/******************************************************************************

 *

 * 

 *

 * Copyright (C) 1997-2008 by Dimitri van Heesch.

 *

 * Permission to use, copy, modify, and distribute this software and its

 * documentation under the terms of the GNU General Public License is hereby 

 * granted. No representations are made about the suitability of this software 

 * for any purpose. It is provided "as is" without express or implied warranty.

 * See the GNU General Public License for more details.

 *

 * Documents produced by Doxygen are derivative works derived from the

 * input used in their production; they are not affected by this license.

 *

 */

#include "qtbc.h"

#include "searchindex.h"

#include "config.h"

#include "util.h"

#include <qfile.h>

#include <ctype.h>

#include <qregexp.h>

// file format: (all multi-byte values are stored in big endian format)

//   4 byte header

//   256*256*4 byte index (4 bytes)

//   for each index entry: a zero terminated list of words 

//   for each word: a \0 terminated string + 4 byte offset to the stats info

//   padding bytes to align at 4 byte boundary

//   for each word: the number of urls (4 bytes) 

//               + for each url containing the word 8 bytes statistics

//                 (4 bytes index to url string + 4 bytes frequency counter)

//   for each url: a \0 terminated string

const int numIndexEntries = 256*256;

//--------------------------------------------------------------------

IndexWord::IndexWord(const char *word) : m_word(word), m_urls(17)

{

  m_urls.setAutoDelete(TRUE);

  //printf("IndexWord::IndexWord(%s)\n",word);

}

void IndexWord::addUrlIndex(int idx,bool hiPriority)

{

  //printf("IndexWord::addUrlIndex(%d,%d)\n",idx,hiPriority);

  URLInfo *ui = m_urls.find(idx);

  if (ui==0)

  {

    //printf("URLInfo::URLInfo(%d)\n",idx);

    ui=new URLInfo(idx,0);

    m_urls.insert(idx,ui);

  }

  ui->freq+=2;

  if (hiPriority) ui->freq|=1; // mark as high priority document

}

//--------------------------------------------------------------------

SearchIndex::SearchIndex() : m_words(328829), m_index(numIndexEntries), m_urlIndex(-1)

{

  int i;

  m_words.setAutoDelete(TRUE);

  m_urls.setAutoDelete(TRUE);

  m_index.setAutoDelete(TRUE);

  for (i=0;i<numIndexEntries;i++) m_index.insert(i,new QList<IndexWord>);

}

void SearchIndex::setCurrentDoc(const char *name,const char *baseName,const char *anchor)

{

  if (name==0 || baseName==0) return;

  //printf("SearchIndex::setCurrentDoc(%s,%s,%s)\n",name,baseName,anchor);

  QCString url=baseName+Config_getString("HTML_FILE_EXTENSION");

  if (anchor) url+=(QCString)"#"+anchor;  

  m_urlIndex++;

  m_urls.insert(m_urlIndex,new URL(name,url));

}

static int charsToIndex(const char *word)

{

  if (word==0) return -1;

  // Fast string hashing algorithm

  //register ushort h=0;

  //const char *k = word;

  //ushort mask=0xfc00;

  //while ( *k ) 

  //{

  //  h = (h&mask)^(h<<6)^(*k++);

  //}

  //return h;

  // Simple hashing that allows for substring searching

  uint c1=word[0];

  if (c1==0) return -1;

  uint c2=word[1];

  if (c2==0) return -1;

  return c1*256+c2;

}

void SearchIndex::addWord(const char *word,bool hiPriority,bool recurse)

{

  static QRegExp nextPart("[_a-z:][A-Z]");

  //printf("SearchIndex::addWord(%s,%d)\n",word,hiPriority);

  QString wStr(word);

  if (wStr.isEmpty()) return;

  wStr=wStr.lower();

  IndexWord *w = m_words[wStr];

  if (w==0)

  {

    int idx=charsToIndex(wStr);

    if (idx<0) return;

    w = new IndexWord(wStr);

    //fprintf(stderr,"addWord(%s) at index %d\n",word,idx);

    m_index[idx]->append(w);

    m_words.insert(wStr,w);

  }

  w->addUrlIndex(m_urlIndex,hiPriority);

  int i;

  bool found=FALSE;

  if (!recurse) // the first time we check if we can strip the prefix

  {

    i=getPrefixIndex(word);

    if (i>0)

    {

      addWord(word+i,hiPriority,TRUE);

      found=TRUE;

    }

  }

  if (!found) // no prefix stripped

  {

    if ((i=nextPart.match(word))>=1)

    {

      addWord(word+i+1,hiPriority,TRUE);

    }

  }

}

static void writeInt(QFile &f,int index)

{

  f.putch(((uint)index)>>24);

  f.putch((((uint)index)>>16)&0xff);

  f.putch((((uint)index)>>8)&0xff);

  f.putch(((uint)index)&0xff);

