// -*- mode:c++; tab-width:2; indent-tabs-mode:nil; c-basic-offset:2 -*-
/*
 *  DecodedBitStreamParser.cpp
 *  zxing
 *
 *  Created by Christian Brunschen on 20/05/2008.
 *  Copyright 2008 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 <zxing/qrcode/decoder/DecodedBitStreamParser.h>
#include <zxing/common/CharacterSetECI.h>
#include <zxing/FormatException.h>
#include <zxing/common/StringUtils.h>
#include <iostream>

#include <qglobal.h>

#ifndef NO_ICONV
#include <iconv.h>
#endif

// Required for compatibility. TODO: test on Symbian
#ifdef ZXING_ICONV_CONST
#undef ICONV_CONST
#define ICONV_CONST const
#endif

#ifndef ICONV_CONST
#define ICONV_CONST /**/
#endif

using namespace std;
using namespace zxing;
using namespace zxing::qrcode;
using namespace zxing::common;

const char DecodedBitStreamParser::ALPHANUMERIC_CHARS[] =
{ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B',
  'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
  'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
  'Y', 'Z', ' ', '$', '%', '*', '+', '-', '.', '/', ':'
};

namespace {int GB2312_SUBSET = 1;}

void DecodedBitStreamParser::append(std::string &result,
                                    string const& in,
                                    const char *src) {
    append(result, (unsigned char const*)in.c_str(), in.length(), src);
}

void DecodedBitStreamParser::append(std::string &result,
                                    const unsigned char *bufIn,
                                    size_t nIn,
                                    const char *src) {
#ifndef NO_ICONV
    if (nIn == 0) {
        return;
    }

    iconv_t cd = iconv_open(StringUtils::UTF8, src);
    if (cd == (iconv_t)-1) {
        result.append((const char *)bufIn, nIn);
        return;
    }

    const int maxOut = 4 * nIn + 1;
    unsigned char* bufOut = new unsigned char[maxOut];

    /*ICONV_CONST*/ char *fromPtr = (/*ICONV_CONST*/ char *)bufIn;
    size_t nFrom = nIn;
    char *toPtr = (char *)bufOut;
    size_t nTo = maxOut;

    while (nFrom > 0) {
#if defined(Q_OS_SYMBIAN)
        size_t oneway = iconv(cd, (const char**)&fromPtr, &nFrom, &toPtr, &nTo); // for Symbian and Mingw
#else
        size_t oneway = iconv(cd, (char**)&fromPtr, &nFrom, &toPtr, &nTo); // for Harmattan
#endif

        if (oneway == (size_t)(-1)) {
            iconv_close(cd);
            delete[] bufOut;
            throw ReaderException("error converting characters");
        }
    }
    iconv_close(cd);

    int nResult = maxOut - nTo;
    bufOut[nResult] = '\0';
    result.append((const char *)bufOut);
    delete[] bufOut;
#else
    result.append((const char *)bufIn, nIn);
#endif
}

void DecodedBitStreamParser::decodeHanziSegment(Ref<BitSource> bits_,
                                                string& result,
                                                int count) {
    BitSource& bits (*bits_);
    // Don't crash trying to read more bits than we have available.
    if (count * 13 > bits.available()) {
        throw FormatException();
    }

    // Each character will require 2 bytes. Read the characters as 2-byte pairs
    // and decode as GB2312 afterwards
    size_t nBytes = 2 * count;
    unsigned char* buffer = new unsigned char[nBytes];
    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 < 0x003BF) {
            // In the 0xA1A1 to 0xAAFE range
            assembledTwoBytes += 0x0A1A1;
        } else {
            // In the 0xB0A1 to 0xFAFE range
            assembledTwoBytes += 0x0A6A1;
        }
        buffer[offset] = (unsigned char) ((assembledTwoBytes >> 8) & 0xFF);
        buffer[offset + 1] = (unsigned char) (assembledTwoBytes & 0xFF);
        offset += 2;
        count--;
    }

    try {
        append(result, buffer, nBytes, StringUtils::GB2312);
    } catch (ReaderException const& re) {
        delete [] buffer;
        throw FormatException();
    }

