/*
 * Portions Copyright (c) 2005 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * - Redistribution of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * 
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
 * MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
 * ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
 * DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
 * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
 * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
 * SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 * 
 * You acknowledge that this software is not designed or intended for use
 * in the design, construction, operation or maintenance of any nuclear
 * facility.
 * 
 * Sun gratefully acknowledges that this software was originally authored
 * and developed by Kenneth Bradley Russell and Christopher John Kline.
 */

package com.sun.opengl.util.texture.spi;

import java.io.*;
import javax.media.opengl.*;
import com.sun.opengl.util.*;

/** <p> Reads and writes SGI RGB/RGBA images. </p>

    <p> Written from <a href =
    "http://astronomy.swin.edu.au/~pbourke/dataformats/sgirgb/">Paul
    Bourke's adaptation</a> of the <a href =
    "http://astronomy.swin.edu.au/~pbourke/dataformats/sgirgb/sgiversion.html">SGI
    specification</a>. </p>
*/

public class SGIImage {
    private Header header;
    private int    format;
    private byte[] data;
    // Used for decoding RLE-compressed images
    private int[]  rowStart;
    private int[]  rowSize;
    private int    rleEnd;
    private byte[] tmpData;
    private byte[] tmpRead;

    private static final int MAGIC = 474;

    static class Header {
        short magic;        // IRIS image file magic number
        // This should be decimal 474
        byte  storage;      // Storage format
        // 0 for uncompressed
        // 1 for RLE compression
        byte  bpc;          // Number of bytes per pixel channel 
        // Legally 1 or 2
        short dimension;    // Number of dimensions
        // Legally 1, 2, or 3
        // 1 means a single row, XSIZE long
        // 2 means a single 2D image
        // 3 means multiple 2D images
        short xsize;        // X size in pixels 
        short ysize;        // Y size in pixels 
        short zsize;        // Number of channels
        // 1 indicates greyscale
        // 3 indicates RGB
        // 4 indicates RGB and Alpha
        int pixmin;         // Minimum pixel value
        // This is the lowest pixel value in the image
        int pixmax;         // Maximum pixel value
        // This is the highest pixel value in the image
        int dummy;          // Ignored
        // Normally set to 0
        String imagename;   // Image name; 80 bytes long
        // Must be null terminated, therefore at most 79 bytes
        int colormap;       // Colormap ID
        // 0 - normal mode
        // 1 - dithered, 3 mits for red and green, 2 for blue, obsolete
        // 2 - index colour, obsolete
        // 3 - not an image but a colourmap
        // 404 bytes  char    DUMMY      Ignored
        // Should be set to 0, makes the header 512 bytes.

        Header() {
            magic = MAGIC;
        }

        Header(DataInputStream in) throws IOException {
            magic      = in.readShort();
            storage    = in.readByte();
            bpc        = in.readByte();
            dimension  = in.readShort();
            xsize      = in.readShort();
            ysize      = in.readShort();
            zsize      = in.readShort();
            pixmin     = in.readInt();
            pixmax     = in.readInt();
            dummy      = in.readInt();
            byte[] tmpname = new byte[80];
            in.read(tmpname);
            int numChars = 0;
            while (tmpname[numChars++] != 0);
            imagename  = new String(tmpname, 0, numChars);
            colormap   = in.readInt();
            byte[] tmp = new byte[404];
            in.read(tmp);
        }

        public String toString() {
            return ("magic: " + magic +
                    " storage: " + (int) storage +
                    " bpc: " + (int) bpc +
                    " dimension: " + dimension +
                    " xsize: " + xsize +
                    " ysize: " + ysize +
                    " zsize: " + zsize +
                    " pixmin: " + pixmin +
                    " pixmax: " + pixmax +
                    " imagename: " + imagename +
                    " colormap: " + colormap);
        }
    }

    private SGIImage(Header header) {
        this.header = header;
    }

    /** Reads an SGI image from the specified file. */
    public static SGIImage read(String filename) throws IOException {
        return read(new FileInputStream(filename));
    }

    /** Reads an SGI image from the specified InputStream. */
    public static SGIImage read(InputStream in) throws IOException {
        DataInputStream dIn = new DataInputStream(new BufferedInputStream(in));

        Header header = new Header(dIn);
        SGIImage res = new SGIImage(header);
        res.decodeImage(dIn);
        return res;
    }

