/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.commons.compress.harmony.pack200;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.stream.IntStream;
  
  /**
   * Abstract superclass for a set of bands
   */
  public abstract class BandSet {
  
      /**
       * Results obtained by trying different Codecs to encode a band
       */
      public class BandAnalysisResults {
  
          // The number of Codecs tried so far
          private int numCodecsTried;
  
          // The number of bytes saved by using betterCodec instead of the default codec
          private int saved;
  
          // Extra metadata to pass to the segment header (to be appended to the
          // band_headers band)
          private int[] extraMetadata;
  
          // The results of encoding the band with betterCodec
          private byte[] encodedBand;
  
          // The best Codec found so far, or should be null if the default is the
          // best so far
          private Codec betterCodec;
  
          /**
           * Constructs a new instance.
           */
          public BandAnalysisResults() {
              // empty
          }
  
      }
  
      /**
       * BandData represents information about a band, for example largest value etc and is used in the heuristics that calculate whether an alternative Codec
       * could make the encoded band smaller.
       */
      public class BandData {
  
          private final int[] band;
          private int smallest = Integer.MAX_VALUE;
          private int largest = Integer.MIN_VALUE;
          private int smallestDelta;
          private int largestDelta;
  
          private int deltaIsAscending;
          private int smallDeltaCount;
  
          private double averageAbsoluteDelta;
          private double averageAbsoluteValue;
  
          private Map<Integer, Integer> distinctValues;
  
          /**
           * Constructs a new instance of BandData. The band is then analyzed.
           *
           * @param band the band of integers
           */
          public BandData(final int[] band) {
              this.band = band;
              final Integer one = Integer.valueOf(1);
              for (int i = 0; i < band.length; i++) {
                  if (band[i] < smallest) {
                      smallest = band[i];
                  }
                  if (band[i] > largest) {
                      largest = band[i];
                 }
                 if (i != 0) {
                     final int delta = band[i] - band[i - 1];
                     if (delta < smallestDelta) {
                         smallestDelta = delta;
                     }
                     if (delta > largestDelta) {
                         largestDelta = delta;
                     }
                     if (delta >= 0) {
                         deltaIsAscending++;
                     }
                     averageAbsoluteDelta += (double) Math.abs(delta) / (double) (band.length - 1);
                     if (Math.abs(delta) < 256) {
                         smallDeltaCount++;
                     }
                 } else {
                     smallestDelta = band[0];
                     largestDelta = band[0];
                 }
                 averageAbsoluteValue += (double) Math.abs(band[i]) / (double) band.length;
                 if (effort > 3) { // do calculations needed to consider population codec
                     if (distinctValues == null) {
                         distinctValues = new HashMap<>();
                     }
                     final Integer value = Integer.valueOf(band[i]);
                     Integer count = distinctValues.get(value);
                     if (count == null) {
                         count = one;
                     } else {
                         count = Integer.valueOf(count.intValue() + 1);
                     }
                     distinctValues.put(value, count);
                 }
             }
         }
 
         /**
          * Returns true if any band elements are negative.
          *
          * @return true if any band elements are negative.
          */
         public boolean anyNegatives() {
             return smallest < 0;
         }
 
         /**
          * Returns true if the band deltas are mainly positive (heuristic).
          *
          * @return true if the band deltas are mainly positive (heuristic).
          */
         public boolean mainlyPositiveDeltas() {
             // Note: the value below has been tuned - please test carefully if changing it
             return (float) deltaIsAscending / (float) band.length > 0.95F;
         }
 
         /**
          * Returns true if the deltas between adjacent band elements are mainly small (heuristic).
          *
          * @return true if the deltas between adjacent band elements are mainly small (heuristic).
          */
         public boolean mainlySmallDeltas() {
             // Note: the value below has been tuned - please test carefully if changing it
             return (float) smallDeltaCount / (float) band.length > 0.7F;
         }
 
         /**
          * Returns the total number of distinct values found in the band.
          *
          * @return the total number of distinct values found in the band.
          */
         public int numDistinctValues() {
             if (distinctValues == null) {
                 return band.length;
             }
             return distinctValues.size();
         }
 
