/*  Copyright (c) 2010 Xiaoyun Zhu
 * 
 *  Permission is hereby granted, free of charge, to any person obtaining a copy  
 *  of this software and associated documentation files (the "Software"), to deal  
 *  in the Software without restriction, including without limitation the rights  
 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell  
 *  copies of the Software, and to permit persons to whom the Software is  
 *  furnished to do so, subject to the following conditions:
 *  
 *  The above copyright notice and this permission notice shall be included in  
 *  all copies or substantial portions of the Software.
 *  
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE  
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER  
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,  
 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN  
 *  THE SOFTWARE.  
 */

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.CharBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CoderResult;
import java.nio.charset.CodingErrorAction;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;

/**
 * Lingoes LD2/LDF File Reader
 * 
 * <pre>
 * Lingoes Format overview:
 * 
 * General Information:
 * - Dictionary data are stored in deflate streams.
 * - Index group information is stored in an index array in the LD2 file itself.
 * - Numbers are using little endian byte order.
 * - Definitions and xml data have UTF-8 or UTF-16LE encodings.
 * 
 * LD2 file schema:
 * - File Header
 * - File Description
 * - Additional Information (optional)
 * - Index Group (corresponds to definitions in dictionary) 
 * - Deflated Dictionary Streams
 * -- Index Data
 * --- Offsets of definitions
 * --- Offsets of translations
 * --- Flags
 * --- References to other translations
 * -- Definitions
 * -- Translations (xml)
 * 
 * TODO: find encoding / language fields to replace auto-detect of encodings
 * 
 * </pre>
 * 
 * @author keke
 * 
 */
public class LingoesLd2Reader {
  private static final SensitiveStringDecoder[] AVAIL_ENCODINGS = { new SensitiveStringDecoder(Charset.forName("UTF-8")),
      new SensitiveStringDecoder(Charset.forName("UTF-16LE")), new SensitiveStringDecoder(Charset.forName("UTF-16BE")),
      new SensitiveStringDecoder(Charset.forName("EUC-JP"))    };

  public static void main(final String[] args) throws IOException {
    // download from
    // https://skydrive.live.com/?cid=a10100d37adc7ad3&sc=documents&id=A10100D37ADC7AD3%211172#cid=A10100D37ADC7AD3&sc=documents
    // String ld2File = Helper.DIR_IN_DICTS+"\\lingoes\\Prodic English-Vietnamese Business.ld2";
    final String ld2File = "D:\\kr.ld2";

    // read lingoes ld2 into byte array
    final ByteBuffer dataRawBytes;
    try (RandomAccessFile file = new RandomAccessFile(ld2File, "r"); final FileChannel fChannel = file.getChannel();) {
      dataRawBytes = ByteBuffer.allocate((int) fChannel.size());
      fChannel.read(dataRawBytes);
    }
    dataRawBytes.order(ByteOrder.LITTLE_ENDIAN);
    dataRawBytes.rewind();

    System.out.println("文件：" + ld2File);
    System.out.println("类型：" + new String(dataRawBytes.array(), 0, 4, "ASCII"));
    System.out.println("版本：" + dataRawBytes.getShort(0x18) + "." + dataRawBytes.getShort(0x1A));
    System.out.println("ID: 0x" + Long.toHexString(dataRawBytes.getLong(0x1C)));

    final int offsetData = dataRawBytes.getInt(0x5C) + 0x60;
    if (dataRawBytes.limit() > offsetData) {
      System.out.println("简介地址：0x" + Integer.toHexString(offsetData));
      final int type = dataRawBytes.getInt(offsetData);
      System.out.println("简介类型：0x" + Integer.toHexString(type));
      final int offsetWithInfo = dataRawBytes.getInt(offsetData + 4) + offsetData + 12;
      if (type == 3) {
        // without additional information
        LingoesLd2Reader.readDictionary(ld2File, dataRawBytes, offsetData);
      } else if (dataRawBytes.limit() > (offsetWithInfo - 0x1C)) {
        LingoesLd2Reader.readDictionary(ld2File, dataRawBytes, offsetWithInfo);
      } else {
        System.err.println("文件不包含字典数据。网上字典？");
      }
    } else {
      System.err.println("文件不包含字典数据。网上字典？");
    }
  }

  private static final long decompress(final String inflatedFile, final ByteBuffer data, final int offset, final int length, final boolean append)
      throws IOException {
    final Inflater inflator = new Inflater();
    try (final InflaterInputStream in = new InflaterInputStream(new ByteArrayInputStream(data.array(), offset, length), inflator, 1024 * 8);
        final FileOutputStream out = new FileOutputStream(inflatedFile, append);) {
      LingoesLd2Reader.writeInputStream(in, out);
    }
    final long bytesRead = inflator.getBytesRead();
    inflator.end();
    return bytesRead;
  }