    /** Writes this SGIImage to the specified file name. If
        flipVertically is set, outputs the scanlines from top to bottom
        rather than the default bottom to top order. */
    public void write(String filename, boolean flipVertically) throws IOException {
        write(new File(filename), flipVertically);
    }

    /** Writes this SGIImage to the specified file. If flipVertically is
        set, outputs the scanlines from top to bottom rather than the
        default bottom to top order. */
    public void write(File file, boolean flipVertically) throws IOException {
        writeImage(file, data, header.xsize, header.ysize, header.zsize, flipVertically);
    }

    /** Creates an SGIImage from the specified data in either RGB or
        RGBA format. */
    public static SGIImage createFromData(int width,
                                          int height,
                                          boolean hasAlpha,
                                          byte[] data) {
        Header header = new Header();
        header.xsize = (short) width;
        header.ysize = (short) height;
        header.zsize = (short) (hasAlpha ? 4 : 3);
        SGIImage image = new SGIImage(header);
        image.data = data;
        return image;
    }

    /** Determines from the magic number whether the given InputStream
        points to an SGI RGB image. The given InputStream must return
        true from markSupported() and support a minimum of two bytes
        of read-ahead. */
    public static boolean isSGIImage(InputStream in) throws IOException {
        if (!(in instanceof BufferedInputStream)) {
            in = new BufferedInputStream(in);
        }
        if (!in.markSupported()) {
            throw new IOException("Can not test non-destructively whether given InputStream is an SGI RGB image");
        }
        DataInputStream dIn = new DataInputStream(in);
        dIn.mark(4);
        short magic = dIn.readShort();
        dIn.reset();
        return (magic == MAGIC);
    }

    /** Returns the width of the image. */
    public int getWidth() {
        return header.xsize;
    }

    /** Returns the height of the image. */
    public int getHeight() {
        return header.ysize;
    }

    /** Returns the OpenGL format for this texture; e.g. GL.GL_RGB or GL.GL_RGBA. */
    public int getFormat() {
        return format;
    }

    /** Returns the raw data for this texture in the correct
        (bottom-to-top) order for calls to glTexImage2D. */
    public byte[] getData()  { return data; }

    public String toString() {
        return header.toString();
    }

    //----------------------------------------------------------------------
    // Internals only below this point
    //
  
    private void decodeImage(DataInputStream in) throws IOException {
        if (header.storage == 1) {
            // Read RLE compression data; row starts and sizes
            int x = header.ysize * header.zsize;
            rowStart = new int[x];
            rowSize  = new int[x];
            rleEnd   = 4 * 2 * x + 512;
            for (int i = 0; i < x; i++) {
                rowStart[i] = in.readInt();
            }
            for (int i = 0; i < x; i++) {
                rowSize[i] = in.readInt();
            }
            tmpRead = new byte[header.xsize * 256];
        }
        tmpData = readAll(in);

        int xsize = header.xsize;
        int ysize = header.ysize;
        int zsize = header.zsize;
        int lptr  = 0;

        data = new byte[xsize * ysize * 4];
        byte[] rbuf = new byte[xsize];
        byte[] gbuf = new byte[xsize];
        byte[] bbuf = new byte[xsize];
        byte[] abuf = new byte[xsize];
        for (int y = 0; y < ysize; y++) {
            if (zsize >= 4) {
                getRow(rbuf, y, 0);
                getRow(gbuf, y, 1);
                getRow(bbuf, y, 2);
                getRow(abuf, y, 3);
                rgbatorgba(rbuf, gbuf, bbuf, abuf, data, lptr);
            } else if (zsize == 3) {
                getRow(rbuf, y, 0);
                getRow(gbuf, y, 1);
                getRow(bbuf, y, 2);
                rgbtorgba(rbuf, gbuf, bbuf, data, lptr);
            } else if (zsize == 2) {
                getRow(rbuf, y, 0);
                getRow(abuf, y, 1);
                latorgba(rbuf, abuf, data, lptr);
            } else {
                getRow(rbuf, y, 0);
                bwtorgba(rbuf, data, lptr);
            }
            lptr += 4 * xsize;
        }
        rowStart = null;
        rowSize  = null;
        tmpData  = null;
        tmpRead  = null;
        format   = GL.GL_RGBA;
        header.zsize = 4;
    }