         /**
          * Returns true if the band is well correlated (i.e. would be suitable for a delta encoding) (heuristic).
          *
          * @return true if the band is well correlated (i.e. would be suitable for a delta encoding) (heuristic).
          */
         public boolean wellCorrelated() {
             // Note: the value below has been tuned - please test carefully if changing it
             return averageAbsoluteDelta * 3.1 < averageAbsoluteValue;
         }
 
     }
 
     private static final byte[] EMPTY_BYTE_ARRAY = {};
 
     // Minimum size of band for each effort level where we consider alternative codecs
     // Note: these values have been tuned - please test carefully if changing them
     private static final int[] effortThresholds = { 0, 0, 1000, 500, 100, 100, 100, 100, 100, 0 };
 
     protected final SegmentHeader segmentHeader;
     final int effort;
 
     private long[] canonicalLargest;
 
     private long[] canonicalSmallest;
 
     /**
      * Constructs a new BandSet.
      *
      * @param effort the packing effort to be used (must be 1-9)
      * @param header the segment header
      */
     public BandSet(final int effort, final SegmentHeader header) {
         this.effort = effort;
         this.segmentHeader = header;
     }
 
     private BandAnalysisResults analyseBand(final String name, final int[] band, final BHSDCodec defaultCodec) throws Pack200Exception {
 
         final BandAnalysisResults results = new BandAnalysisResults();
 
         if (canonicalLargest == null) {
             canonicalLargest = new long[116];
             canonicalSmallest = new long[116];
             for (int i = 1; i < canonicalLargest.length; i++) {
                 canonicalLargest[i] = CodecEncoding.getCanonicalCodec(i).largest();
                 canonicalSmallest[i] = CodecEncoding.getCanonicalCodec(i).smallest();
             }
         }
         final BandData bandData = new BandData(band);
 
         // Check that there is a reasonable saving to be made
         final byte[] encoded = defaultCodec.encode(band);
         results.encodedBand = encoded;
 
         // Note: these values have been tuned - please test carefully if changing them
         if (encoded.length <= band.length + 23 - 2 * effort) { // TODO: tweak
             return results;
         }
 
         // Check if we can use BYTE1 as that's a 1:1 mapping if we can
         if (!bandData.anyNegatives() && bandData.largest <= Codec.BYTE1.largest()) {
             results.encodedBand = Codec.BYTE1.encode(band);
             results.betterCodec = Codec.BYTE1;
             return results;
         }
 
         // Consider a population codec (but can't be nested)
         if (effort > 3 && !name.equals("POPULATION")) {
             final int numDistinctValues = bandData.numDistinctValues();
             final float distinctValuesAsProportion = (float) numDistinctValues / (float) band.length;
 
             // Note: these values have been tuned - please test carefully if changing them
             if (numDistinctValues < 100 || distinctValuesAsProportion < 0.02 || effort > 6 && distinctValuesAsProportion < 0.04) { // TODO: tweak
                 encodeWithPopulationCodec(band, defaultCodec, bandData, results);
                 if (timeToStop(results)) {
                     return results;
                 }
             }
         }
 
         final List<BHSDCodec[]> codecFamiliesToTry = new ArrayList<>();
 
         // See if the deltas are mainly small increments
         if (bandData.mainlyPositiveDeltas() && bandData.mainlySmallDeltas()) {
             codecFamiliesToTry.add(CanonicalCodecFamilies.deltaUnsignedCodecs2);
         }
 
