* Mapmode to add nodes, create and extend ways.

*/

    private final Cursor cursorJoinNode;

    private final Cursor cursorJoinWay;

    private Node lastUsedNode = null;

    private static final double PHI = Math.toRadians(90);

    private double toleranceMultiplier;

    private Node mouseOnExistingNode;

    private Set<Way> mouseOnExistingWays = new HashSet<>();

    // old highlights store which primitives are currently highlighted. This

    // is true, even if target highlighting is disabled since the status bar

    // derives its information from this list as well.

    private Set<OsmPrimitive> oldHighlights = new HashSet<>();

    // new highlights contains a list of primitives that should be highlighted

    // but haven’t been so far. The idea is to compare old and new and only

    // repaint if there are changes.

    private Set<OsmPrimitive> newHighlights = new HashSet<>();

    private boolean drawHelperLine;

    private boolean wayIsFinished = false;

    private boolean drawTargetHighlight;

    private Point mousePos;

    private Point oldMousePos;

    private Color rubberLineColor;

    private Node currentBaseNode;

    private Node previousNode;

    private EastNorth currentMouseEastNorth;

    private final SnapHelper snapHelper = new SnapHelper();

    private final Shortcut backspaceShortcut;

    private final BackSpaceAction backspaceAction;

    private final Shortcut snappingShortcut;

    private boolean ignoreNextKeyRelease;

    private final SnapChangeAction snapChangeAction;

    private final JCheckBoxMenuItem snapCheckboxMenuItem;

    private boolean useRepeatedShortcut;

    private Stroke rubberLineStroke;

    private static final BasicStroke BASIC_STROKE = new BasicStroke(1);

    private static int snapToIntersectionThreshold;

    public DrawAction(MapFrame mapFrame) {

        super(tr("Draw"), "node/autonode", tr("Draw nodes"),

                Shortcut.registerShortcut("mapmode:draw", tr("Mode: {0}", tr("Draw")), KeyEvent.VK_A, Shortcut.DIRECT),

                mapFrame, ImageProvider.getCursor("crosshair", null));

        snappingShortcut = Shortcut.registerShortcut("mapmode:drawanglesnapping",

                tr("Mode: Draw Angle snapping"), KeyEvent.CHAR_UNDEFINED, Shortcut.NONE);

        snapChangeAction = new SnapChangeAction();

        snapCheckboxMenuItem = addMenuItem();

        snapHelper.setMenuCheckBox(snapCheckboxMenuItem);

        backspaceShortcut = Shortcut.registerShortcut("mapmode:backspace",

                tr("Backspace in Add mode"), KeyEvent.VK_BACK_SPACE, Shortcut.DIRECT);

        backspaceAction = new BackSpaceAction();

        cursorJoinNode = ImageProvider.getCursor("crosshair", "joinnode");

        cursorJoinWay = ImageProvider.getCursor("crosshair", "joinway");

        readPreferences();

        snapHelper.init();

    }

    private JCheckBoxMenuItem addMenuItem() {

        int n=Main.main.menu.editMenu.getItemCount();

        for (int i=n-1;i>0;i--) {

            JMenuItem item = Main.main.menu.editMenu.getItem(i);

            if (item!=null && item.getAction() !=null && item.getAction() instanceof SnapChangeAction) {

                Main.main.menu.editMenu.remove(i);

            }

        }

        return MainMenu.addWithCheckbox(Main.main.menu.editMenu, snapChangeAction, MainMenu.WINDOW_MENU_GROUP.VOLATILE);

    }

    /**

     * Checks if a map redraw is required and does so if needed. Also updates the status bar

     */

    private boolean redrawIfRequired() {

        updateStatusLine();

        // repaint required if the helper line is active.

        boolean needsRepaint = drawHelperLine && !wayIsFinished;

        if(drawTargetHighlight) {

            // move newHighlights to oldHighlights; only update changed primitives

            for(OsmPrimitive x : newHighlights) {

                if(oldHighlights.contains(x)) {

                    continue;

                }

                x.setHighlighted(true);

                needsRepaint = true;

            }

            oldHighlights.removeAll(newHighlights);

            for(OsmPrimitive x : oldHighlights) {

                x.setHighlighted(false);

                needsRepaint = true;

            }

        }

        // required in order to print correct help text

        oldHighlights = newHighlights;

        if (!needsRepaint && !drawTargetHighlight)

            return false;

        // update selection to reflect which way being modified

        DataSet currentDataSet = getCurrentDataSet();

        if (currentBaseNode != null && currentDataSet != null && !currentDataSet.getSelected().isEmpty()) {

            Way continueFrom = getWayForNode(currentBaseNode);

            if (alt && continueFrom != null && (!currentBaseNode.isSelected() || continueFrom.isSelected())) {

                addRemoveSelection(currentDataSet, currentBaseNode, continueFrom);

                needsRepaint = true;

            } else if (!alt && continueFrom != null && !continueFrom.isSelected()) {

                currentDataSet.addSelected(continueFrom);

                needsRepaint = true;