  private static final SensitiveStringDecoder[] detectEncodings(final ByteBuffer inflatedBytes, final int offsetWords, final int offsetXml, final int defTotal,
      final int dataLen, final int[] idxData, final String[] defData) {
    final int test = Math.min(defTotal, 10);
    for (int j = 0; j < LingoesLd2Reader.AVAIL_ENCODINGS.length; j++) {
      for (int k = 0; k < LingoesLd2Reader.AVAIL_ENCODINGS.length; k++) {
        try {
          for (int i = 0; i < test; i++) {
            LingoesLd2Reader.readDefinitionData(inflatedBytes, offsetWords, offsetXml, dataLen, LingoesLd2Reader.AVAIL_ENCODINGS[j],
                LingoesLd2Reader.AVAIL_ENCODINGS[k], idxData, defData, i);
          }
          System.out.println("词组编码：" + LingoesLd2Reader.AVAIL_ENCODINGS[j].name);
          System.out.println("XML编码：" + LingoesLd2Reader.AVAIL_ENCODINGS[k].name);
          return new SensitiveStringDecoder[] { LingoesLd2Reader.AVAIL_ENCODINGS[j], LingoesLd2Reader.AVAIL_ENCODINGS[k] };
        } catch (final Throwable e) {
          // ignore
        }
      }
    }
    System.err.println("自动识别编码失败！选择UTF-16LE继续。");
    return new SensitiveStringDecoder[] { LingoesLd2Reader.AVAIL_ENCODINGS[1], LingoesLd2Reader.AVAIL_ENCODINGS[1] };
  }

  private static final void extract(final String inflatedFile, final String indexFile, final String extractedWordsFile, final String extractedXmlFile,
      final String extractedOutputFile, final int[] idxArray, final int offsetDefs, final int offsetXml) throws IOException, FileNotFoundException,
      UnsupportedEncodingException {
    System.out.println("写入'" + extractedOutputFile + "'。。。");

    int counter = 0;
    try (RandomAccessFile file = new RandomAccessFile(inflatedFile, "r");
        final FileWriter indexWriter = new FileWriter(indexFile);
        final FileWriter defsWriter = new FileWriter(extractedWordsFile);
        final FileWriter xmlWriter = new FileWriter(extractedXmlFile);
        final FileWriter outputWriter = new FileWriter(extractedOutputFile);
        // read inflated data
        final FileChannel fChannel = file.getChannel();) {
      final ByteBuffer dataRawBytes = ByteBuffer.allocate((int) fChannel.size());
      fChannel.read(dataRawBytes);
      fChannel.close();
      dataRawBytes.order(ByteOrder.LITTLE_ENDIAN);
      dataRawBytes.rewind();

      final int dataLen = 10;
      final int defTotal = (offsetDefs / dataLen) - 1;

      final String[] words = new String[defTotal];
      final int[] idxData = new int[6];
      final String[] defData = new String[2];

      final SensitiveStringDecoder[] encodings = LingoesLd2Reader.detectEncodings(dataRawBytes, offsetDefs, offsetXml, defTotal, dataLen, idxData, defData);

      dataRawBytes.position(8);

      for (int i = 0; i < defTotal; i++) {
        LingoesLd2Reader.readDefinitionData(dataRawBytes, offsetDefs, offsetXml, dataLen, encodings[0], encodings[1], idxData, defData, i);

        words[i] = defData[0];
        defsWriter.write(defData[0]);
        defsWriter.write("\n");

        xmlWriter.write(defData[1]);
        xmlWriter.write("\n");

        outputWriter.write(defData[0]);
        outputWriter.write("=");
        outputWriter.write(defData[1]);
        outputWriter.write("\n");

