Implemented custom order alignment

- Implemented a custom model for a JList that allows for reordering elements using JButtons
- Ask the user whether to sort alphabetically or using an order they decide
- Ensured that the list in the OrderableListPanel keeps its order between multiple sorting times (this saves the user the work of re-sorting every time)

src/main/java/nl/andrewlalis/erme/control/actions/AutoPositionAction.java

@@ -1,10 +1,10 @@
 package nl.andrewlalis.erme.control.actions;
 
-import lombok.Getter;
 import lombok.Setter;
 import nl.andrewlalis.erme.model.MappingModel;
 import nl.andrewlalis.erme.model.Relation;
 import nl.andrewlalis.erme.view.DiagramPanel;
+import nl.andrewlalis.erme.view.OrderableListPanel;
 
 import javax.swing.*;
 import java.awt.*;
@@ -13,10 +13,22 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.concurrent.atomic.AtomicInteger;
 
+/**
+ * A class that implements an AutoPositionAction. This automatically (vertically) positions all relations in the model
+ * based either on alphabetic ordering (by name) or an order that's set by the user
+ */
 public class AutoPositionAction extends AbstractAction {
-	private static AutoPositionAction instance;
 	private final static int MARGIN = 10;
 	private final static int PADDING = 10;
+	private static AutoPositionAction instance;
+	@Setter
+	private DiagramPanel diagramPanel;
+	@Setter
+	private MappingModel model;
+	public AutoPositionAction() {
+		super("Position Relations");
+		this.putValue(SHORT_DESCRIPTION, "Automatically Position Relations");
+	}
 
 	public static AutoPositionAction getInstance() {
 		if (instance == null) {
@@ -25,32 +37,63 @@ public class AutoPositionAction extends AbstractAction {
 		return instance;
 	}
 
-	@Setter
-	private DiagramPanel diagramPanel;
-	@Setter
-	private MappingModel model;
-
-	public AutoPositionAction() {
-		super("Position Relations");
-		this.putValue(SHORT_DESCRIPTION, "Automatically Position Relations");
-	}
-
 	@Override
 	public void actionPerformed(ActionEvent actionEvent) {
-		this.positionRelations();
+		if (model.getRelations().size() == 0) {
+			JOptionPane.showMessageDialog(
+					null,
+					"Cannot position all relations when there are no relations present",
+					"Relations Required",
+					JOptionPane.WARNING_MESSAGE
+			);
+			return;
+		}
+		String[] choices = new String[]{"Alphabeticaly", "Custom Order"};
+		String choice = (String) JOptionPane.showInputDialog(
+				null,
+				"Select how to sort the relations",
+				"Position Relations",
+				JOptionPane.PLAIN_MESSAGE,
+				null,
+				choices,
+				0);
+		if (choice == null) return;
+		if (choice.equals(choices[0])) {
+			positionRelation();
+		} else if (choice.equals(choices[1])) {
+			JOptionPane.showConfirmDialog(
+					null,
+					OrderableListPanel.getInstance(),
+					"teststring",
+					JOptionPane.OK_CANCEL_OPTION,
+					JOptionPane.PLAIN_MESSAGE);
+			this.positionRelations(OrderableListPanel.getInstance().getOrderList());
+		}
 		diagramPanel.repaint();
 	}
 
-	private void positionRelations() {
-		diagramPanel.resetTranslation();
-		ArrayList<Relation> relationList = new ArrayList<>(model.getRelations());
-		Collections.sort(relationList);
-		if (relationList.isEmpty()) return;
+	/**
+	 * Sets the location on all relations in the orderList to be vertically aligned
+	 * @param orderList The ordered list of relations to be aligned
+	 */
+	private void positionRelations(ArrayList<Relation> orderList) {
+		if (orderList.isEmpty()) return;
 
-		int vertSpace = (int) relationList.get(0).getViewModel().getBounds(diagramPanel.getGraphics2D()).getHeight() + PADDING;
+		int vertSpace = (int) orderList.get(0).getViewModel().getBounds(diagramPanel.getGraphics2D()).getHeight() + PADDING;
 		AtomicInteger vertPos = new AtomicInteger(MARGIN);
-		relationList.forEach(r -> {
+		orderList.forEach(r -> {
 			r.setPosition(new Point(MARGIN, vertPos.getAndAdd(vertSpace)));
 		});
+
+		diagramPanel.centerModel();
+	}
+
+	/**
+	 * Creates an orderList by grabbing all relations and sorting them
+	 */
+	private void positionRelation() {
+		ArrayList<Relation> relationList = new ArrayList<>(model.getRelations());
+		Collections.sort(relationList);
+		positionRelations(relationList);
 	}
 }

src/main/java/nl/andrewlalis/erme/model/MappingModel.java

@@ -1,6 +1,7 @@
 package nl.andrewlalis.erme.model;
 
 import lombok.Getter;
+import nl.andrewlalis.erme.view.OrderableListPanel;
 import nl.andrewlalis.erme.view.view_models.MappingModelViewModel;
 import nl.andrewlalis.erme.view.view_models.ViewModel;
 
