/*
 * Help Access Library 
 * A Library to access the contents of Windows Help files.
 *
 * Copyright (C) 1995-2000 Bernd Herd, http://www.herdsoft.com
 *                                                                  
 * This program is free software; you can redistribute it and/or    
 * modify it under the terms of the GNU General Public License as   
 * published by the Free Software Foundation; either version 2 of   
 * the License.              
 *                                                                  
 * This program is distributed in the hope that it will be useful,  
 * but WITHOUT ANY WARRANTY; without even the implied warranty of   
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the    
 * GNU General Public License for more details.                     
 *                                                                  
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software      
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.        
 */
/* ENUMKW.C -------------------------------------------
 * @doc
 * @module ENUMKW.C |
 * Enumerates the list of Keywords contained in a Help file.
 *
 * Help Access Library Project.
 *
 *-----------------------------------------------------*/

#include <windows.h>
#include <windowsx.h>
#include <time.h>
#include <stdio.h>
#include <string.h>
#include "hlpacces.h"


BOOL LOCAL nEnumerateKeywords(HIFSFILE hKWBTree, KWENUMPROC fnKWEnumProc, LPCSTR StartKeyWord, LPARAM lParam);
BOOL LOCAL nEnumeratePage(HIFSFILE hKWBTree, int PageCount, int CurrentLevel, int PageSize, int CurrPage, KWENUMPROC fnKWEnumProc, LPCSTR StartKeyWord, LPARAM lParam);


/* @func BOOL | HlpEnumKeyWords |
 *
 * This Function enumerates the List of Keywords from a Help or Media Viewer
 * Tile. This Function is relatively fast.
 *
 * Note that one Help or Media Viewer file can Have several Keyword lists.
 * Usually in Help Files the Keyword list is named "K" in Media Viewe it's
 * Named "0K", the ALink-List in Windows 95 Files is named "A", others are
 * also possible.
 *
 * @rdesc
 * TRUE if the Function was Successfull
 * FALSE else
 */
BOOL WINAPI DLLEXP HlpEnumKeyWords(
                HIFS ifs,                       // @parm Handle to a opened File-System opened by <f IFSOpen>
                KWENUMPROC fnKWEnumProc,        // @parm <t KWENUMPROC> Application-Defined Callback-Procedure to be called for every Keyword retrieved. from the help file
                LPCSTR StartKeyWord,            // @parm Keyword to start the scan with.
                LPCSTR KWListName,              // @parm Name of the Keyword Table (K,0K,A...)
                LPARAM lParam)                  // @parm Aplication-defined parameter to be transfered to the Callback-function
{ BOOL      Success=FALSE;
  HIFSFILE  hKWBTree = IFSOpenFile(ifs, KWListName);

  if (hKWBTree)
  {
      Success = nEnumerateKeywords(hKWBTree, fnKWEnumProc, StartKeyWord, lParam);

    IFSCloseFile(hKWBTree);
  }
  return Success;
}


/* nEnumerateKeywords
 *
 * Does the bunch of Work to do enumeration
 */
BOOL LOCAL nEnumerateKeywords(HIFSFILE hKWBTree, KWENUMPROC fnKWEnumProc, LPCSTR StartKeyWord, LPARAM lParam)
{ BOOL            Success;

  BTREEHEADER     BTreeHdr;
  DWORD           dwSize;
  UINT            PageCount;


  //--------- Read Title B-Tree header ------------------
  IFSReadFile(hKWBTree, &BTreeHdr, sizeof(BTreeHdr));
  dwSize = IFSSeekFile(hKWBTree, 0L, 2);

  PageCount = (UINT) (dwSize/leword(BTreeHdr.PageSize));

  Success = nEnumeratePage(hKWBTree, PageCount, leword(BTreeHdr.NLevels)-1, leword(BTreeHdr.PageSize), leword(BTreeHdr.RootPage), fnKWEnumProc, StartKeyWord, lParam);

  return Success;
}

#pragma pack(1)
typedef struct
        { LEWORD  Count;
          LEDWORD DataOffset;
        } PACKED KWREC, *PKWREC;
#pragma pack()

/**
 * Windows string comparison emulation:
 * 
 * It seems that the comparison used when creating the Keyword
 * B-Tree for Windows help files comares "Ä" and "A" as being equal.
 * "strcasecmp" on Linux does not, even after setlocale(LC_ALL, "de_DE").
 *
 * So to emulate the Windows-Behaviour we have to implement our own
 * comparison function to be able to go down the B-Tree in the right
 * manner.
 */