            }

        }

        if(needsRepaint) {

            Main.map.mapView.repaint();

        }

        return needsRepaint;

    }

    private static void addRemoveSelection(DataSet ds, OsmPrimitive toAdd, OsmPrimitive toRemove) {

        ds.beginUpdate(); // to prevent the selection listener to screw around with the state

        ds.addSelected(toAdd);

        ds.clearSelection(toRemove);

        ds.endUpdate();

    }

    @Override

    public void enterMode() {

        if (!isEnabled())

            return;

        super.enterMode();

        readPreferences();

        // determine if selection is suitable to continue drawing. If it

        // isn't, set wayIsFinished to true to avoid superfluous repaints.

        determineCurrentBaseNodeAndPreviousNode(getCurrentDataSet().getSelected());

        wayIsFinished = currentBaseNode == null;

        toleranceMultiplier = 0.01 * NavigatableComponent.PROP_SNAP_DISTANCE.get();

        snapHelper.init();

        snapCheckboxMenuItem.getAction().setEnabled(true);

        Main.map.statusLine.getAnglePanel().addMouseListener(snapHelper.anglePopupListener);

        Main.registerActionShortcut(backspaceAction, backspaceShortcut);

        Main.map.mapView.addMouseListener(this);

        Main.map.mapView.addMouseMotionListener(this);

        Main.map.mapView.addTemporaryLayer(this);

        DataSet.addSelectionListener(this);

        Main.map.keyDetector.addKeyListener(this);

        Main.map.keyDetector.addModifierListener(this);

        ignoreNextKeyRelease = true;

        // would like to but haven't got mouse position yet:

        // computeHelperLine(false, false, false);

    }

    private void readPreferences() {

        rubberLineColor = Main.pref.getColor(marktr("helper line"), null);

        if (rubberLineColor == null) rubberLineColor = PaintColors.SELECTED.get();

        rubberLineStroke = GuiHelper.getCustomizedStroke(Main.pref.get("draw.stroke.helper-line","3"));

        drawHelperLine = Main.pref.getBoolean("draw.helper-line", true);

        drawTargetHighlight = Main.pref.getBoolean("draw.target-highlight", true);

        snapToIntersectionThreshold = Main.pref.getInteger("edit.snap-intersection-threshold",10);

    }

    @Override

    public void exitMode() {

        super.exitMode();

        Main.map.mapView.removeMouseListener(this);

        Main.map.mapView.removeMouseMotionListener(this);

        Main.map.mapView.removeTemporaryLayer(this);

        DataSet.removeSelectionListener(this);

        Main.unregisterActionShortcut(backspaceAction, backspaceShortcut);

        snapHelper.unsetFixedMode();

        snapCheckboxMenuItem.getAction().setEnabled(false);

        Main.map.statusLine.getAnglePanel().removeMouseListener(snapHelper.anglePopupListener);

        Main.map.statusLine.activateAnglePanel(false);

        removeHighlighting();

        Main.map.keyDetector.removeKeyListener(this);

        Main.map.keyDetector.removeModifierListener(this);

        // when exiting we let everybody know about the currently selected

        // primitives

        //

        DataSet ds = getCurrentDataSet();

        if(ds != null) {

            ds.fireSelectionChanged();

        }

    }

    /**

     * redraw to (possibly) get rid of helper line if selection changes.

     */

    @Override

    public void modifiersChanged(int modifiers) {

        if (!Main.isDisplayingMapView() || !Main.map.mapView.isActiveLayerDrawable())

            return;

        updateKeyModifiers(modifiers);

        computeHelperLine();

        addHighlighting();

    }

    @Override

    public void doKeyPressed(KeyEvent e) {

        if (!snappingShortcut.isEvent(e) && !(useRepeatedShortcut && getShortcut().isEvent(e)))

            return;

        snapHelper.setFixedMode();

        computeHelperLine();

        redrawIfRequired();

    }

    @Override

    public void doKeyReleased(KeyEvent e) {

        if (!snappingShortcut.isEvent(e) && !(useRepeatedShortcut && getShortcut().isEvent(e)))

            return;

        if (ignoreNextKeyRelease) {

            ignoreNextKeyRelease = false;

            return;

        }

        snapHelper.unFixOrTurnOff();

        computeHelperLine();

        redrawIfRequired();

    }

    /**

     * redraw to (possibly) get rid of helper line if selection changes.

     */

    @Override

    public void selectionChanged(Collection<? extends OsmPrimitive> newSelection) {

        if(!Main.map.mapView.isActiveLayerDrawable())

            return;

        computeHelperLine();

        addHighlighting();

    }

    private void tryAgain(MouseEvent e) {

        getCurrentDataSet().setSelected();

        mouseReleased(e);

    }

    /**

     * This function should be called when the user wishes to finish his current draw action.

     * If Potlatch Style is enabled, it will switch to select tool, otherwise simply disable

     * the helper line until the user chooses to draw something else.

