Add support for book front covers

jabgui/src/main/java/org/jabref/gui/externalfiles/ImportHandler.java

@@ -414,7 +414,7 @@ public List<BibEntry> handleStringData(String data) throws FetcherException {
         LOGGER.trace("Checking if URL is a PDF: {}", data);
 
         if (URLUtil.isURL(data)) {
-            String fileName = data.substring(data.lastIndexOf('/') + 1);
+            String fileName = FileUtil.getFileNameFromUrl(data);
             if (FileUtil.isPDFFile(Path.of(fileName))) {
                 try {
                     return handlePdfUrl(data);
@@ -481,7 +481,10 @@ private List<BibEntry> handlePdfUrl(String pdfUrl) throws IOException {
             return List.of();
         }
         URLDownload urlDownload = new URLDownload(pdfUrl);
-        String filename = URLUtil.getFileNameFromUrl(pdfUrl);
+        String filename = FileUtil.getFileNameFromUrl(pdfUrl);
+        if (filename.isBlank()) {
+            filename = "downloaded.pdf";
+        }
         Path targetFile = targetDirectory.get().resolve(filename);
         try {
             urlDownload.toFile(targetFile);

jabgui/src/main/java/org/jabref/gui/importer/BookCoverFetcher.java

@@ -0,0 +1,131 @@
+package org.jabref.gui.importer;
+
+import java.net.MalformedURLException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.io.File;
+import java.nio.file.Path;
+import java.util.Optional;
+import java.util.regex.Pattern;
+import java.util.regex.Matcher;
+
+import org.apache.hc.core5.net.URIBuilder;
+
+import org.jabref.gui.externalfiletype.ExternalFileType;
+import org.jabref.gui.externalfiletype.ExternalFileTypes;
+import org.jabref.gui.frame.ExternalApplicationsPreferences;
+import org.jabref.model.database.BibDatabaseContext;
+import org.jabref.logic.FilePreferences;
+import org.jabref.model.entry.BibEntry;
+import org.jabref.model.entry.identifier.ISBN;
+import org.jabref.model.entry.LinkedFile;
+import org.jabref.logic.importer.FetcherException;
+import org.jabref.logic.net.URLDownload;
+import org.jabref.logic.util.io.FileUtil;
+
+import kong.unirest.core.UnirestException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Searches web resources for bibliographic information.
+ */
+public class BookCoverFetcher {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(BookCoverFetcher.class);
+
+    private static final Pattern JSON_CONTAINING_URL_PATTERN = Pattern.compile("^\\s*\\{\\s*\"url\"\\s*:\\s*\"([^\"]*)\"\\s*\\}\\s*$");
+
+    public static Optional<BibEntry> withAttachedCoverFileIfExists(Optional<BibEntry> possible, BibDatabaseContext databaseContext, FilePreferences filePreferences, ExternalApplicationsPreferences externalApplicationsPreferences) {
+        if (possible.isPresent() && filePreferences.shouldDownloadCovers()) {
+            BibEntry entry = possible.get();
+            Optional<ISBN> isbn = entry.getISBN();
+            if (isbn.isPresent()) {
+                final String url = getCoverImageURLForIsbn(isbn.get());
+                final Path directory = databaseContext.getFirstExistingFileDir(filePreferences).orElse(filePreferences.getWorkingDirectory());
+
+                // Cannot use pattern for name, as auto-generated citation keys aren't available where function is used (org.jabref.gui.newentry.NewEntryViewModel#withCoversAttached)
+                final String name = "isbn-"+isbn.get().asString();
+
+                Optional<LinkedFile> file = tryToDownloadLinkedFile(externalApplicationsPreferences, directory, url, filePreferences.coversDownloadLocation(), name);
+                if (file.isPresent()) {
+                    entry.addFile(file.get());
+                }
+            }
+            possible = Optional.of(entry);
+        }
+        return possible;
+    }
+
+    private static String getCoverImageURLForIsbn(ISBN isbn) {
+        if (isbn.isIsbn13()) {
+            String url = "https://bookcover.longitood.com/bookcover/" + isbn.asString();
+            try {
+                LOGGER.info("Downloading book cover url from {}", url);
+
+                URLDownload download = new URLDownload(url);
+                download.canBeReached();
+
+                String json = download.asString();
+                Matcher matches = JSON_CONTAINING_URL_PATTERN.matcher(json);
+
+                if (matches.find()) {
+                    String coverUrlString = matches.group(1);
+                    if (coverUrlString != null) {
+                        return coverUrlString;
+                    }
+                }
+            } catch (MalformedURLException | FetcherException e) {
+                LOGGER.error("Error while querying cover url, using fallback", e);
+            }
+        }
+        return "https://covers.openlibrary.org/b/isbn/" + isbn.asString() + "-L.jpg";
+    }
+
+    private static Optional<LinkedFile> tryToDownloadLinkedFile(ExternalApplicationsPreferences externalApplicationsPreferences, Path directory, String url, String location, String name) {
+        final Path subdirectory = directory.resolve(location);
+
+        subdirectory.toFile().mkdirs();
+        if (subdirectory.toFile().exists()) {
+            final Optional<String> extension = FileUtil.getFileExtension(FileUtil.getFileNameFromUrl(url));
+            final Path destination = subdirectory.resolve(extension.map(x -> name + "." + x).orElse(name));
+            final String link = directory.relativize(destination).toString();
+
+            if (destination.toFile().exists()) {
+                return Optional.of(new LinkedFile("[cover]", link, inferFileTypeFromExtension(externalApplicationsPreferences, extension), url));
+
+            } else try {
+                LOGGER.info("Downloading cover image file from {}", url);
+
+                URLDownload download = new URLDownload(url);
+                download.canBeReached();
+
+                final String type = inferFileType(externalApplicationsPreferences, download.getMimeType(), extension);
+                download.toFile(destination);
+                return Optional.of(new LinkedFile("[cover]", link, type, url));
+
+            } catch (UnirestException | FetcherException | MalformedURLException e) {
+                LOGGER.error("Error while downloading cover image file", e);
+            }
+        } else {
+            LOGGER.warn("File directory not available while downloading cover image {}. Storing as URL in file field.", url);
+            return Optional.of(new LinkedFile("[cover]", url, ""));
+        }
+
+        return Optional.empty();
+    }
+
+    private static String inferFileType(ExternalApplicationsPreferences externalApplicationsPreferences, Optional<String> mime, Optional<String> extension) {
+        if (mime.isPresent()) {
+            Optional<ExternalFileType> suggested = ExternalFileTypes.getExternalFileTypeByMimeType(mime.get(), externalApplicationsPreferences);
+            if (suggested.isPresent()) {
+                return suggested.get().getName();
+            }
+        }
+        return inferFileTypeFromExtension(externalApplicationsPreferences, extension);
+    }
+
+    private static String inferFileTypeFromExtension(ExternalApplicationsPreferences externalApplicationsPreferences, Optional<String> extension) {
+        return extension.map(x -> ExternalFileTypes.getExternalFileTypeByExt(x, externalApplicationsPreferences).map(t -> t.getName()).orElse("")).orElse("");
+    }
+}