/**
 * Map one character to the windows compare character space
 *
 * @param c     The raw upper/lower case character
 *
 * @todo   It is likely that there are characters missing from this simple
 *         implementation.
 *
 * @return The character after conversion to upper case.
 */
static
char
_kwmapchar(char c)
{
  switch (c)
    {
    case '_': case '\"':                                        c=' ';  break;
    case 'ä': case 'Ä': case 'á': case 'Á': case 'à': case 'À': c='A';  break;
    case 'ö': case 'Ö': case 'ó': case 'Ó': case 'ò': case 'Ò': c='O';  break;
    case 'ü': case 'Ü': case 'ú': case 'Ú': case 'ù': case 'Ù': c='U';  break;
    case 'é': case 'É': case 'è': case 'È':                     c='E';  break;
    case 'ñ': case 'Ñ':                                         c='N';  break;
    case 'ß':                                                   c='S';  break;

    default:
      c=toupper(c);
    }
  return c;
}


/**
 * Perform a byte-for-byte comparison between two strings,
 * that emulates the windows-type behaviour.
 *
 * @param s1     First string to compare
 * @param s2     Second string to compare
 *
 * @return >0 if s1 is alphabetically later than s2, 0 if the match, <0 if s1 is alphabetically before s2
 */
static
int
_kwstrcmp(const char *s1, const char *s2)
{
  int result = 0;
  const char *p1=s1;
  const char *p2=s2;
  
  while ((*s1 || *s2) && result==0)
    {
      result=_kwmapchar(*s1++) - _kwmapchar(*s2++);
    }

  //  fprintf(stderr, "_kwstrcmp(\"%s\", \"%s\")=%d\n", p1, p2, result);

  return result;
}



BOOL LOCAL nEnumeratePage(HIFSFILE hKWBTree, int PageCount, int CurrentLevel, int PageSize, int CurrPage, KWENUMPROC fnKWEnumProc, LPCSTR StartKeyWord, LPARAM lParam)
{ BOOL             Success    = TRUE;
  DWORD            loc        = sizeof(BTREEHEADER) + PageSize * (DWORD) CurrPage;
  LPSTR            page       = (LPSTR) Hlpmalloc(PageSize),
                   nxt;
  PKWREC           pKWRec;
  BTREENODEHEADER *CurrNode    = (BTREENODEHEADER *)page;       /* Current Node in B-Tree  */
  int              i;

  if (page)
  {
     //----------- Read Page ----------------------------------------
     IFSSeekFile(hKWBTree, loc, 0);
     if (PageSize == IFSReadFile(hKWBTree, page, PageSize))
     { 
      if (CurrentLevel > 0)
      {  Success = TRUE;
         //-- We're in a node, search for next sub-node or leaf --
         for (i=0,                             nxt = page+sizeof(BTREEINDEXHEADER);
              i<leword(CurrNode->NEntries)+1 && Success;
              ++i,                             nxt+=lstrlen(nxt+2)+1+sizeof(WORD))
         {

             //------- We're currently in a node, so recurse down... ----
             if (_kwstrcmp(nxt+2,StartKeyWord)>=0 || i==leword(CurrNode->NEntries))
                Success &= nEnumeratePage(hKWBTree, PageCount, CurrentLevel-1, PageSize, CurrPage=leword(((LEWORD *) (nxt))[0]), fnKWEnumProc, StartKeyWord, lParam);
         }
      }
      else
      {
         //-- We're in the right leaf now, scan for Data ---------
         for (i=0,                  nxt = page+sizeof(BTREENODEHEADER);
              i<leword(CurrNode->NEntries) && Success;
              ++i                  ,nxt+=lstrlen(nxt)+1+sizeof(KWREC))
            {pKWRec=(PKWREC)(nxt+lstrlen(nxt)+1);
             if (_kwstrcmp(nxt,StartKeyWord)>=0)
                Success &= fnKWEnumProc(nxt, ledword(pKWRec->DataOffset), leword(pKWRec->Count), lParam);
            }
      }
     }
     else
       Success=FALSE;

     //----------- Free Page data except Header ---------------------
     Hlpfree(page);
  } else
    Success = FALSE;

  return Success;
}