     */

    private void finishDrawing() {

        // let everybody else know about the current selection

        //

        Main.main.getCurrentDataSet().fireSelectionChanged();

        lastUsedNode = null;

        wayIsFinished = true;

        Main.map.selectSelectTool(true);

        snapHelper.noSnapNow();

        // Redraw to remove the helper line stub

        computeHelperLine();

        removeHighlighting();

    }

    private Point rightClickPressPos;

    @Override

    public void mousePressed(MouseEvent e) {

        if (e.getButton() == MouseEvent.BUTTON3) {

            rightClickPressPos = e.getPoint();

        }

    }

    /**

     * If user clicked with the left button, add a node at the current mouse

     * position.

     *

     * If in nodeway mode, insert the node into the way.

     */

    @Override

    public void mouseReleased(MouseEvent e) {

        if (e.getButton() == MouseEvent.BUTTON3) {

            Point curMousePos = e.getPoint();

            if (curMousePos.equals(rightClickPressPos)) {

                tryToSetBaseSegmentForAngleSnap();

            }

            return;

        }

        if (e.getButton() != MouseEvent.BUTTON1)

            return;

        if(!Main.map.mapView.isActiveLayerDrawable())

            return;

        // request focus in order to enable the expected keyboard shortcuts

        //

        Main.map.mapView.requestFocus();

        if(e.getClickCount() > 1 && mousePos != null && mousePos.equals(oldMousePos)) {

            // A double click equals "user clicked last node again, finish way"

            // Change draw tool only if mouse position is nearly the same, as

            // otherwise fast clicks will count as a double click

            finishDrawing();

            return;

        }

        oldMousePos = mousePos;

        // we copy ctrl/alt/shift from the event just in case our global

        // keyDetector didn't make it through the security manager. Unclear

        // if that can ever happen but better be safe.

        updateKeyModifiers(e);

        mousePos = e.getPoint();

        DataSet ds = getCurrentDataSet();

        Collection<OsmPrimitive> selection = new ArrayList<>(ds.getSelected());

        Collection<Command> cmds = new LinkedList<>();

        Collection<OsmPrimitive> newSelection = new LinkedList<>(ds.getSelected());

        List<Way> reuseWays = new ArrayList<>(),

                replacedWays = new ArrayList<>();

        boolean newNode = false;

        Node n = null;

        n = Main.map.mapView.getNearestNode(mousePos, OsmPrimitive.isSelectablePredicate);

        if (ctrl) {

            Iterator<Way> it = getCurrentDataSet().getSelectedWays().iterator();

            if (it.hasNext()) {

                // ctrl-click on node of selected way = reuse node despite of ctrl

                if (!it.next().containsNode(n)) n = null;

            } else {

                n=null; // ctrl-click + no selected way = new node

            }

        }

        if (n != null && !snapHelper.isActive()) {

            // user clicked on node

            if (selection.isEmpty() || wayIsFinished) {

                // select the clicked node and do nothing else

                // (this is just a convenience option so that people don't

                // have to switch modes)

                getCurrentDataSet().setSelected(n);

                // If we extend/continue an existing way, select it already now to make it obvious

                Way continueFrom = getWayForNode(n);

                if (continueFrom != null) {

                    getCurrentDataSet().addSelected(continueFrom);

                }

                // The user explicitly selected a node, so let him continue drawing

                wayIsFinished = false;

                return;

            }

        } else {

            EastNorth newEN;

            if (n!=null) {

                EastNorth foundPoint = n.getEastNorth();

                // project found node to snapping line

                newEN = snapHelper.getSnapPoint(foundPoint);

                // do not add new node if there is some node within snapping distance

                double tolerance = Main.map.mapView.getDist100Pixel() * toleranceMultiplier;

                if (foundPoint.distance(newEN) > tolerance) {

                    n = new Node(newEN); // point != projected, so we create new node

                    newNode = true;

                }

            } else { // n==null, no node found in clicked area

                EastNorth mouseEN = Main.map.mapView.getEastNorth(e.getX(), e.getY());

                newEN = snapHelper.isSnapOn() ? snapHelper.getSnapPoint(mouseEN) : mouseEN;

                n = new Node(newEN); //create node at clicked point

                newNode = true;

            }

            snapHelper.unsetFixedMode();

        }

        if (newNode) {

            if (n.getCoor().isOutSideWorld()) {

                JOptionPane.showMessageDialog(

                        Main.parent,

                        tr("Cannot add a node outside of the world."),

                        tr("Warning"),

                        JOptionPane.WARNING_MESSAGE

                        );

                return;

            }

            cmds.add(new AddCommand(n));

            if (!ctrl) {

                // Insert the node into all the nearby way segments

                List<WaySegment> wss = Main.map.mapView.getNearestWaySegments(

                        Main.map.mapView.getPoint(n), OsmPrimitive.isSelectablePredicate);

                if (snapHelper.isActive()) {

                    tryToMoveNodeOnIntersection(wss,n);

                }

                insertNodeIntoAllNearbySegments(wss, n, newSelection, cmds, replacedWays, reuseWays);

            }

        }

        // now "n" is newly created or reused node that shoud be added to some way

        // This part decides whether or not a "segment" (i.e. a connection) is made to an

        // existing node.

