/*************************************************************************

"FreePastry" Peer-to-Peer Application Development Substrate 

Copyright 2002, Rice University. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.

- Redistributions 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 Rice  University (RICE) nor  the names  of its
contributors may be  used to endorse or promote  products derived from
this software without specific prior written permission.

This software is provided by RICE and the contributors on an "as is"
basis, without any representations or warranties of any kind, express
or implied including, but not limited to, representations or
warranties of non-infringement, merchantability or fitness for a
particular purpose. In no event shall RICE or contributors be liable
for any direct, indirect, incidental, special, exemplary, or
consequential damages (including, but not limited to, procurement of
substitute goods or services; loss of use, data, or profits; or
business interruption) however caused and on any theory of liability,
whether in contract, strict liability, or tort (including negligence
or otherwise) arising in any way out of the use of this software, even
if advised of the possibility of such damage.

********************************************************************************/
package rice.p2p.glacier;

import java.io.*;
import java.util.Arrays;

import rice.environment.Environment;
import rice.environment.logging.*;
import rice.environment.random.RandomSource;
import rice.environment.random.simple.SimpleRandomSource;
import rice.p2p.commonapi.Endpoint;
import rice.p2p.past.PastContent;
import rice.p2p.past.rawserialization.*;
import rice.p2p.util.rawserialization.*;

/**
 * DESCRIBE THE CLASS
 *
 * @version $Id: ErasureCodec.java 3274 2006-05-15 16:17:47Z jeffh $
 * @author ahae
 */
public class ErasureCodec {

  /**
   * DESCRIBE THE FIELD
   */
  protected int numFragments;
  /**
   * DESCRIBE THE FIELD
   */
  protected int numSurvivors;

  /**
   * DESCRIBE THE FIELD
   */
  protected Environment environment;
  /**
   * DESCRIBE THE FIELD
   */
  protected Logger logger;

  final static int Lfield = 10;
  final static int MultField = (1 << Lfield) - 1;

  static int[] ExpToFieldElt;
  static int[] FieldEltToExp;
  static boolean isEltInitialized = false;

  /**
   * Constructor for ErasureCodec.
   *
   * @param _numFragments DESCRIBE THE PARAMETER
   * @param _numSurvivors DESCRIBE THE PARAMETER
   * @param env DESCRIBE THE PARAMETER
   */
  public ErasureCodec(int _numFragments, int _numSurvivors, Environment env) {
    environment = env;
    logger = environment.getLogManager().getLogger(getClass(), null);
    numFragments = _numFragments;
    numSurvivors = _numSurvivors;

    if (!isEltInitialized) {
      initElt();
    }
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param data DESCRIBE THE PARAMETER
   */
  public void dump(byte[] data) {
    String hex = "0123456789ABCDEF";
    String s = "";
    for (int i = 0; i < data.length; i++) {
      int d = data[i];
      if (d < 0) {
        d += 256;
      }
      int hi = (d >> 4);
      int lo = (d & 15);

      s += hex.charAt(hi) + "" + hex.charAt(lo);
      if (((i % 16) == 15) || (i == (data.length - 1))) {
        s += "\n";
      } else {
        s += " ";
      }
    }
    if (logger.level <= Logger.INFO) {
      logger.log(
        s);
    }
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param obj DESCRIBE THE PARAMETER
   * @param generateFragment DESCRIBE THE PARAMETER
   * @return DESCRIBE THE RETURN VALUE
   */
  public Fragment[] encodeObject(PastContent obj, boolean[] generateFragment) {
    return encodeObject(obj instanceof RawPastContent ? (RawPastContent) obj : new JavaSerializedPastContent(obj), generateFragment);
  }

  /**
   * Serializes the object.
   *
   * @param obj
   * @param generateFragment
   * @return
   */
  public Fragment[] encodeObject(RawPastContent obj, boolean[] generateFragment) {
    if (logger.level <= Logger.FINER) {
      logger.log(
        "Serialize object: " + obj);
    }

    try {
      SimpleOutputBuffer sob = new SimpleOutputBuffer();
      sob.writeShort(obj.getType());
      obj.serialize(sob);
      return encode(sob.getBytes(), sob.getWritten(), generateFragment);
    } catch (IOException ioe) {
      if (logger.level <= Logger.WARNING) {
        logger.log(
          "Cannot serialize object: " + ioe);
      }
      return null;
    }
  }


