/* This file is (c) 2008-2012 Konstantin Isakov <ikm@goldendict.org>
 * Part of GoldenDict. Licensed under GPLv3 or later, see the LICENSE file */

#include "sdict.hh"
#include "btreeidx.hh"
#include "folding.hh"
#include "utf8.hh"
#include "chunkedstorage.hh"
#include "langcoder.hh"
#include "gddebug.hh"
#include "fsencoding.hh"
#include "decompress.hh"
#include "htmlescape.hh"
#include "ftshelpers.hh"
#include "wstring_qt.hh"

#include <map>
#include <set>
#include <string>

#ifdef _MSC_VER
#include <stub_msvc.h>
#endif

#include <QString>
#include <QSemaphore>
#include <QThreadPool>
#include <QAtomicInt>
#include <QRegExp>
#include <QDebug>

#include "ufile.hh"

namespace Sdict {

using std::map;
using std::multimap;
using std::pair;
using std::set;
using std::string;
using gd::wstring;

using BtreeIndexing::WordArticleLink;
using BtreeIndexing::IndexedWords;
using BtreeIndexing::IndexInfo;

namespace {

DEF_EX_STR( exNotDctFile, "Not an Sdictionary file", Dictionary::Ex )
DEF_EX_STR( exCantReadFile, "Can't read file", Dictionary::Ex )
DEF_EX_STR( exWordIsTooLarge, "Enountered a word that is too large:", Dictionary::Ex )
DEF_EX_STR( exSuddenEndOfFile, "Sudden end of file", Dictionary::Ex )

#pragma pack( push, 1 )

/// DCT file header
struct DCT_header
{
    char signature[4];
    char inputLang[3];
    char outputLang[3];
    uint8_t compression;
    uint32_t wordCount;
    uint32_t shortIndexLength;
    uint32_t titleOffset;
    uint32_t copyrightOffset;
    uint32_t versionOffset;
    uint32_t shortIndexOffset;
    uint32_t fullIndexOffset;
    uint32_t articlesOffset;
}
#ifndef _MSC_VER
__attribute__((packed))
#endif
;

struct IndexElement
{
    uint16_t nextWord;
    uint16_t previousWord;
    uint32_t articleOffset;
}
#ifndef _MSC_VER
__attribute__((packed))
#endif
;

enum
{
  Signature = 0x43494453, // SDIC on little-endian, CIDS on big-endian
  CurrentFormatVersion = 1 + BtreeIndexing::FormatVersion + Folding::Version
};

struct IdxHeader
{
  uint32_t signature; // First comes the signature, SDIC
  uint32_t formatVersion; // File format version (CurrentFormatVersion)
  uint32_t chunksOffset; // The offset to chunks' storage
  uint32_t indexBtreeMaxElements; // Two fields from IndexInfo
  uint32_t indexRootOffset;
  uint32_t wordCount;
  uint32_t articleCount;
  uint32_t compressionType; // Data compression in file. 0 - no compression, 1 - zip, 2 - bzip2
  uint32_t langFrom;  // Source language
  uint32_t langTo;    // Target language
}
#ifndef _MSC_VER
__attribute__((packed))
#endif
;

#pragma pack( pop )

bool indexIsOldOrBad( string const & indexFile )
{
  File::Class idx( indexFile, "rb" );

  IdxHeader header;

  return idx.readRecords( &header, sizeof( header ), 1 ) != 1 ||
         header.signature != Signature ||
         header.formatVersion != CurrentFormatVersion;
}

class SdictDictionary: public BtreeIndexing::BtreeDictionary
{
    Mutex idxMutex, sdictMutex;
    File::Class idx;
    IdxHeader idxHeader;
    ChunkedStorage::Reader chunks;
    string dictionaryName;
    File::Class df;

  public:

    SdictDictionary( string const & id, string const & indexFile,
                     vector< string > const & dictionaryFiles );

