/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 * 
 *    (C) 2006-2008, Open Source Geospatial Foundation (OSGeo)
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.
 */
package org.geotools.referencing.operation.matrix;

import java.awt.geom.AffineTransform;

import org.junit.*;
import static org.junit.Assert.*;


/**
 * Tests {@link XAffineTransform} static methods.
 *
 *
 * @source $URL$
 * @version $Id$
 * @author Martin Desruisseaux
 */
public final class XAffineTransformTest {
    /**
     * Tolerance value for comparaisons.
     */
    private static final double EPS = 1E-10;

    /**
     * Tests {@link XAffineTransform} in the unflipped case.
     */
    @Test
    public void testUnflipped() {
        runTest(+1);
    }

    /**
     * Tests {@link XAffineTransform} in the flipped case.
     */
    @Test
    public void testFlipped() {
        runTest(-1);
    }

    /**
     * Gets the flip state using standard {@code AffineTransform} API.
     */
    private static int getFlipFromType(final AffineTransform tr) {
        return (tr.getType() & AffineTransform.TYPE_FLIP) != 0 ? -1 : +1;
    }

    /**
     * Run the test in the flipped or unflipped case.
     *
     * @param f -1 for the flipped case, or +1 for the unflipped case.
     */
    private static void runTest(final int f) {
        // Test identity
        final AffineTransform tr = new AffineTransform();
        tr.setToScale(1, f);
        assertEquals( 1, XAffineTransform.getScaleX0 (tr), EPS);
        assertEquals( 1, XAffineTransform.getScaleY0 (tr), EPS);
        assertEquals( 0, XAffineTransform.getRotation(tr), EPS);
        assertEquals( 1, XAffineTransform.getSwapXY  (tr));
        assertEquals( f, XAffineTransform.getFlip    (tr));
        assertEquals( f, getFlipFromType             (tr));

        // Tests rotation (< 45°)
        double r = Math.toRadians(25);
        tr.rotate(r);
        assertEquals( 1, XAffineTransform.getScaleX0 (tr), EPS);
        assertEquals( 1, XAffineTransform.getScaleY0 (tr), EPS);
        assertEquals( r, XAffineTransform.getRotation(tr), EPS);
        assertEquals( 1, XAffineTransform.getSwapXY  (tr));
        assertEquals( f, XAffineTransform.getFlip    (tr));
        assertEquals( f, getFlipFromType             (tr));

        // Tests more rotation (> 45°)
        r = Math.toRadians(65);
        tr.rotate(Math.toRadians(40));
        assertEquals( 1, XAffineTransform.getScaleX0 (tr), EPS);
        assertEquals( 1, XAffineTransform.getScaleY0 (tr), EPS);
        assertEquals( r, XAffineTransform.getRotation(tr), EPS);
        assertEquals(-1, XAffineTransform.getSwapXY  (tr));
        assertEquals( f, XAffineTransform.getFlip    (tr));
        assertEquals( f, getFlipFromType             (tr));

        // Tests scale
        tr.setToScale(2, 3*f);
        assertEquals( 2, XAffineTransform.getScaleX0 (tr), EPS);
        assertEquals( 3, XAffineTransform.getScaleY0 (tr), EPS);
        assertEquals( 0, XAffineTransform.getRotation(tr), EPS);
        assertEquals( 1, XAffineTransform.getSwapXY  (tr));
        assertEquals( f, XAffineTransform.getFlip    (tr));
        assertEquals( f, getFlipFromType             (tr));

        // Tests rotation + scale
        tr.rotate(r);
        assertEquals( 2, XAffineTransform.getScaleX0 (tr), EPS);
        assertEquals( 3, XAffineTransform.getScaleY0 (tr), EPS);
        assertEquals( r, XAffineTransform.getRotation(tr), EPS);
        assertEquals(-1, XAffineTransform.getSwapXY  (tr));
        assertEquals( f, XAffineTransform.getFlip    (tr));
        assertEquals( 1, getFlipFromType(tr)); // Always unflipped according Java 1.5.0_09...

        // Tests axis swapping
        r = Math.toRadians(-90 * f);
        tr.setTransform(0, 1, f, 0, 0, 0);
        assertEquals( 1, XAffineTransform.getScaleX0 (tr), EPS);
        assertEquals( 1, XAffineTransform.getScaleY0 (tr), EPS);
        assertEquals( r, XAffineTransform.getRotation(tr), EPS);
        assertEquals(-1, XAffineTransform.getSwapXY  (tr));
        assertEquals(-f, XAffineTransform.getFlip    (tr));
        assertEquals(-f, getFlipFromType             (tr));

        // Tests axis swapping + scale
        tr.scale(2, 3);
        assertEquals( 3, XAffineTransform.getScaleX0 (tr), EPS);
        assertEquals( 2, XAffineTransform.getScaleY0 (tr), EPS);
        assertEquals( r, XAffineTransform.getRotation(tr), EPS);
        assertEquals(-1, XAffineTransform.getSwapXY  (tr));
        assertEquals(-f, XAffineTransform.getFlip    (tr));
        assertEquals(-f, getFlipFromType             (tr));
    }
}