        System.out.println(defData[0] + " = " + defData[1]);
        counter++;
      }

      for (int i = 0; i < idxArray.length; i++) {
        final int idx = idxArray[i];
        indexWriter.write(words[idx]);
        indexWriter.write(", ");
        indexWriter.write(String.valueOf(idx));
        indexWriter.write("\n");
      }
    }
    System.out.println("成功读出" + counter + "组数据。");
  }

  private static final void getIdxData(final ByteBuffer dataRawBytes, final int position, final int[] wordIdxData) {
    dataRawBytes.position(position);
    wordIdxData[0] = dataRawBytes.getInt();
    wordIdxData[1] = dataRawBytes.getInt();
    wordIdxData[2] = dataRawBytes.get() & 0xff;
    wordIdxData[3] = dataRawBytes.get() & 0xff;
    wordIdxData[4] = dataRawBytes.getInt();
    wordIdxData[5] = dataRawBytes.getInt();
  }

  private static final void inflate(final ByteBuffer dataRawBytes, final List<Integer> deflateStreams, final String inflatedFile) {
    System.out.println("解压缩'" + deflateStreams.size() + "'个数据流至'" + inflatedFile + "'。。。");
    final int startOffset = dataRawBytes.position();
    int offset = -1;
    int lastOffset = startOffset;
    boolean append = false;
    try {
      for (final Integer offsetRelative : deflateStreams) {
        offset = startOffset + offsetRelative.intValue();
        LingoesLd2Reader.decompress(inflatedFile, dataRawBytes, lastOffset, offset - lastOffset, append);
        append = true;
        lastOffset = offset;
      }
    } catch (final Throwable e) {
      System.err.println("解压缩失败: 0x" + Integer.toHexString(offset) + ": " + e.toString());
    }
  }

  private static final void readDefinitionData(final ByteBuffer inflatedBytes, final int offsetWords, final int offsetXml, final int dataLen,
      final SensitiveStringDecoder wordStringDecoder, final SensitiveStringDecoder xmlStringDecoder, final int[] idxData, final String[] defData, final int i) {
    LingoesLd2Reader.getIdxData(inflatedBytes, dataLen * i, idxData);
    int lastWordPos = idxData[0];
    int lastXmlPos = idxData[1];
    // final int flags = idxData[2];
    int refs = idxData[3];
    final int currentWordOffset = idxData[4];
    int currenXmlOffset = idxData[5];

    String xml = LingoesLd2Reader.strip(new String(xmlStringDecoder.decode(inflatedBytes.array(), offsetXml + lastXmlPos, currenXmlOffset - lastXmlPos)));
    while (refs-- > 0) {
      final int ref = inflatedBytes.getInt(offsetWords + lastWordPos);
      LingoesLd2Reader.getIdxData(inflatedBytes, dataLen * ref, idxData);
      lastXmlPos = idxData[1];
      currenXmlOffset = idxData[5];
      if (xml.isEmpty()) {
        xml = LingoesLd2Reader.strip(new String(xmlStringDecoder.decode(inflatedBytes.array(), offsetXml + lastXmlPos, currenXmlOffset - lastXmlPos)));
      } else {
        xml = LingoesLd2Reader.strip(new String(xmlStringDecoder.decode(inflatedBytes.array(), offsetXml + lastXmlPos, currenXmlOffset - lastXmlPos))) + ", "
            + xml;
      }
      lastWordPos += 4;
    }
    defData[1] = xml;

    final String word = new String(wordStringDecoder.decode(inflatedBytes.array(), offsetWords + lastWordPos, currentWordOffset - lastWordPos));
    defData[0] = word;
  }

  private static final void readDictionary(final String ld2File, final ByteBuffer dataRawBytes, final int offsetWithIndex) throws IOException,
      FileNotFoundException, UnsupportedEncodingException {
    System.out.println("词典类型：0x" + Integer.toHexString(dataRawBytes.getInt(offsetWithIndex)));
    final int limit = dataRawBytes.getInt(offsetWithIndex + 4) + offsetWithIndex + 8;
    final int offsetIndex = offsetWithIndex + 0x1C;
    final int offsetCompressedDataHeader = dataRawBytes.getInt(offsetWithIndex + 8) + offsetIndex;
    final int inflatedWordsIndexLength = dataRawBytes.getInt(offsetWithIndex + 12);
    final int inflatedWordsLength = dataRawBytes.getInt(offsetWithIndex + 16);
    final int inflatedXmlLength = dataRawBytes.getInt(offsetWithIndex + 20);
    final int definitions = (offsetCompressedDataHeader - offsetIndex) / 4;
    final List<Integer> deflateStreams = new ArrayList<>();
    dataRawBytes.position(offsetCompressedDataHeader + 8);
    int offset = dataRawBytes.getInt();
    while ((offset + dataRawBytes.position()) < limit) {
      offset = dataRawBytes.getInt();
      deflateStreams.add(Integer.valueOf(offset));
    }
    final int offsetCompressedData = dataRawBytes.position();
    System.out.println("索引词组数目：" + definitions);
    System.out.println("索引地址/大小：0x" + Integer.toHexString(offsetIndex) + " / " + (offsetCompressedDataHeader - offsetIndex) + " B");
    System.out.println("压缩数据地址/大小：0x" + Integer.toHexString(offsetCompressedData) + " / " + (limit - offsetCompressedData) + " B");
    System.out.println("词组索引地址/大小（解压缩后）：0x0 / " + inflatedWordsIndexLength + " B");
    System.out.println("词组地址/大小（解压缩后）：0x" + Integer.toHexString(inflatedWordsIndexLength) + " / " + inflatedWordsLength + " B");
    System.out.println("XML地址/大小（解压缩后）：0x" + Integer.toHexString(inflatedWordsIndexLength + inflatedWordsLength) + " / " + inflatedXmlLength + " B");
    System.out.println("文件大小（解压缩后）：" + ((inflatedWordsIndexLength + inflatedWordsLength + inflatedXmlLength) / 1024) + " KB");
    final String inflatedFile = ld2File + ".inflated";
    LingoesLd2Reader.inflate(dataRawBytes, deflateStreams, inflatedFile);