        // For a connection to be made, the user must either have a node selected (connection

        // is made to that node), or he must have a way selected *and* one of the endpoints

        // of that way must be the last used node (connection is made to last used node), or

        // he must have a way and a node selected (connection is made to the selected node).

        // If the above does not apply, the selection is cleared and a new try is started

        boolean extendedWay = false;

        boolean wayIsFinishedTemp = wayIsFinished;

        wayIsFinished = false;

        // don't draw lines if shift is held

        if (!selection.isEmpty() && !shift) {

            Node selectedNode = null;

            Way selectedWay = null;

            for (OsmPrimitive p : selection) {

                if (p instanceof Node) {

                    if (selectedNode != null) {

                        // Too many nodes selected to do something useful

                        tryAgain(e);

                        return;

                    }

                    selectedNode = (Node) p;

                } else if (p instanceof Way) {

                    if (selectedWay != null) {

                        // Too many ways selected to do something useful

                        tryAgain(e);

                        return;

                    }

                    selectedWay = (Way) p;

                }

            }

            // the node from which we make a connection

            Node n0 = findNodeToContinueFrom(selectedNode, selectedWay);

            // We have a selection but it isn't suitable. Try again.

            if(n0 == null) {

                tryAgain(e);

                return;

            }

            if(!wayIsFinishedTemp){

                if(isSelfContainedWay(selectedWay, n0, n))

                    return;

                // User clicked last node again, finish way

                if(n0 == n) {

                    finishDrawing();

                    return;

                }

                // Ok we know now that we'll insert a line segment, but will it connect to an

                // existing way or make a new way of its own? The "alt" modifier means that the

                // user wants a new way.

                Way way = alt ? null : (selectedWay != null) ? selectedWay : getWayForNode(n0);

                Way wayToSelect;

                // Don't allow creation of self-overlapping ways

                if(way != null) {

                    int nodeCount=0;

                    for (Node p : way.getNodes())

                        if(p.equals(n0)) {

                            nodeCount++;

                        }

                    if(nodeCount > 1) {

                        way = null;

                    }

                }

                if (way == null) {

                    way = new Way();

                    way.addNode(n0);

                    cmds.add(new AddCommand(way));

                    wayToSelect = way;

                } else {

                    int i;

                    if ((i = replacedWays.indexOf(way)) != -1) {

                        way = reuseWays.get(i);

                        wayToSelect = way;

                    } else {

                        wayToSelect = way;

                        Way wnew = new Way(way);

                        cmds.add(new ChangeCommand(way, wnew));

                        way = wnew;

                    }

                }

                // Connected to a node that's already in the way

                if(way.containsNode(n)) {

                    wayIsFinished = true;

                    selection.clear();

                }

                // Add new node to way

                if (way.getNode(way.getNodesCount() - 1) == n0) {

                    way.addNode(n);

                } else {

                    way.addNode(0, n);

                }

                extendedWay = true;

                newSelection.clear();

                newSelection.add(wayToSelect);

            }

        }

        String title;

        if (!extendedWay) {

            if (!newNode)

                return; // We didn't do anything.

            else if (reuseWays.isEmpty()) {

                title = tr("Add node");

            } else {

                title = tr("Add node into way");

                for (Way w : reuseWays) {

                    newSelection.remove(w);

                }

            }

            newSelection.clear();

            newSelection.add(n);

        } else if (!newNode) {

            title = tr("Connect existing way to node");

        } else if (reuseWays.isEmpty()) {

            title = tr("Add a new node to an existing way");

        } else {

            title = tr("Add node into way and connect");

        }

        Command c = new SequenceCommand(title, cmds);

        Main.main.undoRedo.add(c);

        if(!wayIsFinished) {

            lastUsedNode = n;

        }

        getCurrentDataSet().setSelected(newSelection);

        // "viewport following" mode for tracing long features

        // from aerial imagery or GPS tracks.

        if (n != null && Main.map.mapView.viewportFollowing) {

            Main.map.mapView.smoothScrollTo(n.getEastNorth());

        }

        computeHelperLine();

        removeHighlighting();

    }

    private void insertNodeIntoAllNearbySegments(List<WaySegment> wss, Node n, Collection<OsmPrimitive> newSelection, Collection<Command> cmds, List<Way> replacedWays, List<Way> reuseWays) {

        Map<Way, List<Integer>> insertPoints = new HashMap<>();

        for (WaySegment ws : wss) {

            List<Integer> is;

            if (insertPoints.containsKey(ws.way)) {

                is = insertPoints.get(ws.way);

            } else {

                is = new ArrayList<>();

                insertPoints.put(ws.way, is);

