package org.simantics.district.network.ui;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.geom.Path2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import org.simantics.Simantics;
import org.simantics.db.Resource;
import org.simantics.db.WriteGraph;
import org.simantics.db.common.request.WriteRequest;
import org.simantics.db.exception.DatabaseException;
import org.simantics.diagram.ui.DiagramModelHints;
import org.simantics.g2d.canvas.impl.DependencyReflection.Dependency;
import org.simantics.g2d.canvas.impl.SGNodeReflection.SGInit;
import org.simantics.g2d.diagram.IDiagram;
import org.simantics.g2d.diagram.handler.PickContext;
import org.simantics.g2d.diagram.handler.PickRequest;
import org.simantics.g2d.diagram.handler.PickRequest.PickPolicy;
import org.simantics.g2d.diagram.participant.AbstractDiagramParticipant;
import org.simantics.g2d.diagram.participant.Selection;
import org.simantics.g2d.element.IElement;
import org.simantics.g2d.participant.TransformUtil;
import org.simantics.g2d.utils.GeometryUtils;
import org.simantics.scenegraph.g2d.G2DNode;
import org.simantics.scenegraph.g2d.G2DParentNode;
import org.simantics.scenegraph.g2d.events.EventTypes;
import org.simantics.scenegraph.g2d.events.MouseEvent;
import org.simantics.scenegraph.g2d.events.EventHandlerReflection.EventHandler;
import org.simantics.scenegraph.g2d.events.MouseEvent.MouseClickEvent;
import org.simantics.scenegraph.g2d.events.MouseEvent.MouseDoubleClickedEvent;
import org.simantics.scenegraph.g2d.events.MouseEvent.MouseMovedEvent;
import org.simantics.scenegraph.utils.NodeUtil;
import org.simantics.utils.datastructures.hints.IHintContext.Key;
import org.simantics.utils.datastructures.hints.IHintContext.KeyOf;

public class NetworkDrawingParticipant extends AbstractDiagramParticipant {

    /**
     * A hint key for terminal pick distance in control pixels.
     * @see #PICK_DIST
     */
    public static final Key KEY_PICK_DISTANCE = new KeyOf(Double.class, "PICK_DISTANCE");

    /**
     * Default terminal pick distance in control pixels.
     * @see #DEFAULT_PICK_DISTANCE
     */
    public static final double PICK_DIST = 10;
    
    private NetworkDrawingNode node;
    
    @Dependency Selection selection;
    @Dependency TransformUtil util;
    @Dependency PickContext pickContext;
    
    @SGInit
    public void initSG(G2DParentNode parent) {
        node = parent.addNode("networkDrawingNode", NetworkDrawingNode.class);
    }
    
    @Override
    protected void onDiagramSet(IDiagram newDiagram, IDiagram oldDiagram) {
        node.setDiagram(newDiagram);
    }
    
    @EventHandler(priority = 1 << 21)
    public boolean handleClick(MouseClickEvent me) {
        
        boolean isLeft = me.button == MouseEvent.LEFT_BUTTON;
        boolean isRight = me.button == MouseEvent.RIGHT_BUTTON;
        if (!isLeft && !isRight)
            return false;
        boolean isShiftPressed = me.hasAllModifiers(MouseEvent.SHIFT_MASK);
        
        int selectionId = me.mouseId;
        
        double pickDist = getPickDistance();
        Rectangle2D controlPickRect = new Rectangle2D.Double(me.controlPosition.getX()-pickDist, me.controlPosition.getY()-pickDist, pickDist*2+1, pickDist*2+1);
        Shape canvasPickRect  = GeometryUtils.transformShape(controlPickRect, util.getInverseTransform());
        
        PickRequest req = new PickRequest(canvasPickRect);
        req.pickPolicy = PickPolicy.PICK_INTERSECTING_OBJECTS;
        //req.pickSorter = PickRequest.PickSorter.CONNECTIONS_LAST;
        List<IElement> pickables = new ArrayList<IElement>();
        pickContext.pick(diagram, req, pickables);
        