    ~SdictDictionary();

    virtual string getName() throw()
    { return dictionaryName; }

    virtual map< Dictionary::Property, string > getProperties() throw()
    { return map< Dictionary::Property, string >(); }

    virtual unsigned long getArticleCount() throw()
    { return idxHeader.articleCount; }

    virtual unsigned long getWordCount() throw()
    { return idxHeader.wordCount; }

    inline virtual quint32 getLangFrom() const
    { return idxHeader.langFrom; }

    inline virtual quint32 getLangTo() const
    { return idxHeader.langTo; }

    virtual sptr< Dictionary::DataRequest > getArticle( wstring const &,
                                                        vector< wstring > const & alts,
                                                        wstring const & )
      throw( std::exception );

    virtual QString const & getDescription();

    virtual sptr< Dictionary::DataRequest > getSearchResults( QString const & searchString,
                                                              int searchMode, bool matchCase,
                                                              int distanceBetweenWords,
                                                              int maxResults );
    virtual void getArticleText( uint32_t articleAddress, QString & headword, QString & text );

    virtual void makeFTSIndex(QAtomicInt & isCancelled, bool firstIteration );

    virtual void setFTSParameters( Config::FullTextSearch const & fts )
    {
      can_FTS = fts.enabled
                && !fts.disabledTypes.contains( "SDICT", Qt::CaseInsensitive )
                && ( fts.maxDictionarySize == 0 || getArticleCount() <= fts.maxDictionarySize );
    }
protected:

    void loadIcon() throw();

private:

    /// Loads the article.
    void loadArticle( uint32_t address,
                      string & articleText );
    string convert( string const & in_data );

    friend class SdictArticleRequest;
};

SdictDictionary::SdictDictionary( string const & id,
                                  string const & indexFile,
                                  vector< string > const & dictionaryFiles ):
    BtreeDictionary( id, dictionaryFiles ),
    idx( indexFile, "rb" ),
    idxHeader( idx.read< IdxHeader >() ),
    chunks( idx, idxHeader.chunksOffset ),
    df( dictionaryFiles[ 0 ], "rb" )
{
    // Read dictionary name

    idx.seek( sizeof( idxHeader ) );
    vector< char > dName( idx.read< uint32_t >() );
    idx.read( &dName.front(), dName.size() );
    dictionaryName = string( &dName.front(), dName.size() );

    // Initialize the index

    openIndex( IndexInfo( idxHeader.indexBtreeMaxElements,
                          idxHeader.indexRootOffset ),
               idx, idxMutex );

    // Full-text search parameters

    can_FTS = true;

    ftsIdxName = indexFile + "_FTS";

    if( !Dictionary::needToRebuildIndex( dictionaryFiles, ftsIdxName )
        && !FtsHelpers::ftsIndexIsOldOrBad( ftsIdxName, this ) )
      FTS_index_completed.ref();
}

SdictDictionary::~SdictDictionary()
{
    df.close();
}

void SdictDictionary::loadIcon() throw()
{
  if ( dictionaryIconLoaded )
    return;

  QString fileName =
    QDir::fromNativeSeparators( FsEncoding::decode( getDictionaryFilenames()[ 0 ].c_str() ) );

  // Remove the extension
  fileName.chop( 3 );

  if( !loadIconFromFile( fileName ) )
  {
    // Load failed -- use default icons
    dictionaryNativeIcon = dictionaryIcon = QIcon(":/icons/icon32_sdict.png");
  }

  dictionaryIconLoaded = true;
}

string SdictDictionary::convert( string const & in )
{
//    DPRINTF( "Source>>>>>>>>>>: %s\n\n\n", in.c_str() );

    string inConverted;

    inConverted.reserve( in.size() );

    bool afterEol = false;

    for( string::const_iterator i = in.begin(), j = in.end(); i != j; ++i )
    {
      switch( *i )
      {
        case '\n':
          afterEol = true;
          inConverted.append( "<br/>" );
        break;

        case ' ':
          if ( afterEol )
          {
            inConverted.append( "&nbsp;" );
            break;
          }
          // Fall-through

        default:
          inConverted.push_back( *i );
          afterEol = false;
      }
    }