@@ -27,6 +28,7 @@ public class MappingModel implements Serializable, Viewable {
 	public MappingModel() {
 		this.relations = new HashSet<>();
 		this.changeListeners = new HashSet<>();
+		this.addChangeListener(OrderableListPanel.getInstance());
 	}
 
 	public void addRelation(Relation r) {

src/main/java/nl/andrewlalis/erme/view/DiagramPanel.java

@@ -131,6 +131,7 @@ public class DiagramPanel extends JPanel implements ModelChangeListener {
 		LolcatAction.getInstance().setDiagramPanel(this);
 		AutoPositionAction.getInstance().setDiagramPanel(this);
 		AutoPositionAction.getInstance().setModel(this.model);
+		OrderableListPanel.getInstance().setModel(this.model);
 	}
 
 	public static void prepareGraphics(Graphics2D g) {

src/main/java/nl/andrewlalis/erme/view/OrderableListModel.java

@@ -1,16 +1,63 @@
 package nl.andrewlalis.erme.view;
 
+import lombok.Getter;
 import nl.andrewlalis.erme.model.Relation;
 
+import javax.swing.*;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 
-public class OrderableListModel {
-    private ArrayList<Relation> list;
+/**
+ * A custom model for a ListModel that supports ordering by publically accessable methods
+ */
+public class OrderableListModel extends AbstractListModel<Relation> {
+	@Getter
+	private final ArrayList<Relation> list = new ArrayList<>();
 
-    public void moveUp(int index) {
-        if (index > 0) {
-            Collections.swap(list, index, index - 1);
+	public OrderableListModel() {
+		super();
+	}
+
+	public void addAll(Collection<Relation> relations) {
+		list.addAll(relations);
+	}
+
+	public void removeAll(Collection<Relation> relations) {
+		list.removeAll(relations);
+	}
+
+	public void add(Relation relation) {
+		list.add(relation);
+	}
+
+	public void remove(Relation relation) {
+		list.remove(relation);
+	}
+
+	public void moveUp(int index) {
+		if (index > 0) {
+			Collections.swap(list, index, index - 1);
+		}
+
+		this.fireContentsChanged(this, index, index - 1);
+	}
+
+	public void moveDown(int index) {
+        if (index < this.getSize() - 1) {
+            Collections.swap(list, index, index + 1);
         }
-    }
+
+        this.fireContentsChanged(this, index, index + 1);
+	}
+
+	@Override
+	public int getSize() {
+		return list.size();
+	}
+
+	@Override
+	public Relation getElementAt(int i) {
+		return list.get(i);
+	}
 }

src/main/java/nl/andrewlalis/erme/view/OrderableListPanel.java

@@ -0,0 +1,82 @@
+package nl.andrewlalis.erme.view;
+
+import lombok.Setter;
+import nl.andrewlalis.erme.model.MappingModel;
+import nl.andrewlalis.erme.model.ModelChangeListener;
+import nl.andrewlalis.erme.model.Relation;
+
+import javax.swing.*;
+import java.awt.event.ActionEvent;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * A panel to be used in a popup that has a OrderableListModel implemented. Implements ModelChangeListener to be able
+ * to update the list of relations when new ones are added or ones are removed.
+ */
+public class OrderableListPanel extends JPanel implements ModelChangeListener {
+	private static OrderableListPanel instance;
+	private final JList<Relation> list;
+	private final OrderableListModel listModel;
+	@Setter
+	private MappingModel model;
+
+	private OrderableListPanel() {
+		list = new JList<>();
+		listModel = new OrderableListModel();
+		list.setModel(listModel);
+
+		JButton up = new JButton(new AbstractAction() {
+			@Override
+			public void actionPerformed(ActionEvent actionEvent) {
+				if (list.isSelectionEmpty()) return;
+				listModel.moveUp(list.getSelectedIndex());
+				list.setSelectedIndex(list.getSelectedIndex() - 1);
+			}
+		});
+		up.setText("\u2227");
+		JButton down = new JButton(new AbstractAction() {
+			@Override
+			public void actionPerformed(ActionEvent actionEvent) {
+				if (list.isSelectionEmpty()) return;
+				listModel.moveDown(list.getSelectedIndex());
+				list.setSelectedIndex(list.getSelectedIndex() + 1);
+			}
+		});
+		down.setText("\u2228");
+
+		this.add(list);
+		this.add(up);
+		this.add(down);
+	}
+
+	public static OrderableListPanel getInstance() {
+		if (instance == null) {
+			instance = new OrderableListPanel();
+		}
+		return instance;
+	}
+
+	/**
+	 * Updates removed and new relations in the listModel. Does it in a special way to preserve existing ordering in the
+	 * list, so user has to do minimal re-sorting.
+	 */
+    @Override
+    public void onModelChanged() {
+    	if (this.model == null) return;
+		Set<Relation> newRelations = new HashSet<>(model.getRelations());
+		newRelations.removeAll(listModel.getList());
+
+        Set<Relation> removedRelations = new HashSet<>(listModel.getList());
+        removedRelations.removeAll(model.getRelations());
+
+        listModel.removeAll(removedRelations);
+        listModel.addAll(newRelations);
+    }
+
+    public ArrayList<Relation> getOrderList() {
+    	return new ArrayList<>(listModel.getList());
+	}
+}