// -*- mode:c++; tab-width:2; indent-tabs-mode:nil; c-basic-offset:2 -*-
/*
 * Copyright 2010, 2012 ZXing authors All rights reserved.
 *
 * Licensed 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
 *
 *      http://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.
 */

#include <stdint.h>
#include <bigint/BigIntegerUtils.hh>
#include <zxing/FormatException.h>
#include <zxing/pdf417/decoder/DecodedBitStreamParser.h>
#include <zxing/common/DecoderResult.h>

using std::string;
using zxing::pdf417::DecodedBitStreamParser;
using zxing::ArrayRef;
using zxing::Ref;
using zxing::DecoderResult;
using zxing::String;

const int DecodedBitStreamParser::TEXT_COMPACTION_MODE_LATCH = 900;
const int DecodedBitStreamParser::BYTE_COMPACTION_MODE_LATCH = 901;
const int DecodedBitStreamParser::NUMERIC_COMPACTION_MODE_LATCH = 902;
const int DecodedBitStreamParser::BYTE_COMPACTION_MODE_LATCH_6 = 924;
const int DecodedBitStreamParser::BEGIN_MACRO_PDF417_CONTROL_BLOCK = 928;
const int DecodedBitStreamParser::BEGIN_MACRO_PDF417_OPTIONAL_FIELD = 923;
const int DecodedBitStreamParser::MACRO_PDF417_TERMINATOR = 922;
const int DecodedBitStreamParser::MODE_SHIFT_TO_BYTE_COMPACTION_MODE = 913;
const int DecodedBitStreamParser::MAX_NUMERIC_CODEWORDS = 15;

const int DecodedBitStreamParser::PL = 25;
const int DecodedBitStreamParser::LL = 27;
const int DecodedBitStreamParser::AS = 27;
const int DecodedBitStreamParser::ML = 28;
const int DecodedBitStreamParser::AL = 28;
const int DecodedBitStreamParser::PS = 29;
const int DecodedBitStreamParser::PAL = 29;

const int DecodedBitStreamParser::EXP900_SIZE = 16;

const char DecodedBitStreamParser::PUNCT_CHARS[] = {
  ';', '<', '>', '@', '[', '\\', '}', '_', '`', '~', '!',
  '\r', '\t', ',', ':', '\n', '-', '.', '$', '/', '"', '|', '*',
  '(', ')', '?', '{', '}', '\''};

const char DecodedBitStreamParser::MIXED_CHARS[] = {
  '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '&',
  '\r', '\t', ',', ':', '#', '-', '.', '$', '/', '+', '%', '*',
  '=', '^'};

ArrayRef<BigInteger> DecodedBitStreamParser::initEXP900() {
  ArrayRef<BigInteger> EXP900 (16);
  EXP900[0] = BigInteger(1);
  BigInteger nineHundred (900);
  EXP900[1] = nineHundred;
  for (int i = 2; i < EXP900->size(); i++) {
    EXP900[i] = EXP900[i - 1] * nineHundred;
  }
  return EXP900;
}

ArrayRef<BigInteger> DecodedBitStreamParser::EXP900 = initEXP900();

DecodedBitStreamParser::DecodedBitStreamParser(){}

/**
 * PDF417 main decoder.
 **/
Ref<DecoderResult> DecodedBitStreamParser::decode(ArrayRef<int> codewords)
{
  Ref<String> result (new String(100));
  // Get compaction mode
  int codeIndex = 1;
  int code = codewords[codeIndex++];
  while (codeIndex < codewords[0]) {
    switch (code) {
      case TEXT_COMPACTION_MODE_LATCH:
        codeIndex = textCompaction(codewords, codeIndex, result);
        break;
      case BYTE_COMPACTION_MODE_LATCH:
        codeIndex = byteCompaction(code, codewords, codeIndex, result);
        break;
      case NUMERIC_COMPACTION_MODE_LATCH:
        codeIndex = numericCompaction(codewords, codeIndex, result);
        break;
      case MODE_SHIFT_TO_BYTE_COMPACTION_MODE:
        codeIndex = byteCompaction(code, codewords, codeIndex, result);
        break;
      case BYTE_COMPACTION_MODE_LATCH_6:
        codeIndex = byteCompaction(code, codewords, codeIndex, result);
        break;
      default:
        // Default to text compaction. During testing numerous barcodes
        // appeared to be missing the starting mode. In these cases defaulting
        // to text compaction seems to work.
        codeIndex--;
        codeIndex = textCompaction(codewords, codeIndex, result);
        break;
    }
    if (codeIndex < codewords->size()) {
      code = codewords[codeIndex++];
    } else {
      throw FormatException();
    }
  }
  return Ref<DecoderResult>(new DecoderResult(ArrayRef<char>(), result));
}

/**
 * Text Compaction mode (see 5.4.1.5) permits all printable ASCII characters to be
 * encoded, i.e. values 32 - 126 inclusive in accordance with ISO/IEC 646 (IRV), as
 * well as selected control characters.
 *
 * @param codewords The array of codewords (data + error)
 * @param codeIndex The current index into the codeword array.
 * @param result    The decoded data is appended to the result.
 * @return The next index into the codeword array.
 */
int DecodedBitStreamParser::textCompaction(ArrayRef<int> codewords,
                                           int codeIndex,
                                           Ref<String> result) {
  // 2 character per codeword
  ArrayRef<int> textCompactionData (codewords[0] << 1);
  // Used to hold the byte compaction value if there is a mode shift
  ArrayRef<int> byteCompactionData (codewords[0] << 1);
  
  int index = 0;
  bool end = false;
  while ((codeIndex < codewords[0]) && !end) {
    int code = codewords[codeIndex++];
    if (code < TEXT_COMPACTION_MODE_LATCH) {
      textCompactionData[index] = code / 30;
      textCompactionData[index + 1] = code % 30;
      index += 2;
    } else {
      switch (code) {
        case TEXT_COMPACTION_MODE_LATCH:
          textCompactionData[index++] = TEXT_COMPACTION_MODE_LATCH;
          break;
        case BYTE_COMPACTION_MODE_LATCH:
          codeIndex--;
          end = true;
          break;
        case NUMERIC_COMPACTION_MODE_LATCH:
          codeIndex--;
          end = true;
          break;
        case MODE_SHIFT_TO_BYTE_COMPACTION_MODE:
          // The Mode Shift codeword 913 shall cause a temporary
          // switch from Text Compaction mode to Byte Compaction mode.
          // This switch shall be in effect for only the next codeword,
          // after which the mode shall revert to the prevailing sub-mode
          // of the Text Compaction mode. Codeword 913 is only available
          // in Text Compaction mode; its use is described in 5.4.2.4.
          textCompactionData[index] = MODE_SHIFT_TO_BYTE_COMPACTION_MODE;
          code = codewords[codeIndex++];
          byteCompactionData[index] = code; //Integer.toHexString(code);
          index++;
          break;
        case BYTE_COMPACTION_MODE_LATCH_6:
          codeIndex--;
          end = true;
          break;
      }
    }
  }
  decodeTextCompaction(textCompactionData, byteCompactionData, index, result);
  return codeIndex;
}

/**
 * The Text Compaction mode includes all the printable ASCII characters
 * (i.e. values from 32 to 126) and three ASCII control characters: HT or tab
 * (ASCII value 9), LF or line feed (ASCII value 10), and CR or carriage
 * return (ASCII value 13). The Text Compaction mode also includes various latch
 * and shift characters which are used exclusively within the mode. The Text
 * Compaction mode encodes up to 2 characters per codeword. The compaction rules
 * for converting data into PDF417 codewords are defined in 5.4.2.2. The sub-mode
 * switches are defined in 5.4.2.3.
 *
 * @param textCompactionData The text compaction data.
 * @param byteCompactionData The byte compaction data if there
 *                           was a mode shift.
 * @param length             The size of the text compaction and byte compaction data.
 * @param result             The decoded data is appended to the result.
 */
void DecodedBitStreamParser::decodeTextCompaction(ArrayRef<int> textCompactionData,
                                                  ArrayRef<int> byteCompactionData,
                                                  int length,
                                                  Ref<String> result)
{
  // Beginning from an initial state of the Alpha sub-mode
  // The default compaction mode for PDF417 in effect at the start of each symbol shall always be Text
  // Compaction mode Alpha sub-mode (uppercase alphabetic). A latch codeword from another mode to the Text
  // Compaction mode shall always switch to the Text Compaction Alpha sub-mode.
  Mode subMode = ALPHA;
  Mode priorToShiftMode = ALPHA;
  int i = 0;
  while (i < length) {
    int subModeCh = textCompactionData[i];
    char ch = 0;
    switch (subMode) {
      case ALPHA:
        // Alpha (uppercase alphabetic)
        if (subModeCh < 26) {
          // Upper case Alpha Character
          ch = (char) ('A' + subModeCh);
        } else {
          if (subModeCh == 26) {
            ch = ' ';
          } else if (subModeCh == LL) {
            subMode = LOWER;
          } else if (subModeCh == ML) {
            subMode = MIXED;
          } else if (subModeCh == PS) {
            // Shift to punctuation
            priorToShiftMode = subMode;
            subMode = PUNCT_SHIFT;
          } else if (subModeCh == MODE_SHIFT_TO_BYTE_COMPACTION_MODE) {
            result->append((char) byteCompactionData[i]);
          } else if (subModeCh == TEXT_COMPACTION_MODE_LATCH) {
            subMode = ALPHA;
          }
        }
        break;
      