            }

            is.add(ws.lowerIndex);

        }

        Set<Pair<Node,Node>> segSet = new HashSet<>();

        for (Map.Entry<Way, List<Integer>> insertPoint : insertPoints.entrySet()) {

            Way w = insertPoint.getKey();

            List<Integer> is = insertPoint.getValue();

            Way wnew = new Way(w);

            pruneSuccsAndReverse(is);

            for (int i : is) {

                segSet.add(Pair.sort(new Pair<>(w.getNode(i), w.getNode(i+1))));

            }

            for (int i : is) {

                wnew.addNode(i + 1, n);

            }

            // If ALT is pressed, a new way should be created and that new way should get

            // selected. This works everytime unless the ways the nodes get inserted into

            // are already selected. This is the case when creating a self-overlapping way

            // but pressing ALT prevents this. Therefore we must de-select the way manually

            // here so /only/ the new way will be selected after this method finishes.

            if(alt) {

                newSelection.add(insertPoint.getKey());

            }

            cmds.add(new ChangeCommand(insertPoint.getKey(), wnew));

            replacedWays.add(insertPoint.getKey());

            reuseWays.add(wnew);

        }

        adjustNode(segSet, n);

    }

    /**

     * Prevent creation of ways that look like this: &lt;----&gt;

     * This happens if users want to draw a no-exit-sideway from the main way like this:

     * ^

     * |&lt;----&gt;

     * |

     * The solution isn't ideal because the main way will end in the side way, which is bad for

     * navigation software ("drive straight on") but at least easier to fix. Maybe users will fix

     * it on their own, too. At least it's better than producing an error.

     *

     * @param selectedWay the way to check

     * @param currentNode the current node (i.e. the one the connection will be made from)

     * @param targetNode the target node (i.e. the one the connection will be made to)

     * @return {@code true} if this would create a selfcontaining way, {@code false} otherwise.

     */

    private boolean isSelfContainedWay(Way selectedWay, Node currentNode, Node targetNode) {

        if(selectedWay != null) {

            int posn0 = selectedWay.getNodes().indexOf(currentNode);

            if( posn0 != -1 && // n0 is part of way

                    (posn0 >= 1                             && targetNode.equals(selectedWay.getNode(posn0-1))) || // previous node

                    (posn0 < selectedWay.getNodesCount()-1) && targetNode.equals(selectedWay.getNode(posn0+1))) {  // next node

                getCurrentDataSet().setSelected(targetNode);

                lastUsedNode = targetNode;

                return true;

            }

        }

        return false;

    }

    /**

     * Finds a node to continue drawing from. Decision is based upon given node and way.

     * @param selectedNode Currently selected node, may be null

     * @param selectedWay Currently selected way, may be null

     * @return Node if a suitable node is found, null otherwise

     */

    private Node findNodeToContinueFrom(Node selectedNode, Way selectedWay) {

        // No nodes or ways have been selected, this occurs when a relation

        // has been selected or the selection is empty

        if(selectedNode == null && selectedWay == null)

            return null;

        if (selectedNode == null) {

            if (selectedWay.isFirstLastNode(lastUsedNode))

                return lastUsedNode;

            // We have a way selected, but no suitable node to continue from. Start anew.

            return null;

        }

        if (selectedWay == null)

            return selectedNode;

        if (selectedWay.isFirstLastNode(selectedNode))

            return selectedNode;

        // We have a way and node selected, but it's not at the start/end of the way. Start anew.

        return null;

    }

    @Override

    public void mouseDragged(MouseEvent e) {

        mouseMoved(e);

    }

    @Override

    public void mouseMoved(MouseEvent e) {

        if(!Main.map.mapView.isActiveLayerDrawable())

            return;

        // we copy ctrl/alt/shift from the event just in case our global

        // keyDetector didn't make it through the security manager. Unclear

        // if that can ever happen but better be safe.

        updateKeyModifiers(e);

        mousePos = e.getPoint();

        if (snapHelper.isSnapOn() && ctrl)

            tryToSetBaseSegmentForAngleSnap();

        computeHelperLine();

        addHighlighting();

    }

    /**

     * This method is used to detect segment under mouse and use it as reference for angle snapping

     */

    private void tryToSetBaseSegmentForAngleSnap() {

        WaySegment seg = Main.map.mapView.getNearestWaySegment(mousePos, OsmPrimitive.isSelectablePredicate);

        if (seg!=null) {

            snapHelper.setBaseSegment(seg);

        }

    }

    /**

     * This method prepares data required for painting the "helper line" from

     * the last used position to the mouse cursor. It duplicates some code from

     * mouseReleased() (FIXME).