    if (new File(inflatedFile).isFile()) {
      final String indexFile = ld2File + ".idx";
      final String extractedFile = ld2File + ".words";
      final String extractedXmlFile = ld2File + ".xml";
      final String extractedOutputFile = ld2File + ".output";

      dataRawBytes.position(offsetIndex);
      final int[] idxArray = new int[definitions];
      for (int i = 0; i < definitions; i++) {
        idxArray[i] = dataRawBytes.getInt();
      }
      LingoesLd2Reader.extract(inflatedFile, indexFile, extractedFile, extractedXmlFile, extractedOutputFile, idxArray, inflatedWordsIndexLength,
          inflatedWordsIndexLength + inflatedWordsLength);
    }
  }

  private static final String strip(final String xml) {
    int open = 0;
    int end = 0;
    if ((open = xml.indexOf("<![CDATA[")) != -1) {
      if ((end = xml.indexOf("]]>", open)) != -1) {
        return xml.substring(open + "<![CDATA[".length(), end).replace('\t', ' ').replace('\n', ' ').replace('\u001e', ' ').replace('\u001f', ' ');
      }
    } else if ((open = xml.indexOf("<Ô")) != -1) {
      if ((end = xml.indexOf("</Ô", open)) != -1) {
        open = xml.indexOf(">", open + 1);
        return xml.substring(open + 1, end).replace('\t', ' ').replace('\n', ' ').replace('\u001e', ' ').replace('\u001f', ' ');
      }
    } else {
      final StringBuilder sb = new StringBuilder();
      end = 0;
      open = xml.indexOf('<');
      do {
        if ((open - end) > 1) {
          sb.append(xml.substring(end + 1, open));
        }
        open = xml.indexOf('<', open + 1);
        end = xml.indexOf('>', end + 1);
      } while ((open != -1) && (end != -1));
      return sb.toString().replace('\t', ' ').replace('\n', ' ').replace('\u001e', ' ').replace('\u001f', ' ');
    }
    return "";
  }

  private static final void writeInputStream(final InputStream in, final OutputStream out) throws IOException {
    final byte[] buffer = new byte[1024 * 8];
    int len;
    while ((len = in.read(buffer)) > 0) {
      out.write(buffer, 0, len);
    }
  }

  private static class SensitiveStringDecoder {
    public final String          name;
    private final CharsetDecoder cd;

    SensitiveStringDecoder(final Charset cs) {
      this.cd = cs.newDecoder().onMalformedInput(CodingErrorAction.REPORT).onUnmappableCharacter(CodingErrorAction.REPORT);
      this.name = cs.name();
    }

    char[] decode(final byte[] ba, final int off, final int len) {
      final int en = (int) (len * (double) this.cd.maxCharsPerByte());
      final char[] ca = new char[en];
      if (len == 0) {
        return ca;
      }
      this.cd.reset();
      final ByteBuffer bb = ByteBuffer.wrap(ba, off, len);
      final CharBuffer cb = CharBuffer.wrap(ca);
      try {
        CoderResult cr = this.cd.decode(bb, cb, true);
        if (!cr.isUnderflow()) {
          cr.throwException();
        }
        cr = this.cd.flush(cb);
        if (!cr.isUnderflow()) {
          cr.throwException();
        }
      } catch (final CharacterCodingException x) {
        // Substitution is always enabled,
        // so this shouldn't happen
        throw new Error(x);
      }
      return SensitiveStringDecoder.safeTrim(ca, cb.position());
    }

    private static char[] safeTrim(final char[] ca, final int len) {
      if (len == ca.length) {
        return ca;
      } else {
        return Arrays.copyOf(ca, len);
      }
    }
  }
}