      case LOWER:
        // Lower (lowercase alphabetic)
        if (subModeCh < 26) {
          ch = (char) ('a' + subModeCh);
        } else {
          if (subModeCh == 26) {
            ch = ' ';
          } else if (subModeCh == AS) {
            // Shift to alpha
            priorToShiftMode = subMode;
            subMode = ALPHA_SHIFT;
          } else if (subModeCh == ML) {
            subMode = MIXED;
          } else if (subModeCh == PS) {
            // Shift to punctuation
            priorToShiftMode = subMode;
            subMode = PUNCT_SHIFT;
          } else if (subModeCh == MODE_SHIFT_TO_BYTE_COMPACTION_MODE) {
            result->append((char) byteCompactionData[i]);
          } else if (subModeCh == TEXT_COMPACTION_MODE_LATCH) {
            subMode = ALPHA;
          }
        }
        break;
      
      case MIXED:
        // Mixed (numeric and some punctuation)
        if (subModeCh < PL) {
          ch = MIXED_CHARS[subModeCh];
        } else {
          if (subModeCh == PL) {
            subMode = PUNCT;
          } else if (subModeCh == 26) {
            ch = ' ';
          } else if (subModeCh == LL) {
            subMode = LOWER;
          } else if (subModeCh == AL) {
            subMode = ALPHA;
          } else if (subModeCh == PS) {
            // Shift to punctuation
            priorToShiftMode = subMode;
            subMode = PUNCT_SHIFT;
          } else if (subModeCh == MODE_SHIFT_TO_BYTE_COMPACTION_MODE) {
            result->append((char) byteCompactionData[i]);
          } else if (subModeCh == TEXT_COMPACTION_MODE_LATCH) {
            subMode = ALPHA;
          }
        }
        break;
      
      case PUNCT:
        // Punctuation
        if (subModeCh < PAL) {
          ch = PUNCT_CHARS[subModeCh];
        } else {
          if (subModeCh == PAL) {
            subMode = ALPHA;
          } else if (subModeCh == MODE_SHIFT_TO_BYTE_COMPACTION_MODE) {
            result->append((char) byteCompactionData[i]);
          } else if (subModeCh == TEXT_COMPACTION_MODE_LATCH) {
            subMode = ALPHA;
          }
        }
        break;
      
      case ALPHA_SHIFT:
        // Restore sub-mode
        subMode = priorToShiftMode;
        if (subModeCh < 26) {
          ch = (char) ('A' + subModeCh);
        } else {
          if (subModeCh == 26) {
            ch = ' ';
          } else {
            if (subModeCh == 26) {
              ch = ' ';
            } else if (subModeCh == TEXT_COMPACTION_MODE_LATCH) {
              subMode = ALPHA;
            }
          }
        }
        break;
      
      case PUNCT_SHIFT:
        // Restore sub-mode
        subMode = priorToShiftMode;
        if (subModeCh < PAL) {
          ch = PUNCT_CHARS[subModeCh];
        } else {
          if (subModeCh == PAL) {
            subMode = ALPHA;
            // 2012-11-27 added from recent java code:
          } else if (subModeCh == MODE_SHIFT_TO_BYTE_COMPACTION_MODE) {
            // PS before Shift-to-Byte is used as a padding character,
            // see 5.4.2.4 of the specification
            result->append((char) byteCompactionData[i]);
          } else if (subModeCh == TEXT_COMPACTION_MODE_LATCH) {
            subMode = ALPHA;
          }
        }
        break;
    }
    if (ch != 0) {
      // Append decoded character to result
      result->append(ch);
    }
    i++;
  }
}

