/*******************************************************************************
 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
 * in Industry THTH ry.
 * 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.modeling.ui.diagramEditor;

import gnu.trove.set.hash.THashSet;

import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DropTargetDragEvent;
import java.awt.geom.AffineTransform;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;

import org.eclipse.jface.viewers.IStructuredSelection;
import org.simantics.Logger;
import org.simantics.db.ReadGraph;
import org.simantics.db.RequestProcessor;
import org.simantics.db.Resource;
import org.simantics.db.Session;
import org.simantics.db.common.request.UnaryRead;
import org.simantics.db.common.request.UniqueRead;
import org.simantics.db.common.utils.NameUtils;
import org.simantics.db.common.utils.OrderedSetUtils;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.SelectionHints;
import org.simantics.db.layer0.variable.Variable;
import org.simantics.db.layer0.variable.Variables;
import org.simantics.db.layer0.variable.Variables.Role;
import org.simantics.diagram.adapter.GraphToDiagramSynchronizer;
import org.simantics.diagram.content.ConnectionUtil;
import org.simantics.diagram.stubs.DiagramResource;
import org.simantics.diagram.ui.DiagramModelHints;
import org.simantics.g2d.diagram.handler.DataElementMap;
import org.simantics.g2d.dnd.DnDHints;
import org.simantics.g2d.dnd.ElementClassDragItem;
import org.simantics.g2d.dnd.IDnDContext;
import org.simantics.g2d.dnd.IDropTargetParticipant;
import org.simantics.g2d.element.ElementHints;
import org.simantics.g2d.element.IElement;
import org.simantics.g2d.utils.Alignment;
import org.simantics.layer0.Layer0;
import org.simantics.modeling.ModelingResources;
import org.simantics.modeling.PropertyVariables;
import org.simantics.modeling.PropertyVariablesImpl;
import org.simantics.modeling.ui.diagram.monitor.MonitorClassFactory2;
import org.simantics.structural.stubs.StructuralResource2;
import org.simantics.ui.dnd.LocalObjectTransfer;
import org.simantics.ui.dnd.LocalObjectTransferable;
import org.simantics.ui.selection.WorkbenchSelectionElement;
import org.simantics.ui.selection.WorkbenchSelectionUtils;
import org.simantics.utils.datastructures.Triple;
import org.simantics.utils.datastructures.hints.IHintContext;
import org.simantics.utils.ui.ISelectionUtils;

public class PopulateElementMonitorDropParticipant extends PopulateElementDropParticipant implements IDropTargetParticipant {

    private static final boolean DEBUG = false;

    // Scale for the monitors
    double scaleX, scaleY;
    // Monitor type
    String typeURI;

    public PopulateElementMonitorDropParticipant(GraphToDiagramSynchronizer synchronizer, double scaleX, double scaleY) {
        super(synchronizer);
        this.scaleX = scaleX;
        this.scaleY = scaleY;
        this.typeURI = DiagramResource.URIs.Monitor;
    }

    public PopulateElementMonitorDropParticipant(GraphToDiagramSynchronizer synchronizer, String typeURI, double scaleX, double scaleY) {
        super(synchronizer);
        this.scaleX = scaleX;
        this.scaleY = scaleY;
        this.typeURI = typeURI;
    }

    @Override
    public void dragEnter(DropTargetDragEvent dtde, final IDnDContext dp) {

        Transferable tr = dtde.getTransferable();

        if (tr.isDataFlavorSupported(LocalObjectTransferable.FLAVOR)) {

            // This must be done to have SWT transfer set the source data
            try {
                Object obj = tr.getTransferData(LocalObjectTransferable.FLAVOR);
                if (DEBUG)
                    System.out.println("GOT FROM AWT: " + obj);

                // Check SWT
                if (!(obj instanceof IStructuredSelection)) {
                    obj = LocalObjectTransfer.getTransfer().getObject();
                    if (DEBUG)
                        System.out.println("GOT FROM SWT: " + obj);
                }

                if (obj instanceof IStructuredSelection) {
                	
                    IStructuredSelection sel = (IStructuredSelection) obj;
                    
                	for(WorkbenchSelectionElement wse : WorkbenchSelectionUtils.getWorkbenchSelectionElements(sel)) {
                		dp.add(new WSEDragItem(wse));
                	}