jabgui/src/main/java/org/jabref/gui/newentry/NewEntryViewModel.java

@@ -25,6 +25,7 @@
 import org.jabref.gui.preferences.GuiPreferences;
 import org.jabref.gui.util.UiTaskExecutor;
 import org.jabref.logic.ai.AiService;
+import org.jabref.gui.importer.BookCoverFetcher;
 import org.jabref.logic.importer.CompositeIdFetcher;
 import org.jabref.logic.importer.FetcherClientException;
 import org.jabref.logic.importer.FetcherException;
@@ -234,6 +235,10 @@ public StringProperty bibtexTextProperty() {
     public ReadOnlyBooleanProperty bibtexTextValidatorProperty() {
         return bibtexTextValidator.getValidationStatus().validProperty();
     }
+
+    private Optional<BibEntry> withCoversAttached(Optional<BibEntry> entry) {
+        return BookCoverFetcher.withAttachedCoverFileIfExists(entry, libraryTab.getBibDatabaseContext(), preferences.getFilePreferences(), preferences.getExternalApplicationsPreferences());
+    }
 
     private class WorkerLookupId extends Task<Optional<BibEntry>> {
         @Override
@@ -245,7 +250,7 @@ protected Optional<BibEntry> call() throws FetcherException {
                 return Optional.empty();
             }
 
-            return fetcher.performSearchById(text);
+            return withCoversAttached(fetcher.performSearchById(text));
         }
     }
 
@@ -260,7 +265,7 @@ protected Optional<BibEntry> call() throws FetcherException {
                 return Optional.empty();
             }
 
-            return fetcher.performSearchById(text);
+            return withCoversAttached(fetcher.performSearchById(text));
         }
     }
 

jabgui/src/main/java/org/jabref/gui/preferences/linkedfiles/LinkedFilesTab.java

@@ -7,6 +7,7 @@
 import javafx.scene.control.ComboBox;
 import javafx.scene.control.RadioButton;
 import javafx.scene.control.TextField;
+import javafx.scene.control.Label;
 
 import org.jabref.gui.actions.ActionFactory;
 import org.jabref.gui.actions.StandardActions;
@@ -25,6 +26,11 @@ public class LinkedFilesTab extends AbstractPreferenceTabView<LinkedFilesTabView
 