/**
 * Byte Compaction mode (see 5.4.3) permits all 256 possible 8-bit byte values to be encoded.
 * This includes all ASCII characters value 0 to 127 inclusive and provides for international
 * character set support.
 *
 * @param mode      The byte compaction mode i.e. 901 or 924
 * @param codewords The array of codewords (data + error)
 * @param codeIndex The current index into the codeword array.
 * @param result    The decoded data is appended to the result.
 * @return The next index into the codeword array.
 */
int DecodedBitStreamParser::byteCompaction(int mode,
                                           ArrayRef<int> codewords,
                                           int codeIndex, Ref<String> result) {
  if (mode == BYTE_COMPACTION_MODE_LATCH) {
    // Total number of Byte Compaction characters to be encoded
    // is not a multiple of 6
    int count = 0;
    int64_t value = 0;
    ArrayRef<char> decodedData = new Array<char>(6);
    ArrayRef<int> byteCompactedCodewords = new Array<int>(6);
    bool end = false;
    int nextCode = codewords[codeIndex++];
    while ((codeIndex < codewords[0]) && !end) {
      byteCompactedCodewords[count++] = nextCode;
      // Base 900
      value = 900 * value + nextCode;
      nextCode = codewords[codeIndex++];
      // perhaps it should be ok to check only nextCode >= TEXT_COMPACTION_MODE_LATCH
      if (nextCode == TEXT_COMPACTION_MODE_LATCH ||
          nextCode == BYTE_COMPACTION_MODE_LATCH ||
          nextCode == NUMERIC_COMPACTION_MODE_LATCH ||
          nextCode == BYTE_COMPACTION_MODE_LATCH_6 ||
          nextCode == BEGIN_MACRO_PDF417_CONTROL_BLOCK ||
          nextCode == BEGIN_MACRO_PDF417_OPTIONAL_FIELD ||
          nextCode == MACRO_PDF417_TERMINATOR)
      {
        end = true;
      }
      else
      {
        if ((count%5 == 0) && (count > 0))
        {
          // Decode every 5 codewords
          // Convert to Base 256
          for (int j = 0; j < 6; ++j)
          {
            decodedData[5 - j] = (char) (value%256);
            value >>= 8;
          }
          result->append(string(&(decodedData->values()[0]), decodedData->values().size()));
          count = 0;
        }
      }
    }

    // if the end of all codewords is reached the last codeword needs to be added
    if (codeIndex == codewords[0] && nextCode < TEXT_COMPACTION_MODE_LATCH)
      byteCompactedCodewords[count++] = nextCode;

    // If Byte Compaction mode is invoked with codeword 901,
    // the last group of codewords is interpreted directly
    // as one byte per codeword, without compaction.
    for (int i = 0; i < count; i++)
    {
      result->append((char)byteCompactedCodewords[i]);
    }

  } else if (mode == BYTE_COMPACTION_MODE_LATCH_6) {
    // Total number of Byte Compaction characters to be encoded
    // is an integer multiple of 6
    int count = 0;
    int64_t value = 0;
    bool end = false;
    while (codeIndex < codewords[0] && !end) {
      int code = codewords[codeIndex++];
      if (code < TEXT_COMPACTION_MODE_LATCH) {
        count++;
        // Base 900
        value = 900 * value + code;
      } else {
        if (code == TEXT_COMPACTION_MODE_LATCH ||
            code == BYTE_COMPACTION_MODE_LATCH ||
            code == NUMERIC_COMPACTION_MODE_LATCH ||
            code == BYTE_COMPACTION_MODE_LATCH_6 ||
            code == BEGIN_MACRO_PDF417_CONTROL_BLOCK ||
            code == BEGIN_MACRO_PDF417_OPTIONAL_FIELD ||
            code == MACRO_PDF417_TERMINATOR) {
          codeIndex--;
          end = true;
        }
      }
      if ((count % 5 == 0) && (count > 0)) {
        // Decode every 5 codewords
        // Convert to Base 256
        ArrayRef<char> decodedData = new Array<char>(6);
        for (int j = 0; j < 6; ++j) {
          decodedData[5 - j] = (char) (value & 0xFF);
          value >>= 8;
        }
        result->append(string(&decodedData[0],6));
        // 2012-11-27 hfn after recent java code/fix by srowen
        count = 0;
      }
    }
  }
  return codeIndex;
}