         if (bandData.wellCorrelated()) { // Try delta encodings
             if (bandData.mainlyPositiveDeltas()) {
                 codecFamiliesToTry.add(CanonicalCodecFamilies.deltaUnsignedCodecs1);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.deltaUnsignedCodecs3);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.deltaUnsignedCodecs4);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.deltaUnsignedCodecs5);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaUnsignedCodecs1);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaUnsignedCodecs3);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaUnsignedCodecs4);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaUnsignedCodecs5);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaUnsignedCodecs2);
             } else {
                 codecFamiliesToTry.add(CanonicalCodecFamilies.deltaSignedCodecs1);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.deltaSignedCodecs3);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.deltaSignedCodecs2);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.deltaSignedCodecs4);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.deltaSignedCodecs5);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaSignedCodecs1);
                 codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaSignedCodecs2);
             }
         } else if (bandData.anyNegatives()) {
             codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaSignedCodecs1);
             codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaSignedCodecs2);
             codecFamiliesToTry.add(CanonicalCodecFamilies.deltaSignedCodecs1);
             codecFamiliesToTry.add(CanonicalCodecFamilies.deltaSignedCodecs2);
             codecFamiliesToTry.add(CanonicalCodecFamilies.deltaSignedCodecs3);
             codecFamiliesToTry.add(CanonicalCodecFamilies.deltaSignedCodecs4);
             codecFamiliesToTry.add(CanonicalCodecFamilies.deltaSignedCodecs5);
         } else {
             codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaUnsignedCodecs1);
             codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaUnsignedCodecs3);
             codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaUnsignedCodecs4);
             codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaUnsignedCodecs5);
             codecFamiliesToTry.add(CanonicalCodecFamilies.nonDeltaUnsignedCodecs2);
             codecFamiliesToTry.add(CanonicalCodecFamilies.deltaUnsignedCodecs1);
             codecFamiliesToTry.add(CanonicalCodecFamilies.deltaUnsignedCodecs3);
             codecFamiliesToTry.add(CanonicalCodecFamilies.deltaUnsignedCodecs4);
             codecFamiliesToTry.add(CanonicalCodecFamilies.deltaUnsignedCodecs5);
         }
         for (final BHSDCodec[] family : codecFamiliesToTry) {
             tryCodecs(band, defaultCodec, bandData, results, encoded, family);
             if (timeToStop(results)) {
                 break;
             }
         }
 
         return results;
     }
 
     /**
      * Converts a list of ConstantPoolEntrys to an int[] array of their indices
      *
      * @param list conversion source.
      * @return conversion result.
      */
     protected int[] cpEntryListToArray(final List<? extends ConstantPoolEntry> list) {
         final int[] array = new int[list.size()];
         for (int i = 0; i < array.length; i++) {
             array[i] = list.get(i).getIndex();
             if (array[i] < 0) {
                 throw new IllegalArgumentException("Index should be > 0");
             }
         }
         return array;
     }
 
     /**
      * Converts a list of ConstantPoolEntrys or nulls to an int[] array of their indices +1 (or 0 for nulls)
      *
      * @param list conversion source.
      * @return conversion result.
      */
     protected int[] cpEntryOrNullListToArray(final List<? extends ConstantPoolEntry> list) {
         final int[] array = new int[list.size()];
         for (int j = 0; j < array.length; j++) {
             final ConstantPoolEntry cpEntry = list.get(j);
             array[j] = cpEntry == null ? 0 : cpEntry.getIndex() + 1;
             if (cpEntry != null && cpEntry.getIndex() < 0) {
                 throw new IllegalArgumentException("Index should be > 0");
             }
         }
         return array;
     }
 
     /**
      * Encode a band of integers. The default codec may be used, but other Codecs are considered if effort is greater than 1.
      *
      * @param name         name of the band (used for debugging)
      * @param ints         the band
      * @param defaultCodec the default Codec
      * @return the encoded band
      * @throws Pack200Exception If a Pack200 semantic error occurs.
      */
     public byte[] encodeBandInt(final String name, final int[] ints, final BHSDCodec defaultCodec) throws Pack200Exception {
         byte[] encodedBand = null;
         // Useful for debugging
 //        if (ints.length > 0) {
 //            System.out.println("encoding " + name + " " + ints.length);
 //        }
         if (effort > 1 && ints.length >= effortThresholds[effort]) {
             final BandAnalysisResults results = analyseBand(name, ints, defaultCodec);
             final Codec betterCodec = results.betterCodec;
             encodedBand = results.encodedBand;
             if (betterCodec != null) {
                 if (betterCodec instanceof BHSDCodec) {
                     final int[] specifierBand = CodecEncoding.getSpecifier(betterCodec, defaultCodec);
                     int specifier = specifierBand[0];
                     if (specifierBand.length > 1) {
                         for (int i = 1; i < specifierBand.length; i++) {
                             segmentHeader.appendBandCodingSpecifier(specifierBand[i]);
                         }
                     }
                     if (defaultCodec.isSigned()) {
                         specifier = -1 - specifier;
                     } else {
                         specifier += defaultCodec.getL();
                     }
                     final byte[] specifierEncoded = defaultCodec.encode(new int[] { specifier });
                     final byte[] band = new byte[specifierEncoded.length + encodedBand.length];
                     System.arraycopy(specifierEncoded, 0, band, 0, specifierEncoded.length);
                     System.arraycopy(encodedBand, 0, band, specifierEncoded.length, encodedBand.length);
                     return band;
                 }
                 if (betterCodec instanceof PopulationCodec) {
                     IntStream.of(results.extraMetadata).forEach(segmentHeader::appendBandCodingSpecifier);
                     return encodedBand;
                 }
                 if (betterCodec instanceof RunCodec) {
                     // TODO?
                 }
             }
         }
 
