docs: add javadocs to download utility

core/src/main/java/dk/gtz/graphedit/util/Download.java

@@ -9,13 +9,34 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+/**
+ * Helper class for downloading files and getting the progress of the download.
+ */
 public class Download implements Runnable {
     private static final Logger logger = LoggerFactory.getLogger(Download.class);
+    /**
+     * The state that the download can be in.
+     */
     public static enum State {
+	/**
+	 * The download is currently in progress.
+	 */
 	DOWNLOADING,
+	/**
+	 * The download is paused. Call {@link Download#resume} to resume.
+	 */
 	PAUSED,
+	/**
+	 * The download is complete. Call {@link Download#downloadedFile} to get the downloaded file.
+	 */
 	COMPLETE,
+	/**
+	 * The download was cancelled. Discard the {@link Download} instance and start again.
+	 */
 	CANCELLED,
+	/**
+	 * An error occurred during the download. Check the logs for more information.
+	 */
 	ERROR
     }
     private static final int MAX_BUFFER_SIZE = 1024;
@@ -26,6 +47,10 @@ public static enum State {
     private Runnable onStateChange;
     private Optional<String> downloadedFilepath;
 
+    /**
+     * Create a new download instance.
+     * @param url The URL to download from.
+     */
     public Download(URL url) {
 	this.url = url;
 	this.onStateChange = () -> {};
@@ -34,37 +59,67 @@ public Download(URL url) {
 	downloaded = 0;
     }
 
+    /**
+     * Set the callback that will be called when the state of the download changes.
+     * This includes when some progress has been made.
+     * @param onStateChange The callback to call.
+     */
     public void setOnStateChanged(Runnable onStateChange) {
 	this.onStateChange = onStateChange;
     }
 
+    /**
+     * Get the URL that is being downloaded from.
+     * @return The URL.
+     */
     public String getUrl() {
 	return url.toString();
     }
 
+    /**
+     * Get the size of the file being downloaded.
+     * @return The size in bytes.
+     */
     public int getSize() {
 	return size;
     }
 
+    /**
+     * Get the current percentage [0.0 - 100.0] of the download.
+     * @return The percentage of completion.
+     */
     public float getProgress() {
 	return ((float) downloaded / size) * 100;
     }
 
+    /**
+     * Get the current state of the download.
+     * @return The state of the download.
+     */
     public State getStatus() {
 	return status;
     }
 
+    /**
+     * Pause the download. Call {@link Download#resume} to resume.
+     */
     public void pause() {
 	status = State.PAUSED;
 	stateChanged();
     }
 
+    /**
+     * Resume the download if it was paused.
+     */
     public void resume() {
 	status = State.DOWNLOADING;
 	stateChanged();
 	download();
     }
 
+    /**
+     * Cancel the download. Discard the this instance and start again.
+     */
     public void cancel() {
 	status = State.CANCELLED;
 	stateChanged();
@@ -76,16 +131,28 @@ private void error(String message) {
 	stateChanged();
     }
 
+    /**
+     * Start the download.
+     */
     public void download() {
 	status = State.DOWNLOADING;
 	new Thread(this).start();
     }
 
-    public String getFileName(URL url) {
+    /**
+     * Get the file name from a URL.
+     * @param url The URL to get the file name from.
+     * @return The file name.
+     */
+    public static String getFileName(URL url) {
 	var fileName = url.getFile();
 	return fileName.substring(fileName.lastIndexOf('/') + 1);
     }
 
+    /**
+     * Get the downloaded file path.
+     * @return The downloaded file path.
+     */
     public Optional<String> downloadedFile() {
 	return downloadedFilepath;	
     }

std/src/main/java/dk/gtz/graphedit/plugins/view/PluginManagementPanelController.java

@@ -6,7 +6,6 @@
 import java.net.URL;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.nio.file.StandardCopyOption;
 import java.util.ArrayList;
 import java.util.List;
@@ -168,7 +167,7 @@ private void downloadPlugin(Button button, PluginDbEntry entry) {
 			    button.setText("download paused");
 			    break;
 			case COMPLETE:
-			    var filepath = String.join(File.separator, EditorActions.getConfigDir(), "plugins", d.getFileName(url));
+			    var filepath = String.join(File.separator, EditorActions.getConfigDir(), "plugins", Download.getFileName(url));
 			    Files.copy(Path.of(d.downloadedFile().get()), Path.of(filepath), StandardCopyOption.REPLACE_EXISTING);
 			case CANCELLED:
 			default: