/*******************************************************************************
 * 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.g2d.participant;

import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

import org.simantics.g2d.canvas.Hints;
import org.simantics.g2d.canvas.ICanvasContext;
import org.simantics.g2d.canvas.impl.AbstractCanvasParticipant;
import org.simantics.g2d.canvas.impl.DependencyReflection.Dependency;
import org.simantics.g2d.canvas.impl.HintReflection.HintListener;
import org.simantics.utils.datastructures.disposable.DisposeState;
import org.simantics.utils.datastructures.hints.IHintContext.Key;
import org.simantics.utils.datastructures.hints.IHintObservable;
import org.simantics.utils.threads.IThreadWorkQueue;

/**
 * Restores orientation of the canvas back to normal (north is up)
 * 
 * 
 * @author Toni Kalajainen
 */
public class OrientationRestorer extends AbstractCanvasParticipant {

    @Dependency
    TransformUtil           util;
    @Dependency
    CanvasGrab              grab;
    @Dependency
    CanvasBoundsParticipant bounds;

    long                    lastTrigger;
    Point2D                 centerPoint        = new Point2D.Double();

    transient ScheduledExecutorService         timer              = Executors.newSingleThreadScheduledExecutor();
    transient boolean       checkRotatePending = false;

    Runnable               task               = new Runnable() {
        @Override
        public void run() {
            ICanvasContext ctx = getContext();
            if (ctx.getDisposeState() != DisposeState.Alive)
                return;
            IThreadWorkQueue thread = ctx.getThreadAccess();
            if (thread == null)
                return;
            thread.asyncExec(new Runnable() {
                @Override
                public void run() {
                    if (checkRotatePending)
                        return;
                    checkRotatePending = true;
                    timerEvent();
                }
            });
        }
    };

    @Override
    public void removedFromContext(ICanvasContext ctx) {
        timer.shutdown();
        try {
            if (!timer.awaitTermination(1, TimeUnit.SECONDS)) {
                timer.shutdownNow();
            }
        } catch (InterruptedException e) {
            // Ignore
        }
        super.removedFromContext(ctx);
    }

    @Override
    public void addedToContext(ICanvasContext ctx) {
        super.addedToContext(ctx);
//        long delay = 1000 / 25; this sounds quite frequent
        long delay = 1000 / 10;
        lastTrigger = System.currentTimeMillis();
        timer.scheduleAtFixedRate(task, delay, delay, TimeUnit.MILLISECONDS);
    }

    @HintListener(Class = Hints.class, Field = "KEY_CANVAS_BOUNDS")
    public void selectionChanged(IHintObservable sender, Key key, Object oldValue, Object newValue) {
        Rectangle2D cb = (Rectangle2D) newValue;
        this.centerPoint.setLocation(cb.getCenterX(), cb.getCenterY());
    }

    void timerEvent() {
        ICanvasContext ctx = getContext();
        if (ctx == null)
            return;
        if (ctx.getDisposeState() != DisposeState.Alive)
            return;
        long cur = System.currentTimeMillis();
        long delta = cur - lastTrigger;
        lastTrigger = cur;
        checkRotatePending = false;

        Point2D centerPoint = new Point2D.Double();
        int grabCount = grab.grabInfo.size();
        if (grabCount == 0) {
            centerPoint = this.centerPoint;
        } else if (grabCount == 1) {
            centerPoint = grab.grabInfo.values().iterator().next().anchorPos;
        } else {
            angVel = 0.0;
            return;
        }

        // turn the canvas a bit
        double theta = util.getRotate();
        if (theta == 0.0)
            return;
//        if (Math.abs(theta) < 0.0001) {
//            angVel = 0.0;
//            return;
//        }
        if (Math.abs(theta) < 0.001) {
            util.restoreOrientation(centerPoint);
            angVel = 0.0;
            return;
        }

        double momentum = theta * 100;
        double dt = ((double) delta) / 1000;
        if (dt > 0.150)
            dt = 0.150;
        angVel += momentum * dt;
        util.rotate(centerPoint, -angVel * dt);
        angVel *= 0.5;
    }

    double angVel = 0.0;

}