         // If we get here then we've decided to use the default codec.
         if (ints.length > 0) {
             if (encodedBand == null) {
                 encodedBand = defaultCodec.encode(ints);
             }
             final int first = ints[0];
             if (defaultCodec.getB() != 1) {
                 if (defaultCodec.isSigned() && first >= -256 && first <= -1) {
                     final int specifier = -1 - CodecEncoding.getSpecifierForDefaultCodec(defaultCodec);
                     final byte[] specifierEncoded = defaultCodec.encode(new int[] { specifier });
                     final byte[] band = new byte[specifierEncoded.length + encodedBand.length];
                     System.arraycopy(specifierEncoded, 0, band, 0, specifierEncoded.length);
                     System.arraycopy(encodedBand, 0, band, specifierEncoded.length, encodedBand.length);
                     return band;
                 }
                 if (!defaultCodec.isSigned() && first >= defaultCodec.getL() && first <= defaultCodec.getL() + 255) {
                     final int specifier = CodecEncoding.getSpecifierForDefaultCodec(defaultCodec) + defaultCodec.getL();
                     final byte[] specifierEncoded = defaultCodec.encode(new int[] { specifier });
                     final byte[] band = new byte[specifierEncoded.length + encodedBand.length];
                     System.arraycopy(specifierEncoded, 0, band, 0, specifierEncoded.length);
                     System.arraycopy(encodedBand, 0, band, specifierEncoded.length, encodedBand.length);
                     return band;
                 }
             }
             return encodedBand;
         }
         return EMPTY_BYTE_ARRAY;
     }
 
     /**
      * Encode a band of longs (values are split into their high and low 32 bits and then encoded as two separate bands
      *
      * @param name        name of the band (for debugging purposes)
      * @param flags       the band
      * @param loCodec     Codec for the low 32-bits band
      * @param hiCodec     Codec for the high 32-bits band
      * @param haveHiFlags ignores the high band if true as all values would be zero
      * @return the encoded band
      * @throws Pack200Exception If a Pack200 semantic error occurs.
      */
     protected byte[] encodeFlags(final String name, final long[] flags, final BHSDCodec loCodec, final BHSDCodec hiCodec, final boolean haveHiFlags)
             throws Pack200Exception {
         if (!haveHiFlags) {
             final int[] loBits = new int[flags.length];
             Arrays.setAll(loBits, i -> (int) flags[i]);
             return encodeBandInt(name, loBits, loCodec);
         }
         final int[] hiBits = new int[flags.length];
         final int[] loBits = new int[flags.length];
         for (int i = 0; i < flags.length; i++) {
             final long l = flags[i];
             hiBits[i] = (int) (l >> 32);
             loBits[i] = (int) l;
         }
         final byte[] hi = encodeBandInt(name, hiBits, hiCodec);
         final byte[] lo = encodeBandInt(name, loBits, loCodec);
         final byte[] total = new byte[hi.length + lo.length];
         System.arraycopy(hi, 0, total, 0, hi.length);
         System.arraycopy(lo, 0, total, hi.length + 1, lo.length);
         return total;
     }
 
