import org.junit.Test;

import static junit.framework.Assert.assertEquals;
import static junit.framework.Assert.assertTrue;


public class InfiniteLoop {


    @Test
    public void testResizeLargerImageHighQuality() {
        int loops = calculateImageRatio(true, 5, 5, 15, 15);
        assertTrue(loops < 1000);
    }

    @Test
    public void testResizeLargerImageLowQuality() {
        int loops = calculateImageRatio(false, 5, 5, 15, 15);
        assertTrue(loops < 1000);
    }

    @Test
    public void testResizeSmallerImageHighQuality() {
        int loops = calculateImageRatio(true, 25, 25, 15, 15);
        // infinite loop
        assertEquals(1000, loops);
    }

    @Test
    public void testResizeSmallerImageLowQuality() {
        int loops = calculateImageRatio(false, 25, 25, 15, 15);
        assertTrue(loops < 1000);
    }


    private int calculateImageRatio(boolean highQuality, int targetWidth, int targetHeight,
                                    int imgWidth, int imgHeight) {
        int loopcounter = 0;
        int width;
        int height;
        if (highQuality) {
            // Use the multiple step technique: start with original size, then scale down in multiple passes with
            // drawImage() until the target size is reached
            width = imgWidth;
            height = imgHeight;
        } else {
            // Use one-step technique: scale directly from original size to target size with a single drawImage() call
            width = targetWidth;
            height = targetHeight;
        }


        do {
            if (highQuality && width > targetWidth) {
                width /= 2;
                width = Math.max(width, targetWidth);
            }

            if (highQuality && height > targetHeight) {
                height /= 2;
                height = Math.max(height, targetHeight);
            }
            loopcounter++;
        } while (loopcounter < 1000 && (width != targetWidth || height != targetHeight));

        return loopcounter;
    }
}