/*******************************************************************************
 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
 * in Industry THTH ry.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.db.procore.cluster;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

import org.simantics.compressions.Compressions;
import org.simantics.db.exception.InternalException;

public class LZ4 {
    static private final int InLength = 1<<20;
    
    public static class DecompressStruct {
        public long[] longs;
        public int[] ints;
        public byte[] bytes;
    }
    static class SourceData {
        SourceData(byte[] data) {
            this.data = data;
            this.offset = 0;
        }
        int left() {
            return data.length - offset;
        }
        int readInt() {
            int inLength = 4; // sizeof(int)
            assert(left() >= inLength); // must have data for input
            ByteBuffer buffer = ByteBuffer.wrap(data, offset, inLength);
            buffer.order(ByteOrder.LITTLE_ENDIAN); // argh!
            int t = buffer.getInt();
            offset += inLength;
            return t;
        }
        void readBytes(byte[] bytes, int aOffset, int inLength) {
            assert(left() >= inLength); // must have data for input
            System.arraycopy(data, offset, bytes, aOffset, inLength);
            offset += inLength;
        }
        byte[] data;
        int offset;
    }
    public static DecompressStruct decompress(byte[] data) throws InternalException {
        assert(data.length > 12); // 3*(table size)
        SourceData sourceData = new SourceData(data);
        DecompressStruct struct = new DecompressStruct();
        int longSize = sourceData.readInt();
        int intSize = sourceData.readInt();
        int byteSize = sourceData.readInt();
        struct.longs = new long[longSize]; 
        try {
            decompress(sourceData, struct.longs);
            struct.ints = new int[intSize]; 
            decompress(sourceData, struct.ints);
            struct.bytes = new byte[byteSize];
            decompress(sourceData, struct.bytes);
        } catch (CompressionException e) {
            throw new InternalException("Failed to decompress.", e);
        }
        return struct;
    }
    private static void decompress(SourceData sourceData, long[] longs) throws CompressionException {
        int length = longs.length * 8;
        ByteBuffer bytes = ByteBuffer.allocate(length);
        int size = decompressRaw(sourceData, bytes.array());
        assert(size == length);
        bytes.order(ByteOrder.LITTLE_ENDIAN); // argh
        for (int i=0; i<longs.length; ++i)
            longs[i] = bytes.getLong();
    }
    private static void decompress(SourceData sourceData, int[] ints) throws CompressionException {
        int length = ints.length * 4;
        ByteBuffer bytes = ByteBuffer.allocate(length);
        int size = decompressRaw(sourceData, bytes.array());
        assert(size == length);
        bytes.order(ByteOrder.LITTLE_ENDIAN); // argh
        for (int i=0; i<ints.length; ++i)
            ints[i] = bytes.getInt();
    }
    private static void decompress(SourceData sourceData, byte[] bytes) throws CompressionException {
        int size = decompressRaw(sourceData, bytes);
        assert(size == bytes.length);
    }
    private static int decompressRaw(SourceData sourceData, byte[] bytes) throws CompressionException {
        int aDstSize = bytes.length;
        if (aDstSize < 1)
            return aDstSize;
        int dstOffset = 0;
        for (int dstSize = 0;;) {
            int dataLength = sourceData.readInt(); 
            assert(dataLength <= InLength); // data is written in blocks
            if (0 == dataLength) // EOF
                return dstSize;
            dstSize += dataLength;
            int inLength = sourceData.readInt();

            assert(aDstSize >= dstSize); // must have space for data
            assert(sourceData.left() >= inLength); // must have data for input
            assert(inLength > 0); // no data no block
            assert(inLength <= InLength); // input size is block size or less
            assert(inLength <= dataLength); // input size is never bigger than data size

            if (inLength < dataLength) {// block was actually compressed
                decompress(sourceData.data, sourceData.offset, inLength, bytes, dstOffset, dataLength);
                sourceData.offset += inLength;
                dstOffset += dataLength;
            } else {
                sourceData.readBytes(bytes, dstOffset, inLength);
                dstOffset += inLength;
            }
        }
    }
    private static void decompress(byte[] in, int inOffset, int inLength, byte[] out, int outOffset, int outLength) throws CompressionException {
        ByteBuffer inBuffer = ByteBuffer.allocateDirect(inLength);
        inBuffer.put(in, inOffset, inLength);
        inBuffer.flip();
        ByteBuffer outBuffer = ByteBuffer.allocateDirect(outLength);
        int inflateSize = Compressions.get(Compressions.LZ4).decompressBuffer(inBuffer, 0, inLength, outBuffer, 0, outLength);
//        int inflateSize = org.simantics.fastlz.FastLZ.decompressBuffer(inBuffer, 0, inLength, outBuffer, 0, outLength);
        if (inflateSize != outLength)
            throw new RuntimeException("Decompression error.");
        //outBuffer.flip();
        outBuffer.get(out, outOffset, outLength);
    }
}