import java.awt.Color;
import java.awt.image.BufferedImage;
import java.io.File;
import java.nio.ByteBuffer;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Security;

import javax.imageio.ImageIO;

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Hex;

public class TwelveMonkeysImageTest
{

    public static void main(String[] args) throws Exception
    {
        //
        // Bouncy Castle Security Provider
        //
        Security.addProvider(new BouncyCastleProvider());

        //
        // TwelveMonkeys Java ImageIO extensions
        //
        // (automatically detected just must be in class path).

        //
        // Check args.
        //
        if (args.length < 1)
        {
            System.err.println("Error: Loading needs 1 argument - source path");
            System.exit(1);
        }
        load(args[0]);
    }

    public static void load(String sourcePath) throws Exception
    {
        BufferedImage image;
        BufferedImage loadedImage = ImageIO.read(new File(sourcePath));

        if (loadedImage == null)
        {
            System.out.println("Skipping non-image file.");
            throw new Exception("non-image file");
        }

        int width = loadedImage.getWidth();
        int height = loadedImage.getHeight();

        loadedImage = ImageIO.read(new File(sourcePath));
        System.out.format("Loaded Image SHA-256: %s\n", sha256Image(loadedImage, width, height));
        image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        image.createGraphics().drawImage(loadedImage, 0, 0, Color.WHITE, null);
        System.out.format("SHA-256: %s\n", sha256Image(image, width, height));
        ImageIO.write(image, "tiff", new File("1.tiff"));

        loadedImage = ImageIO.read(new File("1.tiff"));
        System.out.format("Loaded Image SHA-256: %s\n", sha256Image(loadedImage, width, height));
        image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        image.createGraphics().drawImage(loadedImage, 0, 0, Color.WHITE, null);
        System.out.format("SHA-256: %s\n", sha256Image(image, width, height));
        ImageIO.write(image, "tiff", new File("2.tiff"));

        loadedImage = ImageIO.read(new File("2.tiff"));
        System.out.format("Loaded Image SHA-256: %s\n", sha256Image(loadedImage, width, height));
        image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        image.createGraphics().drawImage(loadedImage, 0, 0, Color.WHITE, null);
        System.out.format("SHA-256: %s\n", sha256Image(image, width, height));
        ImageIO.write(image, "tiff", new File("3.tiff"));

        return;
    }

    public static String sha256Image(BufferedImage img, int width, int height) throws NoSuchAlgorithmException,
            NoSuchProviderException
    {
        //
        // SHA256 digest of the image data.
        //
        ByteBuffer byteBuffer = ByteBuffer.allocate(4 * width * height);

        for (int y = 0; y < height; y++)
        {
            for (int x = 0; x < width; x++)
            {
                byteBuffer.putInt(img.getRGB(x, y));
            }
        }

        // hash.reset();
        MessageDigest hash = MessageDigest.getInstance("SHA-256", "BC");
        hash.update(byteBuffer.array());
        return Hex.toHexString(hash.digest());
    }

}