     */

    private void computeHelperLine() {

        MapView mv = Main.map.mapView;

        if (mousePos == null) {

            // Don't draw the line.

            currentMouseEastNorth = null;

            currentBaseNode = null;

            return;

        }

        Collection<OsmPrimitive> selection = getCurrentDataSet().getSelected();

        Node currentMouseNode = null;

        mouseOnExistingNode = null;

        mouseOnExistingWays = new HashSet<>();

        showStatusInfo(-1, -1, -1, snapHelper.isSnapOn());

        if (!ctrl && mousePos != null) {

            currentMouseNode = mv.getNearestNode(mousePos, OsmPrimitive.isSelectablePredicate);

        }

        // We need this for highlighting and we'll only do so if we actually want to re-use

        // *and* there is no node nearby (because nodes beat ways when re-using)

        if(!ctrl && currentMouseNode == null) {

            List<WaySegment> wss = mv.getNearestWaySegments(mousePos, OsmPrimitive.isSelectablePredicate);

            for(WaySegment ws : wss) {

                mouseOnExistingWays.add(ws.way);

            }

        }

        if (currentMouseNode != null) {

            // user clicked on node

            if (selection.isEmpty()) return;

            currentMouseEastNorth = currentMouseNode.getEastNorth();

            mouseOnExistingNode = currentMouseNode;

        } else {

            // no node found in clicked area

            currentMouseEastNorth = mv.getEastNorth(mousePos.x, mousePos.y);

        }

        determineCurrentBaseNodeAndPreviousNode(selection);

        if (previousNode == null) {

            snapHelper.noSnapNow();

        }

        if (currentBaseNode == null || currentBaseNode == currentMouseNode)

            return; // Don't create zero length way segments.

        double curHdg = Math.toDegrees(currentBaseNode.getEastNorth()

                .heading(currentMouseEastNorth));

        double baseHdg=-1;

        if (previousNode != null) {

            baseHdg =  Math.toDegrees(previousNode.getEastNorth()

                    .heading(currentBaseNode.getEastNorth()));

        }

        snapHelper.checkAngleSnapping(currentMouseEastNorth,baseHdg, curHdg);

        // status bar was filled by snapHelper

    }

    private void showStatusInfo(double angle, double hdg, double distance, boolean activeFlag) {

        Main.map.statusLine.setAngle(angle);

        Main.map.statusLine.activateAnglePanel(activeFlag);

        Main.map.statusLine.setHeading(hdg);

        Main.map.statusLine.setDist(distance);

    }

    /**

     * Helper function that sets fields currentBaseNode and previousNode

     * @param selection

     * uses also lastUsedNode field

     */

    private void determineCurrentBaseNodeAndPreviousNode(Collection<OsmPrimitive>  selection) {

        Node selectedNode = null;

        Way selectedWay = null;

        for (OsmPrimitive p : selection) {

            if (p instanceof Node) {

                if (selectedNode != null)

                    return;

                selectedNode = (Node) p;

            } else if (p instanceof Way) {

                if (selectedWay != null)

                    return;

                selectedWay = (Way) p;

            }

        }

        // we are here, if not more than 1 way or node is selected,

        // the node from which we make a connection

        currentBaseNode = null;

        previousNode = null;

        // Try to find an open way to measure angle from it. The way is not to be continued!

        // warning: may result in changes of currentBaseNode and previousNode

        // please remove if bugs arise

        if (selectedWay == null && selectedNode != null) {

            for (OsmPrimitive p: selectedNode.getReferrers()) {

                if (p.isUsable() && p instanceof Way && ((Way) p).isFirstLastNode(selectedNode)) {

                    if (selectedWay!=null) { // two uncontinued ways, nothing to take as reference

                        selectedWay=null;

                        break;

                    } else {

                        // set us ~continue this way (measure angle from it)

                        selectedWay = (Way) p;

                    }

                }

            }

        }

        if (selectedNode == null) {

            if (selectedWay == null)

                return;

            continueWayFromNode(selectedWay, lastUsedNode);

        } else if (selectedWay == null) {

            currentBaseNode = selectedNode;

        } else if (!selectedWay.isDeleted()) { // fix #7118

            continueWayFromNode(selectedWay, selectedNode);

        }

    }

    /**

     * if one of the ends of @param way is given @param node ,

     * then set  currentBaseNode = node and previousNode = adjacent node of way

     */

    private void continueWayFromNode(Way way, Node node) {

        int n = way.getNodesCount();

        if (node == way.firstNode()){

            currentBaseNode = node;

            if (n>1) previousNode = way.getNode(1);

        } else if (node == way.lastNode()) {

            currentBaseNode = node;

            if (n>1) previousNode = way.getNode(n-2);

        }

    }

    /**

     * Repaint on mouse exit so that the helper line goes away.

     */

    @Override

    public void mouseExited(MouseEvent e) {

        if(!Main.map.mapView.isActiveLayerDrawable())

            return;

        mousePos = e.getPoint();

        snapHelper.noSnapNow();

        boolean repaintIssued = removeHighlighting();

        // force repaint in case snapHelper needs one. If removeHighlighting

        // caused one already, don’t do it again.

        if(!repaintIssued) {

            Main.map.mapView.repaint();

        }

    }

    /**

     * @return If the node is the end of exactly one way, return this.

