Add drag and drop for groups -> groups

src/main/java/org/jabref/gui/DragAndDropDataFormats.java

@@ -0,0 +1,12 @@
+package org.jabref.gui;
+
+import javafx.scene.input.DataFormat;
+
+/**
+ * Contains all the different {@link DataFormat}s that may occur in JabRef.
+ */
+public class DragAndDropDataFormats {
+
+    public static final DataFormat GROUP = new DataFormat("dnd/org.jabref.model.groups.GroupTreeNode");
+    public static final DataFormat ENTRIES = new DataFormat("application/x-java-jvm-local-objectref");
+}

src/main/java/org/jabref/gui/groups/AddToGroupAction.java

@@ -35,8 +35,8 @@ public AddToGroupAction(GroupTreeNodeViewModel node, boolean move, BasePanel pan
     }
 
     public AddToGroupAction(boolean move) {
-        super(move ? Localization.lang("Assign entry selection exclusively to this group") :
-                Localization.lang("Add entry selection to this group"));
+        super(move ? Localization.lang("Assign entry selection exclusively to this group") : Localization
+                .lang("Add entry selection to this group"));
         this.move = move;
     }
 
@@ -73,19 +73,19 @@ public void actionPerformed(ActionEvent evt) {
     }
 
     private void moveToGroup(List<BibEntry> entries, NamedCompound undoAll) {
-        List<AbstractGroup> affectedGroups =
-                node.getNode().getRoot().getContainingGroups(entries, false).stream()
-                        .map(GroupTreeNode::getGroup)
-                        .filter(group -> group instanceof GroupEntryChanger)
-                        .collect(Collectors.toList());
+        List<AbstractGroup> affectedGroups = node.getNode().getRoot()
+                .getContainingGroups(entries, false).stream()
+                .map(GroupTreeNode::getGroup)
+                .filter(group -> group instanceof GroupEntryChanger)
+                .collect(Collectors.toList());
         affectedGroups.add(node.getNode().getGroup());
         if (!WarnAssignmentSideEffects.warnAssignmentSideEffects(affectedGroups, panel.frame())) {
             return; // user aborted operation
         }
 
         // first remove
         for (AbstractGroup group : affectedGroups) {
-            GroupEntryChanger entryChanger = (GroupEntryChanger)group;
+            GroupEntryChanger entryChanger = (GroupEntryChanger) group;
             List<FieldChange> changes = entryChanger.remove(entries);
             if (!changes.isEmpty()) {
                 undoAll.addEdit(UndoableChangeEntriesOfGroup.getUndoableEdit(node, changes));

src/main/java/org/jabref/gui/groups/EntryTableTransferHandler.java

@@ -43,22 +43,14 @@
 public class EntryTableTransferHandler extends TransferHandler {
 
     private final MainTable entryTable;
-
     private final JabRefFrame frame;
-
     private final BasePanel panel;
-
     private DataFlavor urlFlavor;
-
     private final DataFlavor stringFlavor;
-
     private static final boolean DROP_ALLOWED = true;
-
     private static final Log LOGGER = LogFactory.getLog(EntryTableTransferHandler.class);
-
     private boolean draggingFile;
 
-
     /**
      * Construct the transfer handler.
      *
@@ -174,14 +166,12 @@ public boolean canImport(JComponent comp, DataFlavor[] transferFlavors) {
         return false;
     }
 
-
-
     @Override
     public void exportAsDrag(JComponent comp, InputEvent e, int action) {
         if (e instanceof MouseEvent) {
             int columnIndex = entryTable.columnAtPoint(((MouseEvent) e).getPoint());
             int modelIndex = entryTable.getColumnModel().getColumn(columnIndex).getModelIndex();
-            if(entryTable.isFileColumn(modelIndex)) {
+            if (entryTable.isFileColumn(modelIndex)) {
                 LOGGER.info("Dragging file");
                 draggingFile = true;
             }

src/main/java/org/jabref/gui/groups/GroupAddRemoveDialog.java

@@ -47,7 +47,6 @@ public class GroupAddRemoveDialog implements BaseAction {
     private List<BibEntry> selection;
     private JTree tree;
 
-
     public GroupAddRemoveDialog(BasePanel panel, boolean add, boolean move) {
         this.panel = panel;
         this.add = add;
@@ -199,7 +198,6 @@ private boolean checkGroupEnable(GroupTreeNodeViewModel node) {
         return (add ? node.canAddEntries(selection) : node.canRemoveEntries(selection));
     }
 