    delete [] buffer;
}

void DecodedBitStreamParser::decodeKanjiSegment(Ref<BitSource> bits, std::string &result, int count) {
    // Each character will require 2 bytes. Read the characters as 2-byte pairs
    // and decode as Shift_JIS afterwards
    size_t nBytes = 2 * count;
    unsigned char* buffer = new unsigned char[nBytes];
    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] = (unsigned char)(assembledTwoBytes >> 8);
        buffer[offset + 1] = (unsigned char)assembledTwoBytes;
        offset += 2;
        count--;
    }

    append(result, buffer, nBytes, StringUtils::SHIFT_JIS);
    delete[] buffer;
}

void DecodedBitStreamParser::decodeByteSegment(Ref<BitSource> bits_,
                                               string& result,
                                               int count,
                                               CharacterSetECI* currentCharacterSetECI,
                                               ArrayRef< ArrayRef<unsigned char> >& byteSegments,
                                               Hashtable const& hints) {
    int nBytes = count;
    BitSource& bits (*bits_);
    // Don't crash trying to read more bits than we have available.
    if (count << 3 > bits.available()) {
        throw FormatException();
    }

    ArrayRef<unsigned char> bytes_ (count);
    unsigned char* readBytes = &(*bytes_)[0];
    for (int i = 0; i < count; i++) {
        readBytes[i] = (unsigned char) bits.readBits(8);
    }
    string encoding;
    if (currentCharacterSetECI == 0) {
        // 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, count, hints);
    } else {
        encoding = currentCharacterSetECI->name();
    }
    try {
        append(result, readBytes, nBytes, encoding.c_str());
    } catch (ReaderException const& re) {
        throw FormatException();
    }
    byteSegments->values().push_back(bytes_);
}

void DecodedBitStreamParser::decodeNumericSegment(Ref<BitSource> bits, std::string &result, int count) {
    int nBytes = count;
    unsigned char* bytes = new unsigned char[nBytes];
    int i = 0;
    // Read three digits at a time
    while (count >= 3) {
        // Each 10 bits encodes three digits
        if (bits->available() < 10) {
            throw ReaderException("format exception");
        }
        int threeDigitsBits = bits->readBits(10);
        if (threeDigitsBits >= 1000) {
            ostringstream s;
            s << "Illegal value for 3-digit unit: " << threeDigitsBits;
            delete[] bytes;
            throw ReaderException(s.str().c_str());
        }
        bytes[i++] = ALPHANUMERIC_CHARS[threeDigitsBits / 100];
        bytes[i++] = ALPHANUMERIC_CHARS[(threeDigitsBits / 10) % 10];
        bytes[i++] = ALPHANUMERIC_CHARS[threeDigitsBits % 10];
        count -= 3;
    }
    if (count == 2) {
        if (bits->available() < 7) {
            throw ReaderException("format exception");
        }
        // Two digits left over to read, encoded in 7 bits
        int twoDigitsBits = bits->readBits(7);
        if (twoDigitsBits >= 100) {
            ostringstream s;
            s << "Illegal value for 2-digit unit: " << twoDigitsBits;
            delete[] bytes;
            throw ReaderException(s.str().c_str());
        }
        bytes[i++] = ALPHANUMERIC_CHARS[twoDigitsBits / 10];
        bytes[i++] = ALPHANUMERIC_CHARS[twoDigitsBits % 10];
    } else if (count == 1) {
        if (bits->available() < 4) {
            throw ReaderException("format exception");
        }
        // One digit left over to read
        int digitBits = bits->readBits(4);
        if (digitBits >= 10) {
            ostringstream s;
            s << "Illegal value for digit unit: " << digitBits;
            delete[] bytes;
            throw ReaderException(s.str().c_str());
        }
        bytes[i++] = ALPHANUMERIC_CHARS[digitBits];
    }
    append(result, bytes, nBytes, StringUtils::ASCII);
    delete[] bytes;
}

char DecodedBitStreamParser::toAlphaNumericChar(size_t value) {
    if (value >= sizeof(DecodedBitStreamParser::ALPHANUMERIC_CHARS)) {
        throw FormatException();
    }
    return ALPHANUMERIC_CHARS[value];
}