     @FXML private TextField mainFileDirectory;
     @FXML private RadioButton useMainFileDirectory;
+
+    @FXML private RadioButton bookCoverDownload;
+    @FXML private Label bookCoverLabel;
+    @FXML private TextField bookCoverLocation;
+
     @FXML private RadioButton useBibLocationAsPrimary;
     @FXML private Button browseDirectory;
     @FXML private Button autolinkRegexHelp;
@@ -63,7 +69,11 @@ public void initialize() {
         mainFileDirectory.disableProperty().bind(viewModel.useBibLocationAsPrimaryProperty());
         browseDirectory.disableProperty().bind(viewModel.useBibLocationAsPrimaryProperty());
         useBibLocationAsPrimary.selectedProperty().bindBidirectional(viewModel.useBibLocationAsPrimaryProperty());
-        useMainFileDirectory.selectedProperty().bindBidirectional(viewModel.useMainFileDirectoryProperty());
+
+        bookCoverLocation.textProperty().bindBidirectional(viewModel.coversDownloadLocationProperty());
+        bookCoverLocation.disableProperty().bind(viewModel.shouldDownloadCoversProperty().not());
+        bookCoverLabel.disableProperty().bind(viewModel.shouldDownloadCoversProperty().not());
+        bookCoverDownload.selectedProperty().bindBidirectional(viewModel.shouldDownloadCoversProperty());
 
         moveToTrash.selectedProperty().bindBidirectional(viewModel.moveToTrashProperty());
         moveToTrash.setDisable(!NativeDesktop.get().moveToTrashSupported());

jabgui/src/main/java/org/jabref/gui/preferences/linkedfiles/LinkedFilesTabViewModel.java

@@ -44,6 +44,8 @@ public class LinkedFilesTabViewModel implements PreferenceTabViewModel {
     private final BooleanProperty moveToTrashProperty = new SimpleBooleanProperty();
     private final BooleanProperty openFileExplorerInFilesDirectory = new SimpleBooleanProperty();
     private final BooleanProperty openFileExplorerInLastDirectory = new SimpleBooleanProperty();
+    private final BooleanProperty shouldDownloadCovers = new SimpleBooleanProperty();
+    private final StringProperty coversDownloadLocation = new SimpleStringProperty("");
 
     private final Validator mainFileDirValidator;
 
@@ -90,6 +92,8 @@ public void setValues() {
         moveToTrashProperty.setValue(filePreferences.moveToTrash());
         openFileExplorerInFilesDirectory.setValue(filePreferences.shouldOpenFileExplorerInFileDirectory());
         openFileExplorerInLastDirectory.setValue(filePreferences.shouldOpenFileExplorerInLastUsedDirectory());
+        shouldDownloadCovers.setValue(filePreferences.shouldDownloadCovers());
+        coversDownloadLocation.setValue(filePreferences.coversDownloadLocation());
 
         // Autolink preferences
         switch (autoLinkPreferences.getCitationKeyDependency()) {
@@ -115,6 +119,8 @@ public void storeSettings() {
         filePreferences.setFulltextIndexLinkedFiles(fulltextIndex.getValue());
         filePreferences.setOpenFileExplorerInFileDirectory(openFileExplorerInFilesDirectory.getValue());
         filePreferences.setOpenFileExplorerInLastUsedDirectory(openFileExplorerInLastDirectory.getValue());
+        filePreferences.setShouldDownloadCovers(shouldDownloadCovers.getValue());
+        filePreferences.setOpenFileExplorerInLastUsedDirectory(coversDownloadLocation.getValue());
 
         // Autolink preferences
         if (autolinkFileStartsBibtexProperty.getValue()) {
@@ -216,5 +222,13 @@ public BooleanProperty openFileExplorerInFilesDirectoryProperty() {
     public BooleanProperty openFileExplorerInLastDirectoryProperty() {
         return openFileExplorerInLastDirectory;
     }
+
+    public BooleanProperty shouldDownloadCoversProperty() {
+        return shouldDownloadCovers;
+    }
+
+    public StringProperty coversDownloadLocationProperty() {
+        return coversDownloadLocation;
+    }
 }
 

jabgui/src/main/java/org/jabref/gui/preview/PreviewViewer.java

@@ -2,8 +2,10 @@
 
 import java.io.IOException;
 import java.net.MalformedURLException;
+import java.nio.file.Path;
 import java.util.List;
 import java.util.Objects;
+import java.util.Optional;
 