                    Session session = synchronizer.getSession();

                    List<Variable> properties = resolveVariables(session, (IStructuredSelection) obj);
                    if (properties.isEmpty())
                        return;

                    List<ElementClassDragItem> items = session.syncRequest(new ResolveItems(properties));
                    for (ElementClassDragItem item : items)
                        dp.add(item);

                    dp.getHints().setHint(DnDHints.KEY_DND_GRID_COLUMNS, Integer.valueOf(1));
                }

            } catch (UnsupportedFlavorException e) {
                Logger.defaultLogError(e);
            } catch (IOException e) {
                Logger.defaultLogError(e);
            } catch (DatabaseException e) {
                Logger.defaultLogError(e);
            }

        }

        dtde.acceptDrag(DnDConstants.ACTION_COPY);

    }

    public void setHints(IHintContext context) {
    }

    protected List<Variable> resolveVariables(RequestProcessor processor, IStructuredSelection sel) throws DatabaseException {
        if (sel.isEmpty())
            return Collections.emptyList();

        Variable property = WorkbenchSelectionUtils.getPossibleVariable(sel);
        if(property != null)
            return Collections.singletonList(property);

        property = ISelectionUtils.getSinglePossibleKey(sel, SelectionHints.KEY_SELECTION_PROPERTY, Variable.class);
        if (property != null)
            return Collections.singletonList(property);

        final List<PropertyVariables> vars = ISelectionUtils.getPossibleKeys(sel, SelectionHints.KEY_MAIN, PropertyVariables.class);
        if (!vars.isEmpty()) {
            return processor.syncRequest(new UniqueRead<List<Variable>>() {
                @Override
                public List<Variable> perform(ReadGraph graph) throws DatabaseException {
                    // FIXME: this is a hack for indexed value support
                    List<PropertyVariables> vs = PropertyVariablesImpl.resolve(graph, vars);
                    List<Variable> result = new ArrayList<Variable>(vs.size());
                    for (PropertyVariables v : vs)
                        result.add(v.getVisualVariable());
                    return result;
                }
            });
        }

        return Collections.emptyList();
    }

    protected class ResolveItems extends UnaryRead<List<Variable>, List<ElementClassDragItem>> {

        public ResolveItems(List<Variable> parameter) {
            super(parameter);
        }

        @Override
        public List<ElementClassDragItem> perform(ReadGraph graph) throws DatabaseException {
            List<ElementClassDragItem> result = new ArrayList<ElementClassDragItem>(parameter.size());
            for (Variable property : parameter)
                result.addAll( resolve(graph, property) );
            return result;
        }

        public List<ElementClassDragItem> resolve(ReadGraph graph, Variable parameter) throws DatabaseException {

            if (DEBUG) {
                System.out.println("PARAM: " + parameter.getURI(graph));
                Variable parent = parameter.browsePossible(graph, "..");
                System.out.println("PARENT: " + parent.getURI(graph));
                Resource parentComposite = parent.getPossibleRepresents(graph);
                System.out.println("PARENT REPRESENTS: " + NameUtils.getSafeLabel(graph, parentComposite));
                String prvi = Variables.getRVI(graph, parent);
                System.out.println("PARENT RVI: " + prvi);
                String parvi = Variables.getRVI(graph, parameter);
                System.out.println("PARAM RVI: " + parvi);
            }

            Triple<Variable, Resource, IElement> match = findElementInDiagram(graph, parameter, false);
            if (match == null)
                return Collections.emptyList();
            
            if(match.third == null) {
                // We are in a different diagram, prevent creation of monitors
                // from UCs to different UCs or model configuration
                Resource diagram = synchronizer.getDiagram().getHint(DiagramModelHints.KEY_DIAGRAM_RESOURCE);
                Resource commonParent = findCommonParent(graph, diagram, match.second);
                StructuralResource2 STR = StructuralResource2.getInstance(graph);
                if(!graph.isInstanceOf(commonParent, STR.Composite))
                    return Collections.emptyList();
            }

            if (DEBUG) {
                System.out.println("p=" + parameter.getURI(graph));
                System.out.println("c=" + match.first.getURI(graph));
            }