    QString result = QString::fromUtf8( inConverted.c_str(), inConverted.size() );

    result.replace( QRegExp( "<\\s*(p|br)\\s*>", Qt::CaseInsensitive ), "<br/>" );
    result.remove( QRegExp( "<\\s*/p\\s*>", Qt::CaseInsensitive ) );

    result.replace( QRegExp( "<\\s*t\\s*>", Qt::CaseInsensitive ), "<span class=\"sdict_tr\" dir=\"ltr\">" );
    result.replace( QRegExp( "<\\s*f\\s*>", Qt::CaseInsensitive ), "<span class=\"sdict_forms\">" );
    result.replace( QRegExp( "<\\s*/(t|f)\\s*>", Qt::CaseInsensitive ), "</span>" );

    result.replace( QRegExp( "<\\s*l\\s*>", Qt::CaseInsensitive ), "<ul>" );
    result.replace( QRegExp( "<\\s*/l\\s*>", Qt::CaseInsensitive ), "</ul>" );

    // Links handling

    int n = 0;
    for( ; ; )
    {
      static QRegExp start_link_tag( "<\\s*r\\s*>", Qt::CaseInsensitive );
      static QRegExp end_link_tag( "<\\s*/r\\s*>", Qt::CaseInsensitive );

      n = result.indexOf( start_link_tag, n );
      if( n < 0 )
        break;

      int end = result.indexOf( end_link_tag, n );
      if( end < 0 )
        break;

      int tag_len = start_link_tag.cap().length();
      QString link_text = result.mid( n + tag_len, end - n - tag_len );

      result.replace( end, end_link_tag.cap().length(), "</a>" );
      result.replace( n, tag_len, QString( "<a class=\"sdict_wordref\" href=\"bword:" ) + link_text + "\">");
    }

    // Adjust text direction for lines

    n = 0;
    bool b = true;
    while( b )
    {
      int next = result.indexOf( "<br/>", n );
      if( next < 0 )
      {
        next = result.length();
        b = false;
      }

      if( !result.mid( n, next - n ).contains( '<' ) )
      {
        if( Html::unescape( result.mid( n, next - n ) ).isRightToLeft() != isToLanguageRTL() )
        {
          result.insert( next, "</span>" );
          result.insert( n,
                         QString( "<span dir = \"" )
                         + ( isToLanguageRTL() ? "ltr" : "rtl" )
                         + "\">"
                        );
          next = result.indexOf( "<br/>", n );
        }
      }

      n = next + 5;
    }

    return result.toUtf8().data();
}

void SdictDictionary::loadArticle( uint32_t address,
                                   string & articleText )
{
    uint32_t articleOffset = address;
    uint32_t articleSize;

    vector< char > articleBody;

    {
      Mutex::Lock _( sdictMutex );
      df.seek( articleOffset );
      df.read( &articleSize, sizeof(articleSize) );
      articleBody.resize( articleSize );
      df.read( &articleBody.front(), articleSize );
    }

    if ( articleBody.empty() )
      throw exCantReadFile( getDictionaryFilenames()[ 0 ] );

    if( idxHeader.compressionType == 1 )
        articleText = decompressZlib( articleBody.data(), articleSize );
    else if( idxHeader.compressionType == 2 )
        articleText = decompressBzip2( articleBody.data(), articleSize );
    else
        articleText = string( articleBody.data(), articleSize );

    articleText = convert( articleText );

    string div = "<div class=\"sdict\"";
    if( isToLanguageRTL() )
      div += " dir=\"rtl\"";
    div += ">";

    articleText.insert( 0, div );
    articleText.append( "</div>" );
}

void SdictDictionary::makeFTSIndex( QAtomicInt & isCancelled, bool firstIteration )
{
  if( !( Dictionary::needToRebuildIndex( getDictionaryFilenames(), ftsIdxName )
         || FtsHelpers::ftsIndexIsOldOrBad( ftsIdxName, this ) ) )
    FTS_index_completed.ref();

  if( haveFTSIndex() )
    return;

  if( ensureInitDone().size() )
    return;

  if( firstIteration && getArticleCount() > FTS::MaxDictionarySizeForFastSearch )
    return;

  gdDebug( "SDict: Building the full-text index for dictionary: %s\n",
           getName().c_str() );

  try
  {
    FtsHelpers::makeFTSIndex( this, isCancelled );
    FTS_index_completed.ref();
  }
  catch( std::exception &ex )
  {
    gdWarning( "SDict: Failed building full-text search index for \"%s\", reason: %s\n", getName().c_str(), ex.what() );
    QFile::remove( FsEncoding::decode( ftsIdxName.c_str() ) );
  }
}

void SdictDictionary::getArticleText( uint32_t articleAddress, QString & headword, QString & text )
{
  try
  {
    string articleStr;
    headword.clear();
    text.clear();

    loadArticle( articleAddress, articleStr );

    try
    {
      wstring wstr = Utf8::decode( articleStr );
      text = Html::unescape( gd::toQString( wstr ) );
    }
    catch( std::exception & )
    {
    }
  }
  catch( std::exception &ex )
  {
    gdWarning( "SDict: Failed retrieving article from \"%s\", reason: %s\n", getName().c_str(), ex.what() );
  }
}

sptr< Dictionary::DataRequest > SdictDictionary::getSearchResults( QString const & searchString,
                                                                   int searchMode, bool matchCase,
                                                                   int distanceBetweenWords,
                                                                   int maxResults )
{
  return new FtsHelpers::FTSResultsRequest( *this, searchString,searchMode, matchCase, distanceBetweenWords, maxResults );
}

/// SdictDictionary::getArticle()

class SdictArticleRequest;

class SdictArticleRequestRunnable: public QRunnable
{
  SdictArticleRequest & r;
  QSemaphore & hasExited;

public:

  SdictArticleRequestRunnable( SdictArticleRequest & r_,
                               QSemaphore & hasExited_ ): r( r_ ),
                                                          hasExited( hasExited_ )
  {}

  ~SdictArticleRequestRunnable()
  {
    hasExited.release();
  }

  virtual void run();
};

class SdictArticleRequest: public Dictionary::DataRequest
{
  friend class SdictArticleRequestRunnable;

  wstring word;
  vector< wstring > alts;
  SdictDictionary & dict;

  QAtomicInt isCancelled;
  QSemaphore hasExited;

public:

  SdictArticleRequest( wstring const & word_,
                       vector< wstring > const & alts_,
                       SdictDictionary & dict_ ):
    word( word_ ), alts( alts_ ), dict( dict_ )
  {
    QThreadPool::globalInstance()->start(
      new SdictArticleRequestRunnable( *this, hasExited ) );
  }

  void run(); // Run from another thread by DslArticleRequestRunnable

  virtual void cancel()
  {
    isCancelled.ref();
  }

  ~SdictArticleRequest()
  {
    isCancelled.ref();
    hasExited.acquire();
  }
};

void SdictArticleRequestRunnable::run()
{
  r.run();
}

void SdictArticleRequest::run()
{
  if ( isCancelled )
  {
    finish();
    return;
  }

  vector< WordArticleLink > chain = dict.findArticles( word );

  for( unsigned x = 0; x < alts.size(); ++x )
  {
    /// Make an additional query for each alt

    vector< WordArticleLink > altChain = dict.findArticles( alts[ x ] );

    chain.insert( chain.end(), altChain.begin(), altChain.end() );
  }

  multimap< wstring, pair< string, string > > mainArticles, alternateArticles;

  set< uint32_t > articlesIncluded; // Some synonims make it that the articles
                                    // appear several times. We combat this
                                    // by only allowing them to appear once.

  wstring wordCaseFolded = Folding::applySimpleCaseOnly( word );

  for( unsigned x = 0; x < chain.size(); ++x )
  {
    if ( isCancelled )
    {
      finish();
      return;
    }

    if ( articlesIncluded.find( chain[ x ].articleOffset ) != articlesIncluded.end() )
      continue; // We already have this article in the body.

    // Now grab that article

    string headword, articleText;

    headword = chain[ x ].word;

    try
    {
      dict.loadArticle( chain[ x ].articleOffset, articleText );

      // Ok. Now, does it go to main articles, or to alternate ones? We list
      // main ones first, and alternates after.