    private void getRow(byte[] buf, int y, int z) {
        if (header.storage == 1) {
            int offs = rowStart[y + z * header.ysize] - rleEnd;
            System.arraycopy(tmpData, offs, tmpRead, 0, rowSize[y + z * header.ysize]);
            int iPtr = 0;
            int oPtr = 0;
            for (;;) {
                byte pixel = tmpRead[iPtr++];
                int count = (int) (pixel & 0x7F);
                if (count == 0) {
                    return;
                }
                if ((pixel & 0x80) != 0) {
                    while ((count--) > 0) {
                        buf[oPtr++] = tmpRead[iPtr++];
                    }
                } else {
                    pixel = tmpRead[iPtr++];
                    while ((count--) > 0) {
                        buf[oPtr++] = pixel;
                    }
                }
            }
        } else {
            int offs = (y * header.xsize) + (z * header.xsize * header.ysize);
            System.arraycopy(tmpData, offs, buf, 0, header.xsize);
        }
    }

    private void bwtorgba(byte[] b, byte[] dest, int lptr) {
        for (int i = 0; i < b.length; i++) {
            dest[4 * i + lptr + 0] = b[i];
            dest[4 * i + lptr + 1] = b[i];
            dest[4 * i + lptr + 2] = b[i];
            dest[4 * i + lptr + 3] = (byte) 0xFF;
        }
    }

    private void latorgba(byte[] b, byte[] a, byte[] dest, int lptr) {
        for (int i = 0; i < b.length; i++) {
            dest[4 * i + lptr + 0] = b[i];
            dest[4 * i + lptr + 1] = b[i];
            dest[4 * i + lptr + 2] = b[i];
            dest[4 * i + lptr + 3] = a[i];
        }
    }

    private void rgbtorgba(byte[] r, byte[] g, byte[] b, byte[] dest, int lptr) {
        for (int i = 0; i < b.length; i++) {
            dest[4 * i + lptr + 0] = r[i];
            dest[4 * i + lptr + 1] = g[i];
            dest[4 * i + lptr + 2] = b[i];
            dest[4 * i + lptr + 3] = (byte) 0xFF;
        }
    }

    private void rgbatorgba(byte[] r, byte[] g, byte[] b, byte[] a, byte[] dest, int lptr) {
        for (int i = 0; i < b.length; i++) {
            dest[4 * i + lptr + 0] = r[i];
            dest[4 * i + lptr + 1] = g[i];
            dest[4 * i + lptr + 2] = b[i];
            dest[4 * i + lptr + 3] = a[i];
        }
    }

    private static byte imgref(byte[] i,
                               int x,
                               int y,
                               int z,
                               int xs,
                               int ys,
                               int zs) {
        return i[(xs*ys*z)+(xs*y)+x];
    }


    private void writeHeader(DataOutputStream stream,
                             int xsize, int ysize, int zsize, boolean rle) throws IOException {
        // effects: outputs the 512-byte IRIS RGB header to STREAM, using xsize,
        //          ysize, and depth as the dimensions of the image. NOTE that
        //          the following defaults are used:
        //              STORAGE = 1     (storage format = RLE)
        //              BPC = 1         (# bytes/channel)
        //              DIMENSION = 3
        //              PIXMIN = 0
        //              PIXMAX = 255
        //              IMAGENAME = <80 nulls>
        //              COLORMAP = 0
        //          See ftp://ftp.sgi.com/pub/sgi/SGIIMAGESPEC for more details.

        // write out MAGIC, STORAGE, BPC
        stream.writeShort(474);
        stream.write((rle ? 1 : 0));
        stream.write(1);

        // write out DIMENSION
        stream.writeShort(3);

        // write XSIZE, YSIZE, ZSIZE
        stream.writeShort(xsize);
        stream.writeShort(ysize);
        stream.writeShort(zsize);

        // write PIXMIN, PIXMAX
        stream.writeInt(0);
        stream.writeInt(255);

        // write DUMMY
        stream.writeInt(0);

        // write IMAGENAME
        for (int i = 0; i < 80; i++)
            stream.write(0);

        // write COLORMAP
        stream.writeInt(0);