     *  <code>null</code> otherwise.

     */

    public static Way getWayForNode(Node n) {

        Way way = null;

        for (Way w : Utils.filteredCollection(n.getReferrers(), Way.class)) {

            if (!w.isUsable() || w.getNodesCount() < 1) {

                continue;

            }

            Node firstNode = w.getNode(0);

            Node lastNode = w.getNode(w.getNodesCount() - 1);

            if ((firstNode == n || lastNode == n) && (firstNode != lastNode)) {

                if (way != null)

                    return null;

                way = w;

            }

        }

        return way;

    }

    public Node getCurrentBaseNode() {

        return currentBaseNode;

    }

    private static void pruneSuccsAndReverse(List<Integer> is) {

        HashSet<Integer> is2 = new HashSet<>();

        for (int i : is) {

            if (!is2.contains(i - 1) && !is2.contains(i + 1)) {

                is2.add(i);

            }

        }

        is.clear();

        is.addAll(is2);

        Collections.sort(is);

        Collections.reverse(is);

    }

    /**

     * Adjusts the position of a node to lie on a segment (or a segment

     * intersection).

     *

     * If one or more than two segments are passed, the node is adjusted

     * to lie on the first segment that is passed.

     *

     * If two segments are passed, the node is adjusted to be at their

     * intersection.

     *

     * No action is taken if no segments are passed.

     *

     * @param segs the segments to use as a reference when adjusting

     * @param n the node to adjust

     */

    private static void adjustNode(Collection<Pair<Node,Node>> segs, Node n) {

        switch (segs.size()) {

        case 0:

            return;

        case 2:

            // This computes the intersection between

            // the two segments and adjusts the node position.

            Iterator<Pair<Node,Node>> i = segs.iterator();

            Pair<Node,Node> seg = i.next();

            EastNorth A = seg.a.getEastNorth();

            EastNorth B = seg.b.getEastNorth();

            seg = i.next();

            EastNorth C = seg.a.getEastNorth();

            EastNorth D = seg.b.getEastNorth();

            double u=det(B.east() - A.east(), B.north() - A.north(), C.east() - D.east(), C.north() - D.north());

            // Check for parallel segments and do nothing if they are

            // In practice this will probably only happen when a way has been duplicated

            if (u == 0)

                return;

            // q is a number between 0 and 1

            // It is the point in the segment where the intersection occurs

            // if the segment is scaled to lenght 1

            double q = det(B.north() - C.north(), B.east() - C.east(), D.north() - C.north(), D.east() - C.east()) / u;

            EastNorth intersection = new EastNorth(

                    B.east() + q * (A.east() - B.east()),

                    B.north() + q * (A.north() - B.north()));

            // only adjust to intersection if within snapToIntersectionThreshold pixel of mouse click; otherwise

            // fall through to default action.

            // (for semi-parallel lines, intersection might be miles away!)

            if (Main.map.mapView.getPoint2D(n).distance(Main.map.mapView.getPoint2D(intersection)) < snapToIntersectionThreshold) {

                n.setEastNorth(intersection);

                return;

            }

        default:

            EastNorth P = n.getEastNorth();

            seg = segs.iterator().next();

            A = seg.a.getEastNorth();

            B = seg.b.getEastNorth();

            double a = P.distanceSq(B);

            double b = P.distanceSq(A);

            double c = A.distanceSq(B);

            q = (a - b + c) / (2*c);

            n.setEastNorth(new EastNorth(B.east() + q * (A.east() - B.east()), B.north() + q * (A.north() - B.north())));

        }

    }

    // helper for adjustNode

    static double det(double a, double b, double c, double d) {

        return a * d - b * c;

    }

    private void tryToMoveNodeOnIntersection(List<WaySegment> wss, Node n) {

        if (wss.isEmpty())

            return;

        WaySegment ws = wss.get(0);

        EastNorth p1=ws.getFirstNode().getEastNorth();

        EastNorth p2=ws.getSecondNode().getEastNorth();

        if (snapHelper.dir2!=null && currentBaseNode!=null) {

            EastNorth xPoint = Geometry.getSegmentSegmentIntersection(p1, p2, snapHelper.dir2, currentBaseNode.getEastNorth());

            if (xPoint!=null) {

                n.setEastNorth(xPoint);

            }

        }

    }

    /**

     * Takes the data from computeHelperLine to determine which ways/nodes should be highlighted

     * (if feature enabled). Also sets the target cursor if appropriate. It adds the to-be-

     * highlighted primitives to newHighlights but does not actually highlight them. This work is

     * done in redrawIfRequired. This means, calling addHighlighting() without redrawIfRequired()

     * will leave the data in an inconsistent state.

     *

     * The status bar derives its information from oldHighlights, so in order to update the status

     * bar both addHighlighting() and repaintIfRequired() are needed, since former fills newHighlights

     * and latter processes them into oldHighlights.

