content: /*
   * Copyright 2007 ZXing authors
   *
   * 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.
   */
  
  package com.ailiwean.core.zxing.core.qrcode.decoder;
  
  
  import com.ailiwean.core.zxing.core.DecodeHintType;
  import com.ailiwean.core.zxing.core.FormatException;
  import com.ailiwean.core.zxing.core.common.BitSource;
  import com.ailiwean.core.zxing.core.common.CharacterSetECI;
  import com.ailiwean.core.zxing.core.common.DecoderResult;
  import com.ailiwean.core.zxing.core.common.StringUtils;
  
  import java.io.UnsupportedEncodingException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  import java.util.Map;
  
  /**
   * <p>QR Codes can encode text as bits in one of several modes, and can use multiple modes
   * in one QR Code. This class decodes the bits back into text.</p>
   *
   * <p>See ISO 18004:2006, 6.4.3 - 6.4.7</p>
   *
   * @author Sean Owen
   */
  final class DecodedBitStreamParser {
  
    /**
     * See ISO 18004:2006, 6.4.4 Table 5
     */
    private static final char[] ALPHANUMERIC_CHARS =
        "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:".toCharArray();
    private static final int GB2312_SUBSET = 1;
  
    private DecodedBitStreamParser() {
    }
  
    static DecoderResult decode(byte[] bytes,
                                Version version,
                                ErrorCorrectionLevel ecLevel,
                                Map<DecodeHintType,?> hints) throws FormatException {
      BitSource bits = new BitSource(bytes);
      StringBuilder result = new StringBuilder(50);
      List<byte[]> byteSegments = new ArrayList<>(1);
      int symbolSequence = -1;
      int parityData = -1;
  
      try {
        CharacterSetECI currentCharacterSetECI = null;
        boolean fc1InEffect = false;
        Mode mode;
        do {
          // While still another segment to read...
          if (bits.available() < 4) {
            // OK, assume we're done. Really, a TERMINATOR mode should have been recorded here
            mode = Mode.TERMINATOR;
          } else {
            mode = Mode.forBits(bits.readBits(4)); // mode is encoded by 4 bits
          }
          switch (mode) {
            case TERMINATOR:
              break;
            case FNC1_FIRST_POSITION:
            case FNC1_SECOND_POSITION:
              // We do little with FNC1 except alter the parsed result a bit according to the spec
              fc1InEffect = true;
              break;
            case STRUCTURED_APPEND:
              if (bits.available() < 16) {
                throw FormatException.getFormatInstance();
              }
              // sequence number and parity is added later to the result metadata
              // Read next 8 bits (symbol sequence #) and 8 bits (parity data), then continue
              symbolSequence = bits.readBits(8);
              parityData = bits.readBits(8);
              break;
            case ECI:
              // Count doesn't apply to ECI
              int value = parseECIValue(bits);
              currentCharacterSetECI = CharacterSetECI.getCharacterSetECIByValue(value);
              if (currentCharacterSetECI == null) {
                throw FormatException.getFormatInstance();
              }
              break;
            case HANZI:
              // First handle Hanzi mode which does not start with character count
              // Chinese mode contains a sub set indicator right after mode indicator
              int subset = bits.readBits(4);
              int countHanzi = bits.readBits(mode.getCharacterCountBits(version));
              if (subset == GB2312_SUBSET) {
                decodeHanziSegment(bits, result, countHanzi);
              }
              break;
            default:
              // "Normal" QR code modes:
              // How many characters will follow, encoded in this mode?
              int count = bits.readBits(mode.getCharacterCountBits(version));
              switch (mode) {
                case NUMERIC:
                  decodeNumericSegment(bits, result, count);
                  break;
                case ALPHANUMERIC:
                  decodeAlphanumericSegment(bits, result, count, fc1InEffect);
                  break;
                case BYTE:
                  decodeByteSegment(bits, result, count, currentCharacterSetECI, byteSegments, hints);
                  break;
                case KANJI:
                  decodeKanjiSegment(bits, result, count);
                  break;
                default:
                  throw FormatException.getFormatInstance();
              }
              break;
          }
        } while (mode != Mode.TERMINATOR);
      } catch (IllegalArgumentException iae) {
        // from readBits() calls
        throw FormatException.getFormatInstance();
      }
  
      return new DecoderResult(bytes,
                               result.toString(),
                               byteSegments.isEmpty() ? null : byteSegments,
                               ecLevel == null ? null : ecLevel.toString(),
                               symbolSequence,
                               parityData);
    }
  