            String rvi = Variables.getRVI(graph, match.first, parameter);
            if (DEBUG)
                System.out.println("r=" + rvi);

            Resource type = graph.getResource(typeURI);

            ElementClassDragItem item = new ElementClassDragItem(MonitorClassFactory2.createMonitorClass(type, match.third, new HashMap<String, String>(), match.second, rvi, scaleX, scaleY));
            item.getHintContext().setHint(ElementHints.KEY_HORIZONTAL_ALIGN, Alignment.LEADING);

            if (match.third != null)
                item.getHintContext().setHint(ElementHints.KEY_PARENT_ELEMENT, match.third);

            AffineTransform initialTr = AffineTransform.getScaleInstance(scaleX, scaleY);
            item.getHintContext().setHint(ElementHints.KEY_TRANSFORM, initialTr);

            setHints(item.getHintContext());

            return Collections.singletonList(item);

        }

        private Triple<Variable, Resource, IElement> findElementInDiagram(ReadGraph graph, Variable property, boolean propertyRoleFound) throws DatabaseException {
            if (property == null)
                return null;

            if (DEBUG)
                System.out.println("findElementInDiagram " + property.getURI(graph) + " " + property);

            DiagramResource DIA = DiagramResource.getInstance(graph);
            ModelingResources MOD = ModelingResources.getInstance(graph);
            final Resource diagram = synchronizer.getDiagram().getHint(DiagramModelHints.KEY_DIAGRAM_RESOURCE);

            if (!propertyRoleFound) {
                Role role = property.getPossibleRole(graph);
                propertyRoleFound = role == Role.PROPERTY;
            }

            Resource represents = property.getPossibleRepresents(graph);
            if (represents != null) {
                if (DEBUG)
                    System.out.println("represents " + NameUtils.getSafeName(graph, represents, true));
                Resource elementResource = graph.getPossibleObject(represents, MOD.ComponentToElement);
                // There must have be at least one
                // PROPERTY role variable in the
                // browsed path before finding this
                // element.
                if(elementResource != null && propertyRoleFound) {
                    Resource elementDiagram = OrderedSetUtils.getSingleOwnerList(graph, elementResource, DIA.Diagram);
                    if(diagram.equals(elementDiagram)) {
                        final DataElementMap map = synchronizer.getDiagram().getDiagramClass().getSingleItem(DataElementMap.class);
                        IElement parentElement = map.getElement(synchronizer.getDiagram(), elementResource);

                        if (graph.isInstanceOf(elementResource, DIA.Connection)) {
                            Resource tailNode = ConnectionUtil.getConnectionTailNode(graph, elementResource);
                            if (tailNode != null) {
                                IElement tailNodeElement = map.getElement(synchronizer.getDiagram(), tailNode);
                                if (tailNodeElement != null)
                                    parentElement = tailNodeElement;
                            }
                        }

                        return Triple.make(property, represents, parentElement);
                    } else {
                        // The monitored target module is on another diagram/composite.
                        // No parent for the monitor then.
                        return Triple.make(property, represents, null);
                    }
                }
            }

            return findElementInDiagram(graph, property.browsePossible(graph, "."), propertyRoleFound);
        }

    }

    private static Resource findCommonParent(ReadGraph graph, Resource a, Resource b) throws DatabaseException {
        Layer0 L0 = Layer0.getInstance(graph);
        THashSet<Resource> set = new THashSet<>();
        while(true) {
            if(a != null) {
                if(!set.add(a))
                    return a;
                a = graph.getPossibleObject(a, L0.PartOf);
            }
            else if(b == null)
                return graph.getRootLibrary();
            if(b != null) {
                if(!set.add(b))
                    return b;
                b = graph.getPossibleObject(a, L0.PartOf);
            }
        }
    }

    @Override
    public double getPriority() {
    	return 9.0;
    }
    
}