//  public Fragment[] encodeObject(PastContent obj, boolean[] generateFragment) {
//    byte bytes[];
//
//    try {
//      ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
//      ObjectOutputStream objectStream = new ObjectOutputStream(byteStream);
//
//      objectStream.writeObject(obj);
//      objectStream.flush();
//
//      bytes = byteStream.toByteArray();
//    } catch (IOException ioe) {
//      if (logger.level <= Logger.WARNING) logger.logException(
//          "encodeObject: ", ioe);
//      return null;
//    }
//
//    return encode(bytes, generateFragment);
//  }

  /**
   * Input: buffer of size <numFragments*Lfield>; first <numSurvivors*Lfield>
   * words contain message, rest is zeroes Output: buffer contains fragments
   *
   * @param buffer DESCRIBE THE PARAMETER
   */
  protected void encodeChunk(int[] buffer) {
    for (int row = 0; row < (numFragments - numSurvivors); row++) {
      for (int col = 0; col < numSurvivors; col++) {
        int exponent = (MultField - FieldEltToExp[(row ^ col) ^ (1 << (Lfield - 1))]) % MultField;
        for (int row_bit = 0; row_bit < Lfield; row_bit++) {
          for (int col_bit = 0; col_bit < Lfield; col_bit++) {
            if ((ExpToFieldElt[exponent + row_bit] & (1 << col_bit)) != 0) {
              buffer[numSurvivors * Lfield + row * Lfield + row_bit] ^= buffer[col_bit + col * Lfield];
            }
          }
        }
      }
    }
  }

  /**
   * Generates multiple fragments from the incoming bytes
   *
   * @param bytes
   * @param length
   * @param generateFragment
   * @return
   */
  public Fragment[] encode(byte[] bytes, int length, boolean[] generateFragment) {
    int wantFragments = 0;
    for (int i = 0; i < generateFragment.length; i++) {
      if (generateFragment[i]) {
        wantFragments++;
      }
    }

    // System.outt.println(Systemm.currentTimeMillis()+" XXX before encode("+bytes.length+" bytes, "+wantFragments+" fragments) free="+Runtime.getRuntime().freeMemory()+" total="+Runtime.getRuntime().totalMemory());

    int numWords = (length + 3) / 4;
    int wordsPerGroup = (numSurvivors * Lfield);
    int numGroups = (numWords + (wordsPerGroup - 1)) / wordsPerGroup;
    int wordsPerFragment = numGroups * Lfield;
    int buffer[] = new int[numFragments * Lfield];
    Fragment frag[] = new Fragment[numFragments];

    for (int i = 0; i < numFragments; i++) {
      if (generateFragment[i]) {
        frag[i] = new Fragment(wordsPerFragment * 4);
      } else {
        frag[i] = null;
      }
    }

    //System.outt.println(bytes.length+" bytes => "+numFragments+" fragments with "+wordsPerFragment+" words ("+numGroups+" groups)");

    for (int g = 0; g < numGroups; g++) {
      int offset = g * wordsPerGroup * 4;
      int wordsHere = Math.min((length - offset + 3) / 4, wordsPerGroup);

      Arrays.fill(buffer, 0);
      for (int i = 0; i < wordsHere; i++) {
        byte b0 = (offset + 4 * i + 0 < length) ? bytes[offset + 4 * i + 0] : 0;
        byte b1 = (offset + 4 * i + 1 < length) ? bytes[offset + 4 * i + 1] : 0;
        byte b2 = (offset + 4 * i + 2 < length) ? bytes[offset + 4 * i + 2] : 0;
        byte b3 = (offset + 4 * i + 3 < length) ? bytes[offset + 4 * i + 3] : 0;
        buffer[i] = (b0 << 24) | ((b1 << 16) & 0xFF0000) | ((b2 << 8) & 0xFF00) | (b3 & 0xFF);
      }

      encodeChunk(buffer);

      for (int i = 0; i < numFragments; i++) {
        if (generateFragment[i]) {
          for (int j = 0; j < Lfield; j++) {
            frag[i].payload[4 * (g * Lfield + j) + 0] = (byte) ((buffer[i * Lfield + j]) & 0xFF);
            frag[i].payload[4 * (g * Lfield + j) + 1] = (byte) ((buffer[i * Lfield + j] >> 8) & 0xFF);
            frag[i].payload[4 * (g * Lfield + j) + 2] = (byte) ((buffer[i * Lfield + j] >> 16) & 0xFF);
            frag[i].payload[4 * (g * Lfield + j) + 3] = (byte) ((buffer[i * Lfield + j] >> 24) & 0xFF);
          }
        }
      }
    }

