Add pagination for search based fetchers

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

@@ -6,6 +6,7 @@
 
 import javafx.beans.binding.Bindings;
 import javafx.beans.binding.BooleanBinding;
+import javafx.collections.ListChangeListener;
 import javafx.css.PseudoClass;
 import javafx.fxml.FXML;
 import javafx.geometry.Insets;
@@ -35,6 +36,7 @@
 import org.jabref.gui.util.BaseDialog;
 import org.jabref.gui.util.NoSelectionModel;
 import org.jabref.gui.util.ViewModelListCellFactory;
+import org.jabref.logic.importer.PagedSearchBasedFetcher;
 import org.jabref.logic.importer.ParserResult;
 import org.jabref.logic.l10n.Localization;
 import org.jabref.logic.shared.DatabaseLocation;
@@ -114,6 +116,20 @@ private void initialize() {
         placeholder.textProperty().bind(viewModel.messageProperty());
         entriesListView.setPlaceholder(placeholder);
         entriesListView.setItems(viewModel.getEntries());
+        entriesListView.getCheckModel().getCheckedItems().addListener((ListChangeListener<BibEntry>) change -> {
+            while (change.next()) {
+                if (change.wasAdded()) {
+                    for (BibEntry entry : change.getAddedSubList()) {
+                        viewModel.getCheckedEntries().add(entry);
+                    }
+                }
+                if (change.wasRemoved()) {
+                    for (BibEntry entry : change.getRemoved()) {
+                        viewModel.getCheckedEntries().remove(entry);
+                    }
+                }
+            }
+        });
 
         libraryListView.setEditable(false);
         libraryListView.getItems().addAll(stateManager.getOpenDatabases());
@@ -225,4 +241,24 @@ public void selectAllEntries() {
         unselectAll();
         entriesListView.getCheckModel().checkAll();
     }
+
+    @FXML
+    private void onPrevPage() {
+        viewModel.prevPage();
+        restoreCheckedEntries();
+    }
+
+    @FXML
+    private void onNextPage() {
+        viewModel.nextPage();
+        restoreCheckedEntries();
+    }
+
+    private void restoreCheckedEntries() {
+        for (BibEntry entry : viewModel.getEntries()) {
+            if (viewModel.getCheckedEntries().contains(entry)) {
+                entriesListView.getCheckModel().check(entry);
+            }
+        }
+    }
 }

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

@@ -2,8 +2,10 @@
 
 import java.io.IOException;
 import java.io.StringWriter;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
+import java.util.Set;
 
 import javax.swing.undo.UndoManager;
 
@@ -13,6 +15,7 @@
 import javafx.beans.property.StringProperty;
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
+import javafx.collections.ObservableSet;
 
 import org.jabref.gui.AbstractViewModel;
 import org.jabref.gui.DialogService;
@@ -40,6 +43,7 @@
 public class ImportEntriesViewModel extends AbstractViewModel {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(ImportEntriesViewModel.class);
+    private static final int PAGE_SIZE = 20;
 
     private final StringProperty message;
     private final TaskExecutor taskExecutor;
@@ -53,6 +57,11 @@ public class ImportEntriesViewModel extends AbstractViewModel {
     private final GuiPreferences preferences;
     private final BibEntryTypesManager entryTypesManager;
     private final ObjectProperty<BibDatabaseContext> selectedDb;
+    private final ObservableList<BibEntry> pagedEntries = FXCollections.observableArrayList();
+    private final ObservableSet<BibEntry> checkedEntries = FXCollections.observableSet();
+    private List<BibEntry> allEntries = new ArrayList<>();
+
+    private int currentPage = 0;
 
     /**
      * @param databaseContext the database to import into
@@ -85,6 +94,7 @@ public ImportEntriesViewModel(BackgroundTask<ParserResult> task,
             this.parserResult = parserResult;
             // fill in the list for the user, where one can select the entries to import
             entries.addAll(parserResult.getDatabase().getEntries());
+            loadAllEntries(entries);
             if (entries.isEmpty()) {
                 task.updateMessage(Localization.lang("No entries corresponding to given query"));
             }
@@ -111,7 +121,7 @@ public BibDatabaseContext getSelectedDb() {
     }
 
     public ObservableList<BibEntry> getEntries() {
-        return entries;
+        return pagedEntries;
     }
 
     public boolean hasDuplicate(BibEntry entry) {
@@ -177,4 +187,42 @@ private Optional<BibEntry> findInternalDuplicate(BibEntry entry) {
         }
         return Optional.empty();
     }
+
+    public Set<BibEntry> getCheckedEntries() {
+        return checkedEntries;
+    }
+
+    public void loadAllEntries(List<BibEntry> entries) {
+        this.allEntries = new ArrayList<>(entries);
+        this.currentPage = 0;
+        updatePagedEntries();
+    }
+
+    public void nextPage() {
+        if (hasNextPage()) {
+            currentPage++;
+            updatePagedEntries();
+        }
+    }
+
+    public void prevPage() {
+        if (hasPrevPage()) {
+            currentPage--;
+            updatePagedEntries();
+        }
+    }
+
+    public boolean hasNextPage() {
+        return (currentPage + 1) * PAGE_SIZE < allEntries.size();
+    }
+
+    public boolean hasPrevPage() {
+        return currentPage > 0;
+    }
+
+    private void updatePagedEntries() {
+        int fromIdx = currentPage * PAGE_SIZE;
+        int toIdx = Math.min(fromIdx + PAGE_SIZE, allEntries.size());
+        pagedEntries.setAll(allEntries.subList(fromIdx, toIdx));
+    }
 }

jabgui/src/main/resources/org/jabref/gui/importer/ImportEntriesDialog.fxml

@@ -20,6 +20,10 @@
         <VBox spacing="10.0">
             <Label text="%Select the entries to be imported:"/>
             <CheckListView fx:id="entriesListView" VBox.vgrow="ALWAYS"/>
+            <HBox spacing="10" alignment="CENTER">
+                <Button onAction="#onPrevPage" text="%Previous"/>
+                <Button onAction="#onNextPage" text="%Next"/>
+            </HBox>
             <HBox spacing="4">
                 <VBox spacing="10">
                     <HBox spacing="4">

jablib/src/main/resources/l10n/JabRef_en.properties

@@ -2040,6 +2040,8 @@ Total\ items\ found\:=Total items found:
 Selected\ items\:=Selected items:
 Download\ referenced\ files\ (PDFs,\ ...)=Download referenced files (PDFs, ...)
 Select\ the\ entries\ to\ be\ imported\:=Select the entries to be imported\:
+Previous=Previous
+Next=Next
 Open\ Help\ page=Open Help page
 Add\ new\ keyword=Add new keyword
 Keyword\:=Keyword: