// Copyright (C) 2010, 2011, 2012, 2013 GlavSoft LLC.
// All rights reserved.
//
//-------------------------------------------------------------------------
// This file is part of the TightVNC software.  Please visit our Web site:
//
//                       http://www.tightvnc.com/
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//-------------------------------------------------------------------------
//

package com.glavsoft.rfb.encoding.decoder;

import alice.datasegment.DataSegment;

import com.glavsoft.drawing.Renderer;
import com.glavsoft.exceptions.TransportException;
import com.glavsoft.transport.Reader;

public class ZRLEDecoder extends ZlibDecoder {
    private static final int MAX_TILE_SIZE = 64;
    private int[] decodedBitmap;
    private int[] palette;

    @Override
    public void decode(Reader reader, Renderer renderer,
            FramebufferUpdateRectangle rect) throws TransportException {
        int zippedLength = (int) reader.readUInt32();
        if (0 == zippedLength) return;
        int length = rect.width * rect.height * renderer.getBytesPerPixel();
        byte[] bytes = unzip(reader, zippedLength, length);
        int offset = zippedLength;
        
        AliceVNCMessage message = new AliceVNCMessage();
        message.setRectangle(rect);
        message.buf = bytes.clone();
        message.offset = offset;
        DataSegment.getLocal().put("aliceVNCMessage", message, null);
        decode(renderer, rect, bytes, offset);
    }

    public void decode(Renderer renderer,
            FramebufferUpdateRectangle rect, byte[] bytes, int offset)
            throws TransportException {
        int maxX = rect.x + rect.width;
        int maxY = rect.y + rect.height;
        if (null == palette) {
            palette = new int [128];
        }
        if (null == decodedBitmap) {
            decodedBitmap = new int[MAX_TILE_SIZE * MAX_TILE_SIZE];
        }
        for (int tileY = rect.y; tileY < maxY; tileY += MAX_TILE_SIZE) {
            int tileHeight = Math.min(maxY - tileY, MAX_TILE_SIZE);

            for (int tileX = rect.x; tileX < maxX; tileX += MAX_TILE_SIZE) {
                int tileWidth = Math.min(maxX - tileX, MAX_TILE_SIZE);
                int subencoding = bytes[offset++] & 0x0ff;
                // 128 -plain RLE, 130-255 - Palette RLE
                boolean isRle = (subencoding & 128) != 0;
                // 2 to 16 for raw packed palette data, 130 to 255 for Palette RLE (subencoding - 128)
                int paletteSize = subencoding & 127;
                offset += readPalette(bytes, offset, renderer, paletteSize);
                if (1 == subencoding) { // A solid tile consisting of a single colour
                    renderer.fillRect(palette[0], tileX, tileY, tileWidth, tileHeight);
                    continue;
                }
                if (isRle) {
                    if (0 == paletteSize) { // subencoding == 128 (or paletteSize == 0) - Plain RLE
                        offset += decodePlainRle(bytes, offset, renderer, tileX, tileY, tileWidth, tileHeight);
                    } else {
                        offset += decodePaletteRle(bytes, offset, renderer, tileX, tileY, tileWidth, tileHeight);
                    }
                } else {
                    if (0 == paletteSize) { // subencoding == 0 (or paletteSize == 0) - raw CPIXEL data
                        offset += decodeRaw(bytes, offset, renderer, tileX, tileY, tileWidth, tileHeight);
                    } else {
                        offset += decodePacked(bytes, offset, renderer, paletteSize, tileX, tileY, tileWidth, tileHeight);
                    }
                }
            }
        }
    }

    private int decodePlainRle(byte[] bytes, int offset, Renderer renderer,
            int tileX, int tileY, int tileWidth, int tileHeight) {
        int bytesPerCPixel = renderer.getBytesPerCPixel();
        int decodedOffset = 0;
        int decodedEnd = tileWidth * tileHeight;
        int index = offset;
        while (decodedOffset < decodedEnd) {
            int color = renderer.getCompactPixelColor(bytes, index);
            index += bytesPerCPixel;
            int rlength = 1;
            do {
                rlength += bytes[index] & 0x0ff;
            } while ((bytes[index++] & 0x0ff) == 255);
            assert rlength <= decodedEnd - decodedOffset;
            renderer.fillColorBitmapWithColor(decodedBitmap, decodedOffset, rlength, color);
            decodedOffset += rlength;
        }
        renderer.drawColoredBitmap(decodedBitmap, tileX, tileY, tileWidth, tileHeight);
        return index - offset;
    }

    private int decodePaletteRle(byte[] bytes, int offset, Renderer renderer,
            int tileX, int tileY, int tileWidth, int tileHeight) {
        int decodedOffset = 0;
        int decodedEnd = tileWidth * tileHeight;
        int index = offset;
        while (decodedOffset < decodedEnd) {
            int colorIndex = bytes[index++];
            int color = palette[colorIndex & 127];
            int rlength = 1;
            if ((colorIndex & 128) != 0) {
                do {
                    rlength += bytes[index] & 0x0ff;
                } while (bytes[index++] == (byte) 255);
            }
            assert rlength <= decodedEnd - decodedOffset;
            renderer.fillColorBitmapWithColor(decodedBitmap, decodedOffset, rlength, color);
            decodedOffset += rlength;
        }
        renderer.drawColoredBitmap(decodedBitmap, tileX, tileY, tileWidth, tileHeight);
        return index - offset;
    }

    private int decodePacked(byte[] bytes, int offset, Renderer renderer,
            int paletteSize, int tileX, int tileY, int tileWidth, int tileHeight) {
        int bitsPerPalletedPixel = paletteSize > 16 ? 8 : paletteSize > 4 ? 4
                : paletteSize > 2 ? 2 : 1;
                int packedOffset = offset;
                int decodedOffset = 0;
                for (int i = 0; i < tileHeight; ++i) {
                    int decodedRowEnd = decodedOffset + tileWidth;
                    int byteProcessed = 0;
                    int bitsRemain = 0;

                    while (decodedOffset < decodedRowEnd) {
                        if (bitsRemain == 0) {
                            byteProcessed = bytes[packedOffset++];
                            bitsRemain = 8;
                        }
                        bitsRemain -= bitsPerPalletedPixel;
                        int index = byteProcessed >> bitsRemain & (1 << bitsPerPalletedPixel) - 1 & 127;
                    int color = palette[index];
                    renderer.fillColorBitmapWithColor(decodedBitmap, decodedOffset, 1, color);
                    ++decodedOffset;
                    }
                }
                renderer.drawColoredBitmap(decodedBitmap, tileX, tileY, tileWidth, tileHeight);
                return packedOffset - offset;
    }

    private int decodeRaw(byte[] bytes, int offset, Renderer renderer,
            int tileX, int tileY, int tileWidth, int tileHeight) throws TransportException {
        return renderer.drawCompactBytes(bytes, offset, tileX, tileY, tileWidth, tileHeight);
    }

    private int readPalette(byte[] bytes, int offset, Renderer renderer, int paletteSize) {
        final int bytesPerCPixel = renderer.getBytesPerCPixel();
        for (int i=0; i<paletteSize; ++i) {
            palette[i] = renderer.getCompactPixelColor(bytes, offset + i* bytesPerCPixel);
        }
        return paletteSize * bytesPerCPixel;
    }
}