-
     class AddRemoveGroupTreeCellRenderer extends GroupTreeCellRenderer {
 
         @Override

src/main/java/org/jabref/gui/groups/GroupDescriptions.java

@@ -9,25 +9,25 @@
 public class GroupDescriptions {
 
     public static String getDescriptionForPreview(String field, String expr, boolean caseSensitive, boolean regExp) {
-        String header = regExp ? Localization.lang("This group contains entries whose <b>%0</b> field contains the regular expression <b>%1</b>",
-                field, StringUtil.quoteForHTML(expr))
-                : Localization.lang("This group contains entries whose <b>%0</b> field contains the keyword <b>%1</b>",
-                field, StringUtil.quoteForHTML(expr));
-        String caseSensitiveText = caseSensitive ? Localization.lang("case sensitive") :
-            Localization.lang("case insensitive");
-        String footer = regExp ?
-                Localization.lang("Entries cannot be manually assigned to or removed from this group.")
-                : Localization.lang(
-                "Additionally, entries whose <b>%0</b> field does not contain "
-                        + "<b>%1</b> can be assigned manually to this group by selecting them "
-                        + "then using either drag and drop or the context menu. "
-                        + "This process adds the term <b>%1</b> to "
-                        + "each entry's <b>%0</b> field. "
-                        + "Entries can be removed manually from this group by selecting them "
-                        + "then using the context menu. "
-                        + "This process removes the term <b>%1</b> from "
-                        + "each entry's <b>%0</b> field.",
-                field, StringUtil.quoteForHTML(expr));
+        String header = regExp ? Localization.lang(
+                "This group contains entries whose <b>%0</b> field contains the regular expression <b>%1</b>",
+                field, StringUtil.quoteForHTML(expr)) : Localization.lang(
+                        "This group contains entries whose <b>%0</b> field contains the keyword <b>%1</b>",
+                        field, StringUtil.quoteForHTML(expr));
+        String caseSensitiveText = caseSensitive ? Localization.lang("case sensitive") : Localization
+                .lang("case insensitive");
+        String footer = regExp ? Localization
+                .lang("Entries cannot be manually assigned to or removed from this group.") : Localization.lang(
+                        "Additionally, entries whose <b>%0</b> field does not contain "
+                                + "<b>%1</b> can be assigned manually to this group by selecting them "
+                                + "then using either drag and drop or the context menu. "
+                                + "This process adds the term <b>%1</b> to "
+                                + "each entry's <b>%0</b> field. "
+                                + "Entries can be removed manually from this group by selecting them "
+                                + "then using the context menu. "
+                                + "This process removes the term <b>%1</b> from "
+                                + "each entry's <b>%0</b> field.",
+                        field, StringUtil.quoteForHTML(expr));
         return String.format("%s (%s). %s", header, caseSensitiveText, footer);
     }
 

src/main/java/org/jabref/gui/groups/GroupNodeViewModel.java

@@ -1,7 +1,9 @@
 package org.jabref.gui.groups;
 
+import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Function;
 import java.util.function.Predicate;
@@ -15,18 +17,22 @@
 import javafx.beans.property.SimpleIntegerProperty;
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
+import javafx.scene.input.Dragboard;
 import javafx.scene.paint.Color;
 
+import org.jabref.gui.DragAndDropDataFormats;
 import org.jabref.gui.IconTheme;
 import org.jabref.gui.StateManager;
 import org.jabref.gui.util.BindingsHelper;
 import org.jabref.logic.groups.DefaultGroupsFactory;
 import org.jabref.logic.layout.format.LatexToUnicodeFormatter;
+import org.jabref.model.FieldChange;
 import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.model.entry.BibEntry;
 import org.jabref.model.entry.event.EntryEvent;
 import org.jabref.model.groups.AbstractGroup;
 import org.jabref.model.groups.AutomaticGroup;
+import org.jabref.model.groups.GroupEntryChanger;
 import org.jabref.model.groups.GroupTreeNode;
 import org.jabref.model.strings.StringUtil;
 
@@ -39,6 +45,7 @@ public class GroupNodeViewModel {
     private final boolean isRoot;
     private final ObservableList<GroupNodeViewModel> children;
     private final BibDatabaseContext databaseContext;
+    private final StateManager stateManager;
     private final GroupTreeNode groupNode;
     private final SimpleIntegerProperty hits;
     private final SimpleBooleanProperty hasChildren;
@@ -47,6 +54,7 @@ public class GroupNodeViewModel {
     private final BooleanBinding allSelectedEntriesMatched;
     public GroupNodeViewModel(BibDatabaseContext databaseContext, StateManager stateManager, GroupTreeNode groupNode) {
         this.databaseContext = Objects.requireNonNull(databaseContext);
+        this.stateManager = Objects.requireNonNull(stateManager);
         this.groupNode = Objects.requireNonNull(groupNode);
 