}

static void writeString(QFile &f,const char *s)

{

  const char *p = s;

  while (*p) f.putch(*p++);

  f.putch(0);

}

void SearchIndex::write(const char *fileName)

{

  int i;

  int size=4; // for the header

  size+=4*numIndexEntries; // for the index

  int wordsOffset = size;

  // first pass: compute the size of the wordlist

  for (i=0;i<numIndexEntries;i++)

  {

    QList<IndexWord> *wlist = m_index[i];

    if (!wlist->isEmpty())

    {

      QListIterator<IndexWord> iwi(*wlist);

      IndexWord *iw;

      for (iwi.toFirst();(iw=iwi.current());++iwi)

      {

        int ws = iw->word().length()+1; 

        size+=ws+4; // word + url info list offset

      }

      size+=1; // zero list terminator

    }

  }

  // second pass: compute the offsets in the index

  int indexOffsets[numIndexEntries];

  int offset=wordsOffset;

  for (i=0;i<numIndexEntries;i++)

  {

    QList<IndexWord> *wlist = m_index[i];

    if (!wlist->isEmpty())

    {

      indexOffsets[i]=offset;

      QListIterator<IndexWord> iwi(*wlist);

      IndexWord *iw;

      for (iwi.toFirst();(iw=iwi.current());++iwi)

      {

        offset+= iw->word().length()+1; 

        offset+=4; // word + offset to url info array 

      }

      offset+=1; // zero list terminator

    }

    else

    {

      indexOffsets[i]=0;

    }

  }

  int padding = size;

  size = (size+3)&~3; // round up to 4 byte boundary

  padding = size - padding;

  //int statsOffset = size;

  QDictIterator<IndexWord> wdi(m_words);

  //IndexWord *iw;

  int *wordStatOffsets = new int[m_words.count()];

  int count=0;

  // third pass: compute offset to stats info for each word

  for (i=0;i<numIndexEntries;i++)

  {

    QList<IndexWord> *wlist = m_index[i];

    if (!wlist->isEmpty())

    {

      QListIterator<IndexWord> iwi(*wlist);

      IndexWord *iw;

      for (iwi.toFirst();(iw=iwi.current());++iwi)

      {

        //printf("wordStatOffsets[%d]=%d\n",count,size);

        wordStatOffsets[count++] = size;

        size+=4+iw->urls().count()*8; // count + (url_index,freq) per url

      }

    }

  }

  int *urlOffsets = new int[m_urls.count()];

  //int urlsOffset = size;

  QIntDictIterator<URL> udi(m_urls);

  URL *url;

  for (udi.toFirst();(url=udi.current());++udi)

  {

    urlOffsets[udi.currentKey()]=size;

    size+=url->name.length()+1+

          url->url.length()+1;

  }

  //printf("Total size %x bytes (word=%x stats=%x urls=%x)\n",size,wordsOffset,statsOffset,urlsOffset);

  QFile f(fileName);

  if (f.open(IO_WriteOnly))

  {

    // write header

    f.putch('D'); f.putch('O'); f.putch('X'); f.putch('S');

    // write index

    for (i=0;i<numIndexEntries;i++)

    {

      writeInt(f,indexOffsets[i]);

    }

    // write word lists

    count=0;

    for (i=0;i<numIndexEntries;i++)

    {

      QList<IndexWord> *wlist = m_index[i];

      if (!wlist->isEmpty())

      {

        QListIterator<IndexWord> iwi(*wlist);

        IndexWord *iw;

        for (iwi.toFirst();(iw=iwi.current());++iwi)

        {

          writeString(f,iw->word());

          writeInt(f,wordStatOffsets[count++]);

        }

        f.putch(0);

      }

    }

    // write extra padding bytes

    for (i=0;i<padding;i++) f.putch(0);

    // write word statistics

    for (i=0;i<numIndexEntries;i++)

    {

      QList<IndexWord> *wlist = m_index[i];

      if (!wlist->isEmpty())

      {

        QListIterator<IndexWord> iwi(*wlist);

        IndexWord *iw;

        for (iwi.toFirst();(iw=iwi.current());++iwi)

        {

          int numUrls = iw->urls().count();

          writeInt(f,numUrls);

          QIntDictIterator<URLInfo> uli(iw->urls());

          URLInfo *ui;

          for (uli.toFirst();(ui=uli.current());++uli)

          {

            writeInt(f,urlOffsets[ui->urlIdx]);

            writeInt(f,ui->freq);

          }

        }

      }

    }

    // write urls

    QIntDictIterator<URL> udi(m_urls);

    URL *url;

    for (udi.toFirst();(url=udi.current());++udi)

    {

      writeString(f,url->name);

      writeString(f,url->url);

    }

  }

  delete[] urlOffsets;

  delete[] wordStatOffsets;

}