    // System.out.println(Systemm.currentTimeMillis()+" XXX after encode("+bytes.length+" bytes, "+wantFragments+" fragments) free="+Runtime.getRuntime().freeMemory()+" total="+Runtime.getRuntime().totalMemory());

    return frag;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param buffer DESCRIBE THE PARAMETER
   * @param nExtra DESCRIBE THE PARAMETER
   * @param RowInd DESCRIBE THE PARAMETER
   * @param haveFragment DESCRIBE THE PARAMETER
   * @param InvMat DESCRIBE THE PARAMETER
   * @param ColInd DESCRIBE THE PARAMETER
   */
  protected void decodeChunk(int[] buffer, int nExtra, int[] RowInd, boolean[] haveFragment, long[][] InvMat, int[] ColInd) {

    // *** Second last step ***

    int M[] = new int[(numFragments - numSurvivors) * Lfield];
    for (int i = 0; i < nExtra; i++) {
      for (int j = 0; j < Lfield; j++) {
        M[i * Lfield + j] = buffer[(RowInd[i] + numSurvivors) * Lfield + j];
      }
    }

    for (int row = 0; row < nExtra; row++) {
      for (int col = 0; col < numSurvivors; col++) {
        if (haveFragment[col]) {
          int exponent = (MultField - FieldEltToExp[RowInd[row] ^ col ^ (1 << (Lfield - 1))]) % MultField;
          for (int row_bit = 0; row_bit < Lfield; row_bit++) {
            for (int col_bit = 0; col_bit < Lfield; col_bit++) {
              if ((ExpToFieldElt[exponent + row_bit] & (1 << col_bit)) != 0) {
                M[row_bit + row * Lfield] ^= buffer[col_bit + col * Lfield];
              }
            }
          }
        }
      }
    }

    // *** Last step ***

    for (int row = 0; row < nExtra; row++) {
      for (int col = 0; col < nExtra; col++) {
        int exponent = (int) InvMat[row][col];
        for (int row_bit = 0; row_bit < Lfield; row_bit++) {
          for (int col_bit = 0; col_bit < Lfield; col_bit++) {
            if ((ExpToFieldElt[exponent + row_bit] & (1 << col_bit)) != 0) {
              buffer[row_bit + ColInd[row] * Lfield] ^= M[col_bit + col * Lfield];
            }
          }
        }
      }
    }
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param frag DESCRIBE THE PARAMETER
   * @param endpoint DESCRIBE THE PARAMETER
   * @param pcd DESCRIBE THE PARAMETER
   * @return DESCRIBE THE RETURN VALUE
   */
  public PastContent decode(Fragment frag[], Endpoint endpoint, PastContentDeserializer pcd) {

    Fragment firstFrag = null;
    for (int i = 0; i < frag.length; i++) {
      if (frag[i] != null) {
        firstFrag = frag[i];
      }
    }

    // System.out.println(Systemm.currentTimeMillis()+" XXX before decode("+firstFrag.getPayload().length+" bytes per fragment) free="+Runtime.getRuntime().freeMemory()+" total="+Runtime.getRuntime().totalMemory());

    if (frag.length != numFragments) {
      return null;
    }

    int firstFragment = -1;
    for (int i = 0; (i < numFragments) && (firstFragment == -1); i++) {
      if (frag[i] != null) {
        firstFragment = i;
      }
    }

    int wordsPerFragment = (frag[firstFragment].payload.length + 3) / 4;
    int numGroups = wordsPerFragment / Lfield;

    boolean haveFragment[] = new boolean[numFragments];
    Arrays.fill(haveFragment, false);

    for (int i = 0; i < numFragments; i++) {
      if (frag[i] != null) {
        haveFragment[i] = true;
      }
    }

    int ColInd[] = new int[numSurvivors];
    int RowInd[] = new int[numFragments - numSurvivors];

    int nMissing = 0;

    int nExtra = 0;
    for (int i = 0; i < numSurvivors; i++) {
      if (!haveFragment[i]) {
        ColInd[nMissing++] = i;
      }
    }

    for (int i = 0; i < (numFragments - numSurvivors); i++) {
      if (haveFragment[numSurvivors + i]) {
        RowInd[nExtra++] = i;
      }
    }

    if (nMissing > nExtra) {
      return null;
    }

    if (nMissing < nExtra) {
      nExtra = nMissing;
    }

    int[] C;

    int[] D;

    int[] E;

    int[] F;
    C = new int[numFragments - numSurvivors];
    Arrays.fill(C, 0);
    D = new int[numFragments - numSurvivors];
    Arrays.fill(D, 0);
    E = new int[numFragments - numSurvivors];
    Arrays.fill(E, 0);
    F = new int[numFragments - numSurvivors];
    Arrays.fill(F, 0);

    for (int row = 0; row < nExtra; row++) {
      for (int col = 0; col < nExtra; col++) {
        if (col != row) {
          C[row] += FieldEltToExp[RowInd[row] ^ RowInd[col]];
          D[row] += FieldEltToExp[ColInd[row] ^ ColInd[col]];
        }

