDescription())) {
+                            extensionFilter = ef;
+                            break;
+                        }
+                    }
+                }
+                fileChooser.setSelectedExtensionFilter(extensionFilter);
+            } finally {
+                updatingFromProperty = false;
+            }
+        };
+    }
+
+    /**
+     * Creates a {@link ListChangeListener} that listens for changes in the list of {@link ExtensionFilter}
+     * instances and updates the native {@link FileChooser}'s extension filters accordingly.
+     * <p>
+     * This listener handles both additions and removals of extension filters.
+     * </p>
+     *
+     * @param fileChooser the native file chooser whose extension filters will be updated; must not be {@code null}
+     * @return a list change listener for updating the native file chooser's extension filters
+     */
+    @NotNull
+    final ListChangeListener<ExtensionFilter> getNativeExtensionFilterListChangeListener(FileChooser fileChooser) {
+        return change -> {
+            while (change.next()) {
+                if (change.wasAdded()) {
+                    for (ExtensionFilter extensionFilter : change.getAddedSubList()) {
+                        fileChooser.getExtensionFilters().add(toJavaFXExtensionFilter(extensionFilter));
+                    }
+                } else if (change.wasRemoved()) {
+                    for (ExtensionFilter extensionFilter : change.getRemoved()) {
+                        fileChooser.getExtensionFilters().removeIf(filter ->
+                                filter.getDescription().equals(extensionFilter.description()));
+                    }
+                }
+            }
+        };
+    }
+
+    /**
+     * Creates a {@link ListChangeListener} that listens for changes in the list of {@link ExtensionFilter}
+     * instances and updates the web-based file uploader's supported extensions accordingly.
+     * <p>
+     * This listener handles both additions and removals of extension filters.
+     * </p>
+     *
+     * @param multiFileUploader the web file uploader whose supported extensions will be updated; must not be {@code null}
+     * @return a list change listener for updating the web file uploader's supported extensions
+     */
+    @NotNull
+    final ListChangeListener<ExtensionFilter> getWebExtensionFilterListChangeListener(WebAPI.MultiFileUploader multiFileUploader) {
+        return change -> {
+            while (change.next()) {
+                if (change.wasAdded()) {
+                    for (ExtensionFilter extensionFilter : change.getAddedSubList()) {
+                        extensionFilter.extensions()
+                                .forEach(multiFileUploader.supportedExtensions()::add);
+                    }
+                } else if (change.wasRemoved()) {
+                    for (ExtensionFilter extensionFilter : change.getRemoved()) {
+                        extensionFilter.extensions()
+                                .forEach(multiFileUploader.supportedExtensions()::remove);
+                    }
+                }
+            }
+        };
+    }
 }