         LatexToUnicodeFormatter formatter = new LatexToUnicodeFormatter();
@@ -58,7 +66,7 @@ public GroupNodeViewModel(BibDatabaseContext databaseContext, StateManager state
             // TODO: Update on changes to entry list (however: there is no flatMap and filter as observable TransformationLists)
             children = databaseContext.getDatabase()
                     .getEntries().stream()
-                    .flatMap(stream -> createSubgroups(databaseContext, stateManager, automaticGroup, stream))
+                    .flatMap(stream -> createSubgroups(automaticGroup, stream))
                     .filter(distinctByKey(group -> group.getGroupNode().getName()))
                     .sorted((group1, group2) -> group1.getDisplayName().compareToIgnoreCase(group2.getDisplayName()))
                     .collect(Collectors.toCollection(FXCollections::observableArrayList));
@@ -94,11 +102,25 @@ static GroupNodeViewModel getAllEntriesGroup(BibDatabaseContext newDatabase, Sta
         return new GroupNodeViewModel(newDatabase, stateManager, DefaultGroupsFactory.getAllEntriesGroup());
     }
 
-    private Stream<GroupNodeViewModel> createSubgroups(BibDatabaseContext databaseContext, StateManager stateManager, AutomaticGroup automaticGroup, BibEntry entry) {
+    private Stream<GroupNodeViewModel> createSubgroups(AutomaticGroup automaticGroup, BibEntry entry) {
         return automaticGroup.createSubgroups(entry).stream()
                 .map(child -> new GroupNodeViewModel(databaseContext, stateManager, child));
     }
 
+    public List<FieldChange> addEntriesToGroup(List<BibEntry> entries) {
+        // TODO: warn if assignment has undesired side effects (modifies a field != keywords)
+        //if (!WarnAssignmentSideEffects.warnAssignmentSideEffects(group, groupSelector.frame))
+        //{
+        //    return; // user aborted operation
+        //}
+
+        return groupNode.addEntriesToGroup(entries);
+
+        // TODO: Store undo
+        // if (!undo.isEmpty()) {
+        // groupSelector.concludeAssignment(UndoableChangeEntriesOfGroup.getUndoableEdit(target, undo), target.getNode(), assignedEntries);
+    }
+
     public SimpleBooleanProperty expandedProperty() {
         return expandedProperty;
     }
@@ -133,12 +155,18 @@ public SimpleIntegerProperty getHits() {
 
     @Override
     public boolean equals(Object o) {
-        if (this == o) return true;
-        if (o == null || getClass() != o.getClass()) return false;
+        if (this == o) {
+            return true;
+        }
+        if ((o == null) || (getClass() != o.getClass())) {
+            return false;
+        }
 
         GroupNodeViewModel that = (GroupNodeViewModel) o;
 
-        if (!groupNode.equals(that.groupNode)) return false;
+        if (!groupNode.equals(that.groupNode)) {
+            return false;
+        }
         return true;
     }
 
@@ -205,4 +233,38 @@ boolean isMatchedBy(String searchString) {
     public Color getColor() {
         return groupNode.getGroup().getColor().orElse(IconTheme.getDefaultColor());
     }
+
+    public String getPath() {
+        return groupNode.getPath();
+    }
+
+    public Optional<GroupNodeViewModel> getChildByPath(String pathToSource) {
+        return groupNode.getChildByPath(pathToSource).map(child -> new GroupNodeViewModel(databaseContext, stateManager, child));
+    }
+
+    /**
+     * Decides if the content stored in the given {@link Dragboard} can be droped on the given target row.
+     * Currently, the following sources are allowed:
+     *  - another group (will be added as subgroup on drop)
+     *  - entries if the group implements {@link GroupEntryChanger} (will be assigned to group on drop)
+     */
+    public boolean acceptableDrop(Dragboard dragboard) {
+        // TODO: we should also check isNodeDescendant
+        boolean canDropOtherGroup = dragboard.hasContent(DragAndDropDataFormats.GROUP);
+        boolean canDropEntries = dragboard.hasContent(DragAndDropDataFormats.ENTRIES)
+                && groupNode.getGroup() instanceof GroupEntryChanger;
+        return canDropOtherGroup || canDropEntries;
+    }
+
+    public void moveTo(GroupNodeViewModel target) {
+        // TODO: Add undo and display message
+        //MoveGroupChange undo = new MoveGroupChange(((GroupTreeNodeViewModel)source.getParent()).getNode(),
+        //        source.getNode().getPositionInParent(), target.getNode(), target.getChildCount());
+
+        getGroupNode().moveTo(target.getGroupNode());
+        //panel.getUndoManager().addEdit(new UndoableMoveGroup(this.groupsRoot, moveChange));
+        //panel.markBaseChanged();
+        //frame.output(Localization.lang("Moved group \"%0\".", node.getNode().getGroup().getName()));
+
+    }
 }