 import javafx.beans.InvalidationListener;
 import javafx.beans.Observable;
@@ -25,14 +27,19 @@
 import org.jabref.gui.theme.ThemeManager;
 import org.jabref.gui.util.UiTaskExecutor;
 import org.jabref.gui.util.WebViewStore;
+import org.jabref.gui.externalfiletype.ExternalFileType;
+import org.jabref.gui.externalfiletype.ExternalFileTypes;
 import org.jabref.logic.l10n.Localization;
 import org.jabref.logic.layout.format.Number;
 import org.jabref.logic.preview.PreviewLayout;
 import org.jabref.logic.util.BackgroundTask;
 import org.jabref.logic.util.TaskExecutor;
+import org.jabref.logic.util.io.FileUtil;
 import org.jabref.logic.util.strings.StringUtil;
 import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.model.entry.BibEntry;
+import org.jabref.model.entry.LinkedFile;
+import org.jabref.model.entry.types.StandardEntryType;
 import org.jabref.model.search.query.SearchQuery;
 
 import com.airhacks.afterburner.injection.Injector;
@@ -222,17 +229,67 @@ private String formatError(BibEntry entry, Throwable exception) {
     }
 
     private void setPreviewText(String text) {
+        String coverIfAny = "";
+        Optional<String> image = getCoverImageURI();
+        if (image.isPresent()) {
+            coverIfAny = "<img style=\"border-width:1px; border-style:solid; border-color:black; display:block; height:12rem;\" src=\"%s\"> <br>".formatted(image.get());
+        }
+
         layoutText = """
                 <html>
                     <body id="previewBody">
-                        <div id="content"> %s </div>
+                        %s <div id="content"> %s </div>
                     </body>
                 </html>
-                """.formatted(text);
+            """.formatted(coverIfAny, text);
         highlightLayoutText();
         setHvalue(0);
     }
 
+    private Optional<String> getCoverImageURI() {
+        if (shouldShowCoverImage()) {
+            String nameFromFormat = FileUtil.createFileNameFromPattern(databaseContext.getDatabase(), entry, preferences.getFilePreferences().getFileNamePattern()).orElse("cover");
+
+            List<LinkedFile> linkedFiles = entry.getFiles();
+            for (LinkedFile file : linkedFiles) {
+                // matches images that are either named according to the preferred file name format
+                // or images with case-insensitive "[cover]" in their description, to allow using any image regardless of name
+
+                if (file.getDescription().toLowerCase().contains("[cover]") || isFileTypeAValidCoverImage(file.getFileType()) && (FileUtil.getBaseName(file.getFileName()).equals(nameFromFormat))) {
+                    return file.getURI(databaseContext, preferences.getFilePreferences());
+                }
+            }
+        }
+        return Optional.empty();
+    }
+
+    private boolean shouldShowCoverImage() {
+        //entry is sometimes null when setPreviewText is called
+        if (entry == null) {
+            return false;
+        }
+
+        return switch (entry.getType()) {
+            case StandardEntryType.Book, StandardEntryType.Booklet, StandardEntryType.BookInBook, StandardEntryType.InBook, StandardEntryType.MvBook -> true;
+            default -> false;
+        };
+    }
+
+    private boolean isFileTypeAValidCoverImage(String fileType) {
+        // to allow url links
+        if (fileType.equals("")) {
+            return true;
+        }
+
+        // needed because type names are stored in a localization dependent way
+        Optional<ExternalFileType> actualFileType = ExternalFileTypes.getExternalFileTypeByName(fileType, preferences.getExternalApplicationsPreferences());
+
+        if (actualFileType.isPresent()) {
+            return actualFileType.get().getMimeType().startsWith("image/");
+        }
+        return false;
+    }
+
     private void highlightLayoutText() {
         if (layoutText == null) {
             return;

jabgui/src/main/resources/org/jabref/gui/preferences/linkedfiles/LinkedFilesTab.fxml

@@ -44,6 +44,13 @@
                     text="%When downloading files, or moving linked files to the file directory, use the bib file location."/>
         </tooltip>
     </RadioButton>
+
+    <RadioButton fx:id="bookCoverDownload" text="%Automatically download cover images"/>
+    <HBox alignment="CENTER_LEFT" spacing="10.0">
+        <Label fx:id="bookCoverLabel" text="%Cover image download location"/>
+        <TextField fx:id="bookCoverLocation" HBox.hgrow="ALWAYS"/>
+    </HBox>
+
     <Label styleClass="sectionHeader" text="%Open file explorer"/>
     <RadioButton fx:id="openFileExplorerInFilesDirectory" text="%Open file explorer in files directory"
                  toggleGroup="$fileExplorerToggleGroup" selected="true"/>