import java.awt.*;
import java.awt.color.*;
import java.awt.image.*;
import java.io.*;
import java.util.*;
import javax.imageio.*;
import javax.imageio.metadata.*;
import javax.imageio.stream.*;

public class JPEGPerf {

    private static BufferedImage getScaledInstance(BufferedImage img,
                                                   int targetWidth)
    {
        int w = targetWidth;
        int h = (int)(((double)targetWidth / img.getWidth()) * img.getHeight());
        return getScaledInstance(img, w, h,
                                 RenderingHints.VALUE_INTERPOLATION_BILINEAR,
                                 true);
    }

    private static BufferedImage getScaledInstance(BufferedImage img,
                                                   int targetWidth,
                                                   int targetHeight,
                                                   Object hint,
                                                   boolean higherQuality)
    {
        BufferedImage ret = (BufferedImage)img;
        int w, h;
        if (higherQuality) {
            // Use multi-step technique: start with original size, then
            // scale down in multiple passes with drawImage()
            // until the target size is reached
            w = img.getWidth();
            h = img.getHeight();
        } else {
            // Use one-step technique: scale directly from original
            // size to target size with a single drawImage() call
            w = targetWidth;
            h = targetHeight;
        }
        
        do {
            if (higherQuality && w > targetWidth) {
                w /= 2;
                if (w < targetWidth) {
                    w = targetWidth;
                }
            }

            if (higherQuality && h > targetHeight) {
                h /= 2;
                if (h < targetHeight) {
                    h = targetHeight;
                }
            }

            // NOTE: create a new image in the same format as the original,
            // preserving any embedded color space...
            ColorModel cm = ret.getColorModel();
            WritableRaster raster =
                ret.getRaster().createCompatibleWritableRaster(w, h);
            BufferedImage tmp =
                new BufferedImage(cm, raster, cm.isAlphaPremultiplied(), null);
            Graphics2D g2 = tmp.createGraphics();
            g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
            g2.drawImage(ret, 0, 0, w, h, null);
            g2.dispose();

            ret = tmp;
        } while (w != targetWidth || h != targetHeight);

        return ret;
    }

    private static BufferedImage readImage(String filename, boolean convertToSRGB)
        throws Exception
    {
        File infile = new File(filename);
        ImageInputStream in = ImageIO.createImageInputStream(infile);
        ImageReader reader = ImageIO.getImageReaders(in).next();
        reader.setInput(in);
        ImageReadParam irp = reader.getDefaultReadParam();
        Iterator<ImageTypeSpecifier> specs = reader.getImageTypes(0);
        while (specs.hasNext()) {
            ImageTypeSpecifier spec = specs.next();
            //System.out.println(spec + " " + spec.getColorModel().getColorSpace());
            if (!convertToSRGB && !spec.getColorModel().getColorSpace().isCS_sRGB()) {
                irp.setDestinationType(spec);
                break;
            }
        }
        //System.out.println("TESTING: " + filename + ", convert to sRGB: " + convertToSRGB);
        BufferedImage orig = reader.read(0, irp);
        //System.out.println(orig);
        in.close();
        return orig;
    }

    private static final ColorSpace srgbCS = ColorSpace.getInstance(ColorSpace.CS_sRGB);
    private static BufferedImage maybeColorConvertImage(BufferedImage image) {
        ColorModel origCM = image.getColorModel();
        ColorSpace origCS = origCM.getColorSpace();
        if (!origCS.isCS_sRGB() && (origCM instanceof ComponentColorModel)) {
            WritableRaster raster = image.getRaster();
            ColorConvertOp convert = new ColorConvertOp(origCS, srgbCS, null);
            convert.filter(raster, raster);
            ColorModel newCM =
                new ComponentColorModel(srgbCS, origCM.hasAlpha(),
                                        origCM.isAlphaPremultiplied(),
                                        origCM.getTransparency(),
                                        origCM.getTransferType());
            image = new BufferedImage(newCM, raster, newCM.isAlphaPremultiplied(), null);
        }
        return image;
    }

    private static void test(String filename, boolean optimized)
        throws Exception
    {
        long start = System.currentTimeMillis();
        BufferedImage img = readImage(filename, !optimized);
        img = maybeColorConvertImage(img);
        long end = System.currentTimeMillis();
        System.out.println("total: " + (end-start));
    }

    private static void writeImage(BufferedImage img,
                                   String filename, String format)
        throws Exception
    {
        System.out.println("writing: " + filename);
        File outfile = new File(filename);
        ImageWriter writer = ImageIO.getImageWritersBySuffix(format).next();
        ImageOutputStream out = ImageIO.createImageOutputStream(outfile);
        writer.setOutput(out);
        ImageWriteParam iwp = writer.getDefaultWriteParam();
        if ("jpg".equals(format)) {
            iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
            iwp.setCompressionQuality(0.85f);
        }
        writer.write(null, new IIOImage(img, null, null), iwp);
    }

    public static void main(String[] args) throws Exception {
        //String filename = "flower.jpg";
        String filename = "gorilla.jpg";
        System.out.println("ColorSpace conversion done by JPEGImageReader...");
        for (int i = 0; i < 3; i++) {
            test(filename, false);
        }
        System.out.println("ColorSpace conversion done in-place by ColorConvertOp...");
        for (int i = 0; i < 3; i++) {
            test(filename, true);
        }
    }
}