 // This could be useful if further enhancements are done but is not currently used
 //
 //    private void encodeWithRunCodec(String name, int[] band, int index,
 //            BHSDCodec defaultCodec, BandData bandData,
 //            BandAnalysisResults results) throws Pack200Exception {
 //        int[] firstBand = new int[index];
 //        int[] secondBand = new int[band.length - index];
 //        System.arraycopy(band, 0, firstBand, 0, index);
 //        System.arraycopy(band, index, secondBand, 0, secondBand.length);
 //        BandAnalysisResults firstResults = analyseBand(name + "A", firstBand, defaultCodec);
 //        BandAnalysisResults secondResults = analyseBand(name + "B", secondBand, defaultCodec);
 //        int specifier = 117;
 //        byte[] specifierEncoded = defaultCodec.encode(new int[] {specifier});
 //        int totalLength = firstResults.encodedBand.length + secondResults.encodedBand.length + specifierEncoded.length + 4; // TODO actual
 //        if (totalLength < results.encodedBand.length) {
 //            System.out.println("using run codec");
 //            results.saved += results.encodedBand.length - totalLength;
 //            byte[] encodedBand = new byte[specifierEncoded.length + firstResults.encodedBand.length + secondResults.encodedBand.length];
 //            System.arraycopy(specifierEncoded, 0, encodedBand, 0, specifierEncoded.length);
 //            System.arraycopy(firstResults.encodedBand, 0, encodedBand, specifierEncoded.length, firstResults.encodedBand.length);
 //            System.arraycopy(secondResults.encodedBand, 0, encodedBand, specifierEncoded.length + firstResults.encodedBand.length,
 //              secondResults.encodedBand.length);
 //            results.encodedBand = encodedBand;
 //            results.betterCodec = new RunCodec(index, firstResults.betterCodec, secondResults.betterCodec);
 //        }
 //    }
 
     protected byte[] encodeFlags(final String name, final long[][] flags, final BHSDCodec loCodec, final BHSDCodec hiCodec, final boolean haveHiFlags)
             throws Pack200Exception {
         return encodeFlags(name, flatten(flags), loCodec, hiCodec, haveHiFlags);
     }
 
     /**
      * Encodes a single value with the given Codec.
      *
      * @param value the value to encode.
      * @param codec Codec to use.
      * @return the encoded value.
      * @throws Pack200Exception If a Pack200 semantic error occurs.
      */
     public byte[] encodeScalar(final int value, final BHSDCodec codec) throws Pack200Exception {
         return codec.encode(value);
     }
 
     /**
      * Encode a band without considering other Codecs.
      *
      * @param band  the band.
      * @param codec the Codec to use.
      * @return the encoded band.
      * @throws Pack200Exception If a Pack200 semantic error occurs.
      */
     public byte[] encodeScalar(final int[] band, final BHSDCodec codec) throws Pack200Exception {
         return codec.encode(band);
     }
 
     private void encodeWithPopulationCodec(final int[] band, final BHSDCodec defaultCodec, final BandData bandData, final BandAnalysisResults results)
             throws Pack200Exception {
         results.numCodecsTried += 3; // quite a bit more effort to try this codec
         final Map<Integer, Integer> distinctValues = bandData.distinctValues;
 
         final List<Integer> favored = new ArrayList<>();
         distinctValues.forEach((k, v) -> {
             if (v.intValue() > 2 || distinctValues.size() < 256) { // TODO: tweak
                 favored.add(k);
             }
         });
 
         // Sort the favored list with the most commonly occurring first
         if (distinctValues.size() > 255) {
             favored.sort((arg0, arg1) -> distinctValues.get(arg1).compareTo(distinctValues.get(arg0)));
         }
 
         final Map<Integer, Integer> favoredToIndex = new HashMap<>();
         for (int i = 0; i < favored.size(); i++) {
             favoredToIndex.put(favored.get(i), Integer.valueOf(i));
         }
 
         final IntList unfavoured = new IntList();
         final int[] tokens = new int[band.length];
         for (int i = 0; i < band.length; i++) {
             final Integer favouredIndex = favoredToIndex.get(Integer.valueOf(band[i]));
             if (favouredIndex == null) {
                 tokens[i] = 0;
                 unfavoured.add(band[i]);
             } else {
                 tokens[i] = favouredIndex.intValue() + 1;
             }
         }
         favored.add(favored.get(favored.size() - 1)); // repeat last value
         final int[] favouredBand = integerListToArray(favored);
         final int[] unfavouredBand = unfavoured.toArray();
 
