/*******************************************************************************
 * Copyright (c) 2011 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.diagram.synchronization.runtime;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Set;
import java.util.concurrent.atomic.AtomicReference;

import org.simantics.diagram.ui.DiagramModelHints;
import org.simantics.g2d.canvas.ICanvasContext;
import org.simantics.g2d.diagram.DiagramHints;
import org.simantics.g2d.diagram.IDiagram;
import org.simantics.g2d.diagram.handler.DataElementMap;
import org.simantics.g2d.diagram.participant.Selection;
import org.simantics.g2d.element.IElement;
import org.simantics.utils.datastructures.hints.HintListenerAdapter;
import org.simantics.utils.datastructures.hints.IHintContext.Key;
import org.simantics.utils.datastructures.hints.IHintObservable;
import org.simantics.utils.threads.ThreadUtils;

/**
 * @author Tuukka Lehtonen
 */
public class DiagramSelectionUpdater extends HintListenerAdapter {

    private static final boolean    DEBUG_SELECTION_UPDATE = false;

    private final ICanvasContext    ctx;
    private final Selection         selection;
    private final IDiagram          diagram;

    private int                     selectionId;
    private AtomicReference<Set<?>> newSelection           = new AtomicReference<Set<?>>();

    private boolean                 oneshot                = false;
    private boolean                 tracking               = false;

    public DiagramSelectionUpdater(ICanvasContext ctx) {
        this.ctx = ctx;
        this.selection = ctx.getAtMostOneItemOfClass(Selection.class);
        if (selection == null)
            throw new IllegalArgumentException("no selection participant");
        this.diagram = ctx.getDefaultHintContext().getHint(DiagramHints.KEY_DIAGRAM);
        if (diagram == null)
            throw new IllegalArgumentException("no diagram");
    }

    public DiagramSelectionUpdater(ICanvasContext ctx, IDiagram diagram) {
        this.ctx = ctx;
        this.selection = ctx.getAtMostOneItemOfClass(Selection.class);
        if (selection == null)
            throw new IllegalArgumentException("no selection participant");
        this.diagram = diagram;
        if (diagram == null)
            throw new IllegalArgumentException("no diagram");
    }

    protected Selection getSelectionParticipant() {
        return ctx.getSingleItem(Selection.class);
    }

    public DiagramSelectionUpdater setNewSelection(int selectionId, Set<?> newSelection) {
        this.selectionId = selectionId;
        this.newSelection.set(newSelection);
        return this;
    }

    public Set<?> getNewSelection() {
        return newSelection.get();
    }

    public DiagramSelectionUpdater setOneshot(boolean oneshot) {
        this.oneshot = oneshot;
        return this;
    }

    public DiagramSelectionUpdater track() {
        if (!tracking) {
            diagram.addKeyHintListener(DiagramModelHints.KEY_DIAGRAM_CONTENTS_UPDATED, this);
            tracking = true;
        }
        return this;
    }

    public DiagramSelectionUpdater untrack() {
        if (tracking) {
            diagram.removeKeyHintListener(DiagramModelHints.KEY_DIAGRAM_CONTENTS_UPDATED, this);
            tracking = false;
        }
        return this;
    }

    @Override
    public void hintChanged(IHintObservable sender, Key key, Object oldValue, Object newValue) {
        if (!ctx.isDisposed() && key == DiagramModelHints.KEY_DIAGRAM_CONTENTS_UPDATED) {
            if (DEBUG_SELECTION_UPDATE)
                System.out.println(getClass().getSimpleName() + ": DIAGRAM UPDATED @" + System.currentTimeMillis() + ", selection to set: " + newSelection);
            Set<?> ns = newSelection.getAndSet(null);
            if (ns != null) {
                scheduleSetDiagramSelection(2, ns);
            }
        }

        if (oneshot) {
            // Remove self from listening duties.
            sender.removeHintListener(this);
        }
    }

    private void scheduleSetDiagramSelection(final int tries, final Set<?> data) {
        ThreadUtils.asyncExec(ctx.getThreadAccess(), new Runnable() {
            @Override
            public void run() {
                setDiagramSelectionToData(tries, data);
            }
        });
    }

    private void setDiagramSelectionToData(final int tries, final Set<?> data) {
        if (DEBUG_SELECTION_UPDATE)
            System.out.println("setDiagramSelectionToData(" + tries + ", " + data + ")");

        DataElementMap dem = diagram.getDiagramClass().getAtMostOneItemOfClass(DataElementMap.class);
        if (dem != null) {
            final Collection<IElement> newSelection = new ArrayList<IElement>(data.size());
            for (Object datum : data) {
                IElement element = dem.getElement(diagram, datum);
                if (DEBUG_SELECTION_UPDATE)
                    System.out.println("  DATUM " + datum + " -> " + element);
                if (element != null) {
                    newSelection.add(element);
                } else {
                    if (tries > 0) {
                        // Try later if there are tries left.
                        ThreadUtils.asyncExec(ctx.getThreadAccess(), new Runnable() {
                            @Override
                            public void run() {
                                setDiagramSelectionToData(tries - 1, data);
                            }
                        });
                        return;
                    }
                    // Otherwise select whatever is found.
                }
            }

            if (DEBUG_SELECTION_UPDATE)
                System.out.println("[" + tries + "] final new selection: " + newSelection);

            if (!newSelection.isEmpty()) {
                //for (IElement e : newSelection)
                //    e.setHint(Hints.KEY_DIRTY, Hints.VALUE_SG_DIRTY);
                selection.setSelection(selectionId, newSelection);
            }
        }
    }

}