        // write DUMMY (404 bytes)
        for (int i = 0; i < 404; i++)
            stream.write(0);
    }

    private void writeImage(File file,
                            byte[] data,
                            int xsize,
                            int ysize,
                            int zsize,
                            boolean yflip) throws IOException {
        // Input data is in RGBRGBRGB or RGBARGBARGBA format; first unswizzle it
        byte[] tmpData = new byte[xsize * ysize * zsize];
        int dest = 0;
        for (int i = 0; i < zsize; i++) {
            for (int j = i; j < (xsize * ysize * zsize); j += zsize) {
                tmpData[dest++] = data[j];
            }
        }
        data = tmpData;

        // requires: DATA must be an array of size XSIZE * YSIZE * ZSIZE,
        //           indexed in the following manner:
        //             data[0]    ...data[xsize-1] == first row of first channel
        //             data[xsize]...data[2*xsize-1]   == second row of first channel
        //         ... data[(ysize - 1) * xsize]...data[(ysize * xsize) - 1] ==
        //                                            last row of first channel
        //           Later channels follow the same format.
        //           *** NOTE that "first row" is defined by the BOTTOM ROW of
        //           the image. That is, the origin is in the lower left corner.
        // effects: writes out an SGI image to FILE, RLE-compressed, INCLUDING
        //          header, of dimensions (xsize, ysize, zsize), and containing
        //          the data in DATA. If YFLIP is set, outputs the data in DATA
        //          in reverse order vertically (equivalent to a flip about the
        //          x axis).

        // Build the offset tables
        int[] starttab  = new int[ysize * zsize];
        int[] lengthtab = new int[ysize * zsize];

        // Temporary buffer for holding RLE data.
        // Note that this makes the assumption that RLE-compressed data will
        // never exceed twice the size of the input data.
        // There are surely formal proofs about how big the RLE buffer should
        // be, as well as what the optimal look-ahead size is (i.e. don't switch
        // copy/repeat modes for less than N repeats). However, I'm going from
        // empirical evidence here; the break-even point seems to be a look-
        // ahead of 3. (That is, if the three values following this one are all
        // the same as the current value, switch to repeat mode.)
        int lookahead = 3;
        byte[] rlebuf = new byte[2 * xsize * ysize * zsize];

        int cur_loc = 0;   // current offset location.
        int ptr = 0;
        int total_size = 0;
        int ystart = 0;
        int yincr = 1;
        int yend = ysize;

        if (yflip) {
            ystart = ysize - 1;
            yend = -1;
            yincr = -1;
        }

        boolean DEBUG = false;

        for (int z = 0; z < zsize; z++) {
            for (int y = ystart; y != yend; y += yincr) {
                // RLE-compress each row.
	  
                int x = 0;
                byte count = 0;
                boolean repeat_mode = false;
                boolean should_switch = false;
                int start_ptr = ptr;
                int num_ptr = ptr++;
                byte repeat_val = 0;
	  
                while (x < xsize) {
                    // see if we should switch modes
                    should_switch = false;
                    if (repeat_mode) {
                        if (imgref(data, x, y, z, xsize, ysize, zsize) != repeat_val) {
                            should_switch = true;
                        }
                    } else {
                        // look ahead to see if we should switch to repeat mode.
                        // stay within the scanline for the lookahead
                        if ((x + lookahead) < xsize) {
                            should_switch = true;
                            for (int i = 1; i <= lookahead; i++) {
                                if (DEBUG)
                                    System.err.println("left side was " + ((int) imgref(data, x, y, z, xsize, ysize, zsize)) +
                                                       ", right side was " + (int)imgref(data, x+i, y, z, xsize, ysize, zsize));
			  
                                if (imgref(data, x, y, z, xsize, ysize, zsize) !=
                                    imgref(data, x+i, y, z, xsize, ysize, zsize))
                                    should_switch = false;
                            }
                        }
                    }

                    if (should_switch || (count == 127)) {
                        // update the number of elements we repeated/copied
                        if (x > 0) {
                            if (repeat_mode)
                                rlebuf[num_ptr] = count;
                            else
                                rlebuf[num_ptr] = (byte) (count | 0x80);
                        }
                        // perform mode switch if necessary; output repeat_val if
                        // switching FROM repeat mode, and set it if switching
                        // TO repeat mode.
                        if (repeat_mode) {
                            if (should_switch)
                                repeat_mode = false;
                            rlebuf[ptr++] = repeat_val;
                        } else {
                            if (should_switch)
                                repeat_mode = true;
                            repeat_val = imgref(data, x, y, z, xsize, ysize, zsize);
                        }
		  