         // Analyse the three bands to get the best codec
         final BandAnalysisResults favouredResults = analyseBand("POPULATION", favouredBand, defaultCodec);
         final BandAnalysisResults unfavouredResults = analyseBand("POPULATION", unfavouredBand, defaultCodec);
 
         int tdefL = 0;
         int l = 0;
         Codec tokenCodec = null;
         final byte[] tokensEncoded;
         final int k = favored.size() - 1;
         if (k < 256) {
             tdefL = 1;
             tokensEncoded = Codec.BYTE1.encode(tokens);
         } else {
             final BandAnalysisResults tokenResults = analyseBand("POPULATION", tokens, defaultCodec);
             tokenCodec = tokenResults.betterCodec;
             tokensEncoded = tokenResults.encodedBand;
             if (tokenCodec == null) {
                 tokenCodec = defaultCodec;
             }
             l = ((BHSDCodec) tokenCodec).getL();
             final int h = ((BHSDCodec) tokenCodec).getH();
             final int s = ((BHSDCodec) tokenCodec).getS();
             final int b = ((BHSDCodec) tokenCodec).getB();
             final int d = ((BHSDCodec) tokenCodec).isDelta() ? 1 : 0;
             if (s == 0 && d == 0) {
                 boolean canUseTDefL = true;
                 if (b > 1) {
                     final BHSDCodec oneLowerB = new BHSDCodec(b - 1, h);
                     if (oneLowerB.largest() >= k) {
                         canUseTDefL = false;
                     }
                 }
                 if (canUseTDefL) {
                     switch (l) {
                     case 4:
                         tdefL = 1;
                         break;
                     case 8:
                         tdefL = 2;
                         break;
                     case 16:
                         tdefL = 3;
                         break;
                     case 32:
                         tdefL = 4;
                         break;
                     case 64:
                         tdefL = 5;
                         break;
                     case 128:
                         tdefL = 6;
                         break;
                     case 192:
                         tdefL = 7;
                         break;
                     case 224:
                         tdefL = 8;
                         break;
                     case 240:
                         tdefL = 9;
                         break;
                     case 248:
                         tdefL = 10;
                         break;
                     case 252:
                         tdefL = 11;
                         break;
                     }
                 }
             }
         }
 
         final byte[] favouredEncoded = favouredResults.encodedBand;
         final byte[] unfavouredEncoded = unfavouredResults.encodedBand;
         final Codec favouredCodec = favouredResults.betterCodec;
         final Codec unfavouredCodec = unfavouredResults.betterCodec;
 
         int specifier = 141 + (favouredCodec == null ? 1 : 0) + 4 * tdefL + (unfavouredCodec == null ? 2 : 0);
         final IntList extraBandMetadata = new IntList(3);
         if (favouredCodec != null) {
             IntStream.of(CodecEncoding.getSpecifier(favouredCodec, null)).forEach(extraBandMetadata::add);
         }
         if (tdefL == 0) {
             IntStream.of(CodecEncoding.getSpecifier(tokenCodec, null)).forEach(extraBandMetadata::add);
         }
         if (unfavouredCodec != null) {
             IntStream.of(CodecEncoding.getSpecifier(unfavouredCodec, null)).forEach(extraBandMetadata::add);
         }
         final int[] extraMetadata = extraBandMetadata.toArray();
         final byte[] extraMetadataEncoded = Codec.UNSIGNED5.encode(extraMetadata);
         if (defaultCodec.isSigned()) {
             specifier = -1 - specifier;
         } else {
             specifier += defaultCodec.getL();
         }
         final byte[] firstValueEncoded = defaultCodec.encode(new int[] { specifier });
         final int totalBandLength = firstValueEncoded.length + favouredEncoded.length + tokensEncoded.length + unfavouredEncoded.length;
 
         if (totalBandLength + extraMetadataEncoded.length < results.encodedBand.length) {
             results.saved += results.encodedBand.length - (totalBandLength + extraMetadataEncoded.length);
             final byte[] encodedBand = new byte[totalBandLength];
             System.arraycopy(firstValueEncoded, 0, encodedBand, 0, firstValueEncoded.length);
             System.arraycopy(favouredEncoded, 0, encodedBand, firstValueEncoded.length, favouredEncoded.length);
             System.arraycopy(tokensEncoded, 0, encodedBand, firstValueEncoded.length + favouredEncoded.length, tokensEncoded.length);
             System.arraycopy(unfavouredEncoded, 0, encodedBand, firstValueEncoded.length + favouredEncoded.length + tokensEncoded.length,
                     unfavouredEncoded.length);
             results.encodedBand = encodedBand;
             results.extraMetadata = extraMetadata;
             if (l != 0) {
                 results.betterCodec = new PopulationCodec(favouredCodec, l, unfavouredCodec);
             } else {
                 results.betterCodec = new PopulationCodec(favouredCodec, tokenCodec, unfavouredCodec);
             }
         }
     }
 