    /**
     * See specification GBT 18284-2000
     */
    private static void decodeHanziSegment(BitSource bits,
                                           StringBuilder result,
                                           int count) throws FormatException {
      // Don't crash trying to read more bits than we have available.
      if (count * 13 > bits.available()) {
        throw FormatException.getFormatInstance();
      }
  
      // Each character will require 2 bytes. Read the characters as 2-byte pairs
      // and decode as GB2312 afterwards
      byte[] buffer = new byte[2 * count];
      int offset = 0;
      while (count > 0) {
        // Each 13 bits encodes a 2-byte character
        int twoBytes = bits.readBits(13);
        int assembledTwoBytes = ((twoBytes / 0x060) << 8) | (twoBytes % 0x060);
        if (assembledTwoBytes < 0x00A00) {
          // In the 0xA1A1 to 0xAAFE range
          assembledTwoBytes += 0x0A1A1;
        } else {
          // In the 0xB0A1 to 0xFAFE range
          assembledTwoBytes += 0x0A6A1;
        }
        buffer[offset] = (byte) ((assembledTwoBytes >> 8) & 0xFF);
        buffer[offset + 1] = (byte) (assembledTwoBytes & 0xFF);
        offset += 2;
        count--;
      }
  
      try {
        result.append(new String(buffer, StringUtils.GB2312));
      } catch (UnsupportedEncodingException ignored) {
        throw FormatException.getFormatInstance();
      }
    }
  
    private static void decodeKanjiSegment(BitSource bits,
                                           StringBuilder result,
                                           int count) throws FormatException {
      // Don't crash trying to read more bits than we have available.
      if (count * 13 > bits.available()) {
        throw FormatException.getFormatInstance();
      }
  
      // Each character will require 2 bytes. Read the characters as 2-byte pairs
      // and decode as Shift_JIS afterwards
      byte[] buffer = new byte[2 * count];
      int offset = 0;
      while (count > 0) {
        // Each 13 bits encodes a 2-byte character
        int twoBytes = bits.readBits(13);
        int assembledTwoBytes = ((twoBytes / 0x0C0) << 8) | (twoBytes % 0x0C0);
        if (assembledTwoBytes < 0x01F00) {
          // In the 0x8140 to 0x9FFC range
          assembledTwoBytes += 0x08140;
        } else {
          // In the 0xE040 to 0xEBBF range
          assembledTwoBytes += 0x0C140;
        }
        buffer[offset] = (byte) (assembledTwoBytes >> 8);
        buffer[offset + 1] = (byte) assembledTwoBytes;
        offset += 2;
        count--;
      }
      // Shift_JIS may not be supported in some environments:
      try {
        result.append(new String(buffer, StringUtils.SHIFT_JIS));
      } catch (UnsupportedEncodingException ignored) {
        throw FormatException.getFormatInstance();
      }
    }
  
    private static void decodeByteSegment(BitSource bits,
                                          StringBuilder result,
                                          int count,
                                          CharacterSetECI currentCharacterSetECI,
                                          Collection<byte[]> byteSegments,
                                          Map<DecodeHintType,?> hints) throws FormatException {
      // Don't crash trying to read more bits than we have available.
      if (8 * count > bits.available()) {
        throw FormatException.getFormatInstance();
      }
  
      byte[] readBytes = new byte[count];
      for (int i = 0; i < count; i++) {
        readBytes[i] = (byte) bits.readBits(8);
      }
      String encoding;
      if (currentCharacterSetECI == null) {
        // The spec isn't clear on this mode; see
        // section 6.4.5: t does not say which encoding to assuming
        // upon decoding. I have seen ISO-8859-1 used as well as
        // Shift_JIS -- without anything like an ECI designator to
        // give a hint.
        encoding = StringUtils.guessEncoding(readBytes, hints);
      } else {
        encoding = currentCharacterSetECI.name();
      }
      try {
        result.append(new String(readBytes, encoding));
      } catch (UnsupportedEncodingException ignored) {
        throw FormatException.getFormatInstance();
      }
      byteSegments.add(readBytes);
    }
  
    private static char toAlphaNumericChar(int value) throws FormatException {
      if (value >= ALPHANUMERIC_CHARS.length) {
        throw FormatException.getFormatInstance();
      }
      return ALPHANUMERIC_CHARS[value];
    }
  
    private static void decodeAlphanumericSegment(BitSource bits,
                                                  StringBuilder result,
                                                  int count,
                                                  boolean fc1InEffect) throws FormatException {
      // Read two characters at a time
      int start = result.length();
      while (count > 1) {
        if (bits.available() < 11) {
          throw FormatException.getFormatInstance();
        }
        int nextTwoCharsBits = bits.readBits(11);
        result.append(toAlphaNumericChar(nextTwoCharsBits / 45));
        result.append(toAlphaNumericChar(nextTwoCharsBits % 45));
        count -= 2;
      }
      if (count == 1) {
        // special case: one character left
        if (bits.available() < 6) {
          throw FormatException.getFormatInstance();
        }
        result.append(toAlphaNumericChar(bits.readBits(6)));
      }
      // See section 6.4.8.1, 6.4.8.2
      if (fc1InEffect) {
        // We need to massage the result a bit if in an FNC1 mode:
        for (int i = start; i < result.length(); i++) {
          if (result.charAt(i) == '%') {
            if (i < result.length() - 1 && result.charAt(i + 1) == '%') {
              // %% is rendered as %
              result.deleteCharAt(i + 1);
            } else {
              // In alpha mode, % should be converted to FNC1 separator 0x1D
              result.setCharAt(i, (char) 0x1D);
            }
          }
        }
      }
    }
  
    private static void decodeNumericSegment(BitSource bits,
                                             StringBuilder result,
                                             int count) throws FormatException {
      // Read three digits at a time
      while (count >= 3) {
        // Each 10 bits encodes three digits
        if (bits.available() < 10) {
          throw FormatException.getFormatInstance();
        }
        int threeDigitsBits = bits.readBits(10);
        if (threeDigitsBits >= 1000) {
          throw FormatException.getFormatInstance();
        }
        result.append(toAlphaNumericChar(threeDigitsBits / 100));
        result.append(toAlphaNumericChar((threeDigitsBits / 10) % 10));
        result.append(toAlphaNumericChar(threeDigitsBits % 10));
        count -= 3;
      }
      if (count == 2) {
        // Two digits left over to read, encoded in 7 bits
        if (bits.available() < 7) {
          throw FormatException.getFormatInstance();
        }
        int twoDigitsBits = bits.readBits(7);
        if (twoDigitsBits >= 100) {
          throw FormatException.getFormatInstance();
        }
        result.append(toAlphaNumericChar(twoDigitsBits / 10));
        result.append(toAlphaNumericChar(twoDigitsBits % 10));
      } else if (count == 1) {
        // One digit left over to read
        if (bits.available() < 4) {
          throw FormatException.getFormatInstance();
        }
        int digitBits = bits.readBits(4);
        if (digitBits >= 10) {
          throw FormatException.getFormatInstance();
        }
        result.append(toAlphaNumericChar(digitBits));
      }
    }
  
    private static int parseECIValue(BitSource bits) throws FormatException {
      int firstByte = bits.readBits(8);
      if ((firstByte & 0x80) == 0) {
        // just one byte
        return firstByte & 0x7F;
      }
      if ((firstByte & 0xC0) == 0x80) {
        // two bytes
        int secondByte = bits.readBits(8);
        return ((firstByte & 0x3F) << 8) | secondByte;
      }
      if ((firstByte & 0xE0) == 0xC0) {
        // three bytes
        int secondThirdBytes = bits.readBits(16);
        return ((firstByte & 0x1F) << 16) | secondThirdBytes;
      }
      throw FormatException.getFormatInstance();
    }
  
  }
  