import java.awt.Color;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

public class ResImageConvertor {
    /** Converts and save Images from the TI-Nspire OS to TI.Image used by the Lua API of the
     ** TI-Nspire framework. Also can saves or load a PNG image.
     ** Those images are composed of a header part (20 bytes) and a sequence of pixels
     ** each coded on 2 bytes (RRRRRGGG-GGGBBBBB). Then, comes the alpha channel where
     ** each pixel is coded on 1 byte.
     *
     ** How to use : java ResImageConvertor output_image_path sequence of bytes
     *
     ** Example : java ResImageConvertor -[O|I] ./image.png [10 00 00 00 10 00 00 00 00 00 00 00 20 00 00 00 10 00 01 00 b0 5b b0 5b b0 5b b0 5b b0 5b b0 5b b0 5b ff ff ff ff ff ff ....]
     * Levak 24nd June 2012 */
    public static int string2char(String s) {
        int a = 0;
        String b = s;
        for(int j = 0; j < b.length(); ++j) {
            String c = b.substring(j, j+1);
            a <<= 4;
            try { a += Integer.parseInt(c); }
            catch(Exception err) { a += 10 + (int)(c.toLowerCase().charAt(0)) - (int)'a'; }
        }
        return a;
    }

    public static int readNbytesInt(String[] args, int o, int s) {
        int a = 0;
        int m = 0;
        for(int i = o; i < o + s; a += string2char(args[i]) << m, m += 8, i++);
        return a;
    }

    public static void writeNbytesInt(int n, int s) {
        byte a[] = new byte[s];
        for(int i = 0; i < s; a[i] = (byte) (n&0xFF), n >>= 8, i++);
        System.out.write(a, 0, s);
    }

    public static void output(String[] args) throws IOException {
        // header
        int i = 2;
        int w = readNbytesInt(args, i, 4);
        i += 4;
        int h = readNbytesInt(args, i, 4);
        i += 4;
        readNbytesInt(args, i, 4); // unused : empty
        i += 4;
        readNbytesInt(args, i, 4); // unused : buffer size
        i += 4;
        readNbytesInt(args, i, 2); // unused : image depth
        i += 2;
        readNbytesInt(args, i, 2); // unused : unknown (1)
        i += 2;

        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_4BYTE_ABGR);
        int bufferSize = w*h;
        int headerSize = 20;

        for(i = 2; i < headerSize+2; i++)
            System.out.printf("\\%03d", string2char(args[i]));

        // RGB sequence + Alpha Map
        for(i = 0; i < bufferSize; i++) {
            int b1 = string2char(args[2+headerSize+i*2]);
            int b2 = string2char(args[2+headerSize+i*2+1]);
            int c = (b2 << 8) + b1;
            int r = (c >> 11) << 3;
            int g = (c >> 5 & 0x3F) << 2;
            int b = (c & 0x1F) << 3;
            int alpha = string2char(args[2+headerSize+bufferSize*2+i]);
            int color = new Color(r, g, b, alpha).getRGB();
            image.setRGB(i%w, i/w, color);
            int bb1 = (alpha & 0x80) | ((r >> 1) & 0x7C) | (g >> 6);
            int bb2 = ((g << 2) & 0xE0) | (b >> 3);
            System.out.printf("\\%03d\\%03d", bb2, bb1);
        }
        File file = new File(args[1]);
        ImageIO.write(image, "PNG", file);
        System.out.println();
    }

    public static void input(String[] args) throws IOException {
        File file = new File(args[1]);
        BufferedImage image = ImageIO.read(file);
        int w = image.getWidth();
        int h = image.getHeight();

        // Header
        writeNbytesInt(w, 4);
        writeNbytesInt(h, 4);
        writeNbytesInt(0, 4);
        writeNbytesInt(w*2, 4);
        writeNbytesInt(16, 2);
        writeNbytesInt(1, 2);

        // RGB sequence
        for(int j = 0; j < h; j++) {
            for(int i = 0; i < w; i++) {
                Color c = new Color(image.getRGB(i, j), true);
                int b = ((c.getRed() & 0xF8) << 8) | ((c.getGreen() & 0xFC) << 3) | ((c.getBlue() & 0xF8) >> 3);
                writeNbytesInt(b, 2);
            }
        }

        // Alpha sequence
        for(int j = 0; j < h; j++) {
            for(int i = 0; i < w; i++) {
                Color c = new Color(image.getRGB(i, j), true);
                writeNbytesInt(c.getAlpha(), 1) ;
            }
        }
    }

    public static void main(String[] args) throws IOException {
        if(args[0].equals("-O"))
            output(args);
        else if (args[0].equals("-I"))
            input(args);
        else
            System.out.println("usage : java ResImageConvertor -[O|I] ./image.png [10 00 00 00 10 00 00 00 <TI.Image> ....] ");
    }
}