     /*
      * Flatten a 2-dimension array into a 1-dimension array
      */
     private long[] flatten(final long[][] flags) {
         int totalSize = 0;
         for (final long[] flag : flags) {
             totalSize += flag.length;
         }
         final long[] flatArray = new long[totalSize];
         int index = 0;
         for (final long[] flag : flags) {
             for (final long element : flag) {
                 flatArray[index] = element;
                 index++;
             }
         }
         return flatArray;
     }
 
     /**
      * Converts a list of Integers to an int[] array.
      *
      * @param integerList conversion source.
      * @return conversion result.
      */
     protected int[] integerListToArray(final List<Integer> integerList) {
         return integerList.stream().mapToInt(Integer::intValue).toArray();
     }
 
     /**
      * Converts a list of Longs to an long[] array.
      *
      * @param longList conversion source.
      * @return conversion result.
      */
     protected long[] longListToArray(final List<Long> longList) {
         return longList.stream().mapToLong(Long::longValue).toArray();
     }
 
     /**
      * Writes the packed set of bands to the given output stream.
      *
      * @param out TODO
      * @throws IOException      If an I/O error occurs.
      * @throws Pack200Exception If a Pack200 semantic error occurs.
      */
     public abstract void pack(OutputStream out) throws IOException, Pack200Exception;
 
     private boolean timeToStop(final BandAnalysisResults results) {
         // if tried more than effort number of codecs for this band then return
         // Note: these values have been tuned - please test carefully if changing them
         if (effort > 6) {
             return results.numCodecsTried >= effort * 2;
         }
         return results.numCodecsTried >= effort;
         // May want to also check how much we've saved if performance needs improving, for example saved more than effort*2 %
         // || (float) results.saved/(float) results.encodedBand.length > (float) effort * 2/100;
     }
 
     private void tryCodecs(final int[] band, final BHSDCodec defaultCodec, final BandData bandData, final BandAnalysisResults results, final byte[] encoded,
             final BHSDCodec[] potentialCodecs) throws Pack200Exception {
         for (final BHSDCodec potential : potentialCodecs) {
             if (potential.equals(defaultCodec)) {
                 return; // don't try codecs with greater cardinality in the same 'family' as the default codec as there
                         // won't be any savings
             }
             if (potential.isDelta()) {
                 if (potential.largest() >= bandData.largestDelta && potential.smallest() <= bandData.smallestDelta && potential.largest() >= bandData.largest
                         && potential.smallest() <= bandData.smallest) {
                     // TODO: can represent some negative deltas with overflow
                     final byte[] encoded2 = potential.encode(band);
                     results.numCodecsTried++;
                     final byte[] specifierEncoded = defaultCodec.encode(CodecEncoding.getSpecifier(potential, null));
                     final int saved = encoded.length - encoded2.length - specifierEncoded.length;
                     if (saved > results.saved) {
                         results.betterCodec = potential;
                         results.encodedBand = encoded2;
                         results.saved = saved;
                     }
                 }
             } else if (potential.largest() >= bandData.largest && potential.smallest() <= bandData.smallest) {
                 final byte[] encoded2 = potential.encode(band);
                 results.numCodecsTried++;
                 final byte[] specifierEncoded = defaultCodec.encode(CodecEncoding.getSpecifier(potential, null));
                 final int saved = encoded.length - encoded2.length - specifierEncoded.length;
                 if (saved > results.saved) {
                     results.betterCodec = potential;
                     results.encodedBand = encoded2;
                     results.saved = saved;
                 }
             }
             if (timeToStop(results)) {
                 return;
             }
         }
     }
 
 }