      // We do the case-folded comparison here.

      wstring headwordStripped =
        Folding::applySimpleCaseOnly( Utf8::decode( headword ) );

      multimap< wstring, pair< string, string > > & mapToUse =
        ( wordCaseFolded == headwordStripped ) ?
          mainArticles : alternateArticles;

      mapToUse.insert( pair< wstring, pair< string, string > >(
        Folding::applySimpleCaseOnly( Utf8::decode( headword ) ),
        pair< string, string >( headword, articleText ) ) );

      articlesIncluded.insert( chain[ x ].articleOffset );
    }
    catch( std::exception &ex )
    {
      gdWarning( "SDict: Failed loading article from \"%s\", reason: %s\n", dict.getName().c_str(), ex.what() );
    }
  }

  if ( mainArticles.empty() && alternateArticles.empty() )
  {
    // No such word
    finish();
    return;
  }

  string result;

  multimap< wstring, pair< string, string > >::const_iterator i;

  for( i = mainArticles.begin(); i != mainArticles.end(); ++i )
  {
      result += dict.isFromLanguageRTL() ? "<h3 dir=\"rtl\">" : "<h3>";
      result += i->second.first;
      result += "</h3>";
      result += i->second.second;
  }

  for( i = alternateArticles.begin(); i != alternateArticles.end(); ++i )
  {
      result += dict.isFromLanguageRTL() ? "<h3 dir=\"rtl\">" : "<h3>";
      result += i->second.first;
      result += "</h3>";
      if( dict.isToLanguageRTL() )
        result += "<span dir=\"rtl\">";
      result += i->second.second;
      if( dict.isToLanguageRTL() )
        result += "</span>";
  }

  Mutex::Lock _( dataMutex );

  data.resize( result.size() );

  memcpy( &data.front(), result.data(), result.size() );

  hasAnyData = true;

  finish();
}

sptr< Dictionary::DataRequest > SdictDictionary::getArticle( wstring const & word,
                                                             vector< wstring > const & alts,
                                                             wstring const & )
  throw( std::exception )
{
  return new SdictArticleRequest( word, alts, *this );
}

QString const& SdictDictionary::getDescription()
{
  if( !dictionaryDescription.isEmpty() )
    return dictionaryDescription;

  dictionaryDescription = QString::fromLatin1( "Title: " )
                          + QString::fromUtf8( getName().c_str() );

  try
  {
    Mutex::Lock _( sdictMutex );

    DCT_header dictHeader;

    df.seek( 0 );
    if( df.readRecords( &dictHeader, sizeof(dictHeader), 1 ) != 1 )
      throw exCantReadFile( getDictionaryFilenames()[ 0 ] );

    int compression = dictHeader.compression & 0x0F;

    vector< char > data;
    uint32_t size;
    string str;

    df.seek( dictHeader.copyrightOffset );
    df.read( &size, sizeof( size ) );
    data.resize( size );
    df.read( &data.front(), size );

    if( compression == 1 )
      str = decompressZlib( data.data(), size );
    else if( compression == 2 )
      str = decompressBzip2( data.data(), size );
    else
      str = string( data.data(), size );

    dictionaryDescription += QString::fromLatin1( "\n\nCopyright: " )
                             + QString::fromUtf8( str.c_str(), str.size() );

    df.seek( dictHeader.versionOffset );
    df.read( &size, sizeof( size ) );
    data.resize( size );
    df.read( &data.front(), size );

    if( compression == 1 )
      str = decompressZlib( data.data(), size );
    else if( compression == 2 )
      str = decompressBzip2( data.data(), size );
    else
      str = string( data.data(), size );

    dictionaryDescription += QString::fromLatin1( "\n\nVersion: " )
                             + QString::fromUtf8( str.c_str(), str.size() );
  }
  catch( std::exception &ex )
  {
    gdWarning( "SDict: Failed description reading for \"%s\", reason: %s\n", getName().c_str(), ex.what() );
  }

  if( dictionaryDescription.isEmpty() )
    dictionaryDescription = "NONE";

  return dictionaryDescription;
}

} // anonymous namespace

vector< sptr< Dictionary::Class > > makeDictionaries(
                                      vector< string > const & fileNames,
                                      string const & indicesDir,
                                      Dictionary::Initializing & initializing )
  throw( std::exception )
{
  vector< sptr< Dictionary::Class > > dictionaries;

  for( vector< string >::const_iterator i = fileNames.begin(); i != fileNames.end();
       ++i )
  {
      // Skip files with the extensions different to .dct to speed up the
      // scanning
      if ( i->size() < 4 ||
          strcasecmp( i->c_str() + ( i->size() - 4 ), ".dct" ) != 0 )
        continue;

