Check models are downloaded on selection

src/main/java/qupath/ext/instanseg/core/InstanSegModel.java

@@ -92,17 +92,20 @@ public boolean isValid() {
      * Trigger a download for a model
      * @throws IOException If an error occurs when downloading, unzipping, etc.
      */
-    public void download(Path downloadedModelDir) throws IOException {
+    public void checkIfDownloaded(Path downloadedModelDir, boolean downloadIfNotValid) throws IOException {
         if (path != null && isValidModel(path) && model != null) {
             return;
         }
-        var zipFile = downloadZipIfNeeded(
+        var zipFile = checkZipExists(
                 this.modelURL,
                 downloadedModelDir,
-                getFolderName(name, version));
+                getFolderName(name, version),
+                downloadIfNotValid);
         this.path = unzipIfNeeded(zipFile);
-        this.model = BioimageIoSpec.parseModel(path.toFile());
-        this.version = model.getVersion();
+        if (this.path != null) {
+            this.model = BioimageIoSpec.parseModel(path.toFile());
+            this.version = model.getVersion();
+        }
     }
 
     /**
@@ -266,10 +269,13 @@ private Optional<BioimageIoSpec.BioimageIoModel> getModel() {
         return Optional.ofNullable(model);
     }
 
-    private static Path downloadZipIfNeeded(URL url, Path downloadDirectory, String filename) throws IOException {
+    private static Path checkZipExists(URL url, Path downloadDirectory, String filename, boolean downloadIfNot) throws IOException {
         Files.createDirectories(downloadDirectory);
         var zipFile = downloadDirectory.resolve(filename + ".zip");
         if (!isDownloadedAlready(zipFile)) {
+            if (!downloadIfNot) {
+                return null;
+            }
             try (InputStream stream = url.openStream()) {
                 try (ReadableByteChannel readableByteChannel = Channels.newChannel(stream)) {
                     try (FileOutputStream fos = new FileOutputStream(zipFile.toFile())) {
@@ -295,6 +301,9 @@ private static boolean isDownloadedAlready(Path zipFile) {
     }
 
     private Path unzipIfNeeded(Path zipFile) throws IOException {
+        if (zipFile == null) {
+            return null;
+        }
         var zipSpec = BioimageIoSpec.parseModel(zipFile);
         String version = zipSpec.getVersion();
         var outdir = zipFile.resolveSibling(getFolderName(zipSpec.getName(), version));
@@ -306,7 +315,6 @@ private Path unzipIfNeeded(Path zipFile) throws IOException {
                 logger.error("Error unzipping model", e);
                 // clean up files just in case!
                 Files.deleteIfExists(outdir);
-            } finally {
                 Files.deleteIfExists(zipFile);
             }
         }

src/main/java/qupath/ext/instanseg/ui/InstanSegController.java

@@ -486,6 +486,12 @@ private void refreshModelChoice() {
             return;
 
         var modelDir = InstanSegUtils.getModelDirectory().orElse(null);
+        try {
+            model.checkIfDownloaded(modelDir.resolve("downloaded"), false);
+        } catch (IOException e) {
+            logger.debug("Error checking zip or RDF file(s); this shouldn't happen", e);
+            Dialogs.showErrorNotification(resources.getString("title"), resources.getString("error.checkingModel"));
+        }
         boolean isDownloaded = modelDir != null && model.isValid();
         if (!isDownloaded || qupath.getImageData() == null) {
             return;
@@ -543,7 +549,7 @@ private InstanSegModel downloadModel(InstanSegModel model, Path modelDir) {
         try {
             Dialogs.showInfoNotification(resources.getString("title"),
                     String.format(resources.getString("ui.popup.fetching"), model.getName()));
-            model.download(modelDir.resolve("downloaded"));
+            model.checkIfDownloaded(modelDir.resolve("downloaded"), true);
             Dialogs.showInfoNotification(resources.getString("title"),
                     String.format(resources.getString("ui.popup.available"), model.getName()));
             FXUtils.runOnApplicationThread(() -> {

src/main/resources/qupath/ext/instanseg/ui/strings.properties

@@ -115,4 +115,4 @@ error.querying-local = Error querying local files
 error.localModel = Can't find file in user model directory
 error.tiles-failed = %d tiles failed. This could be a memory issue.\nConsider decreasing tile size or the number of threads used.
 error.modelPath = Unable to fetch model path
-
+error.checkingModel = Downloaded model is missing zip or RDF file(s).\n Try deleting files from your downloaded model directory and retrying.