        E[row] += FieldEltToExp[RowInd[row] ^ ColInd[col] ^ (1 << (Lfield - 1))];
        F[col] += FieldEltToExp[RowInd[row] ^ ColInd[col] ^ (1 << (Lfield - 1))];
      }
    }

    long InvMat[][] = new long[nExtra][nExtra];

    for (int row = 0; row < nExtra; row++) {
      for (int col = 0; col < nExtra; col++) {
        InvMat[row][col] = E[col] + F[row] - C[col] - D[row] -
          FieldEltToExp[RowInd[col] ^ ColInd[row] ^ (1 << (Lfield - 1))];
        if (InvMat[row][col] >= 0) {
          InvMat[row][col] = InvMat[row][col] % MultField;
        } else {
          InvMat[row][col] = (MultField - (-InvMat[row][col] % MultField)) % MultField;
        }
      }
    }

    // *** Second last step ***

    byte[] bytes = new byte[numSurvivors * wordsPerFragment * 4];
    int[] buffer = new int[numFragments * Lfield];
    for (int g = 0; g < numGroups; g++) {
      Arrays.fill(buffer, 0);
      for (int i = 0; i < numFragments; i++) {
        if (haveFragment[i]) {
          for (int j = 0; j < Lfield; j++) {
            buffer[i * Lfield + j] =
              ((frag[i].payload[4 * (g * Lfield + j) + 0]) & 0x0000FF) +
              ((frag[i].payload[4 * (g * Lfield + j) + 1] << 8) & 0x00FF00) +
              ((frag[i].payload[4 * (g * Lfield + j) + 2] << 16) & 0xFF0000) +
              (frag[i].payload[4 * (g * Lfield + j) + 3] << 24);
          }
        }
      }

      decodeChunk(buffer, nExtra, RowInd, haveFragment, InvMat, ColInd);

      for (int i = 0; i < (numSurvivors * Lfield); i++) {
        bytes[4 * (g * (numSurvivors * Lfield) + i) + 0] = (byte) (buffer[i] >> 24);
        bytes[4 * (g * (numSurvivors * Lfield) + i) + 1] = (byte) ((buffer[i] >> 16) & 0xFF);
        bytes[4 * (g * (numSurvivors * Lfield) + i) + 2] = (byte) ((buffer[i] >> 8) & 0xFF);
        bytes[4 * (g * (numSurvivors * Lfield) + i) + 3] = (byte) ((buffer[i]) & 0xFF);
      }
    }

    try {
      return deserialize(bytes, endpoint, pcd);
//      SimpleInputBuffer sib = new SimpleInputBuffer(bytes);
//      short type = sib.readShort();
//      return pcd.deserializePastContent(sib, endpoint, type);

//      ByteArrayInputStream byteinput = new ByteArrayInputStream(bytes);
//      ObjectInputStream objectInput = new ObjectInputStream(byteinput);
//      // System.out.println(Systemm.currentTimeMillis()+" XXX after decode("+firstFrag.getPayload().length+" bytes per fragment) free="+Runtime.getRuntime().freeMemory()+" total="+Runtime.getRuntime().totalMemory());
//      return (Serializable) objectInput.readObject();
    } catch (IOException ioe) {
      if (logger.level <= Logger.WARNING) {
        logger.logException(
          "", ioe);
      }
    } catch (ClassNotFoundException cnfe) {
      if (logger.level <= Logger.WARNING) {
        logger.logException(
          "", cnfe);
      }
    } catch (IllegalStateException ise) {
      if (logger.level <= Logger.WARNING) {
        logger.logException(
          "", ise);
      }
    }