/**
 * Numeric Compaction mode (see 5.4.4) permits efficient encoding of numeric data strings.
 *
 * @param codewords The array of codewords (data + error)
 * @param codeIndex The current index into the codeword array.
 * @param result    The decoded data is appended to the result.
 * @return The next index into the codeword array.
 */
int DecodedBitStreamParser::numericCompaction(ArrayRef<int> codewords,
                                              int codeIndex,
                                              Ref<String> result) {
  int count = 0;
  bool end = false;
  
  ArrayRef<int> numericCodewords = new Array<int>(MAX_NUMERIC_CODEWORDS);
  
  while (codeIndex < codewords[0] && !end) {
    int code = codewords[codeIndex++];
    if (codeIndex == codewords[0]) {
      end = true;
    }
    if (code < TEXT_COMPACTION_MODE_LATCH) {
      numericCodewords[count] = code;
      count++;
    } else {
      if (code == TEXT_COMPACTION_MODE_LATCH ||
          code == BYTE_COMPACTION_MODE_LATCH ||
          code == BYTE_COMPACTION_MODE_LATCH_6 ||
          code == BEGIN_MACRO_PDF417_CONTROL_BLOCK ||
          code == BEGIN_MACRO_PDF417_OPTIONAL_FIELD ||
          code == MACRO_PDF417_TERMINATOR) {
        codeIndex--;
        end = true;
      }
    }
    if (count % MAX_NUMERIC_CODEWORDS == 0 ||
        code == NUMERIC_COMPACTION_MODE_LATCH ||
        end) {
      // Re-invoking Numeric Compaction mode (by using codeword 902
      // while in Numeric Compaction mode) serves  to terminate the
      // current Numeric Compaction mode grouping as described in 5.4.4.2,
      // and then to start a new one grouping.
      Ref<String> s = decodeBase900toBase10(numericCodewords, count);
      result->append(s->getText());
      count = 0;
    }
  }
  return codeIndex;
}

/**
 * Convert a list of Numeric Compacted codewords from Base 900 to Base 10.
 *
 * @param codewords The array of codewords
 * @param count     The number of codewords
 * @return The decoded string representing the Numeric data.
 */
/*
  EXAMPLE
  Encode the fifteen digit numeric string 000213298174000
  Prefix the numeric string with a 1 and set the initial value of
  t = 1 000 213 298 174 000
  Calculate codeword 0
  d0 = 1 000 213 298 174 000 mod 900 = 200

  t = 1 000 213 298 174 000 div 900 = 1 111 348 109 082
  Calculate codeword 1
  d1 = 1 111 348 109 082 mod 900 = 282

  t = 1 111 348 109 082 div 900 = 1 234 831 232
  Calculate codeword 2
  d2 = 1 234 831 232 mod 900 = 632

  t = 1 234 831 232 div 900 = 1 372 034
  Calculate codeword 3
  d3 = 1 372 034 mod 900 = 434

  t = 1 372 034 div 900 = 1 524
  Calculate codeword 4
  d4 = 1 524 mod 900 = 624

  t = 1 524 div 900 = 1
  Calculate codeword 5
  d5 = 1 mod 900 = 1
  t = 1 div 900 = 0
  Codeword sequence is: 1, 624, 434, 632, 282, 200

  Decode the above codewords involves
  1 x 900 power of 5 + 624 x 900 power of 4 + 434 x 900 power of 3 +
  632 x 900 power of 2 + 282 x 900 power of 1 + 200 x 900 power of 0 = 1000213298174000

  Remove leading 1 =>  Result is 000213298174000
*/
Ref<String> DecodedBitStreamParser::decodeBase900toBase10(ArrayRef<int> codewords, int count)
{
  BigInteger result = BigInteger(0);
  for (int i = 0; i < count; i++) {
    result = result + (EXP900[count - i - 1] * BigInteger(codewords[i]));
  }
  string resultString = bigIntegerToString(result);
  if (resultString[0] != '1') {
    throw FormatException("DecodedBitStreamParser::decodeBase900toBase10: String does not begin with 1");
  }
  string resultString2;
  resultString2.assign(resultString.begin()+1,resultString.end());
  Ref<String> res (new String(resultString2));
  return res;
}