                        if (x > 0) {
                            // reset the number pointer
                            num_ptr = ptr++;
                            // reset number of bytes copied
                            count = 0;
                        }
                    }
		    
                    // if not in repeat mode, copy element to ptr
                    if (!repeat_mode) {
                        rlebuf[ptr++] = imgref(data, x, y, z, xsize, ysize, zsize);
                    }
                    count++;

                    if (x == xsize - 1) {
                        // Need to store the number of pixels we copied/repeated.
                        if (repeat_mode) {
                            rlebuf[num_ptr] = count;
                            // If we ended the row in repeat mode, store the
                            // repeated value
                            rlebuf[ptr++] = repeat_val;
                        }
                        else
                            rlebuf[num_ptr] = (byte) (count | 0x80);

                        // output zero counter for the last value in the row
                        rlebuf[ptr++] = 0;
                    }

                    x++;
                }
                // output this row's length into the length table
                int rowlen = ptr - start_ptr;
                if (yflip)
                    lengthtab[ysize*z+(ysize-y-1)] = rowlen;
                else
                    lengthtab[ysize*z+y] = rowlen;
                // add to the start table, and update the current offset
                if (yflip)
                    starttab[ysize*z+(ysize-y-1)] = cur_loc;
                else
                    starttab[ysize*z+y] = cur_loc;
                cur_loc += rowlen;
            }
        }

        // Now we have the offset tables computed, as well as the RLE data.
        // Output this information to the file.
        total_size = ptr;
  
        if (DEBUG) 
            System.err.println("total_size was " + total_size);

        DataOutputStream stream = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(file)));

        writeHeader(stream, xsize, ysize, zsize, true);

        int SIZEOF_INT = 4;
        for (int i = 0; i < (ysize * zsize); i++)
            stream.writeInt(starttab[i] + 512 + (2 * ysize * zsize * SIZEOF_INT));
        for (int i = 0; i < (ysize * zsize); i++)
            stream.writeInt(lengthtab[i]);
        for (int i = 0; i < total_size; i++)
            stream.write(rlebuf[i]);

        stream.close();
    }

    private byte[] readAll(DataInputStream in) throws IOException {
        byte[] dest = new byte[16384];
        int pos = 0;
        int numRead = 0;
    
        boolean done = false;

        do {
            numRead = in.read(dest, pos, dest.length - pos);
            if (pos == dest.length) {
                // Resize destination buffer
                byte[] newDest = new byte[2 * dest.length];
                System.arraycopy(dest, 0, newDest, 0, pos);
                dest = newDest;
            }
            if (numRead > 0) {
                pos += numRead;
            }

            done = ((numRead == -1) || (in.available() == 0));
        } while (!done);

        // Trim destination buffer
        if (pos != dest.length) {
            byte[] finalDest = new byte[pos];
            System.arraycopy(dest, 0, finalDest, 0, pos);
            dest = finalDest;
        }

        return dest;
    }

    // Test case
    /*
      import java.awt.image.*;
      import javax.swing.*;

      public static void main(String[] args) {
      for (int i = 0; i < args.length; i++) {
      try {
      System.out.println(args[i] + ":");
      SGIImage image = SGIImage.read(args[i]);
      System.out.println(image);
      BufferedImage img = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_4BYTE_ABGR);
      WritableRaster raster = img.getRaster();
      DataBufferByte db = (DataBufferByte) raster.getDataBuffer();
      byte[] src  = image.getData();
      byte[] dest = db.getData();
      for (int j = 0; j < src.length; j += 4) {
      dest[j + 0] = src[j + 3];
      dest[j + 1] = src[j + 2];
      dest[j + 2] = src[j + 1];
      dest[j + 3] = src[j + 0];
      }
      // System.arraycopy(src, 0, dest, 0, src.length);
      ImageIcon icon = new ImageIcon(img);
      JLabel label = new JLabel();
      label.setIcon(icon);
      JFrame frame = new JFrame(args[i]);
      frame.getContentPane().add(label);
      frame.pack();
      frame.show();
      } catch (IOException e) {
      e.printStackTrace();
      }
      }
      }
    */
}