    return null;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param bytes DESCRIBE THE PARAMETER
   * @param endpoint DESCRIBE THE PARAMETER
   * @param pcd DESCRIBE THE PARAMETER
   * @return DESCRIBE THE RETURN VALUE
   * @exception IOException DESCRIBE THE EXCEPTION
   * @exception ClassNotFoundException DESCRIBE THE EXCEPTION
   */
  protected PastContent deserialize(byte[] bytes, Endpoint endpoint, PastContentDeserializer pcd) throws IOException, ClassNotFoundException {
//  ByteArrayInputStream byteinput = new ByteArrayInputStream(bytes);
//  ObjectInputStream objectInput = new ObjectInputStream(byteinput);
//  // System.out.println(Systemm.currentTimeMillis()+" XXX after decode("+firstFrag.getPayload().length+" bytes per fragment) free="+Runtime.getRuntime().freeMemory()+" total="+Runtime.getRuntime().totalMemory());
//  return (Serializable) objectInput.readObject();

    SimpleInputBuffer sib = new SimpleInputBuffer(bytes);
    short type = sib.readShort();
    return pcd.deserializePastContent(sib, endpoint, type);
  }

  /**
   * DESCRIBE THE METHOD
   */
  protected void initElt() {
    final int polymask[] = {
      0x0000, 0x0003, 0x0007, 0x000B, 0x0013, 0x0025, 0x0043, 0x0083,
      0x011D, 0x0211, 0x0409, 0x0805, 0x1053, 0x201B, 0x402B, 0x8003
      };

    ExpToFieldElt = new int[MultField + Lfield];

    ExpToFieldElt[0] = 1;
    for (int i = 1; i < MultField + Lfield - 1; i++) {
      ExpToFieldElt[i] = ExpToFieldElt[i - 1] << 1;
      if ((ExpToFieldElt[i] & (1 << Lfield)) != 0) {
        ExpToFieldElt[i] ^= polymask[Lfield];
      }
    }

    /*
     *  This is the inverter for the previous field. Note that 0
     *  is not invertible!
     */
    FieldEltToExp = new int[MultField + 1];

    FieldEltToExp[0] = -1;
    for (int i = 0; i < MultField; i++) {
      FieldEltToExp[ExpToFieldElt[i]] = i;
    }
  }

//  public static void main(String args[]) {
//    Environment env = new Environment();
//    RandomSource rng = env.getRandomSource();
//    ErasureCodec codec = new ErasureCodec(48, 5, env);
//    Serializable s = new String("Habe Mut, Dich Deines eigenen Verstandes zu bedienen! Aufklaerung ist der Ausgang aus Deiner selbstverschuldeten Unmuendigkeit!");
//
//    System.out.println("Encoding...");
//
//    boolean generateFragment[] = new boolean[48];
//    Arrays.fill(generateFragment, true);
//
//    Fragment frag[] = codec.encodeObject(s, generateFragment);
//
//    Fragment frag2[] = new Fragment[48];
//    frag2[9] = frag[9];
//    frag2[11] = frag[11];
//    frag2[12] = frag[12];
//    frag2[17] = frag[17];
//    frag2[33] = frag[33];
//
//    System.out.println("Decoding...");
//    Object d = codec.decode(frag2);
//
//    System.out.println(d);
//
//    for (int i=0; i<100; i++) {
//      int[] theObject = new int[rng.nextInt(100000)];
//      for (int j=0; j<theObject.length; j++)
//        theObject[j] = rng.nextInt(2000000000);
//
//      System.out.println("#"+i+": "+(theObject.length*4)+" bytes");
//
//      int fid[] = new int[5];
//      for (int j=0; j<5; j++) {
//        boolean again = true;
//        while (again) {
//          fid[j] = rng.nextInt(48);
//          again = false;
//          for (int k=0; k<j; k++)
//            if (fid[k] == fid[j])
//              again = true;
//        }
//      }
//
//      generateFragment = new boolean[48];
//      for (int j=0; j<48; j++)
//        generateFragment[j] = false;
//      for (int j=0; j<5; j++)
//        generateFragment[fid[j]] = true;
//
//      Fragment xf[] = codec.encodeObject(theObject, generateFragment);
//
//      Fragment yf[] = new Fragment[48];
//      for (int j=0; j<5; j++)
//        yf[fid[j]] = xf[fid[j]];
//
//      int[] decodedObject = (int[]) codec.decode(yf);
//
//      for (int j=0; j<theObject.length; j++) {
//        if (decodedObject[j] != theObject[j]) {
//          System.err.println("FAIL: Run #"+i+" offset "+j+" decoded="+decodedObject[j]+" original="+theObject[j]);
//          System.exit(1);
//        }
//      }
//    }
//
//    System.out.println("PASS");
//  }
}