     */

    private void addHighlighting() {

        newHighlights = new HashSet<>();

        // if ctrl key is held ("no join"), don't highlight anything

        if (ctrl) {

            Main.map.mapView.setNewCursor(cursor, this);

            redrawIfRequired();

            return;

        }

        // This happens when nothing is selected, but we still want to highlight the "target node"

        if (mouseOnExistingNode == null && getCurrentDataSet().getSelected().isEmpty()

                && mousePos != null) {

            mouseOnExistingNode = Main.map.mapView.getNearestNode(mousePos, OsmPrimitive.isSelectablePredicate);

        }

        if (mouseOnExistingNode != null) {

            Main.map.mapView.setNewCursor(cursorJoinNode, this);

            newHighlights.add(mouseOnExistingNode);

            redrawIfRequired();

            return;

        }

        // Insert the node into all the nearby way segments

        if (mouseOnExistingWays.isEmpty()) {

            Main.map.mapView.setNewCursor(cursor, this);

            redrawIfRequired();

            return;

        }

        Main.map.mapView.setNewCursor(cursorJoinWay, this);

        newHighlights.addAll(mouseOnExistingWays);

        redrawIfRequired();

    }

    /**

     * Removes target highlighting from primitives. Issues repaint if required.

     * Returns true if a repaint has been issued.

     */

    private boolean removeHighlighting() {

        newHighlights = new HashSet<>();

        return redrawIfRequired();

    }

    @Override

    public void paint(Graphics2D g, MapView mv, Bounds box) {

        // sanity checks

        if (Main.map.mapView == null || mousePos == null

                // don't draw line if we don't know where from or where to

                || currentBaseNode == null || currentMouseEastNorth == null

                // don't draw line if mouse is outside window

                || !Main.map.mapView.getBounds().contains(mousePos))

            return;

        Graphics2D g2 = g;

        snapHelper.drawIfNeeded(g2,mv);

        if (!drawHelperLine || wayIsFinished || shift)

            return;

        if (!snapHelper.isActive()) { // else use color and stoke from  snapHelper.draw

            g2.setColor(rubberLineColor);

            g2.setStroke(rubberLineStroke);

        } else if (!snapHelper.drawConstructionGeometry)

            return;

        GeneralPath b = new GeneralPath();

        Point p1=mv.getPoint(currentBaseNode);

        Point p2=mv.getPoint(currentMouseEastNorth);

        double t = Math.atan2(p2.y-p1.y, p2.x-p1.x) + Math.PI;

        b.moveTo(p1.x,p1.y); b.lineTo(p2.x, p2.y);

        // if alt key is held ("start new way"), draw a little perpendicular line

        if (alt) {

            b.moveTo((int)(p1.x + 8*Math.cos(t+PHI)), (int)(p1.y + 8*Math.sin(t+PHI)));

            b.lineTo((int)(p1.x + 8*Math.cos(t-PHI)), (int)(p1.y + 8*Math.sin(t-PHI)));

        }

        g2.draw(b);

        g2.setStroke(BASIC_STROKE);

    }

    @Override

    public String getModeHelpText() {

        StringBuilder rv;

        /*

         *  No modifiers: all (Connect, Node Re-Use, Auto-Weld)

         *  CTRL: disables node re-use, auto-weld

         *  Shift: do not make connection

         *  ALT: make connection but start new way in doing so

         */

        /*

         * Status line text generation is split into two parts to keep it maintainable.

         * First part looks at what will happen to the new node inserted on click and

         * the second part will look if a connection is made or not.

         *

         * Note that this help text is not absolutely accurate as it doesn't catch any special

         * cases (e.g. when preventing <---> ways). The only special that it catches is when

         * a way is about to be finished.

         *

         * First check what happens to the new node.

         */

        // oldHighlights stores the current highlights. If this

        // list is empty we can assume that we won't do any joins

        if (ctrl || oldHighlights.isEmpty()) {

            rv = new StringBuilder(tr("Create new node."));

        } else {

            // oldHighlights may store a node or way, check if it's a node

            OsmPrimitive x = oldHighlights.iterator().next();

            if (x instanceof Node) {

                rv = new StringBuilder(tr("Select node under cursor."));

            } else {

                rv = new StringBuilder(trn("Insert new node into way.", "Insert new node into {0} ways.",

                        oldHighlights.size(), oldHighlights.size()));

            }

        }

        /*

         * Check whether a connection will be made

         */

        if (currentBaseNode != null && !wayIsFinished) {

            if (alt) {

                rv.append(" ").append(tr("Start new way from last node."));

            } else {

                rv.append(" ").append(tr("Continue way from last node."));

            }

            if (snapHelper.isSnapOn()) {

                rv.append(" ").append(tr("Angle snapping active."));

            }

        }

        Node n = mouseOnExistingNode;

        /*

         * Handle special case: Highlighted node == selected node => finish drawing

         */

        if (n != null && getCurrentDataSet() != null && getCurrentDataSet().getSelectedNodes().contains(n)) {