        Set<IElement> currentSelection = selection.getSelection(selectionId);
        
        if (!pickables.isEmpty()) {
            /*
             * Select the one object the mouse points to. If multiple object
             * are picked, select the one that is after the earliest by
             * index of the current selection when shift is pressed. Otherwise
             * always pick the topmost element.
             */
            IElement selectedPick = isShiftPressed
                    ? rotatingPick(currentSelection, pickables)
                            : pickables.get(pickables.size() - 1);
    
            // Only select when
            // 1. the selection would actually change
            // AND
            //   2.1. left button was pressed
            //   OR
            //   2.2. right button was pressed and the element to-be-selected
            //        is NOT a part of the current selection
            if (!Collections.singleton(selectedPick).equals(currentSelection)
                    && (isLeft || (isRight && !currentSelection.contains(selectedPick)))) {
                selection.setSelection(selectionId, selectedPick);
            }
        }
        
        return false;
    }
    
    private double getPickDistance() {
        Double pickDistance = getHint(KEY_PICK_DISTANCE);
        return pickDistance == null ? PICK_DIST : Math.max(pickDistance, 0);
    }
    
    private IElement rotatingPick(int selectionId, List<IElement> pickables) {
        Set<IElement> sel = selection.getSelection(selectionId);
        return rotatingPick(sel, pickables);
    }

    private IElement rotatingPick(Set<IElement> sel, List<IElement> pickables) {
        int earliestIndex = pickables.size();
        for (int i = pickables.size() - 1; i >= 0; --i) {
            if (sel.contains(pickables.get(i))) {
                earliestIndex = i;
                break;
            }
        }
        if (earliestIndex == 0)
            earliestIndex = pickables.size();
        IElement selectedPick = pickables.get(earliestIndex - 1);
        return selectedPick;
    }

    public static class NetworkDrawingNode extends G2DNode {

        private static final long serialVersionUID = -3475301184009620573L;
        
        private List<Point2D> nodes = new ArrayList<>();

        private Rectangle2D rect = new Rectangle2D.Double(10, 10, 10, 10);

        private Set<Path2D> paths = new HashSet<>();

        private Resource diagramResource;

        private boolean committed;
        
        @Override
        public void init() {
            super.init();
            addEventHandler(this);
        }
        
        public void setDiagram(IDiagram diagram) {
            if (diagram != null)
                this.diagramResource = diagram.getHint(DiagramModelHints.KEY_DIAGRAM_RESOURCE);
        }

        @Override
        public void render(Graphics2D g2d) {
            Color old = g2d.getColor();
            g2d.setColor(Color.BLUE);
            
            paths.forEach(p -> {
                g2d.draw(p);
            });
            
            g2d.setColor(old);
        }

        @Override
        public Rectangle2D getBoundsInLocal() {
            return rect.getBounds2D();
        }
        
        @Override
        public int getEventMask() {
            return EventTypes.MouseMask;
        }
        
        @Override
        protected boolean mouseDoubleClicked(MouseDoubleClickedEvent e) {
            // nodes to path2d
            Point2D start = null;
            Point2D end = null;
            Iterator<Point2D> nodeIter = nodes.iterator();
            while (nodeIter.hasNext()) {
                if (end == null) {
                    start = nodeIter.next();
                } else {
                    start = end;
                }
                end = nodeIter.next();
                
                createEdge(start, end);
            }
            
            nodes.clear();
            committed = true;
            
            repaint();
            
            return true;
        }
        
        private void createEdge(Point2D start, Point2D end) {
            double[] startCoords = new double[] { start.getX(), start.getY() };
            double[] endCoords = new double[] { end.getX(), end.getY() };
            
            DNEdgeBuilder builder = new DNEdgeBuilder(diagramResource);
            Simantics.getSession().asyncRequest(new WriteRequest() {
                
                @Override
                public void perform(WriteGraph graph) throws DatabaseException {
                    builder.create(graph, startCoords, endCoords);
                }
            });
            
        }
        
        @Override
        protected boolean mouseClicked(MouseClickEvent e) {
            if (committed) {
                committed = false;
                return false;
            }
            Point2D localPos = NodeUtil.worldToLocal(this, e.controlPosition, new Point2D.Double());
            nodes.add(new Point2D.Double(localPos.getX(), localPos.getY()));
            return super.mouseClicked(e);
        }
        
        @Override
        protected boolean mouseMoved(MouseMovedEvent e) {
            return super.mouseMoved(e);
        }
    }
}