/*******************************************************************************
 * Copyright (c) 2007 VTT Technical Research Centre of Finland and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.diagram.participant;

import java.awt.Font;
import java.awt.RenderingHints;
import java.awt.geom.Rectangle2D;
import java.io.StringWriter;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.batik.dom.GenericDOMImplementation;
import org.apache.batik.svggen.SVGGeneratorContext;
import org.apache.batik.svggen.SVGGeneratorContext.GraphicContextDefaults;
import org.apache.batik.svggen.SVGGraphics2D;
import org.apache.batik.svggen.SVGGraphics2DIOException;
import org.eclipse.swt.dnd.Clipboard;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.widgets.Display;
import org.simantics.diagram.elements.TextNode;
import org.simantics.g2d.canvas.ICanvasContext;
import org.simantics.g2d.canvas.impl.DependencyReflection.Dependency;
import org.simantics.g2d.diagram.participant.AbstractDiagramParticipant;
import org.simantics.g2d.diagram.participant.Selection;
import org.simantics.g2d.element.ElementHints;
import org.simantics.g2d.element.ElementUtils;
import org.simantics.g2d.element.IElement;
import org.simantics.scenegraph.INode;
import org.simantics.scenegraph.g2d.G2DNode;
import org.simantics.scenegraph.g2d.G2DSceneGraph;
import org.simantics.scenegraph.g2d.events.EventHandlerReflection.EventHandler;
import org.simantics.scenegraph.g2d.events.command.CommandEvent;
import org.simantics.scenegraph.g2d.events.command.Commands;
import org.simantics.scenegraph.g2d.nodes.LinkNode;
import org.simantics.scenegraph.g2d.nodes.SelectionNode;
import org.simantics.scenegraph.g2d.nodes.SingleElementNode;
import org.simantics.scenegraph.g2d.nodes.connection.RouteGraphNode;
import org.simantics.scenegraph.utils.NodeMapper;
import org.simantics.scenegraph.utils.NodeUtil;
import org.simantics.utils.ui.ErrorLogger;
import org.w3c.dom.DOMImplementation;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

public class CopyAsSVGParticipant extends AbstractDiagramParticipant {

    @Dependency
    protected Selection sel;

    @EventHandler(priority = 0)
    public boolean handleCommand(CommandEvent e) {
        if (e.command.equals(Commands.COPY_AS_SVG)) {
            Set<IElement> ss = sel.getSelection(0);
            copyAsSVG(getContext(), ss);
            return true;
        }
        return false;
    }

    private static void copyAsSVG(ICanvasContext canvasContext, Set<IElement> elements) {
        G2DSceneGraph sg = canvasContext.getSceneGraph();
        NodeMapper clipboardNodeMapper = new NodeMapper();
        List<G2DNode> selectionRenderingDisabledNodes = new ArrayList<G2DNode>();
        SingleElementNode clipboardNode = sg.addNode("svg-clipboard-temp", SingleElementNode.class); 

        try {
            for (IElement e : elements) {
                INode node = e.getHint(ElementHints.KEY_SG_NODE);
                if (node != null) {
                    // Don't render selection. Selection rendering could be a global rendering hint that is adhered by nodes!  
                    for(RouteGraphNode n : NodeUtil.collectNodes(node, RouteGraphNode.class)) {
                        n.setIgnoreSelection(true);
                        selectionRenderingDisabledNodes.add(n);
                    }
                    for(SelectionNode n : NodeUtil.collectNodes(node, SelectionNode.class)) {
                        n.setIgnore(true);
                        selectionRenderingDisabledNodes.add(n);
                    }
                    for(TextNode n : NodeUtil.collectNodes(node, TextNode.class)) {
                        n.setShowSelection(false);
                        selectionRenderingDisabledNodes.add(n);
                    }

                    String nodeId = clipboardNodeMapper.add(node);
                    LinkNode delegate = clipboardNode.addNode(ElementUtils.generateNodeId(e), LinkNode.class);
                    delegate.setDelegateId( nodeId );
                }
            }

            DOMImplementation domImpl =  GenericDOMImplementation.getDOMImplementation();

            String svgNS = "http://www.w3.org/2000/svg";
            Document document = domImpl.createDocument(svgNS, "svg", null);

            GraphicContextDefaults gcDefaults = new GraphicContextDefaults();
            SVGGeneratorContext ctx = SVGGeneratorContext.createDefault(document);
            Map<java.awt.RenderingHints.Key, Object> hintMap = new HashMap<java.awt.RenderingHints.Key, Object>();

            hintMap.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
            hintMap.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            hintMap.put(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
            hintMap.put(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
            hintMap.put(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);

            gcDefaults.setRenderingHints(new RenderingHints(hintMap));
            gcDefaults.setFont(Font.decode(null));
            ctx.setGraphicContextDefaults(gcDefaults);

            SVGGraphics2D svgG2D = new SVGGraphics2D(ctx, false);

            StringWriter writer = new StringWriter();

            // Track connection crossings manually since we will render only the clipboard node.
            sg.getNode(ConnectionCrossingsParticipant.CONNECTION_CROSSINGS_NODE_KEY).render(svgG2D);
            clipboardNode.render(svgG2D);

            Element root = svgG2D.getRoot();

            Rectangle2D bounds = clipboardNode.getBoundsInLocal(true);
            if (bounds != null) {
                root.setAttributeNS(null, "viewBox", bounds.getMinX() + " " + bounds.getMinY() + " " + bounds.getWidth() + " " + bounds.getHeight()); 
                root.setAttributeNS(null, "height", Double.toString(bounds.getHeight()));
                root.setAttributeNS(null, "width", Double.toString(bounds.getWidth()));
            }

            try {
                svgG2D.stream(root, writer, false, false);
            } catch (SVGGraphics2DIOException e1) {
                ErrorLogger.defaultLogError("Failed to copy the diagram selection as SVG." , e1);
            }

            byte[] svgContent = writer.toString().getBytes(StandardCharsets.UTF_8);

            Display.getDefault().asyncExec(new Runnable() {
                @Override
                public void run() {
                    Clipboard cb = new Clipboard(Display.getCurrent());
                    cb.setContents(new byte[][] {svgContent}, 
                            new Transfer[] {
                                SVGTransfer.getInstance()
                            }
                    );
                }
            });

        } finally {
            clipboardNode.removeNodes();
            clipboardNodeMapper.clear();
            clipboardNode.remove();

            // Restore the selection rendering state for changed nodes.
            for (G2DNode n : selectionRenderingDisabledNodes) {
                if (n instanceof RouteGraphNode) {
                    ((RouteGraphNode) n).setIgnoreSelection(false);
                } else if (n instanceof SelectionNode) {
                    ((SelectionNode)n).setIgnore(false);
                } else if (n instanceof TextNode) {
                    ((TextNode)n).setShowSelection(true);
                }
            }
        }
    }
}