      // Got the file -- check if we need to rebuid the index

      vector< string > dictFiles( 1, *i );

      string dictId = Dictionary::makeDictionaryId( dictFiles );

      string indexFile = indicesDir + dictId;

      if ( Dictionary::needToRebuildIndex( dictFiles, indexFile ) ||
           indexIsOldOrBad( indexFile ) )
      {
        try
        {
          gdDebug( "SDict: Building the index for dictionary: %s\n", i->c_str() );

          File::Class df( *i, "rb" );

          DCT_header dictHeader;

          df.read( &dictHeader, sizeof(dictHeader) );
          if( strncmp( dictHeader.signature, "sdct", 4 ) )
          {
              gdWarning( "File \"%s\" is not valid SDictionary file", i->c_str() );
              continue;
          }
          int compression = dictHeader.compression & 0x0F;

          vector< char > data;
          uint32_t size;

          df.seek( dictHeader.titleOffset );
          df.read( &size, sizeof( size ) );
          data.resize( size );
          df.read( &data.front(), size );

          string dictName;

          if( compression == 1 )
              dictName = decompressZlib( data.data(), size );
          else if( compression == 2 )
              dictName = decompressBzip2( data.data(), size );
          else
              dictName = string( data.data(), size );

          initializing.indexingDictionary( dictName );

          File::Class idx( indexFile, "wb" );
          IdxHeader idxHeader;
          memset( &idxHeader, 0, sizeof( idxHeader ) );

          // We write a dummy header first. At the end of the process the header
          // will be rewritten with the right values.

          idx.write( idxHeader );

          idx.write( (uint32_t) dictName.size() );
          idx.write( dictName.data(), dictName.size() );

          IndexedWords indexedWords;

          ChunkedStorage::Writer chunks( idx );

          uint32_t wordCount = 0;
          set< uint32_t > articleOffsets;
          uint32_t pos = dictHeader.fullIndexOffset;

          for( uint32_t j = 0; j < dictHeader.wordCount; j++ )
          {
            IndexElement el;
            df.seek( pos );
            df.read( &el, sizeof(el) );
            uint32_t articleOffset = dictHeader.articlesOffset + el.articleOffset;
            size = el.nextWord - sizeof(el);
            if( el.nextWord < sizeof(el) )
                break;
            wordCount++;
            data.resize( size );
            df.read( &data.front(), size );

            if( articleOffsets.find( articleOffset ) == articleOffsets.end() )
                articleOffsets.insert( articleOffset );

            // Insert new entry

            indexedWords.addWord( Utf8::decode( string( data.data(), size ) ), articleOffset);

            pos += el.nextWord;
          }
          // Finish with the chunks

          idxHeader.chunksOffset = chunks.finish();

          // Build index

          IndexInfo idxInfo = BtreeIndexing::buildIndex( indexedWords, idx );

          idxHeader.indexBtreeMaxElements = idxInfo.btreeMaxElements;
          idxHeader.indexRootOffset = idxInfo.rootOffset;

          indexedWords.clear(); // Release memory -- no need for this data

          // That concludes it. Update the header.

          idxHeader.signature = Signature;
          idxHeader.formatVersion = CurrentFormatVersion;

          idxHeader.articleCount = articleOffsets.size();
          idxHeader.wordCount = wordCount;

          idxHeader.langFrom = LangCoder::code2toInt( dictHeader.inputLang );
          idxHeader.langTo = LangCoder::code2toInt( dictHeader.outputLang );
          idxHeader.compressionType = compression;

          idx.rewind();

          idx.write( &idxHeader, sizeof( idxHeader ) );
        }
        catch( std::exception & e )
        {
          gdWarning( "Sdictionary dictionary indexing failed: %s, error: %s\n",
                     i->c_str(), e.what() );
          continue;
        }
        catch( ... )
        {
          qWarning( "Sdictionary dictionary indexing failed\n" );
          continue;
        }
      } // if need to rebuild
      try
      {
        dictionaries.push_back( new SdictDictionary( dictId,
                                                     indexFile,
                                                     dictFiles ) );
      }
      catch( std::exception & e )
      {
        gdWarning( "Sdictionary dictionary initializing failed: %s, error: %s\n",
                   i->c_str(), e.what() );
      }
  }
  return dictionaries;
}

}