void DecodedBitStreamParser::decodeAlphanumericSegment(Ref<BitSource> bits_,
                                                       string& result,
                                                       int count,
                                                       bool fc1InEffect) {
    BitSource& bits (*bits_);
    ostringstream bytes;
    // Read two characters at a time
    while (count > 1) {
        if (bits.available() < 11) {
            throw FormatException();
        }
        int nextTwoCharsBits = bits.readBits(11);
        bytes << toAlphaNumericChar(nextTwoCharsBits / 45);
        bytes << toAlphaNumericChar(nextTwoCharsBits % 45);
        count -= 2;
    }
    if (count == 1) {
        // special case: one character left
        if (bits.available() < 6) {
            throw FormatException();
        }
        bytes << toAlphaNumericChar(bits.readBits(6));
    }
    // See section 6.4.8.1, 6.4.8.2
    string s = bytes.str();
    if (fc1InEffect) {
        // We need to massage the result a bit if in an FNC1 mode:
        ostringstream r;
        for (size_t i = 0; i < s.length(); i++) {
            if (s[i] != '%') {
                r << s[i];
            } else {
                if (i < s.length() - 1 && s[i + 1] == '%') {
                    // %% is rendered as %
                    r << s[i++];
                } else {
                    // In alpha mode, % should be converted to FNC1 separator 0x1D
                    r << (char)0x1D;
                }
            }
        }
        s = r.str();
    }
    append(result, s, StringUtils::ASCII);
}

namespace {
int parseECIValue(BitSource bits) {
    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();
}
}

Ref<DecoderResult>
DecodedBitStreamParser::decode(ArrayRef<unsigned char> bytes,
                               Version* version,
                               ErrorCorrectionLevel const& ecLevel,
                               Hashtable const& hints) {
    Ref<BitSource> bits_ (new BitSource(bytes));
    BitSource& bits (*bits_);
    string result;
    CharacterSetECI* currentCharacterSetECI = 0;
    bool fc1InEffect = false;
    ArrayRef< ArrayRef<unsigned char> > byteSegments (size_t(0));
    Mode* mode = 0;
    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 {
            try {
                mode = &Mode::forBits(bits.readBits(4)); // mode is encoded by 4 bits
            } catch (IllegalArgumentException const& iae) {
                throw iae;
                // throw FormatException.getFormatInstance();
            }
        }
        if (mode != &Mode::TERMINATOR) {
            if ((mode == &Mode::FNC1_FIRST_POSITION) || (mode == &Mode::FNC1_SECOND_POSITION)) {
                // We do little with FNC1 except alter the parsed result a bit according to the spec
                fc1InEffect = true;
            } else if (mode == &Mode::STRUCTURED_APPEND) {
                // not really supported; all we do is ignore it
                // Read next 8 bits (symbol sequence #) and 8 bits (parity data), then continue
                bits.readBits(16);
            } else if (mode == &Mode::ECI) {
                // Count doesn't apply to ECI
                int value = parseECIValue(bits);
                currentCharacterSetECI = CharacterSetECI::getCharacterSetECIByValue(value);
                if (currentCharacterSetECI == 0) {
                    throw FormatException();
                }
            } else {
                // First handle Hanzi mode which does not start with character count
                if (mode == &Mode::HANZI) {
                    //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);
                    }
                } else {
                    // "Normal" QR code modes:
                    // How many characters will follow, encoded in this mode?
                    int count = bits.readBits(mode->getCharacterCountBits(version));
                    if (mode == &Mode::NUMERIC) {
                        decodeNumericSegment(bits_, result, count);
                    } else if (mode == &Mode::ALPHANUMERIC) {
                        decodeAlphanumericSegment(bits_, result, count, fc1InEffect);
                    } else if (mode == &Mode::BYTE) {
                        decodeByteSegment(bits_, result, count, currentCharacterSetECI, byteSegments, hints);
                    } else if (mode == &Mode::KANJI) {
                        decodeKanjiSegment(bits_, result, count);
                    } else {
                        throw FormatException();
                    }
                }
            }
        }
    } while (mode != &Mode::TERMINATOR);

    return Ref<DecoderResult>(new DecoderResult(bytes, Ref<String>(new String(